tag:theconversation.com,2011:/fr/topics/uv-index-23203/articlesUV index – The Conversation2021-12-20T22:06:13Ztag:theconversation.com,2011:article/1731462021-12-20T22:06:13Z2021-12-20T22:06:13ZWhat is the UV index? An expert explains what it means and how it’s calculated<figure><img src="https://images.theconversation.com/files/436236/original/file-20211208-21-lr2oni.jpeg?ixlib=rb-1.1.0&rect=26%2C0%2C3000%2C1823&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’ve probably seen the UV index in the day’s weather forecast, and you know it tells you when you need to cover up and wear sunscreen. </p>
<p>But where does that number come from? We produce it at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).</p>
<p>It’s our job to help keep Australia safe from all kinds of radiation, and that doesn’t just mean nuclear reactors and mobile phone signals – it also means radiation from the Sun.</p>
<p>Australia has one of the highest rates of skin cancer in the world, accounting for about <a href="https://www.cancer.org.au/cancer-information/types-of-cancer/skin-cancer">80% of cancers diagnosed in Australia each year</a>. Most skin cancers are caused by exposure to UV radiation from the sun.</p>
<h2>What is the UV index?</h2>
<p>The UV index tells you how much ultraviolet radiation is around at ground level on a given day, and its potential to harm your skin.</p>
<p>UV radiation is a component of sunlight that can cause tanning and sunburn in the short term. In the longer term, too much exposure to UV can cause cataracts and skin cancer.</p>
<p>In 2002, the <a href="https://www.who.int/uv/publications/en/UVIGuide.pdf">World Health Organization</a> devised the UV index in an effort to make people around the world more aware of the risks.</p>
<p>The index boils down several factors into a single number that gives you an idea of how careful you need to be in the sun. A score of 1 or 2 is low, 3–5 is moderate, 6 or 7 is high, 8–10 is very high, and 11 and above is extreme. </p>
<h2>What is UV radiation?</h2>
<p>The Sun showers Earth with light at a huge spectrum of different wavelengths, and each wavelength can have a slightly different effect on human skin.</p>
<p>An important part of the spectrum is ultraviolet or UV radiation: light with wavelengths too short for our eyes to see, from around 400 nanometres to 10 nanometres.</p>
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Read more:
<a href="https://theconversation.com/sun-damage-and-cancer-how-uv-radiation-affects-our-skin-34538">Sun damage and cancer: how UV radiation affects our skin</a>
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<p>There are two important kinds of UV radiation: UV-A, with wavelengths from 400–315 nanometres, and UV-B with wavelengths from 315–280 nanometres. (Shorter wavelengths are called UV-C, but are mainly blocked by the atmosphere so we don’t need to worry about it.)</p>
<p>UV-A and UV-B both contribute to skin damage, ageing and skin cancer. But UV-B is the more dangerous: it is the major cause of sunburn, cataracts and skin cancer. </p>
<h2>How is the UV index calculated?</h2>
<p>The UV index takes into account how much UV radiation of different wavelengths is around and <a href="https://cie.co.at/publications/erythema-reference-action-spectrum-and-standard-erythema-dose-0">how each of those wavelengths affects our skin</a>.</p>
<p>ARPANSA has a network of sensors around Australia measuring sunlight at different wavelengths to determine the UV index, with the information <a href="https://www.arpansa.gov.au/our-services/monitoring/ultraviolet-radiation-monitoring">available online in real time</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=536&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=536&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436239/original/file-20211208-138695-17iu540.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=536&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">Real-time data shows how the UV index rises and falls over the course of the day.</span>
<span class="attribution"><a class="source" href="https://www.arpansa.gov.au/our-services/monitoring/ultraviolet-radiation-monitoring/ultraviolet-radiation-index">ARPANSA</a></span>
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<p>This data is combined with other information about location, cloud cover and atmospheric conditions to produce <a href="http://www.bom.gov.au/uv/">maps and forecasts</a> of the UV index for the whole country. </p>
<h2>How are UV levels different around the world?</h2>
<p>The UV index you see reported is usually the daily maximum – that’s the highest it will be all day.</p>
<p>How high it gets depends on lots of factors, including your location, the time of year, the amount of cloud cover, and ozone and pollution in the atmosphere.</p>
<p>The index tends to be higher closer to the Equator and at high altitudes, as the sunlight has to pass through less air before it reaches the ground.</p>
<p>People often experience the sun in Australia as particularly harsh, compared with places in North America or Europe. In a British summer, for example, the maximum UV index might be between 6 and 8. In an Australian summer it can <a href="https://www.sunsmart.com.au/uv-radiation/what-is-uv">range from 10 to 14</a>. </p>
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<img alt="" src="https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=483&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=483&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=483&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=607&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=607&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436230/original/file-20211207-149721-186cwc0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=607&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">The Bureau of Meteorology produces UV index forecast maps every day.</span>
<span class="attribution"><a class="source" href="http://www.bom.gov.au/australia/meteye/?loc=AUS_FA001">Bureau of Meteorology</a></span>
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<p>There are a few reasons for this. One is that Australia’s cities are closer to the Equator than many big cities in Europe and North America. </p>
<p>Another is that Earth is very slightly closer to the Sun in the southern hemisphere’s summer than the northern summer, meaning the sunlight is a few percent brighter.</p>
<p>A third reason is the “hole” in the ozone layer. The layer of ozone in the upper atmosphere, which absorbs some UV-B, is thinner towards the South Pole. This was caused by the use of chemicals called chlorofluorocarbons or CFCs, and it has been improving since they were banned by an <a href="https://www.awe.gov.au/environment/protection/ozone/montreal-protocol">international agreement</a> in 1987.</p>
<p>And finally, the air in Australia generally has less smoke, dust and other small particle pollution than many places in the northern hemisphere. While this makes the air nicer to breathe, pollution does absorb or block some UV radiation.</p>
<h2>Is UV changing over time?</h2>
<p>We know UV levels have increased in recent decades.</p>
<p>In Australia, <a href="https://link.springer.com/article/10.1007%2Fs00484-011-0474-x">a study in 2011</a> found the average UV index had increased by 2–6% between the 1970s and the period 1990–2009, due to depletion of the ozone layer. A <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009JD012219">NASA study</a> found similar results for 1979–2008.</p>
<p>It’s harder to say what will happen in the future, as there are several uncertain factors.</p>
<p>We expect the ozone layer to slowly recover from the impact of CFCs, which is likely to reduce UV levels.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/after-30-years-of-the-montreal-protocol-the-ozone-layer-is-gradually-healing-84051">After 30 years of the Montreal Protocol, the ozone layer is gradually healing</a>
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<p>However, we also expect less fossil fuel will be burned, which would mean less air pollution and higher UV levels. On the flip side, we may also have more bushfires due to climate change, which would mean more air pollution and lower UV.</p>
<p>Clouds are also likely to behave differently due to climate change, but we’re not sure exactly how.</p>
<p>Researchers in Japan found reductions in clouds and tiny particles in the air are <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011JD015749">expected to have a bigger impact</a> than the recovery of the ozone layer, which would mean UV levels are likely to go up overall. </p>
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<img alt="" src="https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436240/original/file-20211208-159504-1sbq4ge.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&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">The future of UV levels depends on what happens to the ozone layer, cloud cover, and atmospheric pollution.</span>
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<p>Regardless of the long-term trends, we’ll still be measuring the daily levels and letting the public know the important sun protection times. So keep an eye on the forecasts and remember to cover up, wear sunscreen, sunglasses and a broad-brimmed hat, and stick to the shade when the index is 3 or above.</p>
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<p><em>The author would like to thank Dr Stuart Henderson, Assistant Director EMR and UVR Exposure Assessment at ARPANSA, for contributing valuable information and expertise.</em></p><img src="https://counter.theconversation.com/content/173146/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Loughran receives funding from The National Health and Medical Research Council of Australia (NHMRC). She is the Principal Researcher and EME Program Director at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). She is also affiliated with the University of Wollongong, is currently a member of the Scientific Expert Group at the International Commission on Non-Ionizing Radiation Protection (ICNIRP).</span></em></p>The UV index measures how much UV radiation is around and how much damage it’s likely to do to your skin.Sarah Loughran, Principal Researcher and Electromagnetic Energy Program Manager, ARPANSA, and Adjunct Associate Professor, University of WollongongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1607292021-05-14T17:04:38Z2021-05-14T17:04:38ZHow to avoid sun damage after months in lockdown<figure><img src="https://images.theconversation.com/files/400549/original/file-20210513-14-ylxf00.jpg?ixlib=rb-1.1.0&rect=71%2C26%2C5919%2C3961&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/beautiful-cute-cat-taking-sun-bath-1580179945">OlegRi/Shutterstock</a></span></figcaption></figure><p>After a winter of lockdown and with coronavirus restrictions beginning to lift across the UK, many will be hoping for good weather this summer. <a href="https://www.bbc.com/news/explainers-52544307">Restrictions on foreign travel</a> have meant that more people plan to stay within the UK for their summer holidays than ever before. </p>
<p>This shift, along with our social lives increasingly being based outside, makes it particularly important that people don’t underestimate the risks posed by the sun in the UK.</p>
<p>Skin damage caused by the sun is associated with both skin cancer and premature ageing of the skin. The culprit in both cases is ultraviolet radiation (UV). Invisible to human eyes, although it can be seen by many animals, including <a href="https://medium.com/@BBSRC/10-things-you-never-knew-about-reindeer-5b5767bf8ab0">reindeer</a>, UV sits just beyond the purple end of the visible light spectrum.</p>
<p>One reason that it is so harmful is that its energy can be absorbed by our cells’ DNA, causing it to become damaged. If the cell isn’t able to repair this DNA damage, this can lead to genetic changes, or mutations, which in turn can cause cancer. Because of their location on the surface of the body, skin cells are the main target for UV damage.</p>
<p>The body does have some protection against these harmful effects. Molecular mechanisms within our cells are able to detect and repair the DNA damage before it can cause mutation. When skin cells detect DNA damage, they activate alarm signals that get passed on to pigment-producing cells to tell them to start producing more pigment to help protect against further damage. It’s the production of this pigment, melanin, that causes a suntan. </p>
<p>A tan is therefore a sign that your skin has been damaged. The protection it provides has been estimated to be equivalent to an <a href="https://www.scientificamerican.com/article/fact-or-fiction-a-base-tan-can-protect-against-sunburn/">SPF of around 4</a>. This means that although it will take four times longer in the sun to do so, you can still burn. </p>
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<img alt="A reindeer with its tongue out." src="https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/400545/original/file-20210513-18-19dprr2.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">
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<span class="caption">If you don’t have easy access to a reindeer, you can always check the UV index online.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/reindeer-head-portrait-tongue-flatruet-sweden-705950374">MM.Wildlifephotos/Shutterstock</a></span>
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<p>If you’re exposed to lots of UV, then the amount of DNA damage can overwhelm cells’ defences. All is not lost though, because a damaged cell has a final line of defence where it can activate death programmes, “choosing” to die by a process called <a href="https://www.genome.gov/genetics-glossary/apoptosis">apoptosis</a>. This means that badly damaged cells, which could go on to become cancerous, are eliminated from the body before they can cause harm. </p>
<p>Anyone who’s ever had sunburn has experienced this process in action. Huge amounts of dying cells in the skin leads to inflammation, causing the characteristic painful reddening of the skin that can be an unpleasant end to a day out in the sun.</p>
<h2>The risk of cancer</h2>
<p>But sometimes these defences aren’t enough, and the damage to the skin caused by UV can lead to skin cancer. UK skin cancer rates have soared over the past decades as foreign travel has become more common and attitudes towards tanning have changed. Staggeringly, <a href="https://www.thelancet.com/journals/lanepe/article/PIIS2666-7762(21)00001-6/fulltext">a recent study</a> has shown that skin cancer is up to eight times more common today than it was in the early 1980s.</p>
<p>What does this mean as we all keep our fingers crossed for a “BBQ summer”? </p>
<p>While it’s true that the intensity of UV is not as high in the UK as in the Mediterranean or other low-latitude holiday destinations, the country is about to enter the months where <a href="https://www.weatheronline.co.uk/reports/wxfacts/The-UV-Index.htm">UV intensity is at its peak</a>. It’s important to bear in mind that it’s still possible to be exposed to harmful levels of UV when out and about in the UK, particularly for children or people with fair skin that tends to burn easily or freckle. After months of lockdown, many might be desperate to get out into the sunshine, but it’s important not to overdo it and there are <a href="https://www.bbc.co.uk/programmes/p06l5g86">safer ways to get a tan</a>.</p>
<p>It can be quite difficult to judge how much UV you’re being exposed to, as levels can be quite high even on some cloudy days. One way to protect yourself is to be aware of <a href="https://www.metoffice.gov.uk/public/weather/uv-index-forecast/#?tab=map&map=MaxUVIndex&zoom=5&lon=-4.00&lat=55.71&fcTime=1620864000">the UV index</a>, which is a measure of how strong the UV rays are each day. </p>
<p>This will help you know whether you need to use sun protection such as hats, clothes and a broad protection suncream of SPF 20 or above, thinking about how long you’ll be out for. It’s a good idea to take extra care between 11am and 3pm when the sun is at its peak.</p>
<p>Taking a few simple precautions means that everyone can enjoy the sun safely when lockdown ends. Now let’s just hope this summer has plenty of sunny days to enjoy.</p><img src="https://counter.theconversation.com/content/160729/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Allinson has received funding from Alliance Boots and North West Cancer Research for her work on ultraviolet radiation.</span></em></p>Even if you live in the UK, you’re still at risk of skin cancer. Here’s how to stay safe .Sarah Allinson, Senior Lecturer, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/760782017-04-24T05:54:54Z2017-04-24T05:54:54ZResearch Check: are Aussie women ageing up to 20 years faster than US women?<figure><img src="https://images.theconversation.com/files/166043/original/file-20170420-2426-1by24ce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's more to ageing than wrinkles and crow's feet.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>Across the developed world, looking older than your chronological age is considered a drawback. Western societies value physical beauty and vitality while science is actively trying to find a <a href="https://theconversation.com/the-search-to-extend-lifespan-is-gaining-ground-but-can-we-truly-reverse-the-biology-of-ageing-75127">way to reverse the ageing process</a> altogether.</p>
<p>This is probably why a study published in the latest issue of <a href="http://onlinelibrary.wiley.com/doi/10.1111/ajd.12637/abstract">The Australasian Journal of Dermatology</a>, that concluded Australian women report more severe signs of facial ageing sooner than other women, received a <a href="https://news.google.com/news/story?ncl=dwL1pRkK3Ut25EM6GZL7v8C_U2hRM&q=ageing+australian+women+us+women&lr=English&hl=en&sa=X&ved=0ahUKEwi8yrbcr7LTAhUCtJQKHWvuBCIQqgIIIjAA">fair amount of media coverage</a>.</p>
<p>It generated alarming <a href="http://www.smh.com.au/lifestyle/health-and-wellbeing/wellbeing/why-aussie-women-are-ageing-up-to-20-years-faster-than-us-women-20170410-gvho9k.html">headlines such as</a>:</p>
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<p>Why Aussie women are ageing up to 20 years faster than US women</p>
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<p>Like the research paper itself, these articles focused on photoageing – the damage done to our skin by exposure to high UV levels. But there is quite a bit more to the ageing process than wrinkles and crow’s feet. And the “20 years faster” claim also deserves scrutiny.</p>
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<img alt="" src="https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=831&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=831&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=831&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166388/original/file-20170424-12658-19cxur.png?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">
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<span class="attribution"><span class="source">The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>How was the study done?</h2>
<p>The paper was published in a reputable, peer-reviewed outlet – the official journal of the Australasian College of Dermatologists and the New Zealand Dermatological Society.</p>
<p>The sample was 1,472 women aged 18-75 (averaging late 40s) from Australia, the UK, Canada and the US. They were recruited between December 2013 and February 2014 from an internet-based polling panel. </p>
<p>The women were asked to use a mirror to compare their own facial features to photographs illustrating increasing signs of ageing (from none to severe) for eight different characteristics.</p>
<p>These were static forehead lines, crow’s feet, glabellar (frown) lines, tear troughs (groove between lower eyelid and cheek), mid-face volume loss, nasolabial folds (the two skin folds that run from the nose to the corner of the mouth), oral commissures (the corners of the mouth) and perioral lines (wrinkles around the lips). </p>
<p>They were asked to choose one image – out of four to six (depending on the feature) – that most represented their current facial features in the absence of facial expression.</p>
<p>People were excluded if they had significant facial trauma or burns, or if they’d had any form of plastic surgery, including Botox, fillers or laser treatments. </p>
<p>Skin colour can be categorised by its typical response to UV light: from type one, which is very fair skin that always burns and never tans, to type six, which is dark brown skin that never burns and always tans. In this study, only women with skin types one to three were included. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=506&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=506&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=506&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=636&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=636&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166046/original/file-20170420-2418-kilq9x.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=636&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 women were asked to use a mirror to compare their own facial features to photographs illustrating increasing signs of ageing.</span>
<span class="attribution"><a class="source" href="http://onlinelibrary.wiley.com/doi/10.1111/ajd.12637/full">Screenshot/Australasian Journal of Dermatology</a></span>
</figcaption>
</figure>
<h2>What were the results?</h2>
<p>Australian women reported more severe facial lines and higher rates of facial change with age than women from the other countries, particularly those from the US. Though, interestingly, for women in their 70s, the average severity of facial lines was generally similar from country to country.</p>
<p>The researchers then looked at the 30% or more of women who reported moderate or severe ageing for all features. They found that in Australia, this occurred:</p>
<blockquote>
<p>from the ages of 30-59 years […] but this proportion of US women did not report this level of severity until the ages of 40–69 years. </p>
</blockquote>
<p>This seems to be the crux of the paper, and the finding that underpins the conclusion that we’re ageing 20 years faster than we should be.</p>
<p>The study has many strengths. It is elegantly written and some aspects of the methodology are robust. For example, Asian women experience skin wrinkling later than Caucasian women, and smoking is associated with more skin ageing. So the researchers made sure these factors were not responsible for the results by adjusting their analyses for age, race and smoking status. </p>
<p>The results are certainly plausible and consistent with other studies. People living in Australia are exposed to higher levels of UV radiation, which is responsible for most age-associated cosmetic skin problems in fair-skinned people. </p>
<p>A <a href="https://www.ncbi.nlm.nih.gov/pubmed/21196710">study</a> of 1,400 randomly selected residents of a Queensland community used casts of the back of the hand and dermatological assessment to show that premature ageing of the skin was associated with high sun exposure during leisure or work.</p>
<h2>What is the problem?</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166434/original/file-20170424-12640-1wrfeks.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"></a>
<figcaption>
<span class="caption">People living in Australia are exposed to higher levels of UV radiation.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>There are two main limitations of the study. First, the differences in self-reported facial lines may be statistically significant across countries, but this does not mean they are clinically significant. </p>
<p>Figures in the research plot the average severity of each line against age, with different colours representing each of the four countries. </p>
<p>Participants had up to six photographs to choose from, so the severity scale could range from 0 to 6. In the figures, the colours follow very similar trajectories and often overlap. Even the biggest gap between the countries looks like it represents a difference of 0.3 or 0.5. This is relatively small and may not be something anyone could observe.</p>
<p>Second, it is not clear why the researchers decided to focus on the 30% or more of women who reported moderate or severe ageing for all features. No other studies have used this cut-off.</p>
<p>The authors said that:</p>
<blockquote>
<p>this cut-off was chosen to yield the best sensitivity in detecting differences in facial ageing severity among countries.</p>
</blockquote>
<p>This suggests fewer differences were found than if another cut-off was considered. For example, would there have been significant differences when 20% of women rated each feature as having moderate or severe signs of ageing? Or 50%? Or 90%? Choosing a cut-off which is not based on a clinically meaningful or validated proportion raises questions about the true significance of the reported changes.</p>
<h2>What else should we consider?</h2>
<p>The title of the study is an accurate reflection of its content, stating that it is a comparison of self-reported signs of facial ageing. But the accompanying media coverage implies Australian women are ageing prematurely.</p>
<p>There is no evidence this is true. Robust studies of many tens of thousands of women show Australians are very similar to women in Europe and North America, through middle age to the extremes of old age. The <a href="http://www.alswh.org.au/">Australian Longitudinal Study on Women’s Health</a> provides a wealth of data in this field.</p>
<p>More important markers of health status in older people – disability, self-rated health, depression and anxiety, dementia – are all comparable. Life expectancy at birth (84.4 years for women) is slightly <a href="http://www.aihw.gov.au/deaths/life-expectancy/">higher in Australia</a> than in the other countries studied in this paper. </p>
<h2>What is the take-home message?</h2>
<p>Despite the methodological limitations of the study, in some ways it is good for it to be widely publicised. </p>
<p>Just like public health campaigns about premature ageing were used to decrease smoking rates in women (and thus reduced multiple smoking-related disease), the message Aussies may be looking older because of UV radiation may encourage us to limit our sun exposure. This would then reduce melanoma and other skin cancers. </p>
<p>As a type one redhead living in Brisbane, I shall certainly continue to wear my hat. <strong>– Ruth Hubbard</strong></p>
<hr>
<h2>Peer Review</h2>
<p>This Research Check fairly outlines the strengths (number of participants, accounting for age and other factors like smoking) and limitations (self-reporting and limitations in adjusting for confounding variables).</p>
<p>It also addresses the issue that caused the alarmist headlines – the graph showing when more than 30% of women rated a facial feature as reflecting moderate or severe signs of ageing. The author correctly points out there is no justification in choosing the 30% cutoff, that no other study uses it and that it is unlikely to be of any clinical significance.</p>
<p>More importantly, the Research Check analyses the figure that presents data for women across the various age groups. It points out most of the curves overlap, and that differences between groups of women are actually hard to see.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=508&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=508&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=508&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=639&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=639&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166422/original/file-20170424-27254-4s22ze.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=639&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s difficult to see the variations between countries in the graphs.</span>
<span class="attribution"><a class="source" href="http://onlinelibrary.wiley.com/doi/10.1111/ajd.12637/full">Screenshot/Australasian Journal of Dermatology</a></span>
</figcaption>
</figure>
<p>I would go even further and say that while the 95% confidence interval - an important estimate of variation - is presented in the tables, it is not applied to the graphs. If you show the 95% confidence intervals reported in the tables to the graphs, you would see most of the values for the women in other countries would not be significantly different to those in Australia. </p>
<p>For example, in the graph showing nasolabial folds, women in the light-poor UK have the same (age 18-29, 40-49) or marginally worse (age 70-79) nasolabial folds than in Australia. </p>
<p>This Research Check gives a clear, detailed and easily understandable background to the paper made visible by somewhat frenetic media reports. <strong>– Ian Musgrave</strong></p><img src="https://counter.theconversation.com/content/76078/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Musgrave receives funding from the National Health and Medical Research Council to study adverse reactions to herbal medicines and has previously been funded by the Australian Research Council to study potential natural product treatments for Alzheimer's disease. He is co-investigator of a grant to explore the metabolism of rodenticides. He lectures in biostatistics and the toxicology of retinoids, which have been used in "anti-aging" creams</span></em></p><p class="fine-print"><em><span>Ruth Hubbard 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>A recent study suggests Australian women are ageing 20 years earlier than their US counterparts. But this claim deserves some close scrutiny.Ruth Hubbard, Associate Professor, Centre for Research in Geriatric Medicine, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/685822016-12-19T00:40:54Z2016-12-19T00:40:54ZHealth Check: will I damage my eyes if I don’t wear sunglasses?<figure><img src="https://images.theconversation.com/files/149184/original/image-20161208-31396-t8ax7r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sunglasses should be worn at all times when outdoors during the day when the UV index is 3 or above.</span> <span class="attribution"><a class="source" href="https://unsplash.com/search/sunglasses?photo=6qzw-entUOw">Amy Humphries/Unsplash</a></span></figcaption></figure><p>The iconic <a href="https://youtu.be/tGgn5nwYtj0">“Slip Slop Slap”</a> campaign was launched in Australia in 1981. Sid the Seagull encouraged people to slip on a shirt, slop on sunscreen and slap on a hat to minimise ultraviolet (UV) radiation exposure and reduce the risk of sunburn and skin cancer. </p>
<p>In 2007, the slogan was updated to <a href="http://www.cancer.org.au/preventing-cancer/sun-protection/campaigns-and-events/slip-slop-slap-seek-slide.html">“Slip Slop Slap Seek Slide”</a>. So now it includes seeking shade and sliding on sunglasses to further reduce the risk of UV-related damage. This emphasises the importance of protecting eyes – and the skin around them – from UV radiation. </p>
<h2>Short-term effects</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149183/original/image-20161208-31391-1g479v0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Prolonged exposure to the welder’s arcs without eye protection can cause photokeratitis.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Briefly exposing an unprotected eye to UV rays usually won’t cause any symptoms. </p>
<p>But prolonged or intense UV exposure without eye protection (including to the sun, welder’s arcs, snow and tanning beds) can cause a <a href="http://www.who.int/uv/faq/uvhealtfac/en/index3.html">condition called photokeratitis</a>. </p>
<p>This can be thought of as sunburn of the cornea, the clear window on the front of the eye. UV rays cause death of the outermost layer of cells of the cornea. </p>
<p>This results in severe pain affecting both eyes, which begins six to 12 hours after exposure. </p>
<p>Treatment involves oral painkillers and antibiotic eye ointments (to prevent infection of the damaged cornea) while waiting for the corneal cells to regenerate. </p>
<p>The process takes 24 to 72 hours and people can expect a full recovery with no complications from photokeratitis.</p>
<h2>Long-term effects</h2>
<p>Repeated exposure to UV radiation without adequate eye protection can result in permanent eye damage. Eye diseases associated with chronic UV exposure include the following.</p>
<p><strong>Cataracts</strong></p>
<p>Here, the normally transparent lens of the eye <a href="https://www.ncbi.nlm.nih.gov/pubmed/21617534">becomes cloudy</a>. This causes blurred vision and eventually blindness if untreated. It is <a href="http://www.unep.org/pdf/Solar_Index_Guide.pdf">estimated up to 20% of cataract cases</a> are caused or made worse by UV exposure. </p>
<p>Wearing sunglasses remains one of the most effective ways of preventing <a href="https://theconversation.com/explainer-what-are-cataracts-63699">cataract formation</a>. </p>
<p>When they cause troublesome visual impairment, cataracts require surgical extraction. This costs Australia more than <a href="http://wiki.cancer.org.au/policy/Position_statement_-_Eye_protection">A$320 million a year</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=547&fit=crop&dpr=1 754w, https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=547&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/135769/original/image-20160829-17859-bvfh20.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=547&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cataracts are one of the leading causes of visual impairment globally.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Cataract_in_human_eye.png">Rakesh Ahuja, MD/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><strong>Pterygium</strong></p>
<p>This is a <a href="https://www.ncbi.nlm.nih.gov/pubmed/10511020">benign growth of conjunctival tissue</a> on the cornea. The conjunctiva is the transparent membrane overlying the sclera (the white part of the eye) and usually does not cover the cornea. Although non-cancerous, the presence of a pterygium can cause chronic irritation, redness and inflammation. </p>
<p>Pterygia grow slowly over months and years and can obstruct vision when they grow over the pupil. They may also induce astigmatism (an improper curvature of the cornea), which blurs vision. </p>
<p>Treatment for mild pterygia not affecting vision involves lubrication with artificial tears. Those that affect vision may require surgical excision. </p>
<p>Again, chronic UV exposure to unprotected eyes is a <a href="https://www.ncbi.nlm.nih.gov/pubmed?term=10684840">major cause of pterygium development</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149200/original/image-20161208-31385-1tnilkl.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">Pterygium is a benign growth of conjunctival tissue on the cornea.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/3/34/Pterygium_Slitlamp.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p><strong>Macular degeneration</strong></p>
<p>This is <a href="https://www.ncbi.nlm.nih.gov/pubmed/21617534">a degenerative disease</a> affecting the central part of the retina (the macula) responsible for central vision. <a href="https://theconversation.com/explainer-what-is-age-related-macular-degeneration-59889">Macular degeneration</a> may result in severe visual impairment. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/130187/original/image-20160712-9302-127na3r.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"></a>
<figcaption>
<span class="caption">The macula allows you to see fine detail.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Treatment comprises injections of medications directly into the eye and aims to limit disease progression; it cannot reverse damage that has already occurred.</p>
<p>While the link between UV exposure and macular degeneration is less clear than with cataracts or pterygia, short-wavelength radiation and blue light (present in bright sunshine) cause damage to the retina. There is a correlation between <a href="https://www.ncbi.nlm.nih.gov/pubmed/21646979">light exposure and macular degeneration</a>. </p>
<p>Wearing sunglasses is therefore important to limit excessive light exposure of the retina.</p>
<p><strong>Cancer</strong></p>
<p>Although less common, chronic UV exposure is associated with increased rates of certain types of eye cancers. These are: <a href="https://www.ncbi.nlm.nih.gov/pubmed/9037556">squamous cell carcinoma of the conjunctiva</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/4033707">melanoma within the eye</a>, and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1771324/">skin cancers of the eyelid</a> and around the eye where people do not routinely apply sunscreen. </p>
<p>Treatment of these cancers may sometimes require surgical removal of the entire eye.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149193/original/image-20161208-31379-nvwhzy.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 UV exposure is associated with increased rates of certain types of eye cancers.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p><strong>Climatic droplet keratopathy</strong></p>
<p>This is a <a href="https://www.ncbi.nlm.nih.gov/pubmed/1549808">rare disease</a> caused by UV exposure in which the cornea becomes cloudy, obstructing vision and potentially requiring a corneal transplant to restore vision.</p>
<h2>What kind of sunglasses should I wear?</h2>
<p>All sunglasses sold in Australia are regulated under the <a href="http://wiki.cancer.org.au/policy/Position_statement_-_Eye_protection">Australian/New Zealand Standard</a> for sunglasses and fashion spectacles, which assigns a category from zero to four for each pair of sunglasses. </p>
<p>Categories zero and one aren’t sunglasses and so aren’t considered adequate for UV protection. Categories two to four provide effective UV protection and increasing levels of sun glare reduction (although category four must not be worn when driving). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149203/original/image-20161208-31379-13hz56e.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">More than 90% of UV rays can penetrate through cloud.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/justinwkern/11591028305/in/photolist-iEg3TB-iEheG8-gD1AQf-hyCy9T-afqDfo-eaRir-8wU6hW-aLLcyX-Bp6cz-bPoF8r-5jPra-6Qi17A-6QhZzy-iEmX1H-iEgJ1K-iEicEt-dt5LsA-4z5AY2-pfbjTe-9LE1CS-iEsZsq-fp8Mp6-roCJtM-iEt4FW-i1HNB2-iEi1xD-iEoHjQ-iEipFc-iEp1rs-jfSy1-9R3pm-a5pQyF-8RqbFc-ctJx5W-hdrRGw-27Mot8-8VJP1N-curced-iEsTim-iEhteZ-iEkGBz-iEqBS5-i1GWi8-iEubDS-c2HhJu-hKW4WM-iEj842-kqxNeu-i1GUs4-dVn7JV">Justin Kern/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>It’s important to note price is not an indicator of effectiveness in UV protection. Effective sunglasses should be close-fitting and wrap-around to minimise the amount of UV radiation that can reach the eye.</p>
<p>Some contact lenses also contain UV filters. However, as they cover only the cornea, they provide no protection against the development of pterygia or cancers on or around the eye. </p>
<h2>When should I wear them?</h2>
<p>Sunglasses should be worn at all times when outdoors during the day when the <a href="http://www.bom.gov.au/uv/index.shtml">UV index is 3 or above</a> as there is no defined “safe level” of eye exposure to UV radiation. </p>
<p>They should also be worn regardless of cloudiness, as more than <a href="http://www.unep.org/pdf/Solar_Index_Guide.pdf">90% of UV rays can penetrate through cloud</a>. UV rays also reflect off sand, water and snow. The daily peak period of UV exposure is between 10am and 2pm; seeking shade during these hours is preferable.</p>
<p>The eyes of children are particularly <a href="https://www.ncbi.nlm.nih.gov/pubmed/11227927">susceptible to UV radiation</a>, so children should be encouraged to wear sunglasses as soon as they can tolerate them.</p><img src="https://counter.theconversation.com/content/68582/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Yosar 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>Whether cheap or expensive, sunglasses play a crucial role in eye protection against ultraviolet radiation.Jason Yosar, Associate Lecturer, School of Medicine, The University of QueenslandLicensed 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.