tag:theconversation.com,2011:/ca/topics/uv-light-2259/articlesUV light – The Conversation2023-12-28T09:20:09Ztag:theconversation.com,2011:article/2194412023-12-28T09:20:09Z2023-12-28T09:20:09ZSix ways to look after your eyes in 2024<figure><img src="https://images.theconversation.com/files/564923/original/file-20231211-27-7cymn4.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C6523%2C4342&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-mature-man-fitting-o-1832804689">Inside Creative House/Shutterstock</a></span></figcaption></figure><p>The World Health Organization estimates that <a href="https://www.who.int/news/item/09-10-2003-up-to-45-million-blind-people-globally---and-growing">over 80%</a> of all vision impairment around the world can be prevented and even cured. Reducing the risk of eye diseases involves adopting a combination of lifestyle changes, protective measures, and regular eye care. Here are six ways to look after your eyes in 2024. </p>
<h2>1. Have regular eye tests</h2>
<p>Many eye diseases don’t have symptoms – at least, initially. <a href="https://www.nhs.uk/conditions/glaucoma/#:%7E:text=Glaucoma%20is%20a%20common%20eye,not%20diagnosed%20and%20treated%20early.">Glaucoma</a>, for example, will cause irreversible damage to the eye if not picked up early enough as it damages the peripheral visual field to start with. People tend not to notice and merely compensate for this loss of peripheral vision by moving their heads more. </p>
<p>Eye disease linked to diabetes also causes irreversible damage to the eyes without much noticeable vision loss as it damages the <a href="https://www.nhs.uk/conditions/diabetic-retinopathy/#:%7E:text=Diabetic%20retinopathy%20is%20a%20complication,it%20could%20threaten%20your%20sight.">small blood vessels</a> in the eye. </p>
<p>Going for an eye test with a qualified optometrist will enable them to detect eye diseases and refer you to a specialist if needed. Early detection of changes in the eye due to diabetes will reduce the <a href="https://diabetesjournals.org/clinical/article/27/4/140/1721/Diabetic-Retinopathy-Screening-Updatelink">risk of blindness by 60-90%</a>. </p>
<p>And a visit to the optometrist does not necessarily mean you have to fork out for expensive new glasses if your vision hasn’t changed. People in the UK qualify for <a href="https://www.nhs.uk/nhs-services/opticians/free-nhs-eye-tests-and-optical-vouchers/">free NHS eye tests</a> if they are over 60 or under 18 years, have a family history of glaucoma, or receive certain state benefits. </p>
<h2>2. Check your eyes at home</h2>
<p>As most of us use both eyes at the same time, it can be difficult to know if one is not seeing so well. Try covering each eye every week and look at a number plate in the distance to make sure both eyes are seeing well. </p>
<p>Differences between the two eyes will affect your depth perception, which then ends up with you not being able to judge how far a person is when driving. </p>
<p><a href="https://www.nhs.uk/conditions/age-related-macular-degeneration-amd/">Age-related macular degeneration</a> usually affects one eye earlier than the other. And the “wet” type – caused by tiny blood vessels at the back of the eye leaking fluid – needs to be treated as soon as possible to avoid any further damage. </p>
<p>Use graph paper held at a near distance, wearing near glasses if you need them, and if lines appear to be wavy or missing, seek an appointment with your optometrist. </p>
<h2>3. Protect your eyes from mechanical and UV damage</h2>
<p>Ultraviolet light can damage the macula, the most central and important part of the eye. Make sure you wear good quality sunglasses that block 100% of UVA and UVB rays to protect your eyes from harmful ultraviolet radiation. </p>
<p>If you are a DIY enthusiast, it’s really important to wear safety goggles. In the summer, gardening accidents, such as getting caught in the eye with a twig when pruning are quite frequent and can cause permanent damage.</p>
<p>Playing squash and other sports without adequate protection can also cause permanent damage. A squash ball is just a bit smaller than the orbit of the eye and this can cause a lot of damage to the soft tissues within the eye as the orbital wall cannot stop the ball’s entry into the eye. </p>
<figure class="align-center ">
<img alt="Woman wearing sunglasses" src="https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564933/original/file-20231211-15-nslvhc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wear good-quality sunglasses.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-shot-stylish-young-woman-sunglasses-459775861">Jacob Lund/Shutterstock</a></span>
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</figure>
<h2>4. Reduce digital eye strain</h2>
<p>Excessive exposure to computers and smartphones can lead to eyestrain. While eyestrain does not normally cause permanent damage or affect your glasses prescription, it can be very uncomfortable. </p>
<p>Most people forget to blink when they are working on screens, and this leads to dry eyes. To reduce this discomfort, try consciously blinking more often during screen time. </p>
<p>It helps keep your eyes moist and reduces that tired, dry feeling. You can set a reminder on your phone for blinking exercises where you forcibly blink at least ten times every hour. </p>
<p>Regular breaks will not only give your eyes a rest but will also give your back a rest, too. Remember the <a href="https://www.rnib.org.uk/your-eyes/how-to-keep-your-eyes-healthy/eye-safety/#:%7E:text=Taking%20frequent%20breaks%20from%20the,cause%20you%20to%20need%20spectacles.">20-20-20 rule</a>: every 20 minutes, take a 20-second break, and look at something 20 feet away.</p>
<h2>5. Have a good diet</h2>
<p>While many of us know that vitamin A from carrots is good for the eyes, our eyes need <a href="https://www.medicalnewstoday.com/articles/326758">more than vitamin A</a> to function healthily. </p>
<p>Vitamin C found in citrus fruits, strawberries, bell peppers and broccoli helps protect the eyes from oxidative damage as does vitamin E found in nuts, seeds, spinach and fortified cereals. </p>
<p>Green leafy vegetables have been shown to reduce the risk of macular damage, which is the <a href="https://www.cdc.gov/visionhealth/resources/features/macular-degeneration.html#:%7E:text=AMD%20is%20a%20major%20cause,to%2088%20million%20in%202050.">leading cause of blindness</a> in the elderly. </p>
<p>A healthy diet is also linked to good control of diabetes, and poor control of diabetes will lead to a much higher risk of blindness from diabetic-related eye disease. </p>
<h2>6. Quit smoking and be more active</h2>
<p>Smoking is a significant risk factor for most systemic diseases in the body <a href="https://www.fda.gov/tobacco-products/health-effects-tobacco-use/how-smoking-can-contribute-vision-loss-and-blindness">including the eyes</a>. Smoking increases the risk of macular degeneration and cataracts. Quitting can be tough, but your eyes will appreciate it in the long run. </p>
<p>Exercise is not only important for the rest of the body but also for the eyes. Outdoor activity is a <a href="https://www.sciencedirect.com/science/article/pii/S0161642007013644?via%3Dihub">significant protective factor</a> against the progression of myopia (shortsightedness) in children. </p>
<p>Physical activity increases blood circulation to the eyes, which is essential for delivering oxygen and nutrients to the eyes and removing waste products. It has also been linked to reducing the risk of <a href="https://www.sciencedirect.com/science/article/pii/S0002939417302180?via%3Dihub">age-related macular degeneration</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/29610523/">diabetic retinopathy and glaucoma</a>. </p>
<p>Physical activity is also essential for controlling diabetes, which reduces the risk of blindness in patients with this condition. It is important to note that physical activity is not just about joining a gym. It can involve free activities, including brisk walking, which would be a wonderful opportunity to spend time with family and reduce the progression of myopia in our children.</p><img src="https://counter.theconversation.com/content/219441/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span><a href="mailto:shahina.pardhan@aru.ac.uk">shahina.pardhan@aru.ac.uk</a> receives funding from various NHS bodies, Charities and EU. </span></em></p>Your eyes are your windows on the world. Here’s how to stop them getting smudgy.Shahina Pardhan, Professor of Optometry, Anglia Ruskin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2145842023-10-03T23:06:07Z2023-10-03T23:06:07ZFrom glowing cats to wombats, fluorescent mammals are much more common than you’d think<p>Recently, several mammals have been reported to “glow” under ultraviolet (UV) light, including our beloved platypus. But no one knew how common it was among mammals until now.</p>
<p>Our research, published <a href="https://royalsocietypublishing.org/doi/10.1098/rsos.230325">in Royal Society Open Science today</a>, found this glow – known as fluorescence – is extremely common. Almost every mammal we studied showed some form of fluorescence.</p>
<p>We also examined the glow to determine if it was really fluorescence and not some other phenomenon. Then, we tested if the fluorescence we observed in museum specimens was natural and not caused by preservation methods.</p>
<p>We also searched for links between the type and degree of fluorescence and the lifestyle of each species, to gain insights on whether there are any benefits to glowing under UV if you’re a mammal.</p>
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<h2>Nightclub lights</h2>
<p>Nightclub visitors will be familiar with white clothes, or perhaps their gin and tonic, glowing blue under UV light. This is a great example of fluorescence – when the energy from UV light, which is a form of electromagnetic radiation invisible to humans, is absorbed by certain chemicals. </p>
<p>These chemicals then emit visible light, which is lower-energy electromagnetic radiation. In the case of gin and tonic, this is due to the presence of the quinine molecule in the tonic water. </p>
<p>In the case of animals, this can be due to proteins or pigments in their scales, skin or fur. Fluorescence is quite common among animals. It <a href="https://royalsocietypublishing.org/doi/full/10.1098/rstb.2016.0335?rss=1">has been reported</a> for birds, reptiles, amphibians, fish, corals, molluscs and most famously scorpions and other arthropods.</p>
<p>However, it has been described less frequently in mammals, although recent studies have provided several examples. We already knew that bones and teeth glow with fluorescence, as do white human hair and nails. Some rodents have a pink glow under UV light and platypuses <a href="https://www.degruyter.com/document/doi/10.1515/mammalia-2020-0027/html">glow blue-green</a>. </p>
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Read more:
<a href="https://theconversation.com/explainer-what-is-the-electromagnetic-spectrum-8046">Explainer: what is the electromagnetic spectrum?</a>
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<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A glowing blue drink on a table in a dark restaurant" src="https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551604/original/file-20231003-19-ee6wee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The reason a gin and tonic looks fluorescent under UV lighting is thanks to the quinine in the tonic.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Glowing_cocktail.jpg">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<h2>How often do mammals glow?</h2>
<p>Our team came together because we were curious about fluorescence in mammals. We wanted to know if the glow reported recently for various species was really fluorescence, and how widespread this phenomenon was. We obtained preserved and frozen specimens from museums and wildlife parks to study.</p>
<p>We started with the platypus to see if we could replicate the previously reported fluorescence. We photographed preserved and frozen platypus specimens under UV light and observed a fluorescent (although rather faint) glow.</p>
<p>To make sure it was fluorescence and not some other effect that looked like it, we used a technique called fluorescence spectroscopy. </p>
<p>This involved shining various sources of light at the samples and recording the specific “fingerprints” of the resulting glow, known as an <a href="https://www.britannica.com/science/spectrum#ref11393">emission spectrum</a>. This way, we could confirm what we saw was indeed fluorescence.</p>
<p>We repeated this process for other mammals and found clear evidence of fluorescence in the white fur, spines and even skin and nails of koalas, Tasmanian devils, short-beaked echidnas, southern hairy-nosed wombats, quendas (bandicoots), greater bilbies and even cats.</p>
<p>Both fresh-frozen and chemically treated museum specimens were fluorescent. This meant it wasn’t preservation chemicals such as borax or arsenic causing the fluorescence. So, we concluded this was a real biological phenomenon. </p>
<h2>Mammals in dazzling lights</h2>
<p>Using specimens from the Western Australian Museum’s collection, we took the experiment to the next stage. We recorded every species of mammal that was fluorescent when we exposed the specimens to UV light.</p>
<p>As a result, we found 125 fluorescent species of mammal, representing all known orders. Fluorescence is clearly common and widely distributed among mammals.</p>
<p>In particular, we noticed that white and light-coloured fur is fluorescent, with dark pigmentation preventing fluorescence. For example, a zebra’s white stripes fluoresced while the dark stripes didn’t.</p>
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Read more:
<a href="https://theconversation.com/zebras-stripes-are-a-no-fly-zone-for-flies-111888">Zebra's stripes are a no fly zone for flies</a>
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<p>We then used our dataset to test if fluorescence might be more common in nocturnal species. To do this, we correlated the total area of fluorescence with ecological traits such as nocturnality, diet and locomotion.</p>
<p>Nocturnal mammals were indeed more fluorescent, while aquatic species were less fluorescent than those that burrowed, lived in trees, or on land. </p>
<p>Based on our results, we think fluorescence is very common in mammals. In fact, it is likely the default status of hair unless it is heavily pigmented. This doesn’t mean fluorescence has a biological function – it may just be an artefact of the structural properties of unpigmented hair.</p>
<p>However, we suggest florescence may be important for brightening pale-coloured parts of animals that are used as visual signals. This could improve their visibility, especially in poor light – just like the fluorescent optical brighteners that are added to white paper and clothing.</p><img src="https://counter.theconversation.com/content/214584/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kenny Travouillon received funding from the Australian Biological Resources Study and is an adjunct at Curtin University. </span></em></p><p class="fine-print"><em><span>Christine Elizabeth Cooper receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jemmy Bouzin receives funding from the Government of Seychelles. </span></em></p><p class="fine-print"><em><span>Linette Umbrello receives funding from the Australian Biological Resources Study and is a Research Associate at the Western Australian Museum. </span></em></p><p class="fine-print"><em><span>Simon Lewis does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>After combing through museum collections, our team of researchers found a whopping 125 fluorescent mammal species – from polar bears and dolphins, to leopards, zebras and wombats.Kenny Travouillon, Curator of Mammals, Western Australian MuseumChristine Elizabeth Cooper, Senior Lecturer, Curtin UniversityJemmy Bouzin, PhD candidate, Curtin UniversityLinette Umbrello, Postdoctoral research associate, Queensland University of TechnologySimon Lewis, Professor of Forensic and Analytical Chemistry, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1991022023-02-17T02:06:10Z2023-02-17T02:06:10ZDo beach cabanas actually protect you from the sun?<p>You may have seen them popping up on beaches everywhere – colourful, breezy, shady, beach cabanas. </p>
<p>Unlike beach umbrellas, they’re sturdy enough to withstand a stiff sea breeze and have pockets for sand to anchor them firmly. Best of all, there’s plenty of room for you, and your friends and family.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1623491902275190785"}"></div></p>
<p>Some people have <a href="https://www.smh.com.au/national/nsw/does-sydney-need-us-style-cabana-ban-to-curb-beach-spreading-20230202-p5chgi.html">complained</a> about beach cabanas blocking the view for other beach goers, and surf lifesavers. But beach cabanas are certainly having a moment in Australia. It’s a trend <a href="https://www.abc.net.au/news/2023-01-26/cancer-council-beach-cabanas-skin-cancer-rate-highest-in-qld/101887320">sun safety experts</a> are keen to see continue. </p>
<p>But do beach cabanas provide as much sun protection as you think?</p>
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<em>
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Read more:
<a href="https://theconversation.com/i-cant-get-sunburnt-through-glass-shade-or-in-water-right-5-common-sunburn-myths-busted-150640">I can't get sunburnt through glass, shade or in water, right? 5 common sunburn myths busted</a>
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<h2>Chasing shade</h2>
<p>Seeking shade is an important element of the <a href="https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/campaigns-and-events/slip-slop-slap-seek-slide">slip-slop-slap-seek-slide</a> method of sun protection (clothes, sunscreen, hat, shade, sunnies). The aim is to reduce your exposure to UV light, which is responsible for <a href="http://www.assc.org.au/wp-content/uploads/2023/02/SCPQ_Report_Final_2023.pdf">about 95%</a> of all skin cancers. </p>
<p>In Queensland alone, <a href="http://www.assc.org.au/wp-content/uploads/2023/02/SCPQ_Report_Final_2023.pdf">more people die</a> from skin cancer than road crashes. Australia-wide, we spend A$1.7 billion on skin cancer diagnosis and treatment a year.</p>
<p>Shading yourself from the direct sun will reduce your UV exposure by <a href="http://www.assc.org.au/wp-content/uploads/2023/02/SCPQ_Report_Final_2023.pdf">up to 75%</a>, depending on the surrounding environment. </p>
<p>People who frequently use shade <a href="https://www.sciencedirect.com/science/article/pii/S0190962208007330?via%3Dihub">are much</a> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3873510/">less likely</a> to be sunburned than those who rely on sunscreen only. So beach cabanas seem to fit the bill nicely.</p>
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Read more:
<a href="https://theconversation.com/how-long-does-it-take-for-skin-to-repair-after-sun-exposure-196556">How long does it take for skin to repair after sun exposure?</a>
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<h2>How much protection do they provide, exactly?</h2>
<p>Beach cabanas are usually made from canvas, polyester or spandex. Look for fabric with <a href="https://www.sunsmart.com.au/protect-your-skin/seek-shade">UPF 50+ protection</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="UPF 50+ label" src="https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=926&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=926&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=926&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1164&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1164&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510744/original/file-20230216-18-xe6rrf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1164&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Look for fabric with UPF 50+ protection.</span>
<span class="attribution"><a class="source" href="https://www.arpansa.gov.au/our-services/testing-and-calibration/ultraviolet-radiation-testing/labelling-sun-protective-clothing">ARPANSA</a></span>
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<p>UPF (ultraviolet protection factor) ratings are similar to the SPF (sun protection factor) ratings on sunscreen. They measure the amount of UV that penetrates the fabric.</p>
<p>UPF 50+ means only 1/50th (2%) or less of UV light gets through. That includes both UVA, responsible mostly for accelerated skin ageing, and UVB, responsible mostly for sunburn and skin cancers.</p>
<p>UPF ratings are <a href="https://www.arpansa.gov.au/our-services/testing-and-calibration/ultraviolet-radiation-testing/labelling-sun-protective-clothing">accredited</a> by the Australian Radiation Protection and Nuclear Safety Agency. Anything with its tag has been laboratory tested to show it does what it claims to.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-does-sunscreen-work-what-is-spf-and-can-i-still-tan-with-it-on-88869">Explainer: how does sunscreen work, what is SPF and can I still tan with it on?</a>
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<h2>Beware: reflection and scattering</h2>
<p>However, you could still get sunburned under your cabana. Although some brands say they offer “100% protection”, that’s only from UV rays coming from above.</p>
<p>Sand can reflect <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6069363/">up to 18%</a> of UV rays reaching the ground, concrete can reflect around 10%, and a grassy park or backyard 2-3%. In other words, you’ll still be exposed to UV reflecting off the surrounding surfaces and into the cabana from the sides.</p>
<p>Also, because of the way light is scattered in the atmosphere, UV light does not just come straight down from the sun but is also diffusely scattered in all directions.</p>
<p>So even when you are under shade, some of this scattered UV <a href="https://onlinelibrary.wiley.com/doi/abs/10.5694/j.1326-5377.1998.tb138960.x">will still reach you</a>. The more sky you can see, the more <a href="https://onlinelibrary.wiley.com/doi/10.1111/php.12237">diffuse UV</a> you are exposed to. This is where larger beach cabanas really win out over beach umbrellas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Sandy beach, blue sky, headland in distance" src="https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510508/original/file-20230216-22-3bvtm9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sand can reflect up to 18% of UV light reaching the ground. So you can still get burnt in the shade.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/brown-sands-near-body-of-water-458917/">Flo Dahm/Pexels</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-is-the-sky-blue-and-where-does-it-start-81165">Curious Kids: Why is the sky blue and where does it start?</a>
</strong>
</em>
</p>
<hr>
<h2>So, can you still get burnt?</h2>
<p>The amount of UV that causes just-perceptible sunburn on white skin is called a minimal erythemal dose (MED). A full day outside in the middle of an Australian summer will deliver <a href="https://onlinelibrary.wiley.com/doi/abs/10.5694/j.1326-5377.1998.tb138960.x">20-30 MEDs</a>.</p>
<p>In the best-case scenario, your cabana shields you from 75% of UV, so you could still get 5 MEDs on a full day at the beach. That’s enough for a very unpleasant burn for many people, even if they spent the whole day under cover. Spending time away from the shelter, exposes people to even more.</p>
<p>There has been little study of beach cabanas specifically. But there has been an <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9772484/">Italian study</a> of similar gazebos used by Tuscan lifesavers. This found that if people sat or stood under a gazebo between 8.30am and 4.30pm, they got 35% of the UV they would have had in the full sun.</p>
<p>Someone lying absolutely flat would only get 10%, but this seems an unlikely posture to maintain all day long.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-treat-sunburn-pain-according-to-skin-experts-150070">How to treat sunburn pain, according to skin experts</a>
</strong>
</em>
</p>
<hr>
<h2>You can’t just rely on your cabana</h2>
<p>Fortunately, there are several <a href="http://www.assc.org.au/wp-content/uploads/2023/02/SCPQ_Report_Final_2023.pdf">sun protection practices</a> you can layer with your shade. </p>
<p>A UPF 50+ rashie, and perhaps leggings, will help block UV reflection and also protect you when you’re in the surf or making an ice-cream run. Use sunglasses to protect your eyes from developing <a href="https://eyewiki.aao.org/Photokeratitis">photokeratitis</a>, a sunburn on the corneas of your eyes. Add a broad-brimmed hat when you leave the cabana.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dog wearing hat and sunglasses sitting on sun lounger" src="https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510507/original/file-20230216-22-7ffik5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hat, check. Sunnies, check. Now for some shade.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/pug-relaxing-on-lawn-chair-195594704">Shutterstock</a></span>
</figcaption>
</figure>
<p><a href="https://theconversation.com/4-myths-about-sunscreen-and-why-theyre-wrong-125879">Sunscreen</a> reapplied <a href="https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/about-sunscreen/sunscreen-faqs">every two hours</a>, and straight after swimming, will also protect you, but it’s not a suit of armour. For long exposure times it’s better to <a href="https://onlinelibrary.wiley.com/doi/10.1111/1753-6405.12873">use it as a back-up</a> to clothing for your face, neck, hands and feet. </p>
<p>Finally, consider heading indoors in the <a href="https://onlinelibrary.wiley.com/doi/10.1111/1753-6405.12873">middle of the day</a> when the <a href="https://theconversation.com/what-is-the-uv-index-an-expert-explains-what-it-means-and-how-its-calculated-173146">UV index</a> is at its peak.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-the-uv-index-an-expert-explains-what-it-means-and-how-its-calculated-173146">What is the UV index? An expert explains what it means and how it's calculated</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/199102/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Katie Lee receives funding from the National Health and Medical Research Council. </span></em></p><p class="fine-print"><em><span>H. Peter Soyer is a shareholder of MoleMap NZ Limited and e-derm consult GmbH and undertakes regular teledermatological reporting for both companies. He is a Medical Consultant for Canfield Scientific Inc and Blaze Bioscience Inc.</span></em></p>Move over beach umbrellas, it’s the summer of the beach cabana. But these popular sun shelters may not protect you as much as you think.Katie Lee, PhD Candidate, The University of QueenslandH. Peter Soyer, Professor of Dermatology, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1875592022-09-06T12:37:31Z2022-09-06T12:37:31ZHuman skin stood up better to the sun before there were sunscreens and parasols – an anthropologist explains why<figure><img src="https://images.theconversation.com/files/480836/original/file-20220824-4026-m7s9pf.jpg?ixlib=rb-1.1.0&rect=663%2C34%2C5087%2C3794&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sun’s rays often feel good on your skin, but can cause serious damage.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-woman-against-sky-during-sunset-royalty-free-image/1340270649">Maksim Chernyshev/EyeEm via Getty Images</a></span></figcaption></figure><p>Human beings have a conflicted relationship with the sun. People love sunshine, but then get hot. Sweat gets in your eyes. Then there are all the protective rituals: the sunscreen, the hats, the sunglasses. If you stay out too long or haven’t taken sufficient precautions, your skin lets us you know with an angry sunburn. First the heat, then the pain, then the remorse.</p>
<p>Were people always this obsessed with what the sun would do to their bodies? <a href="https://scholar.google.com/citations?user=NIAvKr8AAAAJ&hl=en&oi=ao">As a biological anthropologist</a> who has studied primates’ adaptations to the environment, I can tell you the short answer is “no,” and they didn’t need to be. For eons, skin stood up to the sun.</p>
<h2>Skin, between you and the world</h2>
<p>Human beings evolved under the sun. Sunlight was a constant in people’s lives, warming and guiding them through the days and seasons. <em>Homo sapiens</em> spent the bulk of our prehistory and history outside, mostly naked. Skin was the primary interface between our ancestors’ bodies and the world.</p>
<p>Human skin was adapted to whatever conditions it found itself in. People took shelter, when they could find it, in caves and rock shelters, and got pretty good at making portable shelters from wood, animal skins and other gathered materials. At night, they huddled together and probably covered themselves with fur “blankets.” But during the active daylight hours, people were outdoors and their mostly bare skin was what they had.</p>
<p>During a person’s lifetime, <a href="https://medlineplus.gov/ency/anatomyvideos/000125.htm">skin responds to routine exposure to the sun</a> in many ways. The surface layer of the skin – the epidermis – <a href="https://newsinhealth.nih.gov/2014/07/sun-skin">becomes thicker by adding more layers of cells</a>. For most people, the skin becomes gradually darker as specialized cells kick into action to produce a <a href="https://my.clevelandclinic.org/health/body/22615-melanin">protective pigment called eumelanin</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="cross-sectional diagram of skin's layers with sunlight hitting the surface and showing increased production of melanin" src="https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480838/original/file-20220824-12-e8zgi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Exposure to the sun’s rays triggers production of more protective eumelanin, which also darkens the skin’s appearance.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/tanning-process-skin-human-anatomy-royalty-free-illustration/645165034">ttsz/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>This remarkable molecule absorbs most visible light, causing it to look very dark brown, almost black. Eumelanin also absorbs damaging ultraviolet radiation. Depending on their genetics, people produce different amounts of eumelanin. Some have a lot and are able to produce a lot more when their skin is exposed to sun; others have less to start out with and produce less when their skin is exposed.</p>
<p><a href="https://scholar.google.com/citations?user=NIAvKr8AAAAJ&hl=en&oi=ao">My research on</a> <a href="https://doi.org/10.1111/pcmr.12976">the evolution of human skin pigmentation</a> has shown that the skin color of people in prehistory was tuned to local environmental conditions, primarily to local levels of ultraviolet light. People who lived under strong UV light – like you’d find near the equator – year in and year out had darkly pigmented and highly tannable skin capable of making a lot of eumelanin. People who lived under weaker and more seasonal UV levels – like you’d find in much of northern Europe and northern Asia – had lighter skin that had only limited abilities to produce protective pigment.</p>
<p>With only their feet to carry them, our distant ancestors didn’t move around much during their lives. Their skin adapted to subtle, seasonal changes in sunlight and UV conditions by producing more eumelanin and becoming darker in the summer and then losing some pigment in the fall and winter when the sun wasn’t so strong. Even for people with lightly pigmented skin, painful sunburns would have been exceedingly rare because there was never a sudden shock of strong sun exposure. Rather, as the sun strengthened during spring, the top layer of their skin would have gotten <a href="https://doi.org/10.1007/978-3-540-89656-2_60">gradually thicker over weeks and months of sun exposure</a>.</p>
<p>This is not to say that the skin would have been undamaged by today’s standards: Dermatologists would be appalled by the leathery and wrinkled appearance of the sun-exposed skin of our ancestors. Skin color, like the levels of sun itself, changed with the seasons and skin quickly showed its age. This is still the case for people who live traditional, mostly outdoor, lives in many parts of the world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a squatting old man with weathered skin" src="https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479980/original/file-20220818-27-79ac87.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chronic unprotected sun exposure can damage skin, with effects that look like those on this farmer in India.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:2020_Indian_farmers%27_protest_-_old_man_sitting.jpg">Randeep Maddoke/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>There is no preserved skin from thousands of years ago for scientists to study, but we can infer from the effects of sun exposure on modern people that the damage was similar. <a href="https://doi.org/10.1111/j.1365-2133.2009.09565.x">Chronic sun exposure</a> <a href="https://doi.org/10.1016/S1011-1344(01)00198-1">can lead to skin cancer</a>, but rarely of the variety – <a href="https://doi.org/10.1016/j.bjps.2006.05.008">melanoma</a> – that would cause death during reproductive age.</p>
<h2>Indoor living changed skin</h2>
<p>Until around 10,000 years ago – a drop in the bucket of evolutionary history – human beings made their living by <a href="https://www.history.com/topics/pre-history/hunter-gatherers">gathering foods, hunting and fishing</a>. Humanity’s relationship with the sun and sunlight changed a lot after people started to settle down and live in permanent settlements. <a href="https://www.smithsonianmag.com/history/the-seeds-of-civilization-78015429/">Farming and food storage</a> were associated with the development of immovable buildings. By around 6000 B.C. many people throughout the world were spending more time in walled settlements, and more time indoors.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="line drawing of royal bearded man followed by two smaller men with parasol and fly whisk" src="https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1019&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1019&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1019&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1281&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1281&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480840/original/file-20220824-4729-j9lpxl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1281&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Persian King Darius the Great, who lived more than 2,500 years ago, is portrayed being shielded from the sun.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/king-darius-the-great-followed-by-his-royalty-free-illustration/1367186124">Luisa Vallon Fumi/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>While most people still spent most of their time outside, some stayed indoors if they could. Many of them <a href="https://www.folkwear.com/blogs/news/historyoftheparasol">started protecting themselves from the sun</a> when they did go out. By at least 3000 B.C., a whole industry of sun protection grew up to create gear of all sorts – parasols, umbrellas, hats, tents and clothing – that would protect people from the discomfort and inevitable darkening of the skin associated with lengthy sun exposure. While some of these were originally reserved for nobility – like the parasols and umbrellas of ancient Egypt and China – these luxury items <a href="https://doi.org/10.1007/s11199-017-0785-4">began to be made</a> and <a href="https://doi.org/10.1080/17532523.2016.1281875">used more widely</a>.</p>
<p>In some places, people even developed <a href="https://doi.org/10.1371/journal.pone.0136090">protective pastes made out of minerals</a> and plant residues – <a href="https://doi.org/10.1111/jocd.14004">early versions of modern sunscreens</a> – to protect their exposed skin. Some, like the <a href="https://www.scmp.com/lifestyle/fashion-beauty/article/3100999/all-natural-sunscreen-and-beauty-product-thanaka-paste-has">thanaka paste used by people in Myanmar</a>, still persists today.</p>
<p>An important consequence of these practices in traditional agricultural societies was that people who spent most of their time indoors considered themselves privileged, and their lighter skin announced their status. A “farmer’s tan” was not glamorous: <a href="https://www.ucpress.edu/book/9780520283862/living-color">Sun-darkened skin was a penalty associated with hard outdoor work</a>, not the <a href="https://doi.org/10.2105/AJPH.2008.144352">badge of a leisurely vacation</a>. From Great Britain to China, Japan and India, suntanned skin became associated with a life of toil.</p>
<p>As people have moved around more and faster over longer distances in recent centuries, and spend more time indoors, their skin hasn’t caught up with their locations and lifestyles. Your levels of eumelanin probably aren’t perfectly adapted to the sun conditions where you live and so aren’t able to protect you the same way they might have your ancient ancestors.</p>
<p>Even if you’re naturally darkly pigmented or capable of tanning, everyone is susceptible to <a href="https://doi.org/10.1001/jamadermatol.2017.4201">damage caused by episodes of sun exposure</a>, especially after long breaks spent completely out of the sun. The “vacation effect” of sudden strong UV exposure is really bad because a sunburn signals damage to the skin that is never completely repaired. It’s like a bad debt that presents itself as prematurely aged or precancerous skin many years later. There is no healthy tan – a tan doesn’t protect you from further sun damage, it’s the sign of damage itself.</p>
<p>People may love the sun, but we’re not our ancestors. Humanity’s relationship with the sun has changed, and this means changing your behavior to save your skin.</p><img src="https://counter.theconversation.com/content/187559/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nina G. Jablonski consults for L'Oreal and has received funding from the National Science Foundation, The Leakey Foundation, The Wenner-Gren Foundation, The Robert Wood Johnson Foundation, and The Rockefeller Foundation.</span></em></p>Our ancient ancestors didn’t have clothes or houses – but that constant exposure to the sun helped their skin protect itself from the worst sun damage.Nina G. Jablonski, Evan Pugh University Professor of Anthropology, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1696022021-10-26T12:19:57Z2021-10-26T12:19:57ZType of ultraviolet light most effective at killing coronavirus is also the safest to use around people<figure><img src="https://images.theconversation.com/files/428067/original/file-20211022-9818-i87045.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5779%2C3752&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">UV light at most wavelengths can kill COVID–19. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/lamp-for-sterilization-covid-19-prevention-concept-royalty-free-image/1296016011?adppopup=true">andriano_cz/iStock via Getty Images</a></span></figcaption></figure><p>Scientists have long known that ultraviolet light can <a href="https://theconversation.com/ultraviolet-light-can-make-indoor-spaces-safer-during-the-pandemic-if-its-used-the-right-way-141512">kill pathogens on surfaces and in air and water</a>. <a href="https://www.nytimes.com/2020/03/28/travel/coronavirus-hotels-private-jets-virtual-spas.html">UV robots are used to disinfect</a> empty hospital rooms, buses and trains; UV bulbs in HVAC systems eliminate pathogens in building air; and <a href="https://www.nytimes.com/2008/03/02/business/02novel.html">UV lamps kill bugs in drinking water</a>.</p>
<p>Perhaps you have seen UV wands, UV LEDs and UV air purifiers advertised as silver bullets to protect against the coronavirus. While decades of research have looked at the ability of UV light to kill many pathogens, there are no set standards for UV disinfection products with regard to the coronavirus. These products may work to kill SARS-CoV-2, the virus that causes COVID-19, but they also may not. </p>
<p>I am an <a href="https://scholar.google.com/citations?user=uAS7KNUAAAAJ&hl=en&oi=ao">environmental engineer and expert in UV disinfection</a>. In May 2021, my colleagues and I set out to accurately test various UV systems and see <a href="https://doi.org/10.1128/AEM.01532-21">which was the most effective</a> at killing off – or inactivating – SARS-CoV-2.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing UV light breaking down a strand of DNA." src="https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=462&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=462&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=462&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=581&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=581&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428307/original/file-20211025-27-12cylg0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=581&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When UV light enters a cell, it breaks the bonds that hold DNA or RNA together.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:DNA_UV_mutation.svg#/media/File:DNA_UV_mutation.svg">NASA/David Herring via WikimediaCommons</a></span>
</figcaption>
</figure>
<h2>How does UV light kill a virus?</h2>
<p>Light is categorized by wavelength – the distance between peaks of a wave of light – and is measured in nanometers. UV wavelengths range from 100 to 400 nanometers – shorter in wavelength than the violet hues in visible light – and are invisible to the human eye. As wavelength shortens, photons of light contain higher amounts of energy.</p>
<p>Different wavelengths of UV light work better than others for inactivating viruses, and this depends on how well the wavelengths are absorbed by the virus’s DNA or RNA. When UV light gets absorbed, the photons of light transfer their energy to and <a href="https://doi.org/10.1038/s41598-021-93231-7">damage the chemical bonds of the genetic material</a>. The virus is then unable to replicate or cause an infection. Researchers have also shown the proteins that viruses use to attach to a host cell and initiate infection – like the spike proteins on a coronavirus – are also <a href="https://doi.org/10.1021/acs.est.7b04602">vulnerable to UV light</a>.</p>
<p>The dose of light matters too. Light can vary in intensity – bright light is more intense, and there is more energy in it than in dim light. Being exposed to a bright light for a short time can produce the same UV dose as being exposed to a dim light for a longer period. You need to know the right dose that can kill coronavirus particles at each UV wavelength.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man with sunburned shoulders sitting on a beach." src="https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428069/original/file-20211022-17-63e9kd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sunburns are caused by UV light damaging skin cells.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/man-with-sun-burnt-shoulders-sitting-on-beach-rear-royalty-free-image/85775471?adppopup=true">Ian Hooton/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<h2>Making ultraviolet lights safe for people</h2>
<p>Traditional UV systems use wavelengths at or around 254 nanometers. At these wavelengths the light is dangerous to human skin and eyes, <a href="https://doi.org/10.1111/php.13402">even at low doses</a>. Sunlight includes UV light near these wavelengths; anyone who has ever gotten a bad sunburn knows just how dangerous UV light can be. </p>
<p>However, recent research has shown that at certain UV wavelengths – specifically below 230 nanometers – the high-energy photons <a href="https://iuva.org/resources/covid-19/Far%20UV-C%20Radiation-%20Current%20State-of%20Knowledge.pdf">are absorbed by the top layers of dead skin cells</a> and don’t penetrate into the active skin layers where damage can occur. Similarly, the <a href="https://doi.org/10.1111/php.13402">tear layer around eyes also blocks out these germicidal UV rays</a>.</p>
<p>This means that at wavelengths of UV light below 230 nanometers, people can move around more freely while the air around them is being disinfected in real time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing a lamp above a sample of water containing the coronavirus." src="https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=317&fit=crop&dpr=1 600w, https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=317&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=317&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=399&fit=crop&dpr=1 754w, https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=399&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/428310/original/file-20211025-19717-bfs99z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=399&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers used this setup to test multiple different UV lights at various doses to see what it took to kill SARS-CoV-2.</span>
<span class="attribution"><span class="source">Karl Linden</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Testing different wavelengths</h2>
<p>My colleagues and I tested five commonly used UV wavelengths to see which work best to inactivate SARS-CoV-2. Specifically, we tested how large a dose is needed to <a href="https://doi.org/10.1128/AEM.01532-21">kill 90% to 99.9% of the viral particles present</a>.</p>
<p>We ran these tests in a biosafety level three facility at the <a href="https://environmentalscience.cals.arizona.edu/person/charles-chuck-gerba">University of Arizona</a> that is built to handle lethal pathogens. There we tested numerous lights across the UV spectrum, including UV LEDs that emit light at 270 and 282 nanometers, traditional UV tube lamps at 254 nanometers and a newer technology called an <a href="https://www.ushio.eu/excimer-explained/">excited dimer, or excimer, UV source</a> at 222 nanometers. </p>
<p>To test each device we spiked a sample of water with millions of SARS-CoV-2 viruses and coated a petri dish with a thin layer of this mixture. We then shined UV light on the petri dish until we achieved a specific dose. Finally we examined the viral particles to see if they could still infect human cells in culture. If the viruses could infect the cells, the dose was not high enough. If the viruses did not cause an infection, the UV source at that dose had successfully killed the pathogen. We carefully repeated this process for a range of UV doses using the five different UV devices.</p>
<p>While all of the wavelengths we tested can inactivate SARS-CoV-2 at very low doses, the ones that required the lowest dose were the <a href="https://doi.org/10.1128/AEM.01532-21">systems that emit UV light at a wavelength of 222 nanometers</a>. In our experiment, it took a dose of less than 2 millijoules of energy per square centimeter to kill 99.9% of viral particles. This translates to needing about 20 seconds to disinfect a space receiving a low intensity of short wavelength UV light, similar to that used in our test.</p>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p>
<p>These 222-nanometer systems are almost twice as effective as conventional UV tube lamps, which are often used in ultraviolet disinfecting systems. But importantly, the winning lamp also happens to be the safest for humans, too. At the same UV light intensity it takes to kill 99.9% of SARS-CoV-2 in 20 seconds, a person could be safely exposed to 222-nanometer light for <a href="https://doi.org/10.1111/php.13402">up to one hour and 20 minutes</a>.</p>
<p>What this means is that <a href="https://edenpark.com/">widely available</a> types of <a href="https://www.ushio.com/product/care222-filtered-far-uv-c-excimer-lamp-module/">UV lamp</a> lights can be used to safely knock down levels of the coronavirus with people present.</p>
<h2>Better use of existing tech</h2>
<p>Many places or organizations – ranging from the <a href="https://www.defense.gov/News/Feature-Stories/Story/Article/2309289/air-guard-wing-receives-dods-first-uv-light-disinfectant-system/">U.S. Air Force</a> to the <a href="https://www.spaceneedle.com/elevatingclean">Space Needle in Seattle</a> to <a href="https://www.boeing.com/confident-travel/research/CAP-3_Disinfection_with_Far-UV.html">Boeing</a> – are already using or investigating ways to use UV light in the 222 nanometer range to protect public health. </p>
<p>I believe that our findings are important because they quantify the exact doses needed to achieve various levels of SARS-CoV-2 control, whether that be killing 90% or 99.9% of viral particles. </p>
<p>Imagine coffee shops, grocery stores, school classrooms, restaurants and concert venues now made safe by this technology. And this is not a solution for just SARS-CoV-2. These technologies could help protect human health in public spaces in future times of crisis, but also during times of relative normalcy, by reducing exposure to everyday viral and bacterial threats.</p><img src="https://counter.theconversation.com/content/169602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karl Linden advises various companies promoting the use of UV light for disinfection. He receives funding from federal agencies and industry to conduct research in his role as a professor at the University of Colorado Boulder. He is affiliated with the International Ultraviolet Association. </span></em></p>UV lights come in a variety of different wavelengths, but not all are equally effective at disinfection. Researchers tested a number of commercially available lights to find the best.Karl Linden, Professor of Environmental Engineering and the Mortenson Professor in Sustainable Development, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1639742021-07-19T01:51:16Z2021-07-19T01:51:16ZHow museums could light up and display more of the world’s precious objects for longer<p>The two key objectives of museums — exhibition and preservation — are often in conflict. </p>
<p>Exhibiting an object and exposing it to elements like lighting, fluctuating temperature, humidity and variable air quality can cause damage and degradation. </p>
<p>The very decision to exhibit an item may mean its future is compromised. </p>
<p>In fact, the majority of objects in museum collections are in storage. This is only partly to do with resources and display space. It is largely due to conservation requirements.</p>
<p>I am a researcher at the University of Technology Sydney and a lighting designer at Steensen Varming. With other researchers and designers, I am exploring how museums can improve displays for visitors while also addressing preservation with new advances in lighting technology and applications. </p>
<p>These technological advances need to be put into practice for the sake of viewers today and well into the future.</p>
<h2>Lighting the way</h2>
<p>The first public museums of the 19th and the early 20th century used daylight to illuminate the collections. But, as our understanding of conservation advanced, the <a href="https://www.nga.gov/conservation/preventive/effects-of-light-exposure.html">degrading effects</a> of ultraviolet and visible light became a concern. </p>
<p>As electric lighting became increasingly available — and economically viable — museums and galleries were fitted with incandescent light bulbs and fluorescent discharge tubes (commonly referred to as “fluoros”), and daylight was increasingly excluded.</p>
<p><a href="https://cie.co.at/publications/control-damage-museum-objects-optical-radiation">International guidelines</a> — which balanced the needs of viewers and conservation — were developed with these technologies in mind. As all forms of light can cause damage to exhibition materials by fading pigments and affecting structural integrity, lighting must be used delicately and sparsely to protect vulnerable displays. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-always-wondered-do-fluorescent-lights-emit-uv-and-can-it-harm-me-90317">I've always wondered: do fluorescent lights emit UV, and can it harm me?</a>
</strong>
</em>
</p>
<hr>
<p>But this century has seen major advances in light-emitting diodes, or LED lighting. <a href="https://en.wikipedia.org/wiki/Light-emitting_diode#White_LEDs_and_the_illumination_breakthrough">White LEDs</a> greatly improved the quality of LED lighting, which is also recognised for economic and environmental benefits.</p>
<p>LEDs have very different attributes to traditional counterparts: their light spectrum is different, they render colours differently, they offer a greater degree of control and have a lower potential for damage.</p>
<p>But even as museums increasingly adopt LEDs, they are still using the old guidelines. A new approach to museum lighting standards is well overdue.</p>
<h2>Modernising standards</h2>
<p>With LED lighting, we believe the strict exposure limits under the old guidelines can be more specifically tailored. </p>
<p>This means more artefacts can be displayed for longer while incurring less damage.</p>
<p>A key part of <a href="https://www.researchgate.net/publication/348252322_A_Practical_Guide_Towards_Sustainable_Lighting_and_Climate_Control_in_Museums_and_Galleries">our proposed framework</a> is considering the “significance” of objects as a key factor when deciding how much light exposure is adequate. </p>
<p>The question of significance is a complex one in its own right, but helps make more informed decisions for display conditions: how important an object is to display, for how long it can be on display, and how much compromise is acceptable.</p>
<p>Our new proposed standards include suggestions on: </p>
<ul>
<li><p>expanding the classification of the light-sensitivity of museum objects from the four categories to eight</p></li>
<li><p>introducing a three-tier significance scale to consider the importance and relevance of objects, not just the materials they are made of, and</p></li>
<li><p>a flexible framework, allowing museum professionals to adjust the duration of exposure versus light levels without compromising objects.</p></li>
</ul>
<p>This will not solve all the complex questions around light, conservation and visitor experience, but it will serve as an essential adjustment. </p>
<p>By introducing more specificity and flexibility into lighting guidelines, we hope we can offer freedom to curators, designers and conservators, while also giving museum visitors a better experience.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-the-right-lighting-could-save-the-mona-lisa-95938">How the right lighting could save the Mona Lisa</a>
</strong>
</em>
</p>
<hr>
<p>Lighting technology is developing by the day. With smart controls and sensors, museums will increasingly be able to add thematic, theatrical or dynamic lighting overlays to display objects at their best — perhaps even personalised lighting profiles for each visitor.</p>
<p>We now need to adopt the right guidelines for this to happen.</p><img src="https://counter.theconversation.com/content/163974/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emrah Baki Ulas is a Senior Lecturer at University of Technology Sydney and an Associate at Steensen Varming. He has designed lighting projects internationally for museums and galleries.</span></em></p>Museum lighting standards assume galleries are still using incandescent bulbs or fluorescent lights. But LEDs offer more for both audiences and conservation.Emrah Baki Ulas, Senior Lecturer, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1506402021-01-03T18:56:54Z2021-01-03T18:56:54ZI can’t get sunburnt through glass, shade or in water, right? 5 common sunburn myths busted<figure><img src="https://images.theconversation.com/files/374149/original/file-20201210-15-a2nj7x.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3376&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Despite decades of public health campaigns, skin cancer remains a major threat to health in Australia, with more cases diagnosed each year <a href="https://www.aihw.gov.au/reports/cancer/skin-cancer-in-australia/">than all other cancers combined</a>.</p>
<p>Skin cancer rates remain high and sunburn is all too common in Australia.</p>
<p>Our research looks at how best to inform people about the hazards of ultraviolet (UV) radiation, including by evaluating and testing <a href="https://www.coolandcovered.com.au/">shade</a>, as well as the development of wearable UV indicators including <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7378694/">stickers</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7531871/">wristbands</a>. While this technology can help to improve people’s sun protection habits, we continue to come up against some common myths about sunburn.</p>
<p>As we’re in the middle of summer, it seems a good time to debunk some of these. </p>
<h2>Myth 1: “You can’t get burnt in the shade”</h2>
<p>Effective shade can provide protection from the Sun’s UV rays, but we can still get burnt in the shade.</p>
<p>Shade materials with holes or gaps can allow penetration by UV radiation.</p>
<p>The same rule applies for <a href="https://www.sciencedirect.com/science/article/abs/pii/S0143622819301006">tree shade</a>, with denser foliage and wider canopies providing better protection than trees with sparse <a href="https://www.sciencedirect.com/science/article/pii/S2215016119301888">foliage</a> and dappled sunlight.</p>
<p>Similarly, solid roof structures with wide overhangs and little sky view <a href="https://www.sciencedirect.com/science/article/abs/pii/S0360132318306280">provide greater UV radiation protection</a> than smaller structures.</p>
<p>Reflected UV radiation is another factor that means you’re not always safe in the shade. The Sun’s rays reflect from light-coloured surfaces and can bounce back under shade.</p>
<p><a href="https://www.arpansa.gov.au/understanding-radiation/what-is-radiation/non-ionising-radiation/ultraviolet-radiation">Light surfaces</a>, such as concrete, light-coloured paint or metallic surfaces, reflect more than dark ones. Sand can reflect as much as <a href="https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Solar-And-Ultraviolet-Radiation-1992">25% of UV radiation</a>. This means if you’re sitting under a beach umbrella, UV radiation can still damage your skin, even though you feel like you’re covered in the shade.</p>
<figure class="align-center ">
<img alt="Woman sitting at the beach under an umbrella" src="https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373533/original/file-20201208-24-qkur1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sand reflects up to 25% of UV radiation.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Myth 2: “You’re safe from the sun when in water”</h2>
<p>Up to 40% of total UV radiation hits the body even half a metre below the surface of the water, <a href="https://www.sunsmart.com.au/advice-for/sports-groups/top-sunsmart-tips-for-your-sport/swimming#:%7E:text=With%20outdoor%20swimming%20taking%20place,good%20sun%20protection%20is%20essential.">according to SunSmart</a>.</p>
<p>Ordinarily, you would have to dive at least <a href="https://www.int-res.com/abstracts/meps/v144/p109-118/">2.5m inshore and 4.5m in offshore coastal waters</a> to avoid harmful UV radiation. This is because offshore waters tend to be clearer, so UV can penetrate further, whereas inshore waters tend to have sediment and nutrients that can cause a rapid decline in UV.</p>
<p>When swimming, you may not notice when your skin is burning due to the cooling effect of water. Reflective surfaces around water environments can also amplify UV, such as concrete or other hard surfaces around a swimming pool. </p>
<p>The importance of adequate sun protection when participating in water-based activities is highlighted by the rate of sunburn in Queenslanders, with <a href="https://www.health.qld.gov.au/research-reports/reports/public-health/cho-report/current/full">45% of children sunburnt</a> in the previous 12 months and 69% of these sunburns acquired during a water-based activity.</p>
<h2>Myth 3: “Exercise makes my skin red hot, not the sun”</h2>
<p>You might often hear people say, when they return from exercise, that they’re red only because they’ve been running. While this does occur, redness from exercise usually dissipates quickly — so if you’re still red in the 24 hours after exercise, it’s sunburn.</p>
<p>When you exercise, your body temperature increases and your body’s natural mechanism is to cool down by carrying blood towards the skin’s surface, causing one to sweat and cool off.</p>
<p>Sweat washes sunscreen away and towelling down wipes off sunscreen.</p>
<p><a href="https://www.cancer.org.au/cancer-information/causes-and-prevention/sun-safety/about-sunscreen/spf50-sunscreen">Regular reapplication</a> of a water-resistant sunscreen is vital. Work-out tan lines are signs of skin damage. Each time our skin gets damaged we greatly increase our risk for skin cancer.</p>
<figure class="align-center ">
<img alt="Person sweating in the sun" src="https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373217/original/file-20201207-17-uw00cu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sweat can wash sunscreen away. If you don’t reapply regularly, you risk skin damage.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Myth 4: “That’s not sunburn, it’s windburn”</h2>
<p>Windburn can make your skin red, but in Australia, windburn is pretty rare. It’s more likely to occur in instances like skiing, by very windy, cold and dry conditions, with dense mountain clouds and minimal or no sunlight. In Australia, it’s much more likely to be sunburn.</p>
<p>What’s more, high winds can actually increase the likelihood of getting sunburn. Wind dries out and weakens the outer layer of skin. Wind force can make these dead skin cells fall off.</p>
<p>When you apply sunscreen, it coats this outer layer of skin. As wind brushes these skin cells away your sunscreen goes with it, leaving unprotected skin to be burnt by the sun.</p>
<p>Using sun-protective clothing and reapplying sunscreen are the best ways to avoid skin damage when it’s windy.</p>
<h2>Myth 5: “You can’t get burnt in the car through a window”</h2>
<p>Often, glass used in car side windows is untinted. It reduces UV radiation but doesn’t completely block transmission.</p>
<p>This means you can still get skin damage if you spend a long time in the car next to an untinted side window. Tinted windows can help reduce the amount of UV that hits your skin, and the rule of thumb is that the darker the tint, <a href="https://www.wfaanz.org.au/regulations-automotive/">the more it protects</a> — it’s worth noting, though, that legally you can’t tint your whole front window in Australia, which is obviously the biggest window in the car.</p>
<p>More commonly, however, <a href="https://pubmed.ncbi.nlm.nih.gov/20226568/">people are sunburnt in cars</a> when they have the side windows down and are exposed to a short period of high levels of UV radiation.</p>
<figure class="align-center ">
<img alt="A person driving a car with their arm out the window" src="https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373215/original/file-20201207-21-1vpu14p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">It is possible to get sunburnt with the windows up in a car. But it’s more common to get burnt when you’ve wound down the windows.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Simple solutions are the five sun-safe measures — slip, slop, slap, seek, slide:</p>
<ul>
<li><p>slip on a long-sleeved shirt. If you’re in water, this might include a rashie or wetsuit.</p></li>
<li><p>slop on an SPF 30 or higher sunscreen, and reapply at least every two hours, or sooner after swimming or sweating</p></li>
<li><p>slap on a broad-brimmed hat</p></li>
<li><p>seek shade</p></li>
<li><p>slide on sunnies.</p></li>
</ul><img src="https://counter.theconversation.com/content/150640/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elke Hacker receives funding from the Queensland Government Advance Queensland fund. She undertakes contract research projects receiving funding from Cancer Council Victoria, Suncayr Ptd Ltd and SunFly Brands Inc. She'd also like to acknowledge Naomi Stekelenburg from QUT, who contributed to this article.</span></em></p><p class="fine-print"><em><span>Louise Baldwin receives project funding from Cancer Institute NSW and has previously received funding under the Advancing Queensland Age Friendly Community Grant scheme.</span></em></p>UV radiation can reflect off surfaces like sand or concrete, meaning shade doesn’t always prevent sunburn.Elke Hacker, Research Fellow, Queensland University of TechnologyLouise Baldwin, Senior Research Fellow, School of Public Health and Social Work, Faculty of Health, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1396702020-07-28T03:37:53Z2020-07-28T03:37:53ZCurious Kids: how does the Sun help your body make vitamin D?<figure><img src="https://images.theconversation.com/files/345729/original/file-20200706-33926-14yysqc.jpg?ixlib=rb-1.1.0&rect=137%2C77%2C5613%2C3742&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Shutterstock</span> </figcaption></figure><blockquote>
<p><strong>How does the Sun help your body make vitamin D? Wesley, aged 7</strong></p>
</blockquote>
<p><a href="https://theconversation.com/au/topics/curious-kids-36782"><img src="https://images.theconversation.com/files/291898/original/file-20190911-190031-enlxbk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=90&fit=crop&dpr=1" width="100%"></a></p>
<p>Thanks for this great question, Wesley.</p>
<p>Vitamin D is created when the chemicals in our skin react to an invisible type of light from the Sun. </p>
<p>In Australia, most of our vitamin D is made in our skin, but we can can also get a little bit of vitamin D from some of the food we eat like fish, eggs and mushrooms.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-does-the-suns-core-look-like-141785">Curious Kids: what does the Sun's core look like?</a>
</strong>
</em>
</p>
<hr>
<p>It’s important we have vitamin D in our body as it helps to strengthen our bones and make our muscles work properly. </p>
<p>It’s especially important in young people when their bones are growing. </p>
<h2>Invisible and visible light</h2>
<p>Let’s first talk a little bit about sunlight. </p>
<p>Sunlight isn’t just the golden light that wakes you up in the morning or shines on your skin on a summer’s day. Sunlight actually exists in many colours, some we can see and some we can’t see.</p>
<p>A rainbow is an example of visible light, or sunlight you can see. Droplets of water in the sky split the light into all of its different colours. </p>
<p>But not all light is visible like the many colours of the rainbow.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rainbow in a blue sky." src="https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=279&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=279&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=279&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=351&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=351&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345731/original/file-20200706-33926-ff6han.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=351&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rainbows are an example of visible light, but not all light is visible.</span>
<span class="attribution"><span class="source">Nikki Zalewski/ Shutterstock</span></span>
</figcaption>
</figure>
<p>Some types of sunlight are invisible. Infrared sunlight is one of these. If you could see infrared sunlight it would sit just above the red in the rainbow. </p>
<p>Infrared light makes us warm as it produces heat. You might have felt it heat up your skin on a warm sunny day.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-does-the-sun-spin-as-well-as-the-planets-119877">Curious Kids: does the Sun spin as well as the planets?</a>
</strong>
</em>
</p>
<hr>
<p>Another type of invisible light is ultraviolet. If you could see ultraviolet light it would be below the violet colour in the rainbow.</p>
<p>Ultraviolet light is also called UV light, or UV radiation. </p>
<p>You might be interested to know that while we can’t see infrared or ultraviolet light, most animals can. In fact, <a href="https://sciencing.com/animals-can-see-infrared-light-6910261.html">goldfish can see both infrared and ultraviolet light</a>. Imagine what that might be like!</p>
<h2>Which light is important in making vitamin D?</h2>
<p>We often use something called the UV index to tell us how much UV light is outside. The UV index is sometimes reported with the weather forecast, and tells us how strong the UV radiation will be that day.</p>
<p>There are two types of UV light that reach us from the Sun, called UV-A and UV-B. But it’s only the UV-B light hitting our skin that causes vitamin D to be made. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A simplified UV index ranging from low to high." src="https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345937/original/file-20200707-18-9el3s4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The UV index can tell you how careful you need to be about protecting yourself from the sun.</span>
<span class="attribution"><span class="source">Sudowoodo/ shutterstock</span></span>
</figcaption>
</figure>
<p>UV-B light is full of energy, a bit like a child who can’t sit still. It has more energy than UV-A and that extra energy is needed to make vitamin D. </p>
<h2>So how exactly is it made?</h2>
<p>When the UV-B light hits your skin, the energy in the light combines with chemicals in the very top layer of your skin. </p>
<p>Sometimes this results in your body making vitamin D. Other times the combination makes bad chemicals that lead to sunburn, and maybe later to skin cancers. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-dont-burns-bleed-130792">Curious Kids: why don't burns bleed?</a>
</strong>
</em>
</p>
<hr>
<p>When the UV-B energy is taken into a chemical, it gives the chemical more energy – scientists describe this as the chemical being “excited”.</p>
<p>When the heat from the infrared light is added, it gives the excited chemical even more energy – so much that the links holding the chemical together break apart and it changes into a totally different chemical.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A paper chain of people in a circle." src="https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345954/original/file-20200707-27852-1oxub7g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A chain like this is a bit like the structure of the chemicals in your skin before UV-B energy makes them excited and they change shape.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A paper chain of people in a line formation." src="https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345956/original/file-20200707-27833-z87mb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When the chemicals become excited the chain changes shape and becomes vitamin D.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Imagine joining hands with all your friends and making a big circle, then running madly around. Some people lose their grip and their hands come apart. Suddenly it’s not a circle anymore, but a different shape. </p>
<p>This is what happens in the skin. The chemical that takes in the UV-B changes, because the links between atoms in the circle break, to become vitamin D. </p>
<p>The vitamin D is then picked up by the blood that flows through the skin. </p>
<p>But before it works properly in the body it has to go to the liver and then to the kidneys where it turns into the form that can help our bones and muscles.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-is-the-sun-orange-when-white-stars-are-the-hottest-120216">Curious Kids: why is the Sun orange when white stars are the hottest?</a>
</strong>
</em>
</p>
<hr>
<h2>But be careful not to get sunburned</h2>
<p>So getting some sun on your skin is really important, but you don’t want to get too much or you’ll get sunburned.</p>
<p>In summer in Australia, the sun is so strong that you only need to be outside for a few minutes every day to keep your vitamin D up. </p>
<p>But it’s still good to get plenty of time outside, especially in the morning and afternoon. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Young girl rubbing sunscreen on her face, wearing a bucket hat and sunglasses." src="https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349496/original/file-20200727-33-1uir4zp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">If the UV index is 3 or higher it’s very important to consider sun safety. Seek shade if possible and make sure you have a hat and sunscreen on.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Make sure you use sun protection like a hat, clothing, and sunscreen if the UV index is 3 or higher. </p>
<p>In summer it’s best to stay indoors or in the shade in the middle hours of the day because the Sun is very strong. But in winter the Sun’s not as strong, so the middle of the day is a good time to get outside in the sun to get your vitamin D.</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskids@theconversation.edu.au">curiouskids@theconversation.edu.au</a></em></p>
<hr><img src="https://counter.theconversation.com/content/139670/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robyn Lucas receives funding from the National Health and Medical Research Council and Multiple Sclerosis Research Australia.</span></em></p>A light invisible to humans makes chemicals in our skin very excited. In fact, the chemicals become so excited they change shape and become vitamin D.Robyn Lucas, Professor of Epidemiology, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1422772020-07-14T20:01:44Z2020-07-14T20:01:44ZUltraviolet radiation is a strong disinfectant. It may be what our schools, hospitals and airports need<figure><img src="https://images.theconversation.com/files/347025/original/file-20200713-34-1ktnonp.jpg?ixlib=rb-1.1.0&rect=89%2C59%2C4902%2C3270&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>You may remember when US President Donald Trump suggested exposing coronavirus patients to UV (ultraviolet) light – or “just very powerful light” – to help treat them. </p>
<p>The use of UV light is not, in any way, a viable treatment for people infected with SARS-CoV-2. However, due to its powerful sterilisation abilities, this technology does have great potential for managing the COVID-19 pandemic in other ways.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1253482576699969537"}"></div></p>
<h2>What is UV light?</h2>
<p>The visible light we see every day belongs in a unique region of the whole <a href="https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html">electromagnetic spectrum</a>. The full spectrum is composed of radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays – all emitting and carrying energy.</p>
<p>Of these, ultraviolet (UV), X-ray and gamma rays are high-frequency waves. These can have <a href="https://pubmed.ncbi.nlm.nih.gov/24382094/">serious consequences</a> for our health.</p>
<p>The Sun emits <a href="https://www.who.int/uv/faq/whatisuv/en/index2.html">three types</a> of UV radiation: UVA, UVB and UVC. Prolonged UV exposure is associated with skin cancer. Thankfully, our planet’s atmosphere <a href="https://www.who.int/uv/uv_and_health/en/#:%7E:text=As%20sunlight%20passes%20through%20the,less%20affected%20by%20the%20atmosphere.">shields us from the majority</a> of the Sun’s UVB emissions and all UVC emissions. </p>
<h2>Affordable and accessible</h2>
<p>UVC has the ability to kill germs and is an alternative to chemical disinfection. UVC can be <a href="https://nymag.com/strategist/article/does-uv-light-kill-germs-best-sterilizer.html">used</a> to sterilise objects, <a href="https://www.water-research.net/index.php/water-treatment/water-disinfection/uv-disinfection">water</a>, surfaces and materials – whether it’s to clean your phone, a <a href="https://www.bbc.com/news/business-51914722">hospital floor</a>, or an <a href="https://metro.co.uk/2020/03/05/buses-blasted-uv-light-rid-coronavirus-12352400/">entire bus</a> in China. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mobile-phones-are-covered-in-germs-disinfecting-them-daily-could-help-stop-diseases-spreading-135318">Mobile phones are covered in germs. Disinfecting them daily could help stop diseases spreading</a>
</strong>
</em>
</p>
<hr>
<p>The technology needed to generate UVC is <a href="https://www.nature.com/articles/s41598-018-21058-w">not new</a> and there is no reason to suggest this technology could not be implemented cost-effectively. Several companies have developed <a href="https://www.forbes.com/sites/forbes-personal-shopper/2020/04/02/these-uv-sanitizers-can-kill-off-bacteria-and-viruses-including-the-coronavirus-that-caused-covid-19/#70a07e886b03">an array</a> of lamps, machines and even robots capable of sterilising a range of surfaces. </p>
<h2>Isn’t it dangerous?</h2>
<p>It’s well established UV radiation is <a href="https://www.cancer.org/cancer/cancer-causes/radiation-exposure/uv-radiation.html#:%7E:text=Based%20on%20the%20available%20data,UVC">carcinogenic</a> (causes cancer) for humans. </p>
<p>Devices that emit UVC should be calibrated to ensure optimal microbial killing power and are more effective when placed close to the surface or object being treated. When turned off, UVC emission <a href="https://www.arpansa.gov.au/sites/default/files/legacy/pubs/rps/rps12_Supplementary_Information_Artificial_Sources.pdf">is halted</a>, too.</p>
<p>As per the World Health Organisation’s advice, <a href="https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/myth-busters#uv">direct UVC exposure</a> should not be used to disinfect any areas of the skin. Studies are underway to identify particular UVCs that are safe for human cells and still worthwhile as germicides. </p>
<p>Far-UVC (wavelengths between 207-222 nanometres) <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0138418">is promising</a> as it can’t cross physiological barriers, such as the dead outer layer of our skin, or the eye’s outer (tear film) layer.</p>
<p>Nonetheless, UVC still poses risks to our health since our skin and eyes can have cuts and micro-lesions. This would expose susceptible cells in our body to the damaging radiation.</p>
<h2>Can it kill COVID-19?</h2>
<p>Our knowledge of what constitutes “suitable” UVC emission is growing. This includes knowledge of the proper germicidal UVC wavelength that can be applied to surfaces, the amount of light that reaches the surface, and the exposure time needed to completely sterilise the viral particles. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7112912/">Research</a> from 2002 confirmed UVC inactivated SARS (severe acute respiratory syndrome) after six minutes of exposure.</p>
<p>A <a href="https://www.medrxiv.org/content/10.1101/2020.06.05.20123463v1.full.pdf">more recent study</a> (while not peer-reviewed) has shown UVC-based disinfection is helpful for stopping the SARS-CoV-2 virus from replicating. However, this depended on how much of the virus was present and how much UVC exposure it received. </p>
<p>The study centred on the efficiency of UVC to inactivate and inhibit the virus at low, medium and high concentrations. It found the highest viral concentrations required quite high UVC dosage. </p>
<p><a href="https://www.medrxiv.org/content/10.1101/2020.04.02.20051409v1.full.pdf">Another study</a> looking at a different type of coronavirus (SARS-CoV-1) provided further evidence of the utility of UVC disinfection. The authors of this work suggest UV technology may be the solution to filling gaps in the supply of personal protective equipment such as masks.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-a-virus-how-do-they-spread-how-do-they-make-us-sick-133437">What is a virus? How do they spread? How do they make us sick?</a>
</strong>
</em>
</p>
<hr>
<h2>Overcoming major hurdles</h2>
<p>Apart from being carcinogenic, another limitation on using UVC is its poor penetration. It only allows surface-level sterilisation of microbes (such as viruses, bacteria and fungi) by impacting their genetic material. </p>
<p>That said, as the pandemic continues, the deployment of UVC sanitising technology across sectors could greatly contribute to our awareness of the risks presented by microbial pathogens. </p>
<p>The safe implementation of UVC-based measures could undoubtedly enhance public health and even biosecurity. Beyond the novel coronavirus, this arsenal has great potential to prevent costly impacts of future pandemics, too. </p>
<p>But, while enthusiasm is high, there are obvious risks of direct exposure to humans, with consequences ranging from serious burns to cancer. These will need to be carefully managed.</p><img src="https://counter.theconversation.com/content/142277/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Lotti Tajouri is a member of both Dubai Police Scientist Council and Dubai Future Council on Community Security (United Arab Emirates).</span></em></p><p class="fine-print"><em><span>Mariana Campos is affiliated with the Australian Plant Biosecurity Science Foundation.. </span></em></p><p class="fine-print"><em><span>Rashed Alghafri is affiliated with Dubai Police.
Rashed Alghafri is affiliated with Dubai Police Scientists Council.
Rashed Alghafri is affiliated with Dubai Future Council on Community Security.
</span></em></p><p class="fine-print"><em><span>Simon McKirdy does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>UVC radiation is effective for disinfecting objects and surfaces. It could help manage the coronavirus pandemic and fill gaps in PPE supplies.Lotti Tajouri, Associate Professor, Genomics and Molecular Biology; Biomedical Sciences, Bond UniversityMariana Campos, Lecturer and Researcher, Harry Butler Institute, Murdoch UniversityRashed Alghafri, Honorary Adjunct Associate Professor, Health Sciences and Medicine, Bond UniversitySimon McKirdy, Professor of Biosecurity, Murdoch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/959382019-01-09T19:11:50Z2019-01-09T19:11:50ZHow the right lighting could save the Mona Lisa<figure><img src="https://images.theconversation.com/files/249187/original/file-20181206-128199-1bc3u15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lighting causes damage to paintings over time. </span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/DCIncuh0XbY">Juan Di Nella/Unsplash</a></span></figcaption></figure><p>Next time you’re in a museum or art gallery, observe each painting a little more closely. You may notice cracks on the surface of the canvas, especially if the painting is very old. </p>
<p>The damage you see is caused by radiant energy striking the painting’s surface – and light (visible radiation) causes irreversible damage to artwork.</p>
<p>However, all is not lost. <a href="https://doi.org/10.1080/15502724.2018.1533852">Our new research</a> shows that optimised smart lighting systems can reduce damage to paintings while preserving their colour appearance. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/terahertz-spectroscopy-the-new-tool-to-help-detect-art-fraud-77173">Terahertz spectroscopy: the new tool to help detect art fraud</a>
</strong>
</em>
</p>
<hr>
<h2>The dilemma</h2>
<p>Damage to artwork by infrared, ultraviolet and visible radiation is <a href="http://www.cie.co.at/publications/control-damage-museum-objects-optical-radiation">well documented</a>. When a photon (an elementary light particle) is absorbed by a pigment in paint, the pigment molecule elevates to a higher energy state. In this excited state, the molecule’s chemical composition changes. This is called a photochemical action. </p>
<p>Viewed from the human perspective, the photochemical action manifests itself as cracks, discolouration, or surface hardening. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=673&fit=crop&dpr=1 600w, https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=673&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=673&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=846&fit=crop&dpr=1 754w, https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=846&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/249191/original/file-20181206-128208-h0dq28.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=846&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Johannes Vermeer painted The Milkmaid in 1660.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/milkmaid-by-johannes-vermeer-1660-dutch-411416362?src=Do8T0Wf9OQ1JATiVB6PnKw-1-17">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>Not surprisingly, daylight, which includes infrared and ultraviolet radiation, is highly damaging to paintings. In museums, it is common practice to use incandescent, and more recently, light emitting diodes (LEDs), to reduce damage. </p>
<p>However, a group of researchers <a href="http://www.vangogh.ua.ac.be/">showed</a> that light can cause colour degradation regardless of the lighting technology. Bright yellow colours in Van Gogh’s famous Sunflowers are turning dark brown due to absorption of blue and green light from LEDs. Research on the conservation of artwork makes it look like this is a losing battle. </p>
<p>Of course, you will be right in thinking that the best conservation method would be the complete absence of light. But we need light for visibility and to appreciate the beauty of a painting. </p>
<p>This leaves us with a dilemma of two conflicting parameters: visibility and damage. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-does-glow-in-the-dark-paint-work-92438">Curious Kids: How does glow in the dark paint work?</a>
</strong>
</em>
</p>
<hr>
<h2>Light optimisation</h2>
<p>Lighting technology in itself may not be enough to tackle this dilemma. However, the way we use technology can make a difference. </p>
<p>Our approach to address this problem is based on three key facts: </p>
<ol>
<li>light triggers photochemical actions only when it is absorbed by a pigment</li>
<li>the reflectance factor of a pigment (its effectiveness in reflecting light) determines the amount of light absorption</li>
<li>light output (composition of the light spectrum, and the intensity of the light) of lighting devices, such as LEDs, can be fine-tuned. </li>
</ol>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/249193/original/file-20181206-128193-1835fm2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Yellow colours are particularly vulnerable to being damaged by light.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/old-painting-cracked-texture-183476567?src=jrn42ol2Z0PZEk5uu9EFQw-1-7">from www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>It is possible to measure the reflectance factor of a painting and optimise lighting to reduce absorption. Previous research <a href="https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-11-A456">shows</a> that optimising light to lessen absorption can reduce energy consumption significantly, and with <a href="https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-11-12839">no loss</a> in visual experience. Objects look equally natural and attractive under optimised light sources compared to regular white light sources. </p>
<p>In this new study, we optimised LEDs for five paintings to reduce light absorption. Using a <a href="https://ieeexplore.ieee.org/abstract/document/996017">genetic algorithm</a> (an artificial intelligence technique), we reduced light absorption between 19% and 47%. Besides the benefits for the painting, this method almost halved the energy consumed by lighting. </p>
<p>In addition to increased sustainability and art conservation, the colour quality of the paintings was another parameter in our optimisation process. Colour appearance and brightness of paintings were held constant not to lower the appreciation of the artwork. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-eye-disorders-may-have-influenced-the-work-of-famous-painters-92830">How eye disorders may have influenced the work of famous painters</a>
</strong>
</em>
</p>
<hr>
<p>This is possible due to a quirk in our visual system. Photoreceptor cone cells, the cells in our retinas which enable human colour vision, are not equally sensitive to the whole visible spectrum. </p>
<p>Different combinations of wavelength and intensity can result in identical signals in our brain. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1331666/?page=1">This understanding</a> gives us the flexibility of using different light sources to facilitate identical colour appearances. </p>
<p>This smart lighting system requires scanning of the artwork to obtain colour information. Then, a <a href="https://doi.org/10.1117/12.2281482">precise projection system</a> emits optimised lighting to the painting. </p>
<p>This method offers a solution to extend the lifetime of works of art, such as the world-famous Mona Lisa, without leaving them in the dark.</p><img src="https://counter.theconversation.com/content/95938/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dorukalp Durmus does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Researchers have found a way to reduce light damage to artworks by up to 47% by optimising LEDs to prevent light from being absorbed by the artwork.Dorukalp Durmus, Honorary Associate, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/955722018-04-26T10:38:41Z2018-04-26T10:38:41ZMother’s milk holds the key to unlocking an evolutionary mystery from the last ice age<figure><img src="https://images.theconversation.com/files/216345/original/file-20180425-175050-1rnqanl.jpg?ixlib=rb-1.1.0&rect=550%2C202%2C3315%2C2231&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sunrise at noon in the Arctic. Little exposure to sun was a piece of the genetic puzzle.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Winter_Solstice_noon_sunrise_on_the_Bering_Sea_(8433692952).jpg">Bering Land Bridge National Preserve</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>As biologists explore the variation across the genomes of living people, they’ve found evidence of evolution at work. Particular variants of genes increase or decrease in populations through time. Sometimes this happens by chance. Other times these changes in frequency result from the gene’s helping or hindering individuals’ survival, a <a href="https://www.amnh.org/exhibitions/darwin/evolution-today/how-does-natural-selection-work">phenomenon known as selection</a>. If a gene conferred a survival advantage, people with the mutation would have more offspring and the mutation would become more common in subsequent generations.</p>
<p>Most of those past <a href="https://evolution.berkeley.edu/evolibrary/article/evo_25">episodes of selection</a> make sense, as they worked on genes involved with things like <a href="https://www.nature.com/scitable/topicpage/natural-selection-uncovering-mechanisms-of-evolutionary-adaptation-34539">resisting disease</a>, <a href="https://news.nationalgeographic.com/news/2004/02/0224_040225_evolution.html">blood oxygen levels at high altitudes</a>, and having <a href="https://www.nature.com/scitable/topicpage/evolutionary-adaptation-in-the-human-lineage-12397">paler skin at northern latitudes</a>.</p>
<p>However, researchers have also identified an episode of strong selection that doesn’t have such an obvious logic. It’s a mutation on a gene involved with the development of a suite of traits that don’t seem very similar at first glance: hair, teeth, sweat glands and breasts. This one was a mystery — what could have been the adaptive value of this mutation that led to it being common in northeastern Asia but nowhere else?</p>
<p><a href="https://scholar.google.com/citations?user=2B6GhHoAAAAJ&hl=en&oi=ao">My research</a> usually focuses on teeth, specifically genetic influences on their development. I came to this particular evolution puzzle when my colleagues and I gathered in Boston at the AAAS meeting last year to discuss the latest evidence of how people first migrated into the Western Hemisphere. We put together the clues about this episode of selection on human genetic variation – and found an example of <a href="https://doi.org/10.1073/pnas.1711788115">adaptation to life at high latitude during the last ice age</a>.</p>
<h2>Natural selection … of what?</h2>
<p>We were trying to understand selection for a mutation in the gene called EDAR – it encodes the ectodysplasin A receptor that plays a role in how tightly cells adhere to each other during the development of hair, teeth, sweat glands and breasts. All of these anatomical structures form via a very similar developmental process that happens while you’re still in your mother’s womb. Slight changes to the developmental mechanism results in the final differences between hair and teeth and sweat and mammary glands. But there is a fundamental similarity that, among other things, includes the activity of EDAR. </p>
<p>This shared development is especially obvious when things go wrong. For example, 1 in 10,000 newborns have a disorder called <a href="https://www.nfed.org/learn/">ectodermal dysplasia</a>, which causes disruption to the development of their hair, teeth, skin, sweat glands and breasts.</p>
<p>The V370A mutation that we focused on, the one that experienced strong selection, doesn’t disrupt development of these structures; rather, it augments them. People with V370A have thicker and straighter hair shafts, and their incisors have extra buttressing on the tongue side – a feature biologists call “shoveling.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216342/original/file-20180425-175035-1jkd39w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Human upper incisors with significant ‘shoveling’ on the tongue side.</span>
<span class="attribution"><span class="source">Christy G. Turner, II, courtesy G. Richard Scott</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>So why did this mutation provide such an advantage to people who carried it? Mice that have been experimentally induced to have the V370A mutation have thicker fur shafts and increased density of sweat glands. A previous study of modern human genomic variation <a href="https://doi.org/10.1016/j.cell.2013.01.016">interpreted the selection</a> to have occurred in northern China during the last ice age and focused on the sweat glands. The researchers suggested that the selection was for improved sweating that could help with regulating body temperature. But to my colleagues and me, that just didn’t feel like a convincing adaptive scenario given that this took place during the (cold) ice age. </p>
<p>Instead of the sweat glands, our attention was drawn to another trait. Mice with the V370A mutation also have an increase in the branching of their mammary ducts – the tiny tubes that intertwine with breast tissue and extract nutrients to make milk. Maybe it was this change in the breast tissue that was so valuable to people with this mutation?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216356/original/file-20180425-175058-ebxo40.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Christy G. Turner II, shown working in 1975, and his students assessed variation in incisor shoveling in over 30,000 people around the world. The current study relied on a subset of these data collected by co-author G. Richard Scott.</span>
<span class="attribution"><span class="source">G. Richard Scott and Joshua P. Carlson</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Rather than trying to sample DNA from thousands of ancient people’s remains to see if they carried the mutation, we took advantage of the effect V370A has on human incisors. Relying on data collected over many years by my colleague <a href="https://scholar.google.com/citations?user=vtkFh8kAAAAJ&hl=en&oi=ao">G. Richard Scott</a> from the University of Nevada, Reno, our group looked at the dental variation of over 5,000 skeletons from archaeological sites in Europe, Asia and the Americas to get a sense of how this mutation varied through time.</p>
<p><a href="https://doi.org/10.1073/pnas.1711788115">We found that</a> all of the indigenous people living in the Western Hemisphere prior to European colonization had shovel-shaped incisors, which means they all likely had the V370A mutation. In contrast, only about 40 percent of the people in Asia had shovel-shaped incisors, and essentially no one in Europe did.</p>
<p>This pattern suggests that a population ancestral to Native Americans experienced the strong selection for V370A, an interpretation that differed from what my colleagues found when they only looked at genomic variation in living people. Using these ancient teeth, we were able to figure out when and where the selection happened. The next question we needed to address was why this selection occurred. What was going on to make this mutation so helpful and thus so much more prevalent?</p>
<h2>An ice age advantage</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216339/original/file-20180425-175047-1aqtxmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Beringia outlined over today’s Siberia and Alaska.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:BeringiaMap-NPSgov.jpg">U.S. National Park Service</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1371/journal.pone.0000829">Previous genetic work</a> found that Native Americans descend from a common ancestral population that lived in Beringia, the region that links Siberia and Alaska. During the dramatic climate change associated with the last ice age 28,000 to 18,000 years ago, plants and animals that had previously lived in Siberia took refuge in a circumscribed area called the Beringian Refugium. For about 5,000 years, they were genetically isolated from other populations because of a vast dry tundra to the west and a lot of ice to the east. <a href="https://doi.org/10.1002/evan.21478">The people who found haven there too</a> are referred to as the Beringian Standstill population.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=363&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=363&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=363&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216343/original/file-20180425-175050-1gs4hbz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Modern-day mesic shrub tundra near the northwestern Alaskan town of Kotzebue is similar to what the environment would have been like in Beringia during the ice age.</span>
<span class="attribution"><span class="source">Scott Elias</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>It’s not easy to live that far north. Sure, it’s cold. But more importantly, at high latitudes the sun is lower in the sky so sunlight must travel through more atmosphere to reach Earth’s surface. This journey through the atmosphere mostly filters out the Sun’s ultraviolet radiation. Most life forms need sun exposure to be healthy, in large part <a href="https://doi.org/10.1016/j.pbiomolbio.2006.02.016">because UV exposure induces</a> the <a href="https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-20363792">body to make vitamin D</a>.</p>
<p><a href="https://doi.org/10.1073/pnas.0914628107">Lighter skin tones let in more UV</a> and have been selected for multiple times in human history. But once you get to the Arctic, skin depigmentation alone won’t suffice. In order to live with so little UV, people have culturally innovated, <a href="http://scienceline.org/2007/06/ask-dricoll-inuiteskimos/">eating diets rich in vitamin D</a>, such as oily fish. But nursing infants don’t eat these foods. Babies get their nutrients through their mother’s milk.</p>
<p>This is where our EDAR gene comes back into the picture. The V370A mutation in mice increases the branching density of the mammary ducts, and very likely does the same exact thing in human breasts. Scientists know that vitamin D deficient conditions <a href="https://doi.org/10.1016/j.jsbmb.2015.09.035">induce more ductal branching</a> during the breast development that happens with pregnancy. All of the evidence suggests that the increased ductal branching associated with V370A helped transfer nutrients from mother to infant through breast milk in a population that was extremely vitamin D deficient. </p>
<p>So the selection wasn’t for thicker hair or shovel-shaped incisors – instead, it was much more likely to have been on mammary ducts. The thicker hair and tooth variation just went along for the ride because they are created by the same basic developmental pathway. Selection on genetic variation in EDAR is probably related to health consequences for nursing infants rather than its effects on hair, teeth or sweat glands.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/216350/original/file-20180425-175061-1dkjjzs.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Excavation of a site occupied in Beringia 32,000 years ago.</span>
<span class="attribution"><span class="source">V. V. Pitul'ko & E. Yu. Pavlova</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Still traceable genetic inheritance</h2>
<p>Once the Earth started warming up at the end of the last ice age, those ice sheets started to melt, sea level rose and global climate became more humid. The people living in Beringia needed to move again. Some went east, populating the Western Hemisphere rapidly and extensively. Some went west, merging back into populations that were living in northern and eastern Asia. Scientists see traces of this migration today. The occurrence of incisor shoveling <a href="https://doi.org/10.1002/ajpa.1330740316">decreases as you move away from the Arctic</a>, there is <a href="https://doi.org/10.1371/journal.pone.0091722">evidence of a long-lost language</a>, and some of those Beringian Standstill mitochondrial DNA mutations <a href="https://doi.org/10.1371/journal.pone.0000829">can be found in Asian populations</a>.</p>
<p>Today, everyone with shovel-shaped incisors carries a little remnant of this ephemeral population with them and a reminder of the importance of the maternal-infant bond to human survival.</p>
<p>But they also have the other effects of the V370A mutation. The increase in mammary ductal branching seems likely to influence the transfer of nutrients from breast tissue into milk. It may also play a role in susceptibility to breast cancer, given that <a href="https://doi.org/10.2214/AJR.06.0619">breast density differs</a> between Asian and non-Asian women as does the <a href="https://doi.org/10.1093/jnci/djv048">occurrence of breast cancer</a>, a relationship that matches the distribution of V370A around the world today.</p>
<p>These ideas present exciting hypotheses to test in future studies. For now, our research shows that the bones of our ancestors can provide evidence of human adaptation, evidence that shifts our understanding of how genes work.</p><img src="https://counter.theconversation.com/content/95572/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leslea Hlusko does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Why was one gene mutation that affects hair, teeth, sweat glands and breasts ubiquitous among ice age Arctic people? New research points to the advantage it provided for ancestors of Native Americans.Leslea Hlusko, Associate Professor of Integrative Biology, University of California, BerkeleyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/903172018-02-15T04:54:53Z2018-02-15T04:54:53ZI’ve always wondered: do fluorescent lights emit UV, and can it harm me?<figure><img src="https://images.theconversation.com/files/204190/original/file-20180131-38198-nnniki.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fluorescent lights do emit UV, but not enough to harm human health. </span> <span class="attribution"><span class="source">from www.shutterstock.com</span></span></figcaption></figure><p><em>This is an article from I’ve Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to alwayswondered@theconversation.edu.au</em></p>
<hr>
<p><strong>I’ve always wondered, should I be concerned about experiencing UV damage from fluorescent lights? Am I at risk of skin cancer or premature ageing if I work in an office building lit with fluorescent lights? – Damien, Canberra, 26</strong></p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257661/">Ultraviolet radiation</a> is the highest-energy component of the Sun’s rays that reach the Earth’s surface. UV light stimulates the synthesis of vitamin D, which is an essential compound for growth of bones and teeth, as well as improved resistance against certain diseases. </p>
<p>On the other hand, too much UV radiation is the main cause of melanoma, which is a malignant form of skin cancer. This is why you’ve always been advised to protect your skin with sunscreen. </p>
<p>But what about the lights indoors? Do fluorescent lights also emit UV?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-always-wondered-whats-behind-the-belly-button-84598">I've always wondered: what's behind the belly button?</a>
</strong>
</em>
</p>
<hr>
<p>The best way to find the answer is to firstly understand how fluorescent lights work. Inside the bulb, electrical discharge excites a gas (usually neon or mercury vapour in argon), which emits ultraviolet radiation. But the ultraviolet radiation is not visible to human eyes and must be converted into visible light. This is done by the light’s interior fluorescent coating, which is able to absorb most of the UV radiation and emit lower-energy wavelengths in the visible spectrum.</p>
<p>But some UV rays get through the bulb, especially if the bulb’s internal coating is cracked, allowing more UV light to pass through. In fact many types of lighting used in our homes emit small amounts of UV radiation. </p>
<p>But according to the Australian Radiation Protection and Nuclear Safety Agency (<a href="https://www.arpansa.gov.au/sites/g/files/net3086/f/legacy/pubs/factsheets/CompactFluorescentLightsandHealth.pdf">ARPANSA</a>), the UV emissions from most indoor light sources, including fluorescent lights, are below the approved Australian limits. This means they won’t cause any risk to health for normal people, if we use them properly. </p>
<h2>Safe distances</h2>
<p>The emissions from all sources of light decrease rapidly with distance. At a typical use distance (more than 25cm), the UV light emitted from fluorescent lights <a href="https://www.arpansa.gov.au/sites/g/files/net3086/f/legacy/pubs/factsheets/CompactFluorescentLightsandHealth.pdf">falls below the level of general concern</a> for healthy individuals. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-always-wondered-why-do-our-computing-devices-seem-to-slow-down-85390">I’ve always wondered: why do our computing devices seem to slow down?</a>
</strong>
</em>
</p>
<hr>
<p>The only exception is a <a href="https://www.ncbi.nlm.nih.gov/pubmed/21535166">medical condition that makes you particularly sensitive</a> to UV light. The vast majority of people do not suffer from such UV or visible light sensitivities.</p>
<h2>Exposure time</h2>
<p>The longer the exposure time, the higher the UV dosage absorbed by the skin. At a measurement distance of 10cm, an exposure time of less than eight hours would be safe for almost all types of lights. </p>
<p><a href="https://www.arpansa.gov.au/sites/g/files/net3086/f/legacy/pubs/factsheets/CompactFluorescentLightsandHealth.pdf">Compare this to the permissible exposure limits</a> (PELs) in typical midday summer sunshine, which is six minutes in Brisbane and seven minutes in Sydney and Melbourne.</p>
<p>The UV level absorbed by our skin after eight hours’ exposure to indoor lights, at a typical use distance (25cm), would be <a href="http://easilygreen.com.au/fluorescent-vs-led-lights-10-problems-to-consider-with-fluorescent-lights/">equivalent to just over a minute of midday solar exposure</a> on a clear summer day in a city such as Sydney or Melbourne. This shows the risk to us is very small indeed.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-always-wondered-why-do-our-veins-look-blue-when-our-blood-is-red-83143">I've always wondered: why do our veins look blue when our blood is red?</a>
</strong>
</em>
</p>
<hr>
<h2>Does the fluorescent tube have a cover?</h2>
<p>If you have to spend a lot of time under fluorescent light, make sure fluorescent bulbs have plastic diffusers over them. The glass and the coating inside the glass used in fluorescent lights already provide a UV filter, which further reduces the already low levels of UV. </p>
<p>So, if a standard fluorescent tube lighting source is shielded by a standard acrylic plastic diffuser, there’s rarely a risk for human health, even for people who are affected by light sensitivity.</p>
<hr>
<p><em>* Email your question to alwayswondered@theconversation.edu.au
<br>
* Tell us on <a href="https://twitter.com/ConversationEDU">Twitter</a> by tagging <a href="https://twitter.com/ConversationEDU">@ConversationEDU</a> with the hashtag #alwayswondered, or
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* Tell us on <a href="http://www.facebook.com/conversationEDU">Facebook</a></em></p><img src="https://counter.theconversation.com/content/90317/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Noushin Nasiri does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The internet conspiracists are half right: most lights we have inside do emit UV, but not enough to harm us.Noushin Nasiri, Postdoctoral Research Fellow, School of Mathematical and Physical Sciences, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/916982018-02-14T14:24:36Z2018-02-14T14:24:36ZWhite nose syndrome is killing millions of bats via a contagious fungus – here’s how to stop it<figure><img src="https://images.theconversation.com/files/206367/original/file-20180214-174977-lbi6cn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/governmentofalberta/22414730957">Government of Alberta/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>A dangerous fungus has been sweeping across North America with devastating consequences. In the past decade, between 5m and 7m bats in the US and Canada have been wiped out as a result of the fungal disease known as white nose syndrome, which alters their behaviour in potentially deadly ways. But the <a href="https://www.nature.com/articles/s41467-017-02441-z">latest research</a> shows there might be hope for researchers trying to battle the disease, following the discovery that UV light appears to destroy the fungus’s DNA.</p>
<p>White nose syndrome is caused by the fungus <em>Pseudogymnoascus destructans</em>, which grows on the bats’ muzzles (hence the name) and other hairless body parts including wings, and <a href="https://bmcbiol.biomedcentral.com/articles/10.1186/1741-7007-8-135">causes skin lesions</a>. <em>P. destructans</em> is psychrophilic, meaning it thrives in cold temperatures between 4°C and 20°C. This means it affects bats during hibernation.</p>
<p>The itchy, painful lesions cause infected bats to repeatedly wake from hibernation, leaving them confused and causing them to display <a href="http://www.batcon.org/our-work/regions/contact-bci/usa-canada/white-nose-syndrome">highly unusual behavior</a>, such as flying outside during daylight in nearly freezing temperatures. The cold, lack of food and abnormal activity leads to bats depleting their winter fat reserves, and starving, dehydrating or freezing to death. As a result, the disease can kill between <a href="https://www.nature.com/news/2010/100113/full/463144a.html">90% and 100%</a> of bats in affected hibernating colonies.</p>
<p>Out of the 47 bat species native to the US and Canada, over half rely on hibernation for survival. <a href="https://www.whitenosesyndrome.org/about/bats-affected-wns">Nine of these species</a> (including two endangered and one threatened) already show symptoms of white nose syndrome. <em>P. destructans</em> has also been found in another six species (including one endangered) that don’t yet show symptoms. The little brown bat (<em>Myotis lucifugus</em>), once the most common bat in North America, is now predicted to face <a href="http://science.sciencemag.org/content/329/5992/679">regional extinction</a>.</p>
<p>Bats normally live a long time and produce only a single pup each year, so affected species are unlikely to recover quickly. Not only is this bad for biodiversity, but it could also have a serious economic impact on humans. In temperate regions, bats eat up to 600 insects a night and so provide a vital pest-control service for North American farmers, effectively worth <a href="http://science.sciencemag.org/content/332/6025/41">US$3.7 billion a year</a>.</p>
<h2>How did this bat-astrophe come about?</h2>
<p><em>P. destructans</em> has probably co-existed with bats in Eurasia for <a href="https://www.nature.com/articles/s41467-017-02441-z">millions of years</a>. As a result, these bats have evolved defences against the fungus. So in this part of the world, despite the occasional mild outbreak of white nose syndrome, the disease <a href="http://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(11)00192-3">doesn’t significantly impact entire groups of bats</a>. But when <em>P. destructans</em> was introduced to the previously unexposed American bats, the effects were disastrous.</p>
<p>White nose syndrome was discovered in North America <a href="http://science.sciencemag.org/content/323/5911/227">in 2006</a>. We know that the fungus was most likely spread by human activity because the North American fungus is <a href="https://www.sciencedirect.com/science/article/pii/S0960982215000792">almost genetically identical</a> to some of the samples found in Europe. Also, bats don’t migrate between the two continents and some of the distances between contaminated caves in the US are longer than the flying range of affected bats. On top of that, the first reports of white nose syndrome came from a <a href="https://wwwnc.cdc.gov/eid/article/16/8/10-0002_article">popular tourist cave near Albany, New York</a>. So the fungus probably spread via contaminated clothing and caving equipment from tourists visiting affected areas.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/206369/original/file-20180214-175001-nyeuec.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Checking for white nose syndrome.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/wildlife-biologist-checking-wings-big-brown-797424433">Shutterstock</a></span>
</figcaption>
</figure>
<p>Since then, white nose syndrome has become one of the most severe wildlife diseases ever recorded. Yet there may literally be a light at the end of the tunnel. A <a href="https://www.nature.com/articles/s41467-017-02441-z">research team from the US Forest Service</a> has discovered that <em>P. destructans</em> is extremely sensitive to ultra-violet light, particularly to UV-C light that kills germs but doesn’t cause skin cancer. They found that moderate doses of UV-C light killed over 99% of the fungus, and that even low doses killed 85%.</p>
<p>The effect is so potent because UV light destroys the fungus’s DNA, and, unlike <a href="https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-15-6">related fungi</a>, <em>P. destructans</em> can’t repair the damage. Further tests are on the way to check whether UV light causes any damage to the bats themselves. But the fact that UV-C light has already been used in treatments of <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2133.2008.08549.x/abstract;jsessionid=DACFFB496B5103A02CDAC89BD89CB96F.f01t02">other fungal infections</a> in mammals means the discovery is very promising.</p>
<p>Managing wildlife diseases can be difficult and expensive. Think of how hard it would be to apply fungicide skin cream to tens of thousands of bats hanging from the top of a cave. But shining a simple hand-held UV-C light source on them would be much easier. So this research could have huge implications for protecting North American bats.</p><img src="https://counter.theconversation.com/content/91698/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanna M. Bagniewska does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Ultra-violet (UV) light can destroy a fungus that’s devastating the animals in North America.Joanna M. Bagniewska, Teaching Fellow in Zoology and Ecology, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/818032017-09-15T10:21:37Z2017-09-15T10:21:37ZSeeds in space – how well can they survive harsh, non-Earth conditions?<figure><img src="https://images.theconversation.com/files/185909/original/file-20170913-18075-165yqah.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Spend many months attached to the ISS and see how well you grow.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/station/research/experiments/1674.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Will we someday colonize space? Will our children visit other planets? To achieve goals like these, we’ll need to crack one crucial challenge: how to feed ourselves for long periods away from Earth.</p>
<p>A <a href="http://www.mars-one.com/faq/mission-to-mars/how-long-does-it-take-to-travel-to-mars">trip to Mars would take months</a>, and exploring the depths of the galaxy would take even longer. Provision of nutritious food for travelers is a significant obstacle. While stockpiling food is an option, storing enough to last many months strains weight and space limitations in spacecraft – and missions could easily outlast food shelf life. Growing food in space will be essential.</p>
<p>Essential – and not necessarily easy. The conditions in the vacuum of space are quite harsh compared to Earth. Seeds in space must be able to withstand large doses of ultraviolet and cosmic radiation, low pressure and microgravity. </p>
<p>Believe it or not, the first space travelers were seeds. In 1946, <a href="https://www.nasa.gov/pdf/449089main_White_Sands_Missile_Range_Fact_Sheet.pdf">NASA launched a V-2 rocket carrying maize</a> seeds to observe how they’d be affected by radiation. Since then, the scientific community has learned <a href="https://doi.org/10.1079/SSR200193">a great deal</a> about the effects of the space environment on seed <a href="https://doi.org/10.1016/j.asr.2011.05.017">germination</a>, <a href="https://doi.org/10.1016/0273-1177(86)90076-1">metabolism</a>, <a href="https://doi.org/10.1016/j.asr.2005.06.043">genetics</a>, <a href="http://journal.ashspublications.org/content/130/6/848.short">biochemistry</a> and even <a href="https://doi.org/10.1016/S0273-1177(03)00250-3">seed</a> <a href="https://doi.org/10.1016/j.actaastro.2006.09.009">production</a>. </p>
<p>Astrobiologists David Tepfer and Sydney Leach recently investigated <a href="https://doi.org/10.1089/ast.2015.1457">how seeds would do back on Earth</a> after spending extended periods on the International Space Station. The experiments they conducted on the <a href="https://www.nasa.gov/mission_pages/station/research/experiments/696.html">EXPOSE</a> <a href="https://www.nasa.gov/mission_pages/station/research/experiments/211.html">missions</a> were much longer than many other ISS seed experiments, and placed the seeds on the outside of the station, in the dead of space, rather than inside. The goal was to understand not only the effects of long-term radiation exposure, but a bit about the molecular mechanisms of those effects.</p>
<h2>Seeds have some defenses</h2>
<p>Seeds possess a couple of remarkable traits that Tepfer and Leach hypothesized would give these “model space travelers” a fighting chance.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=722&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=722&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185911/original/file-20170913-20280-41e1zd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=722&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seeds protect their important insides with a strong external seed coat.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Dycotyledon_seed_diagram-en.svg">LadyofHats</a></span>
</figcaption>
</figure>
<p>First, they contain multiple copies of important genes – what scientists call redundancy. Genetic redundancy is common in flowering plants, especially food products such as <a href="https://www.sciencedaily.com/releases/2014/09/140930090636.htm">seedless watermelon and strawberries</a>. If one genetic copy is damaged, there’s still another available to do the job.</p>
<p>Secondly, seed coats contain chemicals called flavonoids that act as sunscreens, protecting the seed’s DNA from damage by ultraviolet (UV) light. On Earth, our planet’s atmosphere filters out some harmful UV light before it can reach us. But in space, there is no protective atmosphere.</p>
<p>Would these special features be enough to let the seeds survive or even thrive? To find out, Tepfer and Leach conducted a series of experiments – both outside the International Space Station and back on Earth – with tobacco, <em>Arabidopsis</em> (a flowering plant commonly used in research) and morning glory seeds. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185905/original/file-20170913-20310-w6bmrn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The EXPOSE-R experiment attached to the exterior of the International Space Station.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/station/expeditions/expedition26/russian_eva27.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Bombarded with energy</h2>
<p>Their EXPOSE-E experiment flew to the International Space Station (ISS) in 2008 and lasted 558 days – so just under two years.</p>
<p>They stored the seeds in a single layer on the outside of the ISS behind a special kind of glass that let in ultraviolet radiation only at wavelengths between 110 and 400 nanometers. DNA readily absorbs UV radiation in this wavelength range. A second, identical set of seeds was on the ISS, but shielded completely from UV radiation. The purpose of this experimental design was to observe the effects of UV radiation separately from other types of radiation <a href="https://www.space.com/32644-cosmic-rays.html">like cosmic rays</a> that are everywhere in space.</p>
<p>Tepfer and Leach chose tobacco and <em>Arabidopsis</em> seeds for EXPOSE-E because both have a redundant genome and therefore good odds for survival. They also included a genetically engineered variety of tobacco with an antibiotic resistance gene added; the plan was to later test this gene in bacteria and determine if there was any damage. In addition to normal <em>Arapidopsis</em>, they sent up two genetically modified strains of the plant that contained low and absent UV-protective chemicals in their seed coat. They also sent purified DNA and purified flavonoids. This gave the researchers a wide range of scenarios by which to understand the effects of space on the seeds.</p>
<p>A second ISS mission called EXPOSE-R included only the three types of <em>Arabidopsis</em> seeds. These received a little over double the dose of ultraviolet light because of the longer experiment time, 682 days. Lastly, researchers performed a ground experiment back in the lab that exposed <em>Arabidopsis</em>, tobacco and morning glory seeds to very high doses of UV light for only a month.</p>
<p>After all these various exposure conditions, it was time to see how well the seeds could grow.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185907/original/file-20170913-20270-l4me1j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Expose-R experiment was equipped with three trays containing a variety of biological samples – including seeds.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/station/multimedia/exp18_eva2.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What would researchers reap?</h2>
<p><a href="https://doi.org/10.1089/ast.2015.1457">When the seeds returned to Earth</a>, the researchers measured their germination rates – that is, how quickly the root emerged from the seed coat.</p>
<p>The seeds that had been shielded in the lab did the best, with more than 90 percent of them germinating. Next came the seeds that had been exposed to UV radiation for one month in the laboratory, with better than 80 percent germinating. </p>
<p>For the space-traveling seeds, more than 60 percent of the shielded seeds germinated. A mere 3 percent of space UV-exposed seeds did.</p>
<p>The 11 <em>Arabidopsis</em> plants that did grow from both the wild type and genetically engineered seeds did not survive once planted in soil. Tobacco plants, however, showed reduced growth but that growth rate recovered in subsequent generations. Tobacco has a much heartier seed coat and a more redundant genome, which may explain its apparent survival advantage.</p>
<p>When the researchers plugged the antibiotic resistance gene into bacteria, they found it was still functional after its trip to space. That finding suggests it’s not genetic damage that’s making these seeds less viable. Tepfer and Leach attributed the reduced germination rate to damage to other molecules in the seed besides DNA – such as proteins. A redundant genome or built-in DNA repair mechanisms weren’t going to overcome that damage, further explaining why the <em>Arabidopsis</em> plants didn’t survive transplanting.</p>
<p>In the ground experiments, the researchers found that radiation damage is dose-dependent – the more radiation the seeds received, the worse their germination rate.</p>
<p>These discoveries could inform future directions for research in space agriculture. Scientists may consider genetically engineering seeds to have added protection for the cellular machinery critical for protein synthesis, such as ribosomes. Future research will also need to explore further how seeds stored in space germinate in microgravity, rather than on Earth.</p>
<p>As researchers add to the knowledge of how space affects plants and their seeds, we can continue to make the strides necessary toward producing food in space. It will be a crucial step toward sustainable colonies that can survive beyond the comfortable confines of Earth’s biosphere.</p><img src="https://counter.theconversation.com/content/81803/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gina Riggio is affiliated with Blue Marble Space.</span></em></p>If you want to live on Mars, you’re going to need to grow food. Seeds are naturally equipped to handle challenging Earth environments, but how well can they survive what they’ll encounter off-planet?Gina Misra, Ph.D. Student in Cell and Molecular Biology, University of ArkansasLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/743552017-05-26T01:32:59Z2017-05-26T01:32:59ZHow do the chemicals in sunscreen protect our skin from damage?<figure><img src="https://images.theconversation.com/files/171062/original/file-20170525-23230-m46xg5.jpg?ixlib=rb-1.1.0&rect=0%2C98%2C2000%2C1419&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Don't skimp on the SPF.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/toned-photo-kid-beach-smooth-skin-381581356">Sabphoto via Shutterstock.com</a></span></figcaption></figure><p>Not so long ago, people like my Aunt Muriel thought of sunburn as a necessary evil on the way to a “good base tan.” She used to slather on the baby oil while using a large reflector to bake away. Aunt Muriel’s mantra when the inevitable burn and peel appeared: Beauty has its price.</p>
<p>Was she ever right about that price – but it was a lot higher than any of us at the time recognized. What sun addicts didn’t know then was that we were setting our skin up for damage to its structural proteins and DNA. Hello, wrinkles, liver spots and cancers. No matter <a href="https://doi.org/10.1001/archderm.1988.01670060015008">where your complexion falls</a> on the <a href="http://www.skincancer.org/prevention/are-you-at-risk/fitzpatrick-skin-quiz">Fitzpatrick Skin Type</a> scale, ultraviolet radiation (UV) from the sun or tanning beds will damage your skin.</p>
<p>Today, recognition of the risks posed by UV rays has motivated scientists, myself included, to study what’s going on in our cells when they’re in the sun – and devise modern ways to ward off that damage.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=236&fit=crop&dpr=1 600w, https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=236&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=236&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=297&fit=crop&dpr=1 754w, https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=297&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/170967/original/file-20170525-23279-110s6q8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=297&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">UV light that affects our skin has a shorter wavelength than the parts of the electromagnetic spectrum we can see.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:EM_Spectrum_Properties_edit.svg">Inductiveload, NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>What happens when sun hits skin</h2>
<p>Sunlight is composed of packets of energy called photons. The visible colors we can see by eye are relatively harmless to our skin; it’s the sun’s ultraviolet (UV) light photons that can cause skin damage. UV light can be broken down into two categories: UVA (in the wavelength range 320-400 nanometers) and UVB (in the wavelength range 280–320 nm). </p>
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<p>Our skin contains molecules that are perfectly structured to absorb the energy of UVA and UVB photons. This puts the molecule into an energetically excited state. And as the saying goes, what goes up must come down. In order to release their acquired energy, these molecules undergo chemical reactions – and in the skin that means there are biological consequences.</p>
<p>Interestingly, some of these effects used to be considered helpful adaptations – though we now recognize them as forms of damage. Tanning is due to the production of <a href="https://www.derm101.com/inflammatory/embryologic-histologic-and-anatomic-aspects/melanocytes/">extra melanin pigment induced by UVA rays</a>. Exposure to the sun also turns on the skin’s natural antioxidant network, which <a href="http://www.nature.com/nchembio/journal/v10/n7/pdf/nchembio.1548.pdf">deactivates highly destructive reactive oxygen species (ROS) and free radicals</a>; if left unchecked, these can cause cellular damage and oxidative stress within the skin.</p>
<p>We also know that UVA light penetrates deeper into the skin than UVB, destroying a structural protein called collagen. As collagen degrades, our skin loses its elasticity and smoothness, leading to wrinkles. UVA is responsible for many of the visible signs of aging, while UVB light is considered the primary source of sunburn. Think “A” for aging and “B” for burning.</p>
<p>DNA itself can absorb both <a href="http://www.pnas.org/content/103/37/13765.short">UVA and UVB rays, causing mutations</a> which, if unrepaired, can lead to non-melanoma (basal cell carcinoma, squamous cell carcinoma) or <a href="https://doi.org/10.1126/science.1253735">melanoma skin cancers</a>. Other skin molecules pass absorbed UV energy on to those highly reactive ROS and free radicals. The resulting oxidative stress can overload the skin’s built-in antioxidant network and cause cellular damage. ROS can react with DNA, forming mutations, and with collagen, leading to wrinkles. They can also interrupt cell signaling pathways and gene expression.</p>
<p>The end result of all of these photoreactions is photodamage that accumulates over the course of a lifetime from repeated exposure. And – this cannot be emphasized enough — this applies to all skin types, from Type I (like Nicole Kidman) to Type VI (like Jennifer Hudson). <a href="http://www.skincancer.org/skin-cancer-information/skin-cancer-facts">Regardless of how much melanin we have in our skin</a>, we can develop UV-induced skin cancers and we will all eventually see the signs of photo-induced aging in the mirror.</p>
<h2>Filtering photons before the damage is done</h2>
<p>The good news, of course, is that the risk of skin cancer and the visible signs of aging can be minimized by preventing overexposure to UV radiation. When you can’t avoid the sun altogether, today’s sunscreens have got your back (and all the rest of your skin too).</p>
<p>Sunscreens employ UV filters: molecules specifically designed to help reduce the amount of UV rays that reach through the skin surface. A film of these molecules forms a protective barrier either absorbing (chemical filters) or reflecting (physical blockers) UV photons before they can be absorbed by our DNA and other reactive molecules deeper in the skin. </p>
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<p>In the United States, the Food and Drug Administration regulates sunscreens as drugs. Because we were historically most concerned with protecting against sunburn, <a href="http://dx.doi.org/10.1016/j.jaad.2010.01.005">14 molecules that block sunburn-inducing UVB rays</a> are approved for use. That we have just two UVA-blocking molecules available in the United States – avobenzone, a chemical filter; and zinc oxide, a physical blocker – is a testament to our more recent understanding that UVA causes trouble, not just tans.</p>
<p>The FDA also has enacted <a href="https://www.federalregister.gov/documents/2011/06/17/2011-14766/labeling-and-effectiveness-testing-sunscreen-drug-products-for-over-the-counter-human-use">strict labeling requirements</a> – most obviously about SPF (sun protection factor). On labels since 1971, SPF represents the relative time it takes for an individual to get sunburned by UVB radiation. For example, if it takes 10 minutes typically to burn, then, if used correctly, an SPF 30 sunscreen should provide 30 times that – 300 minutes of protection before sunburn. </p>
<p>“Used correctly” is the key phrase. Research shows that it takes about one ounce, or basically a <a href="https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs">shot glass-sized amount of sunscreen</a>, to cover the exposed areas of the average adult body, and a nickel-sized amount for the face and neck (more or less, depending on your body size). The majority of people apply between a <a href="https://www.ncbi.nlm.nih.gov/pubmed/12374537">quarter to a half of the recommended amounts</a>, placing their skin at risk for sunburn and photodamage.</p>
<p>In addition, sunscreen efficacy decreases in the water or with sweating. To help consumers, FDA now requires sunscreens labeled <a href="https://www.federalregister.gov/documents/2011/06/17/2011-14766/labeling-and-effectiveness-testing-sunscreen-drug-products-for-over-the-counter-human-use">“water-resistant” or “very water-resistant”</a> to last up to 40 minutes or 80 minutes, respectively, in the water, and the <a href="https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs">American Academy of Dermatology</a> and other medical professional groups <a href="https://www.cancer.org/cancer/skin-cancer/prevention-and-early-detection/uv-protection.html">recommend reapplication immediately after any water sports</a>. The general <a href="https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs">rule of thumb</a> is to reapply about every two hours and certainly after water sports or sweating.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/171063/original/file-20170525-23234-v4lxdi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In the U.S., the FDA regulates sunscreens available to consumers.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/alameda-ca-june-05-2016-store-433399849">Sheila Fitzgerald via Shutterstock.com</a></span>
</figcaption>
</figure>
<p>To get high SPF values, multiple UVB UV filters are combined into a formulation based upon <a href="https://www.federalregister.gov/documents/2011/06/17/2011-14766/labeling-and-effectiveness-testing-sunscreen-drug-products-for-over-the-counter-human-use">safety standards set by the FDA</a>. However, the SPF doesn’t account for UVA protection. For a sunscreen to make a claim as having UVA and UVB protection and be labeled “Broad Spectrum,” it must pass <a href="https://www.fda.gov/drugs/guidancecomplianceregulatoryinformation/guidances/ucm330694.htm">FDA’s Broad Spectrum Test</a>, where the sunscreen is hit with a large dose of UVB and UVA light before its effectiveness is tested. </p>
<p>This pre-irradiation step was established in <a href="https://www.fda.gov/drugs/guidancecomplianceregulatoryinformation/guidances/ucm330694.htm">FDA’s 2012 sunscreen labeling rules</a> and acknowledges something significant about UV-filters: some can be photolabile, meaning they can degrade under UV irradiation. The most famous example may be <a href="http://onlinelibrary.wiley.com/doi/10.1046/j.1440-0960.1999.00319.x/full">PABA</a>. This UVB-absorbing molecule is rarely used in sunscreens today because it forms photoproducts that elicit an allergic reaction in some people.</p>
<p>But the Broad Spectrum Test really came into effect only once the UVA-absorbing molecule avobenzone came onto the market. Avobenzone can interact with octinoxate, a strong and widely used UVB absorber, in a way that makes avobenzone less effective against UVA photons. The UVB filter octocrylene, on the other hand, helps stabilize avobenzone so it lasts longer in its UVA-absorbing form. Additionally, you may notice on some sunscreen labels the molecule ethylhexyl methoxycrylene. It helps stabilize avobenzone even in the presence of octinoxate, and provides us with longer-lasting protection against UVA rays.</p>
<p>Next up in sunscreen innovation is the broadening of their mission. Because even the highest SPF sunscreens don’t block 100 percent of UV rays, the addition of antioxidants can supply a second line of protection when the skin’s natural antioxidant defenses are overloaded. Some antioxidant ingredients my colleagues and I have worked with include <a href="http://www.springer.com/us/book/9783319293813">tocopheral acetate (Vitamin E), sodium ascorbyl phosophate (Vitamin C), and DESM</a>. And sunscreen researchers are beginning to investigate if the <a href="http://www.springer.com/us/book/9783319293813">absorption of other colors of light</a>, like infrared, by skin molecules has a role to play in photodamage.</p>
<p>As research continues, one thing we know for certain is that protecting our DNA from UV damage, for people of every color, is synonymous with preventing skin cancers. The Skin Cancer Foundation, American Cancer Society and the American Academy of Dermatology all stress that research shows regular use of an SPF 15 or higher sunscreen prevents sunburn and reduces the risk of <a href="http://dx.doi.org/10.1016/S0140-6736(98)12168-2">non-melanoma cancers by 40 percent</a> and <a href="https://doi.org//10.1200/jco.2010.28.7078">melanoma by 50 percent</a>.</p>
<p>We can still enjoy being in the sun. Unlike my Aunt Muriel and us kids in the 1980s, we just need to use the resources available to us, from long sleeves to shade to sunscreens, in order to protect the molecules in our skin, especially our DNA, from UV damage.</p><img src="https://counter.theconversation.com/content/74355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kerry Hanson has consulted for Bayer, J&J/Neutrogena, and P&G. Her academic work has been funded by Hallstar and through a joint University of California Discovery Grant with Merck. She is a member of the American Chemical Society. </span></em></p>Energy from the sun’s rays can cause skin damage and cancers. Sunscreens can absorb or reflect the dangerous UV light. Here’s how it works.Kerry Hanson, Research Chemist, University of California, RiversideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/731842017-03-01T02:21:56Z2017-03-01T02:21:56ZReprintable paper becomes a reality<figure><img src="https://images.theconversation.com/files/158375/original/image-20170224-22986-jzy0pm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Achievement unlocked: Rewritable paper.</span> <span class="attribution"><span class="source">Yadong Yin</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Since its invention around 100 B.C. in China, paper as a material for spreading information has greatly contributed to the development and spread of civilization. Even in today’s information age, with electronic media omnipresent in homes, offices and even our pockets, paper still plays a critical role.</p>
<p>Our brains process information differently on paper and on screen. <a href="http://www.millwardbrown.com/docs/default-source/insight-documents/case-studies/MillwardBrown_CaseStudy_Neuroscience.pdf">Information presented on paper</a> involves more emotional processing and produces more brain responses connected with internal feelings. That can make printed material more effective and more memorable than digital media. Of course, paper is still in common use, and <a href="http://dx.doi.org/10.1016/j.envsci.2009.01.011">global consumption</a> is expected to grow. </p>
<p>But paper use comes with significant environmental and sustainability problems. For many years, scientists have worked to develop reading media that have the format of conventional paper but can be <a href="https://phys.org/news/2014-01-chemists-unveil-water-jet-printer.html">reprinted</a> without first having to be <a href="https://web.archive.org/web/20111130061422/http://www.tappi.org/paperu/all_about_paper/earth_answers/EarthAnswers_Recycle.pdf">industrially recycled</a>. One promising option has been to coat paper with a thin film of <a href="https://dx.doi.org/10.1021/cr980068l">chemicals that change color</a> when exposed to light. But previous efforts have encountered problems such as high cost and high toxicity – not to mention difficulty both remaining readable and being erased for reuse. </p>
<p>My research group at the University of California, Riverside, in collaboration with <a href="http://www.nccm.sdu.edu.cn/cn/newsshow.php?pcid=8&cid=46&id=444">Wenshou Wang</a> at Shandong University in China, has recently developed a <a href="http://dx.doi.org/10.1021/acs.nanolett.6b03909">new coating</a> for regular paper that needs no ink, and can be printed on with light, erased and reused more than 80 times. The coating combines the functions of two types of nanoparticles, particles <a href="https://www.nano.gov/nanotech-101/what/nano-size">100,000 times thinner than a piece of paper</a>; one particle is able to get energy from light and initiates color change of the other. This represents an important step toward the development of reprintable paper.</p>
<h2>Environmental effects of paper</h2>
<p>About <a href="http://www.ecology.com/2011/09/10/paper-chase/">35 percent</a> of all harvested trees in the world are used to make paper and cardboard. Worldwide, the pulp and paper industry is the <a href="http://www.thepaperlessproject.com/facts-about-paper-the-impact-of-consumption/">fifth largest</a> consumer of energy and uses more water to produce a ton of product than any other industry.</p>
<p>Pulp extraction consumes large amounts of energy and can involve dangerous chemicals like dioxin. Paper production results in the <a href="http://www.ifc.org/wps/wcm/connect/7b62180048855aef878cd76a6515bb18/pulp_PPAH.pdf?MOD=AJPERES">emission of the nutrient phosphorus</a>. That, in turn, boosts plant growth, which can use up all the oxygen in the water and kill any animal life.</p>
<p>Even after paper is made, its use damages the environment. Trucking paper from where it’s made to where it’s used generates air pollution. And making and using ink and toner also <a href="http://globalwarmingisreal.com/2012/07/12/what-effect-does-ink-cartridge-waste-have-on-the-environment/">harm the environment</a>, by contaminating water, poisoning soil and destroying the natural habitats of wildlife.</p>
<p>Our method uses nontoxic ingredients and permits repeated reuse of paper, thereby reducing the environmental effects.</p>
<h2>Switching colors</h2>
<p>In developing a coating for paper, it’s important to find one that is transparent but can change color to something visible – and back. That way, any text or images can be made readable like on normal paper, but also easily erased.</p>
<p>Our method combines <a href="https://www.nano.gov/nanotech-101/what/nano-size">nanoparticles</a> – particles between 1 and 100 nanometers in size – of two different materials that can change from clear to visible and back again. The first material is Prussian blue, a widely used blue pigment most familiar as the blue color in architectural blueprints or inks. Prussian blue nanoparticles normally appear blue, of course, but can become <a href="http://dx.doi.org/10.1016/j.materresbull.2011.08.021">colorless</a> when they are supplied with additional electrons.</p>
<p>The second material is nanoparticles of titanium dioxide. When exposed to ultraviolet light, they release the electrons the Prussian blue needs to turn colorless.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/wnCyTb6bgJA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Printing with UV light and erasing with heat.</span></figcaption>
</figure>
<p>Our technique combines these two nanoparticles into a solid coating on conventional paper. (It can also be applied to other solids, including plastic sheets and glass slides.) When we shine ultraviolet light on the coated paper, the titanium dioxide produces electrons. The Prussian blue particles pick up those electrons and change color from blue to clear.</p>
<p><a href="https://youtu.be/wnCyTb6bgJA">The printing</a> can be done through a mask, which is a clear plastic sheet printed with letters and patterns in black. The paper starts out entirely blue. When UV light passes through the blank areas on the mask, it changes the corresponding areas on the paper underneath into white, replicating the information from the mask to the paper. The printing is fast, taking only a few seconds to complete. </p>
<p>The resolution is very high: It can produce patterns as tiny as 10 micrometers, 10 times smaller than what our eyes can see. The paper will remain readable for more than five days. Its readability will slowly degrade, as the oxygen in the air takes electrons from the Prussian blue nanoparticles and turn them back to blue. The printing can also be done using a laser beam, which scans across the paper surface and exposes the areas that should be white, in a way similar to how today’s laser printers work.</p>
<p>Erasing a page is easy: Heating the paper and film to about 120 degrees Celsius (250 degrees Fahrenheit) speeds up the oxidation reaction, erasing the printed content completely within about 10 minutes. This temperature is far lower than the temperature at which paper ignites, so there is no danger of fire. It is also lower than the temperature involved in current laser printers, which need to reach about <a href="http://dx.doi.org/10.1016/j.jaerosci.2010.02.015">200 degrees Celsius</a> (392 degrees Fahrenheit) to instantly fuse the toner onto the paper. </p>
<h2>Improved chemical stability</h2>
<p>Using Prussian blue as a part of this process offers a significant number of advantages. First, it is <a href="http://dx.doi.org/10.1021/ja066273x">highly chemically stable</a>. Previous rewritable papers usually used organic molecules as the main color-change materials, but they <a href="https://link.springer.com/chapter/10.1007/978-3-540-38522-6_7#page-1">break down</a> easily after being exposed to UV light during printing. As a result, they don’t allow very many cycles of printing and erasing. </p>
<p>By contrast, Prussian blue molecules remain essentially intact even after long-term exposure to ultraviolet light. In our lab, we have been able to write and erase a single sheet more than 80 times without observing any apparent changes to the intensity of the color or the speed of the switch. </p>
<p>In addition, Prussian blue can be easily modified to produce different colors, so blue isn’t the only option. We can change the pigment’s chemical structure, replacing some of its iron with copper to make a green pigment, or entirely replacing the iron with cobalt to make brown. At present, we’re able to print in only one color at a time. </p>
<p>As we develop this technology further, we hope to make rewritable paper available for many uses of displaying information, especially temporary uses like newspapers, magazines and posters. Other uses extend to manufacturing, health care and even simple organizing, such as making rewritable labels. </p>
<p>It’s probably not feasible to hope for a completely paperless society, but we are working on helping people use far less paper than they do – and more easily reusing it when they’re ready.</p><img src="https://counter.theconversation.com/content/73184/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yadong Yin receives funding from U.S. Department of Energy. </span></em></p>Coating paper with an inexpensive thin film can allow users to print and erase a physical page as many as 80 times. That reduces both the cost and the environmental effects of paper use.Yadong Yin, Professor of Chemistry, University of California, RiversideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/623152016-07-12T10:19:50Z2016-07-12T10:19:50ZWhy don’t plants get sunburn?<figure><img src="https://images.theconversation.com/files/130037/original/image-20160711-9289-12hyox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The one fact about plants that most people probably remember from school is that they use sunlight to make their own food. That process, photosynthesis, means that plants are dependent on sunlight. But as anyone who’s forgotten to put suncream on during their day at the beach knows, the sun can also be damaging. So how do plants absorb the light they need while avoiding damage from the sun’s ultraviolet (UV) rays? The short answer is by making their own sunscreen. And new research is helping us to understand exactly how that process works.</p>
<p>We know too much UV can be damaging to human health. In the short-term, excess UV – especially the shortest wavelengths in sunlight, known as UVB – causes sunburn. Repeated skin damage due to UVB exposure over decades can lead to an <a href="http://www.cancerresearchuk.org/about-cancer/causes-of-cancer/sun-uv-and-cancer/sun-facts-and-evidence#sun_facts0">increased risk of skin cancers</a>. Of course, different people can tolerate different amounts of UV. People with deeply pigmented (darker) skin are well protected all the time, whether they are out in the sun or not. Others need some exposure to sun to induce protective skin pigments by developing a sun tan. And some people barely tan at all, leaving them highly vulnerable to sunburn and other UV damage.</p>
<p>Of course we can all also choose to avoid the sun, wear a hat or use suncream. But what about plants? They have to stay in the sun. Is there a plant equivalent to sunburn or to the protective pigments we have in our skin?</p>
<p>Plant scientists really began to think about those questions when depletion of stratospheric ozone – the <a href="https://theconversation.com/shrinking-hole-in-the-ozone-layer-shows-what-collective-action-can-achieve-62007">hole in the ozone layer</a> – threatened to allow much more UVB to reach the Earth’s surface. Research back in the 1980s and 1990s showed that the high levels of UVB that would result from ozone depletion could <a href="http://www.sciencedirect.com/science/article/pii/000527289090156X">directly damage photosynthesis</a>. Other effects of high UV can also reduce growth and crop yields.</p>
<p>But the same body of research showed that plants are well-protected from the worse effects of the UVB levels we experience now. This protection comes from a suite of natural plant chemicals, mostly phenolics. These phenolic compounds <a href="http://www.sciencedirect.com/science/article/pii/S098194281400357X">act as natural sunscreens</a>, strongly absorbing UV but not the wavelengths needed for photosynthesis.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/130038/original/image-20160711-9285-t5r8v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Danger levels.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Just as with human skin pigments, the amount of these natural sunscreens varies between plants. Some plants, typically those that come from the tropics or from high-altitude mountains, have high levels of protection all the time. Others only produce sunscreens when exposed to higher levels of UVB, equivalent to tanning in humans.</p>
<p>That leads to another question. If plants produce their sunscreens based on their exposure to UV, how do they detect that exposure? And how do plants detect UVB?</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=832&fit=crop&dpr=1 600w, https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=832&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=832&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/130209/original/image-20160712-9292-c8ci7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">UVR8 was first detected in <em>Arabidopsis thaliana</em></span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/w/index.php?curid=3668208">Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>It has only been in the last decade or so that plant scientists have shown that <a href="http://science.sciencemag.org/content/332/6025/103">plants detect UVB</a> very specifically using a protein known as UVR8 (short for UV resistance locus 8). Plants that lack UVR8 cannot induce protective sunscreens and are severely damaged by the UV present in summer sunlight. </p>
<p>Researchers are still actively investigating the fundamental mechanisms by which UVR8 controls plant response to UVB. We’ve known for some time that <a href="http://www.plantcell.org/content/19/8/2662">UVR8 absorbs UVB</a>, causing changes that ultimately allow the UVR8 protein to accumulate in the nuclei of the plant’s cells. This is a necessary step in the chain of responses that allow plants to protect themselves against UVB damage.</p>
<p><a href="http://www.pnas.org/cgi/doi/10.1073/pnas.1607074113">New research</a> from the University of Geneva showed that UVB responses depend on interactions between UVR8 and another protein called COP1 (constitutively photomorphogenic 1). This protein interacts with other various molecules (HY5, SPA and RUP) in a plant’s cells to send a signal controlling the build up of sunscreen phenolics in response to UVB. </p>
<h2>More sustainable crops</h2>
<p>This might seem like an alphabet soup of abbreviations but the signalling system it represents affects us all through its role in the plants produced by farms as crops. We now know that plants use UVB as a signal to change their chemistry in ways that affects much more than just their UV protection.</p>
<p>UV exposure produces biochemical changes that can <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1399-3054.2011.01553.x/">increase resistance</a> to pest and disease attack. The UVB in sunlight improves the colour, taste and scent of fruits, vegetables and flowers. UVB exposure also <a href="http://www.sciencedirect.com/science/article/pii/S0168945208001234">increases levels of plant chemicals</a> that are thought to be valuable in the human diet.</p>
<p>The new research adds to our increasing understanding that the UVB in sunlight shouldn’t be seen just in terms of damage. So long as we keep protecting the ozone layer, the effects of UVB will be just one part of plants’ normal responses to their environment. And the more we understand these responses, the more we can use that knowledge to produce <a href="http://www.tunnelberries.org/">more sustainable crops</a>, improving their quality and reducing the use of pesticides.</p><img src="https://counter.theconversation.com/content/62315/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nigel Paul does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research from the University of Geneva is helping us understand how plants protect themselves from the sun.Nigel Paul, Professor of Plant Science, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/536042016-02-11T05:53:57Z2016-02-11T05:53:57ZUV radiation: the risks and benefits of a healthy glow<p>Eighty years ago, when sun exposure was first associated with skin cancer, <a href="http://dx.doi.org/10.1067/mjd.2002.127254">popular culture was exalting tanning</a> by emphasizing that a “fine brown color suggests health and good times, and is a pleasant thing to see.”</p>
<p>We know that sun exposure can be deadly, and today’s public awareness campaigns strongly focus on <a href="http://www.cdc.gov/cancer/skin/chooseyourcover/">sun avoidance</a> to prevent skin cancer. But we also know that sunlight is important to our health and plays a role in many biological processes in our bodies.</p>
<p>In fact, some physicians and scientists are taking a closer look at sunlight to expose the lesser known benefits of ultraviolet (UV) light. </p>
<h2>What is UV light?</h2>
<p>When we are talking about the dangerous component of sunlight, we are really talking UV light. UV light is ionizing radiation, meaning that it frees electrons from atoms or molecules, causing chemical reactions. UV light is divided into three categories listed in order of increasing energy: UVA, UVB, UVC. </p>
<p>UVC is the most harmful, but the ozone layer and other components of the atmosphere filter all of it out before it reaches us. That’s also the case for a large percentage of UVB light. But nearly all UVA light reaches the Earth’s surface.</p>
<p>Both latitude and season play large factors in our individual exposure to UV radiation. Countries farthest from the equator during winter months receive the least amount of UV radiation, while equatorial countries receive the most. </p>
<h2>UV light causes chemical reactions in the body</h2>
<p>Unlike visible light, the energy from UV radiation can be absorbed by molecules in our body, causing chemical reactions. When the energy from UV radiation is absorbed by DNA, it can cause reactions that lead to genetic mutations. Some of these mutations can lead to the development of skin cancer, which is the <a href="http://www.cdc.gov/cancer/skin/statistics/">most common cancer</a> in the U.S. Basal cell carcinoma, squamous cell carcinoma and malignant melanoma (one of the deadliest cancers) are all associated with UV light exposure.</p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/110368/original/image-20160204-2998-1ygxu9g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Making some vitamin D.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/ethermoon/4132039512/in/photolist-7i8Moy-rm1cmh-du2ufd-aSwJKT-ibETe7-bkaJbN-rUiRBC-dneNRZ-pCUs8B-4jkndR-7JHqFx-2kw1iG-9mqoEM-f7J66c-9ZBMjY-6rUF1e-7ScsWZ-7Hor9X-a3EnKp-8dMoSt-8i9sNS-as6MSr-dZAsVR-bmebkv-ecQShd-pGR3qs-psjUQg-p6rKgc-qwaVpz-fwsHEL-5Mocdw-bC4Bsz-rGkHYt-p82M2P-bqPnYe-nXETw3-odHoZh-aiMffw-gCd1Xs-5U7i1F-q9ANm2-4APbGP-qhQucB-bUFhAM-qKhaMc-7j8tzA-ewNTw-abW3Lf-hHaHv7-aukjJa">ethermoon/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>However, not all chemical reactions that UV light induces are harmful. In fact, some of them are beneficial. For instance, we can get vitamin D from eating certain plants and animals, but a main source of vitamin D comes from exposure to UV radiation. </p>
<p>Vitamin D is critical to maintaining bone density by increasing calcium absorption in the gut. Chronically low levels of vitamin D can lead to osteoporosis. Apart from its effects on bone, vitamin D has also been shown to <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1532-5415.2011.03733.x/full">improve balance and muscle strength in the elderly</a>, which decreases the number of falls leading to fracture.</p>
<p>UV light induces the body to synthesize other molecules as well, including <a href="http://dx.doi.org/10.1016/j.cell.2014.04.032">opioid-like molecules</a> thought to cause a tanning “high.”</p>
<h2>UV decreases cancer mortality</h2>
<p>Research suggests that the risk of developing lung, prostate, breast, colorectal and pancreatic cancer may be decreased by sun exposure. This protective effect against cancer is most pronounced in <a href="http://www.sciencedirect.com/science/article/pii/S0959804907003243">sunny countries</a>. While smaller studies of <a href="http://link.springer.com/article/10.1023/A:1018450531136">colorectal</a> and <a href="http://link.springer.com/article/10.1007/BF00051795">prostate</a> cancer have conflicted with this finding, many studies support a beneficial relationship between sun exposure and <a href="http://oem.bmj.com/content/59/4/257.short">internal cancers</a>, and it has been suggested that the risks associated with sun exposure may be outweighed by its ability to prevent <a href="http://www.pnas.org/content/105/2/668.short">certain types of internal cancers</a>. </p>
<p>Sunlight may also improve cancer outcomes. The prognosis for patients diagnosed in summer and fall is better than those <a href="http://link.springer.com/article/10.1023/B:CACO.0000019494.34403.09">diagnosed in winter</a>, and total sun exposure prior to diagnosis is a <a href="http://onlinelibrary.wiley.com/doi/10.1002/ijc.22052/abstract">predictor of survival</a>.</p>
<p>Given the relationship between sun exposure and vitamin D production, it was initially thought that vitamin D was the underlying cause for improved cancer outcomes. Unfortunately, data to support this are still lacking. Initial trials of <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa055222">vitamin D supplementation</a> have failed to demonstrate a benefit on cancer prevention, which has led researchers to believe that this benefit is from the effects of UV radiation. </p>
<h2>UV light decreases blood pressure and inflammation</h2>
<p>UV exposure positively affects blood pressure as well. People living in countries in higher latitudes with less UV exposure have higher blood pressures at baseline than <a href="http://dx.doi.org/10.1161/01.HYP.30.2.150">countries receiving more sunlight</a>. This effect is also seasonal, as more UV exposure in summer results in lower blood pressure. </p>
<p>And clinical trials have proven UVB radiation <a href="http://dx.doi.org/10.1016/S0140-6736(05)60827-6">effectively treats patients with mild hypertension</a>. It was thought that vitamin D was the cause for decreased blood pressure, but follow-up trials proved this effect was due to UVB exposure alone. </p>
<p>Some chemical reactions caused by UV light are known to have anti-inflammatory effects in the skin. Immune cells living in the skin can stop functioning, migrate out of the skin or undergo cell death <a href="http://www.sciencedirect.com/science/article/pii/S0896841109001516">following exposure to UV radiation</a>. Due to its anti-inflammatory effects, UV light can be used to effectively treat inflammatory skin conditions like psoriasis and eczema.</p>
<h2>Protection against autoimmune conditions</h2>
<p>On a larger scale, certain autoimmune conditions are more common in countries with less UV exposure. For instance, there is a higher prevalence of multiple sclerosis (MS) <a href="http://www.mdpi.com/1422-0067/13/9/11718/htm">in Scandinavian countries</a>. </p>
<p>In MS, immune cells attack the insulation around nerve cells in the brain, ultimately leading to nerve damage. While lack of vitamin D is a leading hypothesis for how MS develops, studies have also shown that lack of sun exposure may be an independent <a href="http://www.neurology.org/content/76/6/540.short">risk factor for nerve damage</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/110370/original/image-20160204-11389-9mn266.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Be careful out there.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/alexmartin81/7755295064/in/photolist-cPiV2S-2uMWP-6WFEBx-d9SS2s-5GpLLF-rUix4-33Hx4J-523MXZ-4JgYDx-6Kq83L-uBPtwS-dwJW34-yiwHit-5cpJwZ-4aGwii-4XHaqt-9UHz4k-gtjLDq-9uXwko-a51SM8-e9KsRV-51Y6Qe-5kMNiu-9y4RKd-7qNTG2-nTJvhG-6u5RYo-8p19KJ-nZKFus-7JXLQw-8i5tut-sduZY9-b2TKxn-9y1TFp-8USaWF-8mBLqB-bqfzVF-qpTa9i-9XhCSX-58kJyj-eEv2A2-hiG9kF-9Ts6Kr-a9c1jA-c6ryyj-56UPna-oiDDj3-6q7nCD-7ywGz1-Cqa5t">Alex Liivet/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Of course, sunlight has a dark side</h2>
<p>In addition to skin cancer, UV radiation also causes photoaging. UVA radiation penetrates deep into the skin, destroying collagen, which leads to wrinkles and skin thinning. Also, some autoimmune diseases, such as lupus, flare in response to UV radiation. UV radiation can also affect the eye, causing cataracts. </p>
<p>So, how can you maximize the benefits of sun exposure while minimizing your risk of skin cancer and aging? The key is to practice safe sun habits, which means using sunscreen and avoiding sunburns. This will decrease photoaging, and more importantly, your risk of skin cancer. Also, vitamin D is most effectively synthesized at UV radiation doses below those causing sunburn.</p>
<p>Several factors, including your skin type, latitude, longitude and weather, play into your overall UV exposure. This means different amounts of time in the sun for different people. People living in California may need only brief sun exposure on a cloudless day for adequate vitamin D production. This differs for places like Boston, where there aren’t adequate amounts of UV radiation from November to February. Skin type becomes important because melanin, which gives skin its pigment, effectively blocks UV radiation. This means darker-skinned people need more UV exposure for adequate vitamin D production than lighter-skinned people.</p>
<p>There are online tools that let you <a href="http://zardoz.nilu.no/%7Eolaeng/fastrt/VitD_quartMEDandMED_v2.html">calculate</a> how much time you should spend in the sun to achieve adequate levels of vitamin D without causing sunburn. If you think you aren’t getting enough sun exposure, or you live somewhere with long winters, check with your doctor to see if you are vitamin D deficient.</p><img src="https://counter.theconversation.com/content/53604/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emanual Maverakis receives funding from the NIH. </span></em></p><p class="fine-print"><em><span>Andrea Sukhov does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The risks of UV radiation exposure are well-known, but some scientists are exploring lesser-known benefits of UV light.Emanual Maverakis, Associate Professor- Departments of Medical Microbiology & Immunology and Dermatology | Member- Foods For Health Institute | Member- Comprehensive Cancer Center | Director- Autoimmunity | Director- Immune Monitoring Core, University of California, DavisAndrea Sukhov, Medical student, University of California, DavisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/513842015-12-07T02:03:51Z2015-12-07T02:03:51ZHealth Check: what does the UV Index mean?<figure><img src="https://images.theconversation.com/files/104564/original/image-20151207-22673-18hhkyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The UV Index was created last century largely for North American and European conditions, which rarely reach the 'extreme' range. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/andyinnyc/2593475487/">Andy Cross/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Alongside the day’s high and low temperatures, weather reports generally contain a UV alert for a particular time. But what does it actually mean – and what should you do about it?</p>
<p>Ultraviolet light is a form of radiation invisible to the human eye. Ultraviolet wavelengths of sunlight are made up of UVB, which has shorter wavelengths (of 290 to 320 nanometres) and higher energy, and UVA, which has longer wavelengths (320 to 400 nm) and lower energy. </p>
<p>Both types of UV damage skin cells and both are thought to contribute to skin cancer. But UVB causes sunburn and UVA contributes more to ageing and penetrates deeper skin layers.</p>
<p>It is <a href="http://www.ncbi.nlm.nih.gov/pubmed/26437734">estimated</a> that 7,220 cases of melanoma – 63% of the total number – in Australia in 2010 and all of the 750,000-plus non-melanoma skin cancers were due to exposure to our high-UV climate.</p>
<p>The <a href="http://www.who.int/uv/en/">Ultra Violet Radiation Index</a> (UVI) has been around for more than 20 years and gives a measure of the intensity of the sun, using both UVA and UVB.</p>
<p>The World Health Organisation recommends protecting our skin from the sun when the UVI is 3 or higher. So the “alert” applies to the block of time the UVI is 3 or above though the course of any day.</p>
<p>UVI 1–2 is low, which generally means it’s safe to be outdoors unprotected. </p>
<p>Other classifications are moderate (3–5), high (6–7), very high (8–10) and extreme (11+). To some extent, the moderate to very high labels tell us little except that UV intensity is increasing. The most simple advice is that when the index is at 3 or higher, protect your skin. Hence the “alert”.</p>
<p>To illustrate, today in <a href="http://www.bom.gov.au/qld/uv/#state-table">Cairns</a> the alert period was 8.10am to 4.10 pm, with a UV Index peak of 13 and extreme levels between about 10am and 2pm. </p>
<p>In <a href="http://www.bom.gov.au/tas/uv/index.shtml">Hobart</a>, the UV alert ran from 8.50am to 5.10pm, with a peak of UVI 10 and not reaching the extreme range. </p>
<p><strong>UV forecast for Monday, December 7, 2015</strong></p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/104568/original/image-20151207-22706-1k8cj58.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="http://www.bom.gov.au/australia/uv/">Screen shot from the Bureau of Meteorology website.</a></span>
</figcaption>
</figure>
<p>The <a href="http://www.bom.gov.au/australia/uv/#statelist">Bureau of Meteorology</a> has live <a href="http://www.myuv.com.au/public-real-time-uv-meter/">UV meters</a> for more accurate, on-the-spot local readings around the country.</p>
<p>One challenge is that the UV Index was created last century largely for North American and European conditions. There the UVI rarely gets into the extreme range. </p>
<p>In Australia, we spend most of the summer with “extreme” UV conditions in the middle of the day. There are concerns that the effect of the term “extreme” wears off if it is the norm. This will be one of the points debated at the <a href="http://uvandskincancer2015.org/">International Conference</a> on UV and Skin Cancer Protection in Melbourne this week.</p>
<h2>What affects UV intensity?</h2>
<p>UV radiation is separate from the visible and infrared parts of the spectrum, so you can’t see or feel it. That means you can be at the cricket or the beach in summer at 5pm and feel hot but the UVI might be in the low range of 1 or 2. </p>
<p>Or you can be in the same place, in a cool breeze on a 22 degree summer’s day at 1pm and get seriously burned due to the extreme UV index. </p>
<p>Heavy storm clouds can reduce the UV Index enormously; thin passing cloud, not so much.</p>
<p>UV radiation reflects off many surfaces including concrete, water and snow. Indirect UV (refracted by the atmosphere) can burn even if you are in the shade of a beach umbrella. If you can see lots of sky – even if you are in a little shade – chances are you are getting a pretty big dose of UV.</p>
<p>But there is a lot around to help. Being indoors provides great UV protection, even near the window (most office window glass gives very good UV protection). </p>
<p>Summer clothing can vary from the crocheted bikini (not so good) to a close-knit cotton shirt and shorts or a flowing sundress. The fabric weave and coverage are the keys – and look for UPF50 (ultraviolet protection) ratings. The best thing about clothing is you can see exactly what is or is not protected.</p>
<p>Sunscreen is <a href="http://www.ncbi.nlm.nih.gov/pubmed/24417448">proven</a> effective to reduce skin cancer. But most of us do not use enough to reach the protection claimed on the label. </p>
<p>Shade cloth was originally invented for horticultural purposes and can be as low as an equivalent SPF of 3–4, but some offer more effective UV protection. </p>
<p>Likewise, a small-leaf sparse-canopy gum tree does not provide nearly the same shade protection as a big old Moreton Bay fig.</p>
<p>Finally, skin type is important. Those blessed with naturally dark skin (like Aboriginal people who have evolved in our climate) have inherited a lower skin cancer risk than those of us from northern European heritage with pale, easily burned and sun-sensitive outer casing. </p>
<p><em>Terry Slevin is the editor of <a href="http://www.publish.csiro.au/pid/7227.htm">Sun Skin and Health</a>, released by CSIRO Publishing.</em></p><img src="https://counter.theconversation.com/content/51384/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Terry Slevin works for Cancer Council WA. The Cancer Council sells a range of sun-protection products including sunscreens, the royalties of which fund cancer research, prevention and support programs.</span></em></p>Alongside the day’s high and low, weather reports generally contain a UV alert for a particular time. But what does it actually mean – and what should you do about it?Terry Slevin, Adjunct Professor, School of Psychology and Speech Pathology, Curtin University; Education and Research Director, Cancer Council WA; Chair, Occupational and Environmental Cancer Committee, Cancer Council AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/426752015-06-10T10:17:33Z2015-06-10T10:17:33ZThink indoor tanning is a safer alternative to sitting in the sun? Think again<figure><img src="https://images.theconversation.com/files/84237/original/image-20150608-8697-1m0f3g2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">International Agency for Research on Cancer has classified UV-emitting tanning devices as a Group I carcinogen -- the most dangerous cancer-causing substances. </span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-55286200/stock-photo-solarium-machine-in-spa-salon.html?src=eu2xLFDQk4rmrd32YsbwIw-1-8">Tanning bed via www.shutterstock.com.</a></span></figcaption></figure><p>June 21 marks the official start of summer, signaling months of long days spent in the sun, vacations to warm and tropical locations, and, of course, suntans. </p>
<p>In a quest for a perfect tan, many people – especially young white women between age 18 and 25 – may head to a tanning salon, using tanning booths, sunbeds and sunlamps to kick-start their tan. Others (including people who are more prone to burn instead of tan) may head to the salon to slowly develop a “base tan,” with the <a href="http://www.mayoclinic.org/diseases-conditions/sunburn/expert-answers/tanning/faq-20057866">mistaken</a> belief that it will prevent a sunburn. For many consumers of indoor tanning salons, this approach offers what they believe to be a safer alternative to outdoor tanning. But here’s the thing: indoor tanning is just as damaging to your health as lying out in the real sun.</p>
<h2>Indoor tanning isn’t risk-free</h2>
<p>In the US, approximately five million individuals are diagnosed and treated for skin cancer each year, making it the most common type of cancer in the country, so common that most of us know at least one person who has been diagnosed with skin cancer. Of these, <a href="http://www.mayoclinic.org/diseases-conditions/melanoma/basics/definition/con-20026009">melanoma</a> is the deadliest form of skin cancer (relative to others like <a href="http://www.cancer.org/cancer/skincancer-basalandsquamouscell/detailedguide/skin-cancer-basal-and-squamous-cell-what-is-basal-and-squamous-cell">basal and squamous cell carcinomas</a>), accounting for approximately <a href="http://www.surgeongeneral.gov/library/calls/prevent-skin-cancer/exec-summary.html">9,000 deaths each year</a> in the US.</p>
<p>Skin cancer is associated with ultra violet (UV) radiation exposure from both the sun, and artificial sources such as UV-emitting tanning devices found in indoor tanning salons. These devices emit UVA rays, UVB rays, or a combination of both. Exposure to UV radiation has well-documented <a href="http://www.ncbi.nlm.nih.gov/pubmed/2748244">adverse health effects</a>. It is a known human carcinogen, so exposure to UV radiation may cause cancer. To your skin, there isn’t a difference between UV radiation from the sun and UV radiation from a tanning device.</p>
<p>In 2009 the International Agency for Research on Cancer (IRAC), part of the World Health Organization (WHO), classified UV-emitting tanning devices as a <a href="http://monographs.iarc.fr/ENG/Classification/index.php">Group I carcinogen</a> – the classification for the most dangerous cancer-causing substances. That means tanning booths and beds, sunlamps and other artificial tanning devices are in same category as tobacco smoke. That’s right, the world’s leading authority on cancer research considers indoor tanning devices to be as dangerous as <a href="http://www.ncbi.nlm.nih.gov/pubmed/12738186">tobacco smoke</a> from cigarettes.</p>
<p>That’s a strong statement to make, but it is backed up by a robust and growing body of evidence linking UV tanning devices to health problems. The use of UV tanning devices has been linked to <a href="http://www.ncbi.nlm.nih.gov/pubmed/17131335">skin</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/2400347">eye melanomas</a>. Of the five million cases of skin cancer diagnosed each year in the US, researchers have estimated that 8% (or 400,000) of these cases can be attributed to indoor tanning.</p>
<p>About <a href="https://www.aad.org/media-resources/stats-and-facts/prevention-and-care/dangers-of-indoor-tanning">30 million people tan indoors</a> in the US every year, and about 2.3 million of them are teens. And research indicates, for example, that the lifetime risk of skin melanoma <a href="http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm186687.htm">increases by 75%</a> among people who began using UV tanning devices before age of 35 (called young exposure). Yes – 75%. That figure alone should be enough to make some of us rethink the importance of that tan. </p>
<p>And if the increased risk of skin cancer isn’t enough, what about the increased risk of eye damage, wrinkles and other forms of premature aging of the skin? It begs the question – is that tan really worth it?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84239/original/image-20150608-8732-19ztwgd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">8% of skin cancer cases diagnosed in US annually can be attributed to indoor tanning.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-7010602/stock-photo-illuminated-green-and-blue-tanning-neon-sign-on-black.html?src=TkjqbD6SYxlzhum3lArXqw-2-72">Tanning sign via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>Limited regulatory oversight for indoor tanning</h2>
<p>Indoor tanning might be unhealthy, but its popularity, especially among young people, hasn’t dampened. Researchers in Texas found that apartment buildings near some college campuses offer free indoor tanning <a href="http://www.npr.org/sections/health-shots/2015/06/04/411739662/apartments-lure-students-with-free-access-to-tanning-beds">to lure students</a>. And a study of 125 college and university campuses in the US found <a href="http://archderm.jamanetwork.com/article.aspx?articleid=1919438">that almost half</a> had indoor tanning facilities on campus or in off-campus housing. </p>
<p>Why haven’t governments taken a more aggressive role in regulating the industry, including implementing partial or complete bans for cosmetic tanning? This seems a pretty obvious question, given the flurry of legislative and regulatory action that we have witnessed over the last decade or two in relation to the tobacco industry. Today, smoking cigarettes is more and more expensive (due to ever-increasing taxes), highly regulated, and, in many regions, socially unacceptable. </p>
<p>Several countries have taken steps to <a href="http://archderm.jamanetwork.com/article.aspx?articleid=1216974">regulate indoor tanning</a>. In 2011, Brazil became the first country in the world to ban the use of commercial indoor tanning for nontherapeutic purposes for all age groups (the country had already banned tanning for minors in 2002). Australia quickly followed. As of today, all but one Australian state prohibit individuals from operating a commercial tanning business. There are significant financial penalties for breaking the law. It is anticipated that the ban will help to reduce the incidence of skin cancer in the Australian public over time. </p>
<p>A number of other countries – including France, Italy and the United Kingdom – prohibit people under 18 from indoor cosmetic tanning. </p>
<p>But regulations in the US aren’t nearly as strict. Commercial indoor tanning operations <a href="http://www.ncsl.org/research/health/indoor-tanning-restrictions.aspx">are regulated</a> through a patchwork of state registration, licensing and/or inspection requirements. The nature of the regulations varies greatly and so too does the strength of enforcement. </p>
<p>The majority of states regulate the use of tanning devices by minors in some way. Seventeen states <a href="http://www.ncsl.org/research/health/indoor-tanning-restrictions.aspx">require</a> parental accompaniment, or parental consent, for the use of a tanning bed by minors. Maximum exposure times and the provision of eye protection to the minor are also common in these states. <a href="http://www.nature.com/nature/journal/v515/n7527_supp/box/515S114a_BX1.html">Eleven states</a> – including <a href="http://well.blogs.nytimes.com/2011/10/10/california-bans-indoor-tanning-for-minors/">California</a> and <a href="http://www.texastribune.org/2013/08/30/minors-no-longer-allowed-use-tanning-salons/">Texas</a> – have gone further and created legislation that prohibits indoor tanning by minors. But eight states still have no such protections. In these states, despite the overwhelming epidemiological evidence, minors may engage in unhealthy tanning practices without any checks and balances to help minimize the risks. </p>
<p>On the federal side, the Food and Drug Administration (FDA) <a href="http://www.surgeongeneral.gov/library/calls/prevent-skin-cancer/exec-summary.html">reclassified</a> indoor tanning devices as <a href="https://www.federalregister.gov/articles/2014/06/02/2014-12546/general-and-plastic-surgery-devices-reclassification-of-ultraviolet-lamps-for-tanning-henceforth-to#h-7">Class II medical devices</a> in 2014. That means manufacturers will need to include a warning that people under 18 shouldn’t use these devices and need to meet other regulatory requirements. And as of 2010 there is a <a href="http://money.cnn.com/2012/06/28/pf/taxes/tanning-tax/">10% federal excise tax</a> on tanning services. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/84241/original/image-20150608-8677-6awxbp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Lifetime risk of skin melanoma increases by 75% among people who began using UV tanning devices before 35.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-189514670/stock-photo-sunbathing-on-tanning-bed-beautiful-young-woman-lying-on-tanning-bed-and-keeping-eyes-closed.html?src=eu2xLFDQk4rmrd32YsbwIw-1-45">Woman in tanning bed via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>What can be done to protect minors?</h2>
<p>The demand for that bronzed look remains high (the indoor tanning industry is valued at US$2.6 billion) and this is unlikely to change any time soon given the aesthetic appeal. And while a call for an outright ban may make sense from a public health perspective, such a call would be highly unpalatable to consumers, business operators and the states, which benefit from the economic activity. </p>
<p>But more should and can be done to protect young tanners. A first step would be for all states to follow the lead set by, for example, California, and enact legislation that prohibits minors from using indoor tanning facilities. Across all states, maximum exposure times and requirements for the provision of eye protection for all clients, regardless of age, should be introduced and strictly enforced. Greater education around the risks of exposure, but especially young exposure, is also needed.</p><img src="https://counter.theconversation.com/content/42675/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Diana Bowman does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Researchers have estimated that 8% of the five million cases of skin cancer diagnosed each year in the US can be attributed to indoor tanning.Diana Bowman, Associate Professor of Health Management Policy, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/401912015-04-26T11:58:36Z2015-04-26T11:58:36ZHubble’s ultraviolet telescope has revealed more about the stars than we could ever see<figure><img src="https://images.theconversation.com/files/78432/original/image-20150417-3261-3zlzlr.jpg?ixlib=rb-1.1.0&rect=0%2C53%2C1272%2C837&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The galaxies NGC 4038 and NGC 4039, locked in a destructive embrace.</span> <span class="attribution"><a class="source" href="http://www.spacetelescope.org/images/potw1345a/">ESA/Hubble/NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>It’s probably fair to say that the <a href="http://www.spacetelescope.org/">Hubble Space Telescope</a>, which recently celebrated its 25th birthday, has become the world’s most famous telescope in large part due to the <a href="http://www.spacetelescope.org/images/archive/top100">breathtaking astronomical images</a> it has captured. </p>
<p>Hubble’s images reveal the complex, three-dimensional structure of galaxies, nebulae and star-forming regions with incredible acuity, chiefly because the telescope is in space. For ground-based telescopes, the Earth’s atmosphere has a blurring effect, limiting the sharpness of the images they produce. Hubble’s images are limited only by the telescope’s engineering and the properties of light itself.</p>
<p>In 1990 I was privileged to be present at the space shuttle launch which carried Hubble into orbit. The combination of the launch’s powerful demonstration of the defiance of gravity, coupled with the promise of what Hubble would do for astronomy was overwhelming. Curmudgeonly male scientists wept. </p>
<p>Perhaps the affection directed towards Hubble is also partly due to the telescope’s troubled start: the primary mirror was very precisely manufactured, but to the wrong shape. For the first three years of operation, Hubble’s ability to produce sharp images was <a href="http://quest.nasa.gov/hst/about/history.html">compromised</a>, to the point that “Hubble Telescope” was a joke appearing in cartoons and punch-lines. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=637&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=637&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=637&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=801&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=801&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78428/original/image-20150417-3238-t2hqn5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=801&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Astronauts Hoffman and Musgrave working on the Hubble Space Telescope in 1993.</span>
<span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Hoffman_and_Musgrave_EVA5.jpg">NASA</a></span>
</figcaption>
</figure>
<p>So engineers produced <a href="http://hubblesite.org/the_telescope/nuts_.and._bolts/optics/costar">COSTAR</a>, a component that would correct the optical problems with the primary mirror. Installed during the first space shuttle visit to Hubble, <a href="http://hubblesite.org/the_telescope/nuts_.and._bolts/optics/costar/#compare">it worked a treat</a>. Like a flawed hero or a prodigal child, Hubble’s triumph over adversity has universal appeal – the best stories, like the best images, have contrasts between darkness and light. </p>
<h2>More than just light</h2>
<p>Fortunately, not all of Hubble’s science had to wait three years for the <a href="https://www.spacetelescope.org/about/history/servicing_mission_1">first servicing mission</a>. Scientific astronomy is carried out in other regions of the electromagnetic spectrum than just visible light, for example ultraviolet (UV) light. UV is invisible to our eyes, but forms the continuation of the visible spectrum beyond the violet. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=857&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=857&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=857&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1077&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1077&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78744/original/image-20150421-9017-pjm9pb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1077&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A ‘hot Jupiter’ exoplanet’s atmosphere is stripped away by the heat of its star.</span>
<span class="attribution"><span class="source">ESA/Alfred Vidal-Madjar/NASA</span></span>
</figcaption>
</figure>
<p>Hubble had always been intended to serve as an ultraviolet telescope – from space, UV light that would otherwise be absorbed by Earth’s atmosphere can be collected. Light in this part of the spectrum is more energetic than visible light and is emitted by most stars, including our own, and many other astrophysical objects. Studies in ultraviolet radiation reveal things that can’t be learnt from telescopes on the ground. </p>
<p>Hubble has produced many, many UV science results. My favourite is the spectacular discovery in 2003 that the exoplanet HD209458b is surrounded by a <a href="http://www.spacetelescope.org/images/heic0303a/">huge cloud of hydrogen gas</a>. This type of exoplanet, known as a “hot Jupiter”, orbits its star so closely – only a 20th of the Earth’s distance from the sun – that the star’s heat boils off the planet’s atmosphere.</p>
<h2>Insight into the future</h2>
<p>This sort of discovery offers a great opportunity to <a href="http://hubblesite.org/hubble_discoveries/science_year_in_review/pdf/2010/two_dissipating_exoplanet_atmospheres.pdf">learn what exoplanets are made of</a>. Spectroscopy is the key: each chemical substance has its own spectroscopic fingerprint that allows astronomers to measure chemical compositions – and the UV region of the spectrum is particularly sensitive and useful for this purpose. Hubble has used these strong UV features to reveal the presence of hydrogen, magnesium, iron, silicon and other chemicals in the atmospheres of several hot Jupiter-style exoplanets. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78743/original/image-20150421-9038-1e5ohht.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Our ultimate fate: a white dwarf star collapsed from a giant red, surrounded by remnants of its inner planets.</span>
<span class="attribution"><a class="source" href="http://hubblesite.org/newscenter/archive/releases/2013/18/image/a/">G Bacon/NASA/ESA</a></span>
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<p>The loss of the atmosphere of these exoplanets is a preview of the ultimate fate of the Earth, when the sun becomes a red giant star in about four billion years time. As the sun begins to exhaust hydrogen at its core and begins to burn helium, it will swell and become hotter and brighter, engulfing Earth and the inner planets. Once it has exhausted its nuclear fuel, it will collapse into a white dwarf star – about the size of the Earth, and surrounded by the remnants of our solar system.</p>
<p>Hubble UV spectroscopy of white dwarf stars has revealed that many of them are being continually bombarded by asteroids <a href="http://www.astronomynow.com/news/n1203/30whitedwarf">feeding the stars with rocky material</a>. These observations allow us to learn the types of rocks present in extinct planetary systems which were perhaps once very similar to our own solar system. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78740/original/image-20150421-9051-j2gvmy.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Appearance in UV of aurorae on Ganymede.</span>
<span class="attribution"><span class="source">NASA/ESA</span></span>
</figcaption>
</figure>
<p>Most recently and closer to home, UV images reveal the <a href="http://www.nasa.gov/sites/default/files/thumbnails/image/15-33i2.png">aurorae around Ganymede</a>, Jupiter’s largest moon. Just as with Earth’s <em>aurora borealis</em> and <em>australis</em> (northern and southern lights), Ganymede’s aurorae change continuously with the influence of Jupiter’s magnetic field. Hubble captured changes in the aurorae caused by the presence of an underground salt-water ocean on Ganymede – an ocean that probably has more water than all of Earth’s oceans combined and may provide a habitat for life. </p>
<p>Hubble has continued its mission well beyond its original planned lifetime. It has made over a million observations and generates about ten terabytes of new data each year. The current plan is for it to operate beyond 2020, to allow some overlap with its replacement, the NASA/ESA/Canadian Space Agency joint project, the <a href="http://www.jwst.nasa.gov">James Webb Space Telescope</a> (JWST). </p>
<p>Sadly for UV astronomy, the JWST will work predominantly in infrared and has no UV instruments. This leaves many astronomers keen to see a successor to Hubble that will continue its unique work in UV, which has added so much to human understanding by working beyond what we can see.</p><img src="https://counter.theconversation.com/content/40191/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carole Haswell has received funding from the STFC, Nuffield Foundation, and NASA via the Space Telescope Science Institute to perform observations and analysis using the Hubble Space Telescope. She is a member of the Royal Astronomical Society. The views expressed within the article are those of the author and do not represent the views of the Research Councils.</span></em></p>After a slow start, Hubble’s ultraviolet vision changed the face of astronomy.Carole Haswell, Senior Lecturer in Astrophysics, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/304942014-08-19T05:17:38Z2014-08-19T05:17:38ZA third of sunscreens could have overestimated SPF protection – it’s a scandal<figure><img src="https://images.theconversation.com/files/56534/original/jt6ypfhv-1408024304.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Throwing in the towel. </span> <span class="attribution"><a class="source" href="http://commons.wikimedia.org/wiki/File:Sunbathing_couple.jpg">Mark Probst</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Despite the many awareness-raising campaigns on the harmful effects of ultraviolet (UV) radiation, a walk along any tourist beach will tell you just how many sun worshippers continue to soak up the sun excessively. And despite our use of all kinds of sunscreens, the statistics show a constant increase in the number of skin cancer cases. Why?</p>
<p>Things that protect us against harmful rays from the sun include clothing such as hats and longer sleeves and sunglasses. But topical sun protection from sunscreens is ideal as it allows us to be more free. </p>
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<p>These products only appeared on the market in the 1930s and were promoted as tanning aids. The formulation of sunscreen products is complex and the first ones were especially flawed – because the UV-filters were used at low concentrations and their effectiveness was limited in UVB light range. Since then, the history of topical sun protection has been marked by milestones, or scandals as we could call them. Let’s not forget the Bergasol affair in the 1980s. Products were formulated with bergapten, a photo-sensitising molecule that is found in bergamot essential oil and other oils, but which had no place whatsoever in this type of product because mixed with light it can cause skin irritation.</p>
<p>Today we have the Sun Protection Factor (SPF) to guide us. SPF is a universal indicator that testifies to the effectiveness of a product against UV (which includes UVA and UVB wavelengths), which <a href="http://www.nhs.uk/Livewell/skin/Pages/Sunsafe.aspx">can penetrate and damage</a> the skin and cells. SPF is worked out by putting on a thick layer of a suncream on in the lab and working out the difference it makes based on a multiplier – so if unprotected skin took 15 minutes to burn, a sunscreen with an SPF of 10 would take 150 minutes, and SPF30 would take 450 minutes.</p>
<p>This method of calculating protection is voted for overwhelmingly by manufacturers. Apart from the clear ethical shortcomings of this method (it does, after all involve irradiating volunteers for not insignificant periods or doses), we’ve discovered and revealed a certain number of potential biases. We’ve tested many products each year since 2000 and would say that about a third have much less protection than their SPF would suggest. </p>
<p>Concerns <a href="http://www.medwirenews.com/66/88067/Dermatology/Sunscreen_labels_may_overestimate_SPF_at_temperate_latitudes.html">have previously been raised</a> about SPF performance out in the real world and <a href="http://press.which.co.uk/wp-content/uploads/2014/05/suncream_R2f.pdf">a recent investigation by Which?</a> consumer magazine found three suncreams – Piz Buin, Malibu and Hawaiian Tropic – had lower protection than the SPF30 on the bottle.</p>
<h2>Anti-inflammatories</h2>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/22707250">We’ve highlighted</a> that a certain number of ingredients found in suncreams including allantoin (a molecule found in <em>Symphytum officinale</em>, a plant more commonly known as comfrey but which is now mostly synthetic), bisabolol (found in chamomile, also now mostly synthetic), and liquorice extracts, are likely to inhibit the appearance of redness due to their anti-inflammatory properties. As redness is a clinical sign that is used to determine SPF under current procedures, it can result in an overestimation of the SPF of products that contain these molecules. Using products high in anti-inflammatories can give a false sense of security – your DNA is still being damaged, you just don’t see or feel it happening. </p>
<p>We <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0046187">have also demonstrated</a> that the majority of filters approved in sunscreen products, including salicylates, benzophenones, PABA by-products, cinnamates and octocrylene, are highly anti-inflammatory. The problem is that despite this UV-filters are an essential ingredient for sunscreens to work.</p>
<p>Our current work has been looking at how long these anti-inflammatory effects last and we’ve found that this can be several hours. It’s worth bearing in mind that any molecule that is likely to inhibit the development of the redness, regardless of what other action it has, will plays a part in overestimating SPF using current measures.</p>
<p>Another major problem with topical sun protection comes from mineral products – titanium dioxide and/or zinc oxide – whether or not they are organic. Despite some claims, high SPF factors in sunscreens (50, 50+) <a href="http://www.ncbi.nlm.nih.gov/pubmed/18271305">can’t be obtained</a> with this type of sunscreen. Again the difference is due to an anti-flammatory effect and people who use these type of products for high SPF won’t be well protected.</p>
<h2>A better way to test?</h2>
<p>Instead, we think there should be a new standardised system of testing products based on chemical testing in the lab that only considers the optical properties of filters. This is the only way of quantifying the real effectiveness of sunscreen products.</p>
<p>Sunscreen products are different from all others; they can actively protect against skin cancers. And crucially, we have trust in them so happily stay out in the sun longer, thinking they’re working as well as they claim. It would therefore be appropriate that they return to being classed as a medication, as they are in the US. The marketing of ineffective sunscreen products today will have to take a share of the responsibility in skin cancers – we can’t leave this heavy responsibility to the cosmetics industry.</p><img src="https://counter.theconversation.com/content/30494/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Despite the many awareness-raising campaigns on the harmful effects of ultraviolet (UV) radiation, a walk along any tourist beach will tell you just how many sun worshippers continue to soak up the sun…Laurence Coiffard, Lecturer of Industrial Pharmacy and Cosmetology, Université de NantesCéline Couteau, Lecturer of Industrial Pharmacy and Cosmetology, Université de NantesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/92062012-09-11T20:23:24Z2012-09-11T20:23:24ZHow does the ozone layer protect Earth from radiation?<figure><img src="https://images.theconversation.com/files/15068/original/9gm33jf4-1346820221.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This is bad, but it would be a lot worse without the ozone layer.</span> <span class="attribution"><span class="source">garth.kennedy/Flickr</span></span></figcaption></figure><p><em><a href="https://theconversation.com/topics/saving-the-ozone">SAVING THE OZONE</a>: Part three in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explains why we need an ozone layer.</em></p>
<p>The ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (UVR) from the sun, protecting life on Earth from its potentially harmful effects. When the sky is clear, there is an inverse relationship between stratospheric ozone and solar UVR measured at the Earth’s surface. That is,the lower the ozone levels, the higher the solar UVR.</p>
<p>The level of UVR from the sun measured at the Earth’s surface varies linearly with latitude. There are higher UVR levels nearer the equator and lower UVR nearer the poles (see Figure 1). </p>
<p>Australia has high levels of solar UVR, due mainly to its geographical position. We have capital cities at latitudes ranging from 12°30’S (Darwin) close to the equator down to 42°52’S (Hobart). For comparison with some Northern Hemisphere locations, the south of France is 43°N and London is 51°32’N, while Melbourne at 37°46’S is as far from the equator as the coast of North Africa (37°16’N). </p>
<p>The southern hemisphere generally has higher levels of solar UVR than the northern hemisphere, because the Earth is approximately 1.7% closer to the sun in January (summer) than at the equinox and 1.7% further away in July (northern hemisphere summer). The intensity of solar UVR is proportional to the square of the distance, so this means solar UVR levels are already 3.4% higher in the southern Hemisphere than at equinox and 3.4% lower for an equivalent location in the northern hemisphere. However as the atmosphere in the southern hemisphere is cleaner than that in the northern and transmits UVR more readily, these differences are even larger for similar latitudes, approaching ~15%. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=393&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=393&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=393&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15067/original/2pdcqnw5-1346819312.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Figure 1. Measured solar UVR data versus latitude for a number of locations in different countries. The Southern Hemisphere sites are Australia and New Zealand as well as the Australian Antarctic Stations (at just below 70°S) and are marked as AAD and with UVR levels well above the other high latitude locations due to the effects of the ozone hole. Macquarie Island (at ~ 55°S) has annual UVR levels that are unaffected by the ozone hole. The Northern Hemisphere sites are the US (which has the highest data shown in this graph at Mauna Loa in Hawaii at 20°N and 3800m altitude), Japan and a number of European counties.</span>
</figcaption>
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<p>Australians are predominantly descended from fair-skinned individuals used to European conditions, so exposure to these high levels of solar UVR has resulted in very high rates of skin cancer within the population. Deaths are now more than 1800 per year with a cost to the health system of more than $300M annually.</p>
<p>Generally the higher the sun is in the sky, the shorter the path through the atmosphere and the higher the solar UVR levels. The maximum height of the sun in the sky changes slowly from day to day, but ozone over a location can change considerably from one day to the next due to natural variability. Levels can rise or fall by up to 100 Dobson Units (DU) in 24 hours. </p>
<p>For consecutive clear sky days, large but natural changes in ozone levels in the stratosphere above cities can affect the solar UVR at the surface significantly. There are differences of up to 30 to 40% from one day to the next, with measured daily UV index values increasing or decreasing inversely with large daily decreases or increases in ozone.</p>
<p>The ozone hole - discovered in the early 1980s - and its effects on solar UVR levels over the Antarctic and possibly further north could only add to the problem of population UVR exposures. The southern hemisphere has been affected more by ozone depletion than the northern hemisphere due to several geophysical and atmospheric factors which have lead to the annual appearance of the ozone hole over Antarctica. </p>
<p>Measurements of the solar UVR levels at the Australian Stations in the Antarctic (Casey, Davis and Mawson) show as the ozone hole passes overhead each spring, the annual levels of solar UVR at the stations have increased significantly. They are now equivalent to that received at numerous places in Europe. Interestingly, Macquarie Island, which is outside the reach of the Antarctic ozone hole, shows little in the way of increased annual solar UVR levels. </p>
<p>Because the annual ozone hole breaks up in spring, pockets of ozone-depleted air sometimes move northwards and pass over Australia adding slightly to the solar UVR levels there (this was first observed in the late 1980s). Recently there have been incidents of low ozone over Australia due to other atmospheric processes dragging low-ozone upper-atmospheric air down from equatorial regions (ozone is generally lower over the equator than at mid-latitudes). In such cases UV index levels at the ground are elevated and increase the potential for adverse health effects for populations living in these areas.</p>
<p>If not for the success of the Montreal Protocol it is very likely that the more densely populated areas of the globe would be subject to increased solar UVR with potentially severe consequences for (human) health.</p>
<p><em>This article was co-authored by Stuart Henderson, who works with Peter Gies in the UVR Group in the Radiation Health Services Branch at the Australian Radiation Protection and Nuclear Safety Agency. Stuart Henderson has a PhD in Applied Physics from RMIT.</em></p>
<p><em>Tomorrow: what are ozone depleting substances?</em></p>
<p><em><a href="https://theconversation.com/topics/saving-the-ozone">Read more</a> on the Montreal Protocol’s 25th anniversary.</em></p><img src="https://counter.theconversation.com/content/9206/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Gies does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>SAVING THE OZONE: Part three in our series exploring on the Montreal Protocol on Substances that Deplete the Ozone Layer – dubbed “the world’s most successful environmental agreement” – explains why we…Peter Gies, Senior Principal Research Fellow (Honorary), James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.