tag:theconversation.com,2011:/ca-fr/topics/smog-21013/articlesSmog – La Conversation2022-12-09T11:30:18Ztag:theconversation.com,2011:article/1962392022-12-09T11:30:18Z2022-12-09T11:30:18Z70 years on from London’s Great Smog, we still need cleaner air to protect health<p>London’s Great Smog of December 1952 was the largest in a series of “pea soupers” which brought normal activity to a halt across the capital. The smog lasted from December 5 to December 9 and led to a large spike in hospital admissions and as many as <a href="https://www.jstor.org/stable/3434786#metadata_info_tab_contents">12,000 deaths</a>.</p>
<p>Pollution episodes like this one were driven by smoke from burning coal in city centres to generate power and heat homes (as recently as the 1980s power plants were still found right in the centre of London). This was then exacerbated by cold and windless winter weather: smoke + fog = smog. This was a very visible challenge. The ensuing <a href="https://www.legislation.gov.uk/ukpga/Eliz2/4-5/52/enacted">Clean Air Acts</a> focused on removing these key pollutant sources to make the air cleaner.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Large building with tall chimney beside a river" src="https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499797/original/file-20221208-7255-9vw3eu.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">Bankside Power Station. Or, at it’s now known, the Tate Modern.</span>
<span class="attribution"><span class="source">Neil Lang / shutterstock</span></span>
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</figure>
<p>The air we breathe today looks, and is, much cleaner than in 1952 but is still not clean enough. Poor air quality still contributes to somewhere between <a href="https://www.rcplondon.ac.uk/projects/outputs/every-breath-we-take-lifelong-impact-air-pollution">26,000 and 38,000 early deaths each year</a> in the UK, mostly through impacts on circulatory and respiratory health. The resultant costs to healthcare and business have been said to amount to <a href="https://www.rcplondon.ac.uk/projects/outputs/every-breath-we-take-lifelong-impact-air-pollution">£20 billion</a> every year. This does not include the costs of reduced quality of life or health conditions where links to pollutant exposure have emerged in recent years (including <a href="https://www.gov.uk/government/publications/air-pollution-cognitive-decline-and-dementia">cognitive decline and dementia</a>). </p>
<p>Pregnant women, children and the elderly are more vulnerable to harm, even if their exposure is the same as other population groups. Most health harms are caused by long-term exposure to fine particles (so-called PM2.5) – less than 30 times the diameter of a human hair and invisible to the naked eye.</p>
<p>The latest UK <a href="https://www.gov.uk/government/publications/chief-medical-officers-annual-report-2022-air-pollution">Chief Medical Officer’s Annual Report</a> suggests we need to go further to reduce air pollution and protect health. Importantly, the report highlights advances in our knowledge of the sources, distribution and health impacts of air pollution which can inform evidence-based actions. </p>
<h2>What we now know</h2>
<p>Although the health risks of pollution were recognised early in the industrial revolution (gravestones in the early 19th century reported “<a href="https://www.britannica.com/event/Great-Smog-of-London">fog-related deaths</a>”) our understanding of these harms has advanced in recent decades. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Smoggy monument" src="https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=567&fit=crop&dpr=1 600w, https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=567&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=567&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=712&fit=crop&dpr=1 754w, https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=712&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/500004/original/file-20221209-33096-qh64s7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=712&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nelson’s Column disappears into the smog, December 1952.</span>
<span class="attribution"><span class="source">N T Stobbs / wiki</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Now, 70 years on from the London smogs, we know that health harms exist <a href="https://apps.who.int/iris/handle/10665/345329">even at low pollutant levels</a> and that there is no “safe” level of PM2.5 exposure. We also now understand the relative contribution of different pollutant sources to ambient pollution, including road transport, industry and agriculture (due to ammonia emitted from manure and fertiliser). We are also able to better determine where pollutants originated, enabling targeted approaches to reducing them at source. The report also recognises major gaps in our knowledge, including air pollution in indoor environments.</p>
<p>The Chief Medical Officer’s report sets out a need to focus air quality improvements on the places where people live, work and study. This approach recognises that many of these are public spaces, both indoors and outdoors. People there are exposed to air pollution but can do little about it individually, so society needs to act.</p>
<p>Outdoors, the report recommends continuing electrification of transport and technical measures targeting emissions from heavy goods vehicles and car brakes and tyres wearing down (which, perhaps surprisingly, is now a <a href="https://www.theguardian.com/environment/2022/jun/03/car-tyres-produce-more-particle-pollution-than-exhausts-tests-show">bigger source of particle pollution</a> than exhausts). </p>
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<a href="https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A worn down car tyre" src="https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499816/original/file-20221208-12481-cfpord.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>
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<span class="caption">Car tyres are a major source of particle pollution.</span>
<span class="attribution"><span class="source">Nitiphonphat / shutterstock</span></span>
</figcaption>
</figure>
<p>Industrial emissions have fallen substantially, but those from agriculture have not: simple changes in fertilisation approaches are needed. Town planning should support reducing air pollution concentrations and exposure and encourage travel on foot and by bike. In urban areas, <a href="https://www.theguardian.com/environment/2022/dec/08/eco-wood-burners-produce-450-times-more-pollution-than-gas-heating-report">burning wood</a> can worsen local air quality. Indoors, the optimal balance between ventilation, energy use and heat loss is a priority for reducing air pollution, preventing respiratory infections and achieving net zero.</p>
<p>Our work in the West Midlands is an example of how these advances can support evidence-based clean air solutions. For example, our <a href="https://wm-air.org.uk/">research</a> quantifies “real-world” pollutants emitted from vehicles while being driven on Birmingham’s roads, as opposed to being tested in a laboratory that simulates driving conditions. We can also identify the chemical fingerprint of particles in the air to quantify these different sources. We can simulate future air quality changes expected from a given policy, such as specific traffic changes, and <a href="https://wm-air.org.uk/project/health/">calculate the health benefits</a> in terms of deaths and disease diagnoses avoided among a given population. </p>
<h2>New air quality targets</h2>
<p>Exactly 70 years on from the deadly London smog, we are again on the verge of new legislation to protect people from the harms of air pollution. The Environment Act 2021 enables the government to set new targets for <a href="https://uk-air.defra.gov.uk/library/air-quality-targets">outdoor pollution levels</a>. If sufficiently ambitious, the new targets should balance improvements in the most polluted areas with achieving some benefit for everyone, even if air quality already meets the threshold value.</p>
<p>We now have an opportunity to improve air quality and health through policy choices informed by evidence. Many of these policies will also deliver benefits for the climate, since many air pollution sources involve burning fossil fuels. However, while reducing carbon emissions is a global challenge, air pollution is less dependent on action taken elsewhere. In many cases it doesn’t really matter what the next country or even the next town is doing – the benefits of local actions in terms of human health, reduced inequality and improved lives are clear.</p><img src="https://counter.theconversation.com/content/196239/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Suzanne Bartington receives funding from the National Institute for Health and Care Research, Natural Environment Research Council and Engineering and Physical Sciences Research Council. </span></em></p><p class="fine-print"><em><span>William Bloss receives funding from the Natural Environment Research Council.</span></em></p>A new report by the UK’s Chief Medical Officer sets out what must happen.Suzanne Bartington, Clinical Research Fellow in Environmental Health, University of BirminghamWilliam Bloss, Professor of Atmospheric Science, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1715362021-11-25T17:21:35Z2021-11-25T17:21:35ZMask wearing wasn’t disputed in previous crises – so why is it so hotly contested today?<figure><img src="https://images.theconversation.com/files/433754/original/file-20211124-13-1eynnjs.jpg?ixlib=rb-1.1.0&rect=71%2C229%2C2276%2C1589&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Men wearing masks outside a military hospital in New York during the 1918 influenza pandemic.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/medical-men-wore-masks-avoid-flu-248206198">/Shutterstock</a></span></figcaption></figure><p>Across <a href="https://www.liberties.eu/en/stories/europe-mask-war-culture/18901">western countries</a>, people are <a href="https://www.theguardian.com/world/2020/jun/29/face-masks-us-politics-coronavirus">polarised</a> over <a href="https://www.politico.com/news/2020/07/15/masks-britain-culture-war-365370">wearing masks</a>. While some support wearing them as an <a href="https://www.theguardian.com/world/2021/nov/17/wearing-masks-single-most-effective-way-to-tackle-covid-study-finds">effective counter to the virus</a>, others believe having to mask up is a <a href="https://theconversation.com/face-mask-rules-do-they-really-violate-personal-liberty-143634">contravention of their human rights</a>.</p>
<p>Our <a href="https://gtr.ukri.org/projects?ref=AH%2FW003813%2F1">interdisciplinary team</a> is currently exploring the role the media plays in influencing the British public’s thoughts and decisions on mask wearing. We’ve found that these polarised opinions have been reflected and reinforced by the media, where a clear divide has appeared. </p>
<p>Pro-mask messages are more present in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7989238/">mainstream media</a>, including in public health adverts and on TV. Conversely, anti-mask wearing sentiments are more common in personalised sources <a href="https://journals.sagepub.com/doi/full/10.1177/0957926520970385">like social media</a>. </p>
<p>Here, mask wearing is often associated with the historical commands of authoritarian governments. Some have even <a href="https://edition.cnn.com/2021/05/21/politics/marjorie-taylor-greene-mask-mandates-holocaust/index.html">compared mask mandates</a> to the Nazi policy of forcing Jews to wear distinguishing yellow stars.</p>
<p>This split in attitudes is a relatively new development. People were more cooperative when asked to wear masks in response to earlier health epidemics and other dangers in the 20th century.</p>
<p>Indeed, a <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252315">2021 study</a> outlines how approval rates for face coverings during earlier crises were far more collectively positive. During <a href="https://pubmed.ncbi.nlm.nih.gov/33319388/">influenza in 1918</a>, the <a href="https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(20)30342-4/fulltext">Blitz in Britain in 1941</a>, and the <a href="https://www.telegraph.co.uk/global-health/science-and-disease/wearing-face-mask-not-new-backlash-against-say-historians/">smog outbreaks</a> that occurred in the UK from the 1930s to the 1960s, masks weren’t contested like today. What explains this change?</p>
<h2>The tangibility of past crises</h2>
<p>The coronavirus is invisible to the human eye, and its worst effects aren’t seen publicly – they occur at home or in hospital wards away from people’s gaze. </p>
<p>Smog, on the other hand, could be seen. Similarly, the threat of a <a href="https://theworld.org/stories/2016-01-08/londons-forgotten-network-massive-underground-air-raid-shelters-being-found-again">Nazi attack in the 1940s</a> was manifested in smoke, debris and dust in the air after German bombing, as well as physical destruction and rubble. Even influenza in 1918, despite its symptoms being very similar to COVID’s, had arguably more publicly visual characteristics (such as vomiting and diarrhoea) that allowed it to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7752013/">resist public scepticism</a>.</p>
<p>It may be that the actual visibility of these earlier crises made them seem more threatening, and so wearing a mask seem more necessary. Indeed, in a bid to make the dangers posed by COVID appear more tangible, <a href="https://www.aljazeera.com/news/2021/5/24/un-chief-says-world-at-war-against-covid-19">politicians</a> and the <a href="https://www.cgdev.org/blog/us-losing-global-war-against-covid-19-and-national-security-issue">media</a> have invoked the language of war when discussing COVID, or used <a href="https://www.campaignlive.co.uk/article/will-governments-new-emotive-covid-ad-people-obey-rules/1705634">images of people on ventilators</a> to materialise the threat.</p>
<p>But such tactics have yielded significant debates among health professionals and linguists, as these produce questionable implications, such as potentially identifying infected people as <a href="https://www.tandfonline.com/doi/full/10.1080/10410236.2020.1844989">“enemies” who bear and spread the virus</a>.</p>
<h2>Variety of the media</h2>
<p>A second factor is that formerly, media was restricted to channels controlled or influenced by government, and these all gave positive depictions of masks. Today, however, there are many other channels, which allow for resistance. </p>
<p>During earlier crises, the media promoted mask wearing as a patriotic act. However, the media’s scope in the first half of the 20th century was far more limited than it is today. Promotion of mask wearing was mainly limited to <a href="https://journals.sagepub.com/doi/pdf/10.1177/00333549101250S308">government-approved posters</a> and newsprint in the 1910s. </p>
<p>Mainstream radio didn’t exist until a decade later. And TV was only introduced in the 1930s but wasn’t widespread <a href="https://dspace.library.uu.nl/handle/1874/373997">until much later</a>. Radio, print and newsreels were the main sources of public information during past eras of mask wearing. </p>
<p>By contrast, today’s media landscape – especially <a href="https://www.rollingstone.com/culture/culture-features/mom-influencers-instagram-covid-19-coronavirus-mask-propaganda-misinformation-1033154/">social media</a> – allows for individual and personalised voices to be heard to an extent unthinkable in earlier decades. Media has become a way of <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0250817">denigrating</a> as well as endorsing mask wearing. </p>
<p>Even music videos provide an opportunity for people to speak out against masks, providing a stark contrast to the <a href="https://archive.org/details/ATishOo">propaganda films of the 1940s</a>. For example, in the video for <a href="https://www.youtube.com/watch?v=eOkkWIOkWl8">Living the Dream</a> by US rock band Five Finger Death Punch, mask wearing is depicted as a way of enforcing people’s compliance in an authoritarian reimagining of America. Eventually, though, the public rebel, and are shown ripping their masks off as they head into battle against their hypocritical unmasked leader.</p>
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<h2>Pressure to wear a surgical mask</h2>
<p>Although <a href="https://publichealth.jmir.org/2020/2/e18444/?utm_source=TrendMD">public information from the NHS and UK government</a> specifically promotes the use of any “face coverings” (including bandannas, scarves, old clothes and so on), such messages are nearly always <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252315">accompanied by images of surgical masks</a>. Graphics that represent the need to wear a face covering nearly always depict a surgical mask. </p>
<p>And when looking at a <a href="https://www.lexisnexis.co.uk/">database of British newspaper reporting</a> from the COVID pandemic, it’s also clear that journalists refer to “masks” more often than to “face coverings”. Despite <a href="https://www.gov.uk/guidance/regulatory-status-of-equipment-being-used-to-help-prevent-coronavirus-covid-19?utm_source=Gov&utm_medium=Email&utm_campaign=MHRA_COVID-19_updates&utm_content=HCP7#face-masks-and-face-coverings">official guidance</a> only requiring proper masks to be used in medical settings, the way they are spoken about and depicted suggests other forms of face covering aren’t as broadly acceptable.</p>
<figure class="align-center ">
<img alt="An NHS poster telling people to 'wash hands, cover face, make space'" src="https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/431580/original/file-20211111-27-8614nm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=415&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A typical NHS poster from during the pandemic, with its face covering depicted as a surgical mask.</span>
</figcaption>
</figure>
<p>While there’s good reason for this – surgical masks have been <a href="https://www.caymancompass.com/2021/10/02/study-surgical-masks-more-effective-than-cloth/">shown to be more effective</a> than other forms of face covering – in the mind of the public, this may limit the scope of what is proper to wear. This may then lower people’s willingness to wear a mask, as it’s known that people are <a href="https://books.google.com/books?hl=en&lr=&id=Z6iYwTFY5mIC&oi=fnd&pg=PA1&dq=restricted+choice+leads+to+rebellion+authority&ots=i38bbVGsn_&sig=Iq14oINjC_pTHzWNSu68sk6LxoA">more likely to accept</a> doing something if they <a href="https://psycnet.apa.org/doiLanding?doi=10.1037%2F0033-2909.134.2.270">perceive that there is choice</a> involved. </p>
<p>Yet in the past, the same pressure didn’t exist. During the influenza and smog outbreaks, attitudes towards <a href="https://www.bbc.co.uk/news/uk-england-london-56085529">alternative face coverings</a> were more permissive, with non-standard masks even being celebrated among the <a href="https://trove.nla.gov.au/newspaper/article/52412108">fashion-conscious cultures</a> of London and Manchester that were impacted by the smog epidemic. Surgical masks of the day would also not have so widely available. The leeway this offered may also have led to a less controversial response to mask mandates compared to today.</p><img src="https://counter.theconversation.com/content/171536/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nathan Abrams, Thora Tenbrink, Anaïs Augé and Maciej Nowakowski receive funding from the Arts and Humanities Research Council. </span></em></p><p class="fine-print"><em><span> </span></em></p>How the pandemic is reported by the media can influence people’s behaviour.Nathan Abrams, Professor of Film Studies, Bangor UniversityAnaïs Augé, Assistant Researcher at the School of Arts, Culture and Language, Bangor UniversityMaciej Nowakowski, Research Assistant in Media Communications and Critical Discourse Analysis, Bangor UniversityThora Tenbrink, Professor of Linguistics, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1396222020-07-02T14:04:43Z2020-07-02T14:04:43ZMexico City buried its rivers to prevent disease and unwittingly created a dry, polluted city where COVID-19 now thrives<figure><img src="https://images.theconversation.com/files/345131/original/file-20200701-141278-xa8j31.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5176%2C3445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Situated on a plateau and surrounded by mountains, Mexico City – seen here in a haze on May 20, 2018 – is a 'bowl' that traps smog and dust.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Mexico-Pollution/bf0cb5c6c58140afa6693a2e8c0157cd/75/0">AP Photo/Marco Ugarte</a></span></figcaption></figure><p><em>Leer <a href="https://theconversation.com/contaminacion-el-silencioso-enemigo-de-la-cdmx-en-la-lucha-contra-el-covid-19-143504">en español</a></em></p>
<p>Mexico City is a dust bowl, a <a href="https://www.redalyc.org/pdf/312/31204702.pdf">polluted megalopolis</a> where breathing is hard and newly washed clothes hung out to dry turn stiff by evening. Even before the COVID-19 pandemic began clobbering this capital city, residents regularly wore face masks during the <a href="https://www.cnn.com/2019/05/17/americas/mexico-city-pollution-in-photos-intl/index.html">frequent air quality emergencies</a> there. </p>
<p>Now Mexico City’s bad air pollution – which contributes to high rates of <a href="https://www.gob.mx/inecc/documentos/coronavirus-sars-cov-2-contaminacion-atmosferica-y-riesgos-a-la-salud">respiratory and cardiovascular diseases</a> – is making the metropolitan area’s 21 million people more vulnerable to the coronavirus. </p>
<p>Mexico City wasn’t always an ecological and health disaster. As the center of the Aztec empire, it was verdant and diverse. As late as the early 20th century, 45 rivers ran through the Mexican capital.</p>
<p>The decision to bury and pave over its rivers, creating today’s arid metropolis, was a 20th-century plan meant to protect residents from disease – specifically, cholera, <a href="http://oa.upm.es/57891/1/TFG_20_CODERCH_CARRETERO_PAULA.pdf">malaria and other waterborne illnesses brought on by frequent flooding</a>.</p>
<h2>Origins of Mexico City</h2>
<p>I’m a <a href="https://scholar.google.com/citations?user=LA4-pCYAAAAJ&hl=en">scholar who studies poverty</a> with a focus on urban areas, and Mexico City is my gray, concrete hometown. The relationship between its geography, history and health outcomes are relevant today, as the city struggles with its latest disease outbreak.</p>
<p><a href="https://www.redalyc.org/pdf/312/31204702.pdf">Mexico City was founded</a> by the people now called Aztecs – but who called themselves Tenochcas – in 1325. The Aztecs built their city on a rock in Lake Texcoco, mostly because the more prime locations along the shore were already taken. </p>
<p>By 1427 the powerful Aztecs had defeated their lakeshore neighbors and built a shining capital that spanned the lake. The city, called Tenochtitlan, was built amid water by the development of “<a href="http://zaloamati.azc.uam.mx/handle/11191/5077">chinampas</a>” – small plots of lake filled in with debris, pottery and soil to create solid land, with channels flowing around them. </p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>The foremost chronicler of Spain’s colonization of Mexico, <a href="https://www.gutenberg.org/files/32474/32474-h/32474-h.htm">Bernal Díaz del Castillo</a>, described Tenochtitlan as crisscrossed by engineering marvels like causeways and removable bridges, and full of “splendid” palaces. Diaz del Castillo reports that the city market was larger and better regulated than those of <a href="https://www.gutenberg.org/files/32474/32474-h/32474-h.htm">Constantinople and Rome</a>. As in the Roman empire, aqueducts supplied the city with <a href="https://www.gutenberg.org/files/32474/32474-h/32474-h.htm">fresh water</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=462&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=462&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345079/original/file-20200701-53-1eotava.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=462&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Replica of Tenochtitlan, with its causeways and canals.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/4ULeHK">Randal Sheppard/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Tenochtitlan looked like Venice – gorgeous – and had the same health problems, including contaminated water, mosquitoes and unpleasant smells. But the Aztecs <a href="https://www.redalyc.org/pdf/312/31204702.pdf">managed the city well and prevented flooding</a>. Their dikes and waterways permitted a <a href="https://www.jstor.org/stable/pdf/40315074.pdf?refreqid=excelsior%3A92c9cb15fd681165ffef84e7676e5128">great diversity of plants and animals to flourish</a>, and the chinampa agricultural system – in which land was replenished with soil dredged from the lake bottom – was <a href="https://www.jstor.org/stable/pdf/40315074.pdf?refreqid=excelsior%3A92c9cb15fd681165ffef84e7676e5128">one of the most productive</a> the world has ever known. </p>
<h2>Spanish incompetence</h2>
<p>That good urban management <a href="https://www.redalyc.org/pdf/312/31204702.pdf">ended with the Spanish conquest in 1521</a>. Tenochtitlan was destroyed, its <a href="https://www.gutenberg.org/files/32474/32474-h/32474-h.htm">palaces and causeways turned to rubble at the bottom of the lake</a>.</p>
<p>The Spaniards did not understand the watery ecology of the area, nor <a href="https://www.redalyc.org/pdf/312/31204702.pdf">did they understand or respect</a> Aztec engineering. To rebuild their capital, they drained the lake. </p>
<p>This strategy led to both drought and an inadequate water supply for most of the year. Rainy season, however, brought <a href="https://www.jstor.org/stable/pdf/40315074.pdf?refreqid=excelsior%3A92c9cb15fd681165ffef84e7676e5128">tremendous floods</a>. In 1629, the worst flood in Mexico City’s recorded history is said to have lasted five years and killed more than 30,000 people due to drowning and disease. Churches reportedly <a href="http://oa.upm.es/57891/1/TFG_20_CODERCH_CARRETERO_PAULA.pdf">held rooftop masses</a>. </p>
<p>Rainy season turned parts of the city turned into cesspools, spawning waterborne diseases like <a href="http://www.hmc.mil.ar/webResources/Documentos/inundaciones.pdf">cholera and malaria</a>, as well as meningitis. Gastrointestinal illnesses festered, too, because residents used Mexico City’s rivers for dumping garbage and sewage. <a href="http://oa.upm.es/57891/1/TFG_20_CODERCH_CARRETERO_PAULA.pdf">Human</a> and <a href="http://www.hmc.mil.ar/webResources/Documentos/inundaciones.pdf">animal</a> bodies floated in the stagnant waters, emitting a terrible stench.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=408&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=408&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=408&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=513&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=513&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345061/original/file-20200701-159785-1btcp7p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=513&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Canals in Xochimilco, a part of Mexico City that retains its ancient waterways.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-aztec-canals-at-the-floating-gardens-of-xochimilco-the-news-photo/152201035?adppopup=true">Werner Forman/Universal Images Group/Getty Images</a></span>
</figcaption>
</figure>
<h2>Mexico goes deep</h2>
<p>Mexico gained independence from Spain in 1810. To deal once and for all with its flooding problems, city leaders decided in the 1890s to channel rain, flood waters and sewage away from the city via a <a href="https://blogdelagua.com/actualidad/inundaciones-en-mexico/">30-mile desagüe, or drainage channel</a>. </p>
<p>Around this time, the <a href="https://www.jstor.org/stable/pdf/40315074.pdf?refreqid=excelsior%3A92c9cb15fd681165ffef84e7676e5128">population of the capital began to explode</a>. Mexico City had 350,000 residents in 1900 and 3 million in 1950. By the <a href="http://zaloamati.azc.uam.mx/handle/11191/5077">1930s</a>, its novel sanitation system was already insufficient. Plus, residents were still using Mexico City’s many rivers for <a href="https://www.eluniversal.com.mx/entrada-de-opinion/colaboracion/mochilazo-en-el-tiempo/nacion/sociedad/2017/06/21/los-rios-de-la">washing clothes, as garbage pits and as sewers</a>. </p>
<p>In 1938, the architect Carlos Contreras proposed <a href="http://zaloamati.azc.uam.mx/handle/11191/5077">enclosing</a> three polluted rivers – the Piedad, the Consulado and the Verónica – and turning them into one giant viaduct to <a href="https://www.eluniversal.com.mx/entrada-de-opinion/colaboracion/mochilazo-en-el-tiempo/nacion/sociedad/2017/06/21/los-rios-de-la">prevent flooding, disease and death</a>. Political conditions did not allow this idea to move forward at the time, but the idea of <a href="https://www.eluniversal.com.mx/entrada-de-opinion/colaboracion/mochilazo-en-el-tiempo/nacion/sociedad/2017/06/21/los-rios-de-la">putting Mexico City’s filthy waterways into enormous pipes</a> and burying them stuck. </p>
<p>Over the following decades, rivers began to be put underground. Between 1947 and 1952 most of Mexico City’s 45 rivers were <a href="http://oa.upm.es/57891/1/TFG_20_CODERCH_CARRETERO_PAULA.pdf">channeled into giant tubes, buried and paved over</a>. Today, these rivers are visible only in the names <a href="http://zaloamati.azc.uam.mx/handle/11191/5077">of the streets that run over them</a>: Rio Mixcoac Avenue, Rio Churubusco Avenue and others.</p>
<h2>Smog bowl</h2>
<p>This system gave mid-century Mexico City enough sewer capacity, roads and buildings to serve its population. The foul smell and unsanitary conditions also diminished, because people couldn’t dump garbage into covered waterways. </p>
<p>But without its rivers, Mexico City dried up and grew dusty. And because of its geography – <a href="https://en.mxcity.mx/2016/04/mexico-citys-mountains/">located</a> on a plateau, surrounded by mountains – the dust was unable to escape. Mexico City is in a bowl that traps whatever floats in the air. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&rect=26%2C6%2C4440%2C2967&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&rect=26%2C6%2C4440%2C2967&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/345073/original/file-20200701-13398-bqmlmo.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">Ruins of Teotihuacan, outside Mexico City, March 19, 2020.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Virus-Outbreak-Mexico-Equinox-Closure/4059b21152624ee09a59daf200a6b542/12/0">AP Photo/Rebecca Blackwell</a></span>
</figcaption>
</figure>
<p>Starting in the 1980s, the number of cars <a href="https://www.sciencedirect.com/science/article/pii/S096669231500023X">grew into the millions</a>, trapping pollution too. Today, Mexico City is <a href="https://www.washingtonpost.com/world/2019/05/16/scary-images-mexico-citys-pollution-emergency/">notorious for its smog</a> and for the terrible <a href="https://www.iqair.com/blog/air-quality/air-pollution-particles-in-hearts">health consequences</a> pollution brings, including asthma and heart disease. </p>
<p>The coronavirus outbreak wasn’t caused by polluted air. But the city’s bad air quality – together with <a href="https://www.jornada.com.mx/2009/05/25/capital/043n1cap">overcrowding and other poverty-related factors</a> – creates the conditions for COVID-19 to severely sicken and kill more people.</p>
<p>In trying to eliminate waterborne illness, the Mexican capital ended up helping an airborne virus find more hosts. It’s an irony of history the Aztecs would surely mourn.</p>
<p><em>Editor’s note: A photo caption incorrectly dating Teotihuacan to the Aztec people has been corrected.</em></p><img src="https://counter.theconversation.com/content/139622/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elena Delavega 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 Aztecs had a shining city on a lake, with canals, causeways and aqueducts – until the Spanish came. Mexico City is still suffering the consequences of their bad public health decisions.Elena Delavega, Associate Professor of Social Work, University of MemphisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1346102020-05-08T12:18:51Z2020-05-08T12:18:51ZCOVID-19 shutdowns are clearing the air, but pollution will return as economies reopen<figure><img src="https://images.theconversation.com/files/333198/original/file-20200506-49542-1tfscjx.jpg?ixlib=rb-1.1.0&rect=72%2C0%2C8067%2C5373&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Clear skies over Los Angeles, April 17, 2020.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/view-of-downtown-los-angeles-with-clear-blue-skies-during-news-photo/1219498626?adppopup=true">Araya Diaz/Getty Images</a></span></figcaption></figure><p>With many economies locked down to slow the spread of coronavirus, people from <a href="https://www.youtube.com/watch?v=9654d4dwVmw">Beijing</a> to <a href="https://www.space.com/coronavirus-california-emissions-reduced-blue-skies-ozone-increase.html">Los Angeles</a> have noticed bluer skies and less smog. Photos from <a href="https://www.cnn.com/travel/article/himalayas-visible-lockdown-india-scli-intl/index.html">Punjab</a> and <a href="https://www.npr.org/sections/coronavirus-live-updates/2020/04/14/833996289/from-nairobi-a-rare-clear-glimpse-of-mt-kenya-drives-disbelief-on-social-media">Nairobi</a> reveal mountains that had been shrouded in haze for years. Satellites show cleaner air extending across broad swaths of <a href="https://www.nytimes.com/interactive/2020/climate/coronavirus-pollution.html">Asia</a>, <a href="https://www.space.com/europe-air-pollution-drop-during-coronavirus-lockdowns.html">Europe</a> and <a href="https://www.cnn.com/2020/03/23/health/us-pollution-satellite-coronavirus-scn-trnd/index.html">North America</a>. </p>
<p>These stunning images reflect how the air is changing as the world confronts COVID-19. People are staying home, driving less and taking fewer flights and cruises. This crisis provides a unique experiment to see how the atmosphere responds as nations cut their emissions.</p>
<p>The air is getting cleaner, although these blue skies may be temporary. But it isn’t getting cooler. The buildup of greenhouse gas pollution <a href="https://www.esrl.noaa.gov/gmd/ccgg/trends/">continues</a>, and global temperatures are <a href="https://www.ncdc.noaa.gov/sotc/global/202003/supplemental/page-2">still rising</a>.</p>
<p>Why this difference? As an <a href="https://scholar.google.com/citations?user=U4vSW6MAAAAJ&hl=en">atmospheric scientist</a>, I see it as an illustration of the contrasting challenges posed by air pollution and climate change.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RFsxDqQWjhk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Although cities around the world are seeing the clearest skies in decades, 2020 is still on track to be the warmest year on record.</span></figcaption>
</figure>
<h2>The view from above</h2>
<p>You may have seen maps in the news showing blotches of air pollution that have shrunk since economies started shutting down in the past few months. Most of those maps are plotted from satellite observations of nitrogen dioxide, or NO2, a gas that triggers respiratory illnesses such as <a href="https://www.lung.org/clean-air/outdoors/what-makes-air-unhealthy/nitrogen-dioxide">asthma</a>. It also reacts in the air to form other types of pollution, such as smog, haze and acid rain. </p>
<p>Nitrogen dioxide can be observed from space because it absorbs unique slivers of sunlight’s rainbow of colors. Those observations tell us a lot about what’s happening on Earth.</p>
<p>Some NO2 comes from natural sources like lightning and soils. Those aren’t affected by the current crisis. What has changed is the amount of pollution coming from burning fossil fuels, especially in cars, airplanes and ships. </p>
<p>You can see the impacts of those reductions in satellite observations comparing NO2 concentrations over the United States in the spring of 2020 with the same period in 2019. They show that pollution levels are declining far more sharply over urban regions, where human sources of NO2 tend to dominate, than rural ones.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=250&fit=crop&dpr=1 600w, https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=250&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=250&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=315&fit=crop&dpr=1 754w, https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=315&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/333244/original/file-20200506-49565-1iynyj3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=315&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=259&fit=crop&dpr=1 600w, https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=259&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=259&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=325&fit=crop&dpr=1 754w, https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=325&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/333245/original/file-20200506-49538-19ood3l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=325&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nitrogen dioxide over the United States from March 16 to April 29 in 2019 (top) and 2020 (bottom).</span>
<span class="attribution"><a class="source" href="https://giovanni.gsfc.nasa.gov/giovanni/">Both images from Daniel Cohan, via NASA Giovanni</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Haze at ground level</h2>
<p>In addition to images from space, many people are sharing photos that show haze giving way to blue skies and clearer views of landmarks and mountains. These reflect another change: declining levels of particulate air pollution. </p>
<p>Particles are tiny bits of soot and other substances floating in the air. They too come from a wide range of natural and man-made sources, including fossil fuel combustion, cooking meat, wildfires, trees and dust. As with nitrogen dioxide, the COVID-19 crisis provides an unplanned opportunity to better understand the sources of particulate matter.</p>
<p>This is important because particles are responsible for most of the <a href="https://www.who.int/airpollution/ambient/health-impacts/en/">4.2 million deaths</a> that outdoor air pollution causes globally each year. Those deaths come from respiratory ailments, as well as heart attacks and strokes, since particles can be small enough to pass through the lungs into the bloodstream. </p>
<p>There’s even some preliminary evidence that exposure to <a href="https://projects.iq.harvard.edu/covid-pm">particulate matter</a> and <a href="http://dx.doi.org/10.1016/j.scitotenv.2020.138605">nitrogen dioxide</a> may make people more vulnerable to dying from COVID-19, although major uncertainties remain and more research is needed.</p>
<h2>No COVID cooling</h2>
<p>So what about carbon dioxide, or CO2, the leading cause of global warming? As we breathe cleaner air and see less haze, is that falling too? </p>
<p>Unfortunately, no. </p>
<p>Some observers estimate that the global response to COVID-19 could cause CO2 emissions in 2020 to fall by about 8%, which would be the <a href="https://www.carbonbrief.org/analysis-coronavirus-set-to-cause-largest-ever-annual-fall-in-co2-emissions">sharpest drop in modern history</a>. But unlike the temporary improvements we’re seeing in nitrogen dioxide and particulate matter, the decline in CO2 emissions won’t reduce total atmospheric concentrations of CO2. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=487&fit=crop&dpr=1 600w, https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=487&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=487&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=612&fit=crop&dpr=1 754w, https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=612&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/332428/original/file-20200504-83736-1rh9azh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=612&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global emissions (top) and annual change (bottom) of carbon dioxide from energy use, in gigatons.</span>
<span class="attribution"><a class="source" href="https://www.iea.org/reports/global-energy-review-2020/global-energy-and-co2-emissions-in-2020#abstract">IEA Global Energy Review 2020</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>That’s because CO2 can stay in the air for centuries, while most other pollutants last for only days before they rain out or chemical reactions break them down. Carbon dioxide levels in the air will stabilize only when emissions reach a “net-zero” balance, in which sources are not emitting more CO2 than carbon sinks, such as vegetation, oceans and carbon-capturing devices, can remove. </p>
<p>This year’s declines will be nowhere near enough to achieve that balance. So carbon dioxide levels in the atmosphere are <a href="https://www.esrl.noaa.gov/gmd/ccgg/trends/">still rising</a>, albeit at a somewhat slower rate than they would under business as usual. So are temperatures. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=467&fit=crop&dpr=1 600w, https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=467&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=467&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=587&fit=crop&dpr=1 754w, https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=587&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/329796/original/file-20200422-47832-17lrimq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=587&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Levels of carbon dioxide in the air continue to increase.</span>
<span class="attribution"><a class="source" href="https://www.esrl.noaa.gov/gmd/ccgg/trends/">NOAA</a></span>
</figcaption>
</figure>
<p>Even as billions of people around the world stayed home and fossil-fuel-powered economies slowed down, March 2020 was the <a href="https://www.ncei.noaa.gov/news/global-climate-202003">second-warmest March on record</a>. </p>
<p>Paradoxically, it’s possible that responses to COVID-19 could actually cause a temporary bump in warming because of the way in which particles impact climate. </p>
<p>While CO2 traps the Earth’s heat, many types of particles reflect sunlight away from Earth, which provides a cooling effect. Lower particle pollution levels will allow more sunlight to reach the Earth’s surface. That could <a href="https://doi.org/10.1073/pnas.1819989116">temporarily accelerate warming</a>, although scientists are <a href="https://www.ipcc.ch/report/ar5/wg1/">uncertain how strong that effect might be</a>. </p>
<p>Coincidentally, 2020 marks the start of a global effort to <a href="http://www.imo.org/en/MediaCentre/HotTopics/Pages/Sulphur-2020.aspx">cut sulfur emissions from ships</a>. Those emissions are a leading source of particles <a href="https://earthzine.org/could-cuts-in-sulfur-from-coal-and-ships-help-explain-the-2015-spurt-in-northern-hemisphere-temperatures/">over the oceans</a>. Together, cleaner ships and less fossil fuel use this year will provide an unprecedented test of how climate responds to particles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/329895/original/file-20200422-47804-h6a6dr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This March was the second hottest on record, even though carbon dioxide emissions fell.</span>
<span class="attribution"><a class="source" href="https://www.ncdc.noaa.gov/sotc/global/202003/supplemental/page-1">NOAA</a></span>
</figcaption>
</figure>
<h2>What lies ahead</h2>
<p>What does all of this mean for air and climate beyond the current crisis? Air pollution can return as quickly as it faded if fossil fuel use rebounds. In fact, nitrogen dioxide levels are <a href="https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-5P/COVID-19_nitrogen_dioxide_over_China">already beginning to rise</a> over China as its lockdown eases.</p>
<p>Meanwhile, long-lasting carbon dioxide will continue to accumulate, making it difficult to stabilize the climate even as nations work to cut emissions. Only technologies, policies and investments that replace fossil fuels with energy efficiency and clean fuels can sustainably achieve cleaner air and a stable climate.</p>
<p>[<em>Get facts about coronavirus and the latest research.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=upper-coronavirus-facts">Sign up for The Conversation’s newsletter.</a>]</p><img src="https://counter.theconversation.com/content/134610/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Cohan has previously received funding from NASA, the National Science Foundation, and the U.S. Environmental Protection Agency. </span></em></p>From Nairobi to Los Angeles, pandemic lockdowns have cleared pollution from the skies. But those blue vistas may be temporary, and shutdowns aren’t slowing climate change.Daniel Cohan, Associate Professor of Environmental Engineering, Rice UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1104702019-01-30T13:45:05Z2019-01-30T13:45:05ZAir pollution may be affecting how happy you are<figure><img src="https://images.theconversation.com/files/255894/original/file-20190128-108348-18i4i1m.jpg?ixlib=rb-1.1.0&rect=11%2C5%2C3982%2C2658&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Helen Sushitskaya / shutterstock</span></span></figcaption></figure><p>For decades now, GDP has been the standard measure of a nation’s well-being. But it is becoming clear that an economic boost may not be accompanied by a rise in individual happiness.</p>
<p>While there are many reasons for this, one important factor is that as nations become richer, environmental features such as green space and air quality often come under increasing threat. The mental health benefits of <a href="https://theconversation.com/green-cities-provide-a-mental-health-boost-that-lasts-21901">access to parks or waterfronts</a>, for instance, have long been recognised but more recently researchers have also started to look at the role air pollution can play in our general mental health and happiness.</p>
<p>With more tangible outcomes such as health, <a href="https://theconversation.com/air-pollution-may-be-damaging-childrens-brains-before-they-are-even-born-39409">cognitive performance</a> or <a href="https://theconversation.com/research-shows-if-you-improve-the-air-quality-at-work-you-improve-productivity-76695">labour productivity</a>, the adverse effects of poor air are significant and well-established. The link to infant mortality and respiratory disease is well known, and the World Health Organisation estimates that around <a href="https://www.who.int/airpollution/en/">7m deaths</a> are attributable to air pollution each year.</p>
<p>But while many people will die and many more will acquire a chronic health condition, focusing on objective indicators such as these may still understate the true welfare cost. This is because there is now good evidence of a direct link between air quality and overall mental health and happiness.</p>
<h2>Evidence from all over the world</h2>
<p>This evidence comes from a diverse array of studies in different countries and using different analytical approaches. The most compelling of these studies track the same people over time, and find that changes in the air quality in these people’s neighbourhoods are related to changes in their self-reported happiness.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/256103/original/file-20190129-108367-jognhk.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">Ein Kohlekraftwerk.</span>
<span class="attribution"><span class="source">Uwe Aranas / shutterstock</span></span>
</figcaption>
</figure>
<p>One particularly <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1468-0297.2008.02241.x">innovative study</a> looked at what happened when large power plants in Germany were fitted with equipment designed to reduce emissions. Researchers had access to happiness data from a long-term survey of a panel of around 30,000 Germans, and categorised everyone by whether they lived upwind or downwind of a power plant (or nowhere near). </p>
<p>The research found that those downwind underwent a significant improvement in their happiness levels after the installation, while their upwind neighbours did not benefit. This sort of comparison – a natural experiment that would be impossible and perhaps unethical to replicate in a lab – helps to ensure that the improvement in happiness was due to the improvement in air quality as opposed to other factors.</p>
<p>Economists and scientists are continually on the lookout for new ways to test the association. One example, recently published in <a href="https://www.nature.com/articles/s41562-018-0521-2">Nature Human Behaviour</a>, comes from China. Researchers looked at the sentiment expressed in 210m geotagged messages on the microblog platform Sina Weibo (a Chinese equivalent to Twitter). Given they knew where these tweets had been sent from, and how happy or sad they were, the researchers were then able to match the tweets to a daily local air quality index, providing a real-time connection between air pollution and happiness. Analysing data from 144 Chinese cities, they found that self-reported happiness was significantly lower on days with relatively higher pollution levels.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=204&fit=crop&dpr=1 600w, https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=204&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=204&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=256&fit=crop&dpr=1 754w, https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=256&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/256101/original/file-20190129-39344-xnxgja.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=256&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Shanghai skyscrapers disappear into the smog.</span>
<span class="attribution"><span class="source">Grigvovan / shutterstock</span></span>
</figcaption>
</figure>
<p>This study adds to a pile of research which suggests that air pollution can be <a href="https://www.york.ac.uk/media/economics/documents/hedg/workingpapers/1708.pdf">detrimental to happiness</a> – but we still need more research on <em>why</em> this is. While health is undoubtedly a factor, we know from studies that control for health status that air pollution affects happiness over and above any indirect effects on physical condition. Some possible reasons for the direct link include aesthetics such as haze, smell and even taste, as well as anxiety about personal health or the health of others. Air pollution has also been a focus of several studies on <a href="https://www.sciencedirect.com/science/article/pii/S0140673616323996?via%3Dihub">cognitive impairment</a>, but it is still too early to say if it really plays a role in brain health. </p>
<p>Improving the well-being of citizens remains an obvious and important aim of public policy. To date, the principal focus has been on material well-being but many social scientists and indeed policy makers now argue that we need to take account of how people think and feel about the quality of their life. This is not to ignore material factors like income or physical health. Rather, a comprehensive picture of societal well-being needs to integrate objective indicators with subjective measures like happiness. Doing so will help ensure that we take account of the total cost of environmental degradation such as air pollution. And we will all be better off as a result.</p><img src="https://counter.theconversation.com/content/110470/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Howley 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 in China adds to the evidence of a direct link between air pollution and happiness.Peter Howley, Associate Professor of Economics, University of LeedsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1059332018-11-01T10:50:03Z2018-11-01T10:50:03ZCoal can’t compete with cheaper alternatives and the industry’s true costs are higher than they appear<figure><img src="https://images.theconversation.com/files/243340/original/file-20181031-122168-1mx3qop.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Big Brown coal plant in Fairfield is among the Texas power stations that have been shut down.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Coal-Plant/2b2ed2206ad24aef83f93cd918fe210d/1/0">AP Photo/David J. Phillip</a></span></figcaption></figure><p>There are costs associated with electricity beyond what shows up on your monthly bill.</p>
<p>When that energy comes from coal, residents who live downwind pay through <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1539-6924.2009.01227.x">poorer health</a> and, as with all fossil fuels, the whole world pays for this combustion in the form of a <a href="https://www.ipcc.ch/report/ar5/">warmer climate</a>. Cleaning up or closing the nation’s dirtiest power plants could help stem the damage all around.</p>
<p>As an <a href="https://scholar.google.com/citations?user=U4vSW6MAAAAJ&hl=en">atmospheric scientist</a>, I worked with two students to compute some of the often-overlooked <a href="https://www.tandfonline.com/doi/full/10.1080/10962247.2018.1537984">costs of coal-fired power stations</a>. We found that the damage to public health and the climate this source of electricity causes far exceeds the money power generators earn from the electricity they sell. </p>
<h2>Three cents isn’t enough</h2>
<p>Texans <a href="https://www.eia.gov/electricity/sales_revenue_price/pdf/table5_a.pdf">spend roughly 11 cents for each kilowatt-hour of electricity</a>, enough to <a href="https://electricityplans.com/kwh-kilowatt-hour-can-power/">power a television for few days</a>, no matter how it was generated. Most of that revenue pays for the power to be transmitted to homes and marketed to consumers.
<a href="https://www.eia.gov/electricity/wholesale/">Less than 3 cents</a> from every 11 cents on Texan electric bills flows to the companies that generate the power.</p>
<p>Those three pennies don’t cover even the direct costs of operating coal power plants in every case. </p>
<p><a href="https://www.dallasnews.com/business/energy/2018/09/17/much-texas-dropped-reliance-coal-surprised">Coal-fired power now supplies less than 24 percent</a> of the electricity Texas generates, down from about about a third in 2017 following the closure of <a href="https://www.eia.gov/todayinenergy/detail.php?id=36593">three large coal plants</a> in early 2018. Luminant, the company that shuttered many of those plants called them “<a href="https://www.luminant.com/luminant-close-two-texas-power-plants/">economically challenged</a>” even though <a href="https://www.eia.gov/state/print.php?sid=TX">coal is cheaper in Texas</a> than on average in the U.S.</p>
<p><a href="https://www.eia.gov/electricity/annual/html/epa_03_08.html">Coal’s woes</a> aren’t limited to Texas. As a result of the fuel’s competitive disadvantage, <a href="https://www.utilitydive.com/news/new-campaign-will-ask-coal-users-to-face-the-cold-hard-economic-case-agai/539613/">275 of the nation’s 530 coal plants closed</a> or were <a href="https://www.ucsusa.org/clean-energy/coal-and-other-fossil-fuels/coal-transition#.W9m-22hKhPZ">converted to natural gas</a> between 2002 and 2018.</p>
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<h2>The social cost of carbon</h2>
<p>If utilities had to compensate society for the cost of the pollution Texan coal-fired power plants produce, even more of them would be on the chopping block. The rationale for this concept, known as the <a href="https://19january2017snapshot.epa.gov/climatechange/social-cost-carbon-fact-sheet_.html">social cost of pollution</a>, is that producing electricity releases pollution that harms the climate and public health. Generating each kilowatt-hour of power from coal results in more than 2 pounds of climate-warming <a href="https://www.epa.gov/energy/emissions-generation-resource-integrated-database-egrid">carbon dioxide</a> along with <a href="https://www.eia.gov/tools/faqs/faq.php?id=74&t=11">other pollutants</a> that <a href="https://www.wacotrib.com/news/business/big-brown-among-coal-fired-power-plants-scheduled-to-close/article_15561f3f-991c-57c5-b6bd-533e96540a6a.html">harm human health</a>.</p>
<p>Assuming that the <a href="https://19january2017snapshot.epa.gov/climatechange/social-cost-carbon_.html">social cost of carbon dioxide is around US$52 per ton</a>, near the middle of a range of government estimates, then the damage caused by coal plant emissions is roughly 5 cents per kilowatt-hour, just in terms of climate change.</p>
<p>Those climate impacts are fairly consistent across all of the 13 Texas coal plants that we studied. That’s because each power plant burns a similar amount of coal to generate each kilowatt-hour of electricity. For global warming, the location of emissions is irrelevant, since carbon dioxide accumulates in the atmosphere for centuries and its <a href="https://www.ipcc.ch/report/ar5/">impact is worldwide</a>.</p>
<p>For health, the location of a given coal plant matters, since more people are exposed when coal-fired power plant pollution is emitted near or upwind of densely populated urban areas. Even bigger differences arise from disparities in the various pollution-control devices that coal-fired power stations install.</p>
<p>Most coal plants already control two pollutants that are byproducts of their power generation, <a href="http://www.doi.org/10.1088/1757-899X/330/1/012122">ash</a> and <a href="https://www.eia.gov/todayinenergy/detail.php?id=32952">mercury</a>, very effectively. That leaves two pollutants, nitrogen oxides and sulfur dioxide, that are most damaging to public health.</p>
<p><a href="https://www3.epa.gov/region1/airquality/nox.html">Nitrogen oxide emissions</a> react in the atmosphere to form ground-level ozone, sometimes referred to as smog. <a href="https://www.epa.gov/so2-pollution">Sulfur dioxide</a> converts into microscopic particles known as particulate matter that increase rates of heart attacks, strokes and other diseases.</p>
<p>Together, power plant emissions of these two <a href="https://theconversation.com/the-other-reason-to-shift-away-from-coal-air-pollution-that-kills-thousands-every-year-78874">pollutants kill tens of thousands of Americans</a> each year, scientists estimate.</p>
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<h2>The dirtiest plants</h2>
<p>In our study, we ran computer models to simulate how much air quality and health would improve if certain Texas coal power plants shut down. As we explained in an article published in the <a href="https://www.tandfonline.com/doi/full/10.1080/10962247.2018.1537984">Journal of the Air & Waste Management Association</a>, we found that coal power stations lacking modern devices to control sulfur and nitrogen pollution cause far more damage to public health than cleaner plants. </p>
<p>Certain coal plants emit five times as much nitrogen oxides as cleaner plants, while others emit 20 times more sulfur dioxide than the ones that have modern scrubbers.</p>
<p>Overall, we estimated that Texas coal plants were responsible in 2015 for several hundred deaths per year, mostly due to particulate matter from the unscrubbed sulfur pollution.</p>
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<h2>Sulfur and nitrogen regulations</h2>
<p>The dirtiest power plants continue to emit so much more pollution than their competitors by slipping through the cracks of a patchwork of state and federal regulations.</p>
<p>Nationwide <a href="https://www.edf.org/climate/how-cap-and-trade-works">cap-and-trade programs</a> for nitrogen oxide emissions and sulfur dioxide emissions, such as the federal <a href="https://www.epa.gov/airmarkets/acid-rain-program">Acid Rain Program</a>, let companies trade their allowances for emitting pollution. </p>
<p>That can be a cost-effective approach, since it motivates utilities to clean up their act. But the EPA has failed to cut national caps as quickly as power plants have cleaned up or closed down. This inaction created a glut of pollution allowances and drove their <a href="https://www.epa.gov/airmarkets/2018-so2-allowance-auction">price down to just pennies</a> per ton, even though the resulting health and environmental damage is typically worth <a href="http://www.doi.org/10.1007/s10584-015-1343-0">thousands of dollars per ton</a>. </p>
<p>The authorities have applied more direct regulations unevenly. The EPA has required control devices for nitrogen oxides and sulfur dioxide at new coal plants since the early 1980s, but not necessarily at older ones. A 2014 study by Duke University researchers found that nearly 80 percent of U.S. <a href="https://doi.org/10.1016/j.enpol.2014.03.036">coal power plants did not meet the pollution limits</a> required of new plants.</p>
<p>States have mandated stringent nitrogen oxide controls at power plants in cities that violate ozone smog standards, but not in locations that are at times upwind of those regions. </p>
<p>Most <a href="http://environment.law.harvard.edu/2018/04/regional-haze-rule-rollback/">states required sulfur scrubbers</a> nearly a decade ago as part of their plans for reducing haze in scenic areas. But Texas has failed to finalize its own <a href="https://www.epa.gov/visibility">Regional Haze Rule</a> plan for nearly a decade, leaving it to the EPA to step in.</p>
<p>Although the environmental agency proposed <a href="https://thehill.com/blogs/pundits-blog/energy-environment/312138-the-most-important-pollution-rule-youve-never-heard-of">stringent plant-by-plant sulfur dioxide</a> rules in 2016 that were similar to those other states were enforcing, the EPA now proposes a new <a href="https://www.federalregister.gov/documents/2018/08/27/2018-18497/promulgation-of-air-quality-implementation-plans-state-of-texas-regional-haze-and-interstate">cap-and-trade</a> program that would require no <a href="https://www.texasobserver.org/trump-epa-will-allow-texas-coal-plants-nearly-double-sulfur-dioxide-emissions/">pollution reductions</a> in Texas at all.</p>
<h2>Phasing out</h2>
<p>Even if federal and state regulations remain this lax, coal plants won’t last forever. The <a href="https://www.eia.gov/todayinenergy/detail.php?id=30812">average U.S. coal plant is now 39 years old</a>. The three in Texas that closed in early 2018 were among the five most polluting ones in the state that we studied. A <a href="https://deceleration.news/2018/08/29/deely-coal-plant-cps-energy-closure/">fourth could close by early 2019</a>.</p>
<p>The <a href="http://ieefa.org/ieefa-report-u-s-likely-to-end-2018-with-record-decline-in-coal-fired-capacity/">Texas closures are part of a national</a> and <a href="https://www.carbonbrief.org/mapped-worlds-coal-power-plants">global wave</a>. Coal is becoming a less popular source of electricity <a href="https://www.lazard.com/perspective/levelized-cost-of-energy-2017/">due to it costing</a>, <a href="http://calculators.energy.utexas.edu/lcoe_map/#/county/tech">in most locations</a>, more than alternatives like natural gas, wind energy and solar power.</p>
<p>Still, as coal pollution continues to warm the climate and kill tens of thousands of Americans per year, delaying the inevitable comes at a heavy cost for us all.</p><img src="https://counter.theconversation.com/content/105933/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Cohan has received funding from NASA, the EPA, and the National Science Foundation. </span></em></p>A study of the social cost of carbon emitted by the shrinking fleet of Texan coal plants suggests that closing more of them down would be good for the climate and public health.Daniel Cohan, Associate Professor of Environmental Engineering, Rice UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/991822018-09-14T10:32:53Z2018-09-14T10:32:53ZGround-level ozone continues to damage health, even at low levels<figure><img src="https://images.theconversation.com/files/236250/original/file-20180913-177935-k9nrjo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A study finds that higher ozone levels correlate with slower performance times for college endurance athletes.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/athletics-people-running-on-track-field-749164510?src=pYMfbKU0Pn_dp5FLaLDMZA-1-51">Pavel1964</a></span></figcaption></figure><p>Ground-level ozone is one of six major pollutants regulated nationally under the Clean Air Act. It is not directly emitted, but instead forms in the atmosphere through reactions between other pollutants from cars, power plants and industrial sources. Breathing ozone irritates the airways and can worsen respiratory diseases such as bronchitis, emphysema and asthma.</p>
<p>Regulation has reduced ozone levels across the United States over the past four decades, but exposure to ambient ozone still negatively impacts our health, well-being and productivity. In a <a href="https://doi.org/10.1002/hec.3667">recent article published in the journal Health Economics</a>, I found that harm from ozone extends well beyond the high exposure levels and sensitive groups that have traditionally been studied. In fact, I identify negative effects of ozone exposure on the performances of intercollegiate track and field athletes under the relatively clean conditions common in the United States today. </p>
<p>These findings suggest that ozone exposure may be imposing harm on people even when they don’t end up in the hospital, and that much of the U.S. public may still regularly suffer some degree of negative impact from ozone exposure.</p>
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<h2>Hazardous even at low levels</h2>
<p>Health researchers have long known that exposure to high levels of ozone is associated with acute negative health outcomes. These include <a href="http://www.lung.org/our-initiatives/healthy-air/outdoor/air-pollution/ozone.html">premature death, compromised lung function and cardiovascular issues</a>. </p>
<p>More recent studies have found evidence that ozone also has negative effects at lower exposure levels. For instance, ozone exposures below regulated levels have been shown to <a href="http://dx.doi.org/10.1001/jama.2017.17923">contribute to premature deaths</a> and <a href="http://dx.doi.org/10.1257/aer.102.7.3652">reduce productivity among outdoor agricultural workers</a>. It is also important to note that ozone exposure affects people’s health by inflaming their airways <a href="https://doi.org/10.1164/ajrccm.161.6.9908102">even when functional effects are not measurable</a>. </p>
<p>Ground-level <a href="https://www.epa.gov/ozone-pollution/basic-information-about-ozone">ozone is formed by complex interactions</a> of nitrogen oxides and volatile organic compounds in the presence of sunlight. As a result, ozone levels tend to be highest in summer months. My results are based on outdoor NCAA and NAIA track and field competitions which are held across the contiguous United States during the spring, when ozone levels tend to be below annual maximums. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/236251/original/file-20180913-177950-7oh144.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ground-level ozone forms through reactions between other pollutants in the presence of sunlight.</span>
<span class="attribution"><a class="source" href="https://www.pca.state.mn.us/air/ozone">Minnesota Pollution Control Agency</a></span>
</figcaption>
</figure>
<p>Across the approximately 1,700 outdoor track and field meets that I analyzed, the average daily ozone concentration was only 33.47 parts per billion, which is well below ambient ozone levels regulated anywhere in the world. For instance, the current eight-hour average National Ambient Air Quality Standard for ozone in the United States is <a href="https://www.epa.gov/ozone-pollution/table-historical-ozone-national-ambient-air-quality-standards-naaqs">70 parts per billion</a>, and the current World Health Organization guideline is <a href="http://dx.doi.org/10.1289/ehp.116-a302">approximately 51 parts per billion</a>.</p>
<p>But even at the low ozone levels in my study, and among a young and fit population of college athletes, I found consistent evidence that ozone had negative impacts on competitors in endurance events such as the 800 meter run, 3,000 meter steeplechase and 5,000 meter run. </p>
<h2>Higher ozone levels, slower race times</h2>
<p>Through the analysis of almost 700,000 competition outcomes in 277 different locations over nearly a decade (2005-2013) across the United States, I found that for every 10 parts per billion increase in ambient ozone levels, athlete performance was degraded by 0.4 percent across endurance events. This effect represents more than five percent of the average margin of victory in these races, and suggests that there was a 1.5 percent difference in average athletic performance between the 5th and 95th percentile ozone days in the data.</p>
<p>For a concrete example, consider performances in the 5,000 meter run event. The mean finishing time for men competing in this event was 15 minutes 54.7 seconds. But at meets with average ozone levels above 50 parts per billion, the mean finishing time was 16 minutes 26.0 seconds. The comparable times for women were 19 minutes 5.7 seconds across all ozone levels versus 19 minutes 58.5 seconds at the higher levels.</p>
<p>I found these negative impacts of ozone were larger for longer events in which athletes competed over more extended periods. However, I did not find larger effects for athletes who competed in multiple events. Nor did I observe effects in events which do not heavily tax aerobic capacity. </p>
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<figcaption><span class="caption">Ozone in the stratosphere protects life on Earth from ultraviolet radiation, but at ground level it’s a toxic pollutant.</span></figcaption>
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<p>This makes sense because ozone exposure harms the airways and lungs, which are critical to performance in endurance events. They are less important in sprint events, in which muscles can rely primarily on stored energy reserves, or strength events such as the long jump or shot put, which test a single maximum exertion. While athletes in non-endurance events are undoubtedly harmed by ozone exposure, competitive outcomes in such events did not prove useful for studying the damage. </p>
<p>My findings point to risks for anyone spending time outdoors at current ozone levels. According to the U.S. Bureau of Labor Statistics, nearly half of all U.S. jobs <a href="https://www.bls.gov/careeroutlook/2017/article/outdoor-careers.htm">require outdoor work</a>. In 2004, <a href="https://www.bls.gov/careeroutlook/2017/article/outdoor-careers.htm">nearly 27 million Americans</a> were employed in industry sectors in which at least some workers spent much of their workdays outdoors, such as construction, utilities and agriculture. The agency projects that this number will grow to <a href="https://www.bls.gov/careeroutlook/2017/article/outdoor-careers.htm">nearly 31 million by 2024</a>, representing <a href="https://www.bls.gov/opub/mlr/2015/article/occupational-employment-projections-to-2024.htm">nearly 20 percent of the U.S. workforce</a>. </p>
<h2>US standards under review</h2>
<p>The Clean Air Act requires the Environmental Protection Agency to <a href="https://www.epa.gov/criteria-air-pollutants/process-reviewing-national-ambient-air-quality-standards">review and revise national ambient air quality standards</a> regularly to ensure that they protect public health and the environment. Such reviews led to stricter standards for ozone in <a href="https://www.epa.gov/ozone-pollution/table-historical-ozone-national-ambient-air-quality-standards-naaqs">1997, 2008 and 2015</a>, lowering the regulatory threshold to <a href="https://www.epa.gov/ozone-pollution/table-historical-ozone-national-ambient-air-quality-standards-naaqs">80, 75 and 70 parts per billion respectively</a>. </p>
<p>The agency is currently preparing to carry out its next review of the ozone standard so that any updates can be <a href="https://www.epa.gov/newsreleases/administrator-pruitt-signs-memo-reform-national-ambient-air-quality-standards-review">finalized by October 2020</a>. Earlier this year, then-EPA Administrator Scott Pruitt proposed changes to the review-and-update process that critics argue could <a href="https://theconversation.com/scott-pruitts-approach-to-pollution-control-will-make-the-air-dirtier-and-americans-less-healthy-96501">weaken standards and threaten public health</a>.</p>
<p>Deregulation advocates often emphasize the costs of complying with tightened regulations. For example, the EPA estimated that reducing the ozone standard from 75 to 70 ppb in 2015 <a href="https://www.epa.gov/sites/production/files/2016-02/documents/20151001ria.pdf">would cost US$2.2 billion annually</a>. Importantly however, the agency also projected that this change would generate health benefits worth <a href="https://www.epa.gov/sites/production/files/2016-02/documents/20151001ria.pdf">between $4.1 and $8.0 billion annually</a>. </p>
<h2>A global health risk</h2>
<p>Today more than <a href="https://www3.epa.gov/airquality/greenbook/hnsum.html">105 million Americans</a> live in one of the <a href="https://www3.epa.gov/airquality/greenbook/hnsum.html">168 counties currently designated as part of ozone non-attainment areas</a> due to violations of the current national ozone standard. The situation is worse in many emerging economies, such as India and China, where rapid industrialization has led to high and increasing ozone levels. </p>
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<p>Climate change is expected to contribute to increases in ozone levels by <a href="https://www.epa.gov/air-research/air-quality-and-climate-change-research">warming the atmosphere</a> and extending the annual period of high ozone formation <a href="https://doi.org/10.1073/pnas.1602563113">from summer into fall</a>. These possibilities, along with findings like mine showing ozone’s impacts even at low levels, underscore the continued importance of effective global monitoring and regulation of ozone and its precursor pollutants.</p><img src="https://counter.theconversation.com/content/99182/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jamie T. Mullins received funding from The Property and Environment Research Center.</span></em></p>US ozone pollution has fallen in recent decades, but exposure to low levels of ozone still has serious effects on human health and well-being.Jamie T. Mullins, Assistant Professor of Resource Economics, UMass AmherstLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1001482018-07-18T18:31:09Z2018-07-18T18:31:09ZOzone pollution in US national parks is nearly the same as in large cities<figure><img src="https://images.theconversation.com/files/228253/original/file-20180718-142435-1hzbhw6.jpg?ixlib=rb-1.1.0&rect=3%2C36%2C1989%2C1149&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A clear day at Acadia National Park in Maine.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/dfd2Fv">John Marino</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>“Another glorious day, the air as delicious to the lungs as nectar to the tongue” – John Muir, My First Summer in the Sierra (1911)</p>
<p>Most Americans associate U.S. national parks with pristine environments that represent the very best of nature. In the 1916 law that established the National Park Service, <a href="https://www.nps.gov/grba/learn/management/organic-act-of-1916.htm">Congress directed the new agency</a> to “conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.” </p>
<p>But over the past century it has become increasingly hard to protect the parks from impacts of human activities outside their boundaries. In 2015 the <a href="https://www.npca.org/">National Parks Conservation Association</a>, a national advocacy group, released a <a href="https://www.npca.org/resources/3137-polluted-parks-how-dirty-air-is-harming-america-s-national-parks">blistering report</a> giving many popular parks poor grades for unhealthy air, haze and impacts from climate change. </p>
<p>In a study <a href="http://dx.doi.org/10.1126/sciadv.aat1613">just published in Science Advances</a>, we analyzed levels of ozone, the most widely monitored pollutant in parks, and their impact on visits to 33 national parks from 1990 to 2014. The sites we studied included popular parks such as <a href="https://www.nps.gov/acad/index.htm">Acadia</a>, the <a href="https://www.nps.gov/grca/index.htm">Grand Canyon</a>, <a href="https://www.nps.gov/grsm/index.htm">Great Smoky Mountains</a>, <a href="https://www.nps.gov/jotr/index.htm">Joshua Tree</a>, <a href="https://www.nps.gov/seki/index.htm">Sequoia and Kings Canyon</a> and <a href="https://www.nps.gov/yose/index.htm">Yosemite</a>. We found that while cities once had more “bad air days” with unhealthy ozone levels than national parks, today parks and metro areas have virtually the same number of unhealthy ozone days per year on average. We also found that park visits fall on high ozone days – especially during summer and fall, when peak ozone levels typically occur. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228261/original/file-20180718-142435-ph5dlk.png?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">Trends in ozone concentrations and unhealthy ozone days. (A) Average annual maximum daily 8-hour ozone concentrations. (B) Average summertime maximum daily 8-hour ozone concentrations. (C) Average days per year with maximum daily 8-hour ozone concentrations exceeding 70 ppb. (D) Unhealthy ozone days at Sequoia National Park and the Los Angeles metro area.</span>
<span class="attribution"><span class="source">Keiser et al., Science Advances eaat1613, 18 July 2018</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>The impact of bad air days</h2>
<p>Regulatory efforts to protect the national parks have a long history. The Clean Air Act Amendments of 1977 and 1990 designated parks as Federal Class I Areas, granting them <a href="https://www.nps.gov/subjects/air/class1.htm">special air quality and visibility protections</a>.</p>
<p>The U.S. Environmental Protection Agency’s 1999 <a href="https://www.epa.gov/visibility">Regional Haze Rule</a> increased these protections by requiring states to develop and implement plans to improve visibility and air quality in parks and wilderness areas. </p>
<p>However, these regulatory actions have spurred <a href="https://trib.com/business/energy/most-at-epa-hearing-in-casper-oppose-fed-s-regional/article_b7faa8c8-88d3-58ac-8185-33bbfb536c3d.html">contentious debate</a> and <a href="http://www.chamberlitigation.com/cases/chamber-commerce-v-epa-regional-haze-rule">litigation</a>. Environmental groups argue that these measures are not stringent enough, while some states and industries call them too costly. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228274/original/file-20180718-142432-acxg41.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">Looking west from Shenandoah National Park’s Shaver Hollow on clear (left) and hazy (right) days.</span>
<span class="attribution"><a class="source" href="https://www.nps.gov/media/photo/gallery.htm?id=21C21642-155D-451F-67E688AC226602D3">NPS</a></span>
</figcaption>
</figure>
<p>Major sources of park air pollution include power plants, automobiles and industrial facilities. Unlike other pollutants emitted directly from these sources, like sulfur dioxide or lead, ozone is a <a href="https://www.epa.gov/ozone-pollution">secondary pollutant</a>. It forms in the atmosphere through chemical reactions between <a href="https://www3.epa.gov/region1/airquality/nox.html">nitrogen oxides</a>, <a href="https://www3.epa.gov/region1/airquality/voc.html">volatile organic compounds</a> and sunlight. Nitrogen oxides originate from the usual urban pollution sources, but biogenic sources like trees are actually the largest source of <a href="http://dx.doi.org/10.1038/srep12064">volatile organic compounds</a>, above industrial sources and cars. </p>
<p>Ozone pollution is a serious threat to human health and the environment. It has been linked to increased <a href="http://dx.doi.org/10.1136/bjsm.35.4.214">respiratory symptoms</a>, <a href="https://doi.org/10.1016/0095-0696(90)90048-4">hospitalization rates</a> and <a href="http://dx.doi.org/10.1097/01.ede.0000165821.90114.7f">mortality</a>. It also is correlated with poor visibility in parks, and can <a href="https://www.nps.gov/subjects/air/nature-ozone.htm">damage sensitive plant species</a>.</p>
<h2>Ozone trends over time</h2>
<p>To our surprise, for most of our study period we found that average annual ozone concentrations in national parks were nearly identical to those in metropolitan areas. However, summertime levels and the incidence of unhealthy days told a different story. </p>
<p>Since ozone forms in sunlight, levels typically are highest on hot, sunny days. When ozone levels exceed the national standard, <a href="https://www.epa.gov/ozone-pollution/2015-revision-2008-ozone-national-ambient-air-quality-standards-naaqs-related">which is currently 70 parts per billion</a>, local and regional governments may issue alerts or urge people to avoid outdoor activities.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1107&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1107&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1107&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1391&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1391&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228264/original/file-20180718-142428-1r8dy7u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1391&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Healthy (top) and ozone-injured (bottom) tulip tree (yellow poplar) foliage.</span>
<span class="attribution"><a class="source" href="https://www.nps.gov/subjects/air/nature-ozone.htm">NPS</a></span>
</figcaption>
</figure>
<p>In 1990 cities had far more days bad ozone days on average than national parks. But through the decade, summertime ozone and unhealthy ozone days worsened in national parks. By the year 2000, ozone levels in national parks were, on average, very similar to those in metropolitan areas. Explaining this increase was beyond the scope of our study. According to the National Park Service, pollution in national parks <a href="https://www.nps.gov/subjects/air/sources.htm">can come from many sources</a>, including power plants, industrial sources, vehicle emissions and wildfires. </p>
<p>Since the early 2000s, ozone levels in both national parks and metropolitan areas have improved. But bad air days still occur. On average, among the locations we studied, metro areas currently have 18 unhealthy ozone days per year, while parks have 16. </p>
<h2>Bad air days drive away park visitors</h2>
<p>To see whether visitors responded to changing ozone levels in the parks, we matched monthly visitation data from the National Park Service with various measures of monthly average ozone levels. We found that a one percent increase in ozone concentrations was associated with approximately a one percent decrease in park visitation on average. This response was most pronounced during summer and fall, when both visitation and average ozone levels are highest. </p>
<p>Why do visits decrease when ozone is high? We see two possibilities. First, visitors may worry about adverse impacts on their health. Second, visibility is typically poor when ozone levels are high because ozone participates in <a href="https://www.fsvisimages.com/visdata.aspx">chemical reactions in the air that can form haze</a>.</p>
<p>We found stronger evidence that health concerns keep visitors away. Park visitation has a robust negative correlation with the incidence of unhealthy ozone days, perhaps because of air quality warnings that accompany these high levels. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1019241998149009413"}"></div></p>
<h2>The value of further ozone reductions</h2>
<p>Across the United States, ozone levels <a href="https://www.epa.gov/air-trends/ozone-trends">declined by 31 percent</a> between 1980 and 2016. But city residents and tourists in national parks still experience unhealthy ozone levels for two to three weeks per year. Exposure to high ozone levels may be particularly harmful in national parks, since health effects from ozone are <a href="https://www.mayoclinic.org/healthy-lifestyle/fitness/expert-answers/air-pollution-and-exercise/faq-20058563">greater during exercise</a>, such as hiking, backpacking or rock climbing. </p>
<p>Although we found that some people decrease their visits during unhealthy days, we still observed that since 1990, nearly 80 million visitor days have occurred during high ozone periods. This suggests that improving air quality in U.S. national parks could produce significant human health benefits. We hope that state and federal policy makers will weigh these benefits of improved air quality along with their costs as discussions move forward on air pollution regulations.</p><img src="https://counter.theconversation.com/content/100148/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Keiser has previously received funding from the USDA, USEPA, NSF, Leopold Center for Sustainable Agriculture, Iowa Economic Development Authority and HUD, Iowa Department of Natural Resources, and SESYNC. He also has received free data access from the Environmental Working Group for an unrelated project. </span></em></p><p class="fine-print"><em><span>Gabriel E. Lade received funding from the National Science Foundation, Department of Energy, Alfred P. Sloan Foundation, and National Bureau of Economic Research.</span></em></p><p class="fine-print"><em><span>Ivan Rudik has previously received funding from National Science Foundation, Department of Energy, and National Bureau of Economic Research.</span></em></p>US national parks protect some of America’s most spectacular outdoor settings. But new research shows that ozone pollution levels in the parks are roughly as bad as in major cities.David Keiser, Assistant Professor of Economics, Iowa State UniversityGabriel E. Lade, Assistant Professor of Economics, Iowa State UniversityIvan Rudik, Assistant Professor of Applied Economics, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/960882018-05-11T10:49:23Z2018-05-11T10:49:23ZYour shampoo, hair spray and skin lotion may be polluting the air<figure><img src="https://images.theconversation.com/files/218592/original/file-20180511-34009-b2zqzd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Good for you, bad for the air?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/supermarket-shelves-personal-care-products-247444630?src=V4fvKA8LtTFXPoOR-ybD7A-2-2">Gts/Shutterstock.com</a></span></figcaption></figure><p>Millions of Americans apply personal care products every morning before heading to work or school. But these products don’t stick to our bodies permanently. Over the course of the day, compounds in deodorants, lotions, hair gels and perfumes evaporate from our skin and eventually make their way outdoors. Now there’s new evidence to suggest that these products are major sources of air pollution in urban areas.</p>
<p>For decades, motor vehicles were considered the primary source of air pollutants in major U.S. cities. Vehicle exhaust contains <a href="https://www.epa.gov/air-pollution-transportation/smog-soot-and-local-air-pollution">multiple pollutants</a> that worsen air quality, including nitrogen oxides, particulate matter and volatile organic compounds (VOCs) – a group of reactive gases that contribute to smog formation.</p>
<p>Thanks to advances in catalytic converters and improvements in fuel economy, combined emissions of <a href="https://www.epa.gov/air-pollution-transportation/accomplishments-and-success-air-pollution-transportation">common pollutants</a> from cars have <a href="https://www.epa.gov/air-pollution-transportation/accomplishments-and-success-air-pollution-transportation">decreased by 65 percent</a> since the 1970s. Air pollution is still a problem in urban areas like Los Angeles, but only a fraction of it can be attributed to vehicles. Today, scientists are finding that other non-combustion sources – including common household products – are also major contributors. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/218352/original/file-20180509-4803-1q9m8w9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Volatile organic compounds (VOCs) react in the air with nitrogen oxides to form ozone and smog.</span>
<span class="attribution"><a class="source" href="https://www.pca.state.mn.us/air/ozone">Minnesota Pollution Control Agency</a></span>
</figcaption>
</figure>
<h2>A unique fingerprint</h2>
<p>In a <a href="http://dx.doi.org/10.1021/acs.est.8b00506">recent study</a> with U.S. and Canadian colleagues, our lab found that these sources can include personal care products. We analyzed urban air in two cities: Boulder, Colorado, and Toronto, Ontario, Canada. </p>
<p>In Boulder, our lab had recently invested in new instrumentation, which we wanted to use to measure wood stove emissions during winter months. For five weeks we sampled air from the roof of the <a href="http://www.boulder.doc.gov/noaa/dsrc.html">NOAA David Skaggs Research Center</a> in hope of measuring air parcels contaminated with smoke from residential wood stoves. Surprisingly, we noticed a signal that stood out unexpectedly from all the other data. This compound, which we identified as decamethylcyclopentasiloxane (or D5 siloxane), contains silicon, which uniquely differs from the organic compounds we normally detect. </p>
<p>By reviewing scientific literature, we learned that pure D5 siloxane is produced mainly as an additive for deodorants and hair care products. On average, people use products that contain a total of about 100-200 milligrams of D5 every day – roughly the weight of half an aspirin tablet. Some fraction of these products end up going down the drain when we shower, but the majority of what remains on our bodies ends up in the atmosphere. D5 can also be found in <a href="http://dx.doi.org/10.1021/cr500319v">many other places</a>, including <a href="https://doi.org/10.1002/etc.2941">soil, oceans and the tissues of fish and human beings</a> </p>
<p>Many labs have studied the environmental fate of D5, but from our perspective it is particularly useful because it acts like a fingerprint. If we detect D5 in the atmosphere, we know that the air mass we measured was influenced by emissions from personal care products. By comparing the amount of D5 in the atmosphere to other fingerprint markers, such as compounds present in vehicle exhaust, we can estimate how important personal care products are as an emissions source relative to better-understood sources.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/218353/original/file-20180509-4803-1wvgckm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Air pollution from transportation in the U.S. has fallen in the past 40 years even as population and vehicles miles traveled have increased.</span>
<span class="attribution"><a class="source" href="https://www.epa.gov/air-pollution-transportation/accomplishments-and-success-air-pollution-transportation">USEPA</a></span>
</figcaption>
</figure>
<h2>Emissions spike during morning rush hour</h2>
<p>In Boulder and Toronto, we found that D5 was present in urban air at mass concentrations comparable to those of <a href="https://www.epa.gov/sites/production/files/2016-09/documents/benzene.pdf">benzene</a>, a chemical that is a marker for vehicle exhaust. (Benzene is a known carcinogen and is also found in industrial emissions and cigarette smoke.) </p>
<p>D5 concentrations were highest in the morning – the time when most people shower, apply personal care products and then leave the house to commute to work. We also observed a peak in benzene emissions in the morning, when people drive to work. During morning rush hour, we found that emissions of D5 and benzene were almost equivalent. </p>
<p>In other words, at this time of day, people emitted a plume of organic compounds that was comparable in mass to the plume of organic compounds emitted from their vehicles. Researchers still have a lot to learn about how these chemicals react in the atmosphere to form smog, so the air quality implications of these morning emissions remain unclear. </p>
<p>Benzene emissions remained high throughout the day as people drove around the city, but D5 emissions eventually tapered off as personal care products evaporated from users’ skin. We estimate that, on average, the entire population of the city of Boulder emits 3 to 5 kilograms (6 to 11 pounds) of D5 per day, and that their cars emit about 15 kilograms of benzene in vehicle exhaust.</p>
<h2>VOC emissions from your medicine cabinet</h2>
<p>While these numbers may seem surprisingly high, our findings support recent <a href="http://dx.doi.org/10.1126/science.aaq0524">modeling work</a> conducted by Brian McDonald, a co-author of this study, which showed that personal care product VOC emissions in Los Angeles now rival VOC emissions from gasoline and diesel exhaust. Taken together, these two studies demonstrate that our urban air is remarkably different from what it was decades ago. Cars today emit fewer smog-inducing organic compounds, while other sources are now becoming important contributors to air pollution.</p>
<p>D5 is only one component of personal care product emissions, and many other compounds could be emitted with it. To fully assess how seriously these emissions may affect the environment and human health, researchers have to answer many more questions. What other compounds enter the atmosphere after we apply personal care products? Once in the atmosphere, what happens to them? Are they capable of contributing to smog formation? Our lab and others around the country are considering these questions now in hopes of improving our understanding of urban air pollution.</p><img src="https://counter.theconversation.com/content/96088/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Coggon receives funding from the National Oceanic and Atmospheric Administration. </span></em></p>New research is spotlighting personal care products, such as shampoos and skin lotions, as a significant source of chemicals that contribute to urban air pollution.Matthew Coggon, Research scientist, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/943792018-04-06T10:46:21Z2018-04-06T10:46:21ZWhy California gets to write its own auto emissions standards: 5 questions answered<figure><img src="https://images.theconversation.com/files/213470/original/file-20180405-189830-1st08cd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rush hour on the Hollywood Freeway, Los Angeles, September 9, 2016.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Los-Angeles-Mayor/178af7a4248c43d78e61ee64950ea57f/324/0">AP Photo/Richard Vogel</a></span></figcaption></figure><p><em>Editor’s note: On April 2, 2018, the Trump administration froze the fuel efficiency standards for cars and light-duty trucks, following the EPA’s finding earlier this year that tailpipe emissions standards negotiated by the Obama administration for motor vehicles built between 2022 and 2025 <a href="https://www.epa.gov/newsreleases/epa-administrator-pruitt-ghg-emissions-standards-cars-and-light-trucks-should-be">were set “too high.”</a>. The EPA also revoked California’s historic ability to adopt standards that are more ambitious than the federal government’s. UCLA legal scholars Nicholas Bryner and Meredith Hankins explain why California has this authority – and what may happen if the EPA tries to curb it.</em></p>
<h2>1. Where does California get this special authority?</h2>
<p>The Clean Air Act empowers the EPA to regulate air pollution from motor vehicles. To promote uniformity, the law generally bars states from regulating car emissions. </p>
<p>But when the Clean Air Act was passed, California was already developing innovative laws and standards to address its unique air pollution problems. So Congress carved out an exemption. As long as California’s standards protect public health and welfare at least as strictly as federal law, and are necessary “to meet compelling and extraordinary conditions,” the law <a href="https://www.law.cornell.edu/uscode/text/42/7543">requires</a> the EPA to grant California a waiver so it can continue to apply its own regulations. California has received <a href="https://www.epa.gov/state-and-local-transportation/vehicle-emissions-california-waivers-and-authorizations#notices">numerous waivers</a> as it has worked to reduce vehicle emissions by enacting ever more stringent standards since the 1960s.</p>
<p>Other states can’t set their own standards, but they can opt to follow California’s motor vehicle emission regulations. Currently, <a href="https://database.aceee.org/state/tailpipe-emission-standards">12 states and the District of Columbia</a> have adopted California’s standards.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/213472/original/file-20180405-189813-27gz1i.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">Gov. Ronald Reagan signs legislation establishing the California Air Resources Board to address the state’s air pollution, August 30, 1967.</span>
<span class="attribution"><a class="source" href="https://ww2.arb.ca.gov/about/history">CA ARB</a></span>
</figcaption>
</figure>
<h2>2. What are the “compelling and extraordinary conditions” that California’s regulations are designed to address?</h2>
<p>In the 1950s scientists <a href="https://doi.org/10.1080/00966665.1953.10467586">recognized</a> that the unique combination of enclosed topography, a rapidly growing population and a warm climate in the Los Angeles air basin was a recipe for dangerous smog. Dutch chemist <a href="https://www.arb.ca.gov/research/hsawards/a_lesson_from_the_smog_capital_of_world.pdf">Arie Jan Haagen-Smit</a> discovered in 1952 that worsening Los Angeles smog episodes were caused by photochemical reactions between California’s sunshine and nitrogen oxides and unburned hydrocarbons in motor vehicle exhaust. </p>
<p>California’s Motor Vehicle Pollution Control Board issued <a href="https://www.arb.ca.gov/html/brochure/history.htm">regulations</a> mandating use of the nation’s first vehicle emissions control technology in 1961, and developed the nation’s first vehicle emissions standards in 1966. Two years later the EPA adopted standards identical to California’s for model year 1968 cars. UCLA Law scholar Ann Carlson calls this pattern, in which California innovates and federal regulators piggyback on the state’s demonstrated success, “<a href="https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1115556">iterative federalism</a>.” This process has continued for decades. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/k2Ra8PRtXSU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">California’s severe air pollution problems have made it a pioneer in air quality research.</span></figcaption>
</figure>
<h2>3. California has <a href="https://theconversation.com/will-blazing-a-low-carbon-path-pay-off-for-california-72168">set ambitious goals</a> for slowing climate change. Is that part of this dispute with the EPA?</h2>
<p>Yes. Transportation is now the <a href="https://e360.yale.edu/digest/transportation-replaces-power-in-u-s-as-top-source-of-co2-emissions">largest source</a> of greenhouse gas (GHG) emissions in the United States. The tailpipe standards that the Obama EPA put in place were designed to limit GHG emissions from cars by improving average fuel efficiency. </p>
<p>These standards were developed jointly by the EPA, the U.S. Department of Transportation (DOT), and California, which have overlapping legal authority to regulate cars. EPA and California have the responsibility to control motor vehicle emissions of air pollutants, including GHGs. DOT is in charge of <a href="https://www.law.cornell.edu/uscode/text/49/32902">regulating fuel economy</a>.</p>
<p>Congress began regulating fuel economy in response to the oil crisis in the 1970s. DOT sets the Corporate Average Fuel Economy <a href="https://www.nhtsa.gov/laws-regulations/corporate-average-fuel-economy">(CAFE) standard</a> that each auto manufacturer must meet. Under this program, average fuel economy in the United States improved in the late 1970s but <a href="https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100TGLC.pdf">stagnated</a> from the 1980s to the early 2000s as customers shifted to purchasing larger vehicles, including SUVs, minivans and trucks.</p>
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<p>In 2007 Congress responded with a new law that required DOT to set a standard of at least 35 miles per gallon by 2020, and the “maximum feasible average fuel economy” after that. That same year, the Supreme Court <a href="https://www.law.cornell.edu/supct/html/05-1120.ZS.html">ruled</a> that the Clean Air Act authorized the EPA to regulate GHG emissions from cars.</p>
<p>The Obama administration’s tailpipe standard brought these overlapping mandates together. EPA’s regulation sets how much carbon dioxide can be emitted per mile, which matches with DOT’s increased standard for average fuel economy. It also includes a “midterm review” to assess progress. Administrator Scott Pruitt’s <a href="https://www.epa.gov/sites/production/files/2018-04/documents/mte-final-determination-notice-2018-04-02.pdf">new EPA review</a>, released on April 2, overturned the Obama administration’s midterm review and concluded that the 2022 to 2025 standard was not feasible.</p>
<p>The EPA now <a href="https://www.epa.gov/newsreleases/epa-administrator-pruitt-ghg-emissions-standards-cars-and-light-trucks-should-be">argues</a> that earlier assumptions behind the rule were “optimistic” and can’t be met. However, its review almost entirely ignored the purpose of the standards and the costs of continuing to emit GHGs at high levels. Although the document is 38 pages long, the word “climate” never appears, and “carbon” appears only once.</p>
<p>The EPA’s decision does not yet have any legal impact. It leaves the current standards in place until the EPA and DOT decide on a less-stringent replacement. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=301&fit=crop&dpr=1 600w, https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=301&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=301&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=378&fit=crop&dpr=1 754w, https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=378&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/213476/original/file-20180405-189821-6qv7x2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=378&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">U.S. carbon dioxide emissions from transportation exceeded those from electric power generation in 2016 for the first time since the 1970s.</span>
<span class="attribution"><a class="source" href="https://www.eia.gov/todayinenergy/detail.php?id=29612">USEIA</a></span>
</figcaption>
</figure>
<h2>4. Can the Trump administration take away California’s authority to set stricter targets?</h2>
<p>The EPA has never attempted to revoke an existing waiver. In 2007, under George W. Bush, the agency <a href="https://www.nytimes.com/2007/12/19/washington/20epa-web.html">denied</a> California’s request for a waiver to regulate motor vehicle GHG emissions. California sued, but the EPA reversed course under President Obama and granted the state a waiver before the case was resolved. </p>
<p>California’s <a href="https://www.gpo.gov/fdsys/pkg/FR-2013-01-09/pdf/2013-00181.pdf">current waiver</a> was approved in 2013 as a part of a “<a href="https://obamawhitehouse.archives.gov/the-press-office/2012/08/28/obama-administration-finalizes-historic-545-mpg-fuel-efficiency-standard">grand bargain</a>” between California, federal agencies and automakers. It covers the state’s Advanced Clean Cars program and includes standards to reduce conventional air pollutants like carbon monoxide, nitrogen oxides and particulate matter, as well as the GHG standards jointly developed with the EPA and DOT.</p>
<p>The Trump administration is threatening to revoke this waiver when it decouples the national GHG vehicle standards from California’s standards. EPA Administrator Pruitt has <a href="https://www.epa.gov/newsreleases/epa-administrator-pruitt-ghg-emissions-standards-cars-and-light-trucks-should-be">said</a> that the agency is re-examining the waiver, and that “cooperative federalism doesn’t mean that one state can dictate standards for the rest of the country.” In our view, this statement mischaracterizes how the Clean Air Act works. Other states have voluntarily chosen to follow California’s rules because they see benefits in reducing air pollution. </p>
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<h2>5. How would California respond if the EPA revokes its waiver?</h2>
<p><a href="https://twitter.com/JerryBrownGov/status/980894214903836672">Gov. Jerry Brown</a>, <a href="https://oag.ca.gov/news/press-releases/attorney-general-becerra-epa%E2%80%99s-assault-federal-greenhouse-gas-emission-standards">Attorney General Xavier Becerra</a> and <a href="https://ww2.arb.ca.gov/news/carb-chair-issues-response-epa-press-release-weakening-vehicle-standards">California Air Resources Board Chair Mary Nichols</a> have all made clear that the state will push back. It’s almost certain that any attempt to revoke or weaken California’s waiver will immediately be challenged in court – and that this would be a <a href="http://legal-planet.org/2018/03/16/will-pruitt-join-sessions-in-expanding-the-attack-on-california/">major legal battle</a>.</p><img src="https://counter.theconversation.com/content/94379/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 organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Air pollution could be the next battleground between California and the Trump administration, which is reviewing the Golden State’s special legal authority to regulate tailpipe emissions.Nicholas Bryner, Assistant Professor of Law, Louisiana State University Meredith Hankins, Shapiro Fellow in Environmental Law and Policy, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/893782017-12-20T11:37:50Z2017-12-20T11:37:50ZDelhi should follow Beijing’s example in tackling air pollution<figure><img src="https://images.theconversation.com/files/199892/original/file-20171219-27557-a1ymzc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A pall of inaction and apathy hangs over Delhi's reaction to its air pollution crisis.</span> <span class="attribution"><span class="source">Reuters/Anindito Mukherjee</span></span></figcaption></figure><p>Delhi’s air pollution <a href="https://theconversation.com/delhis-toxic-air-crisis-demands-a-radical-response-88327">crisis</a> made international headlines in early December when a <a href="https://www.express.co.uk/sport/cricket/887424/India-Sri-Lanka-masks-pollution-Delhi">cricket match</a> between India and Sri Lanka was suspended due to poor air quality. </p>
<p>Smog has also led to numerous <a href="https://timesofindia.indiatimes.com/city/delhi/all-schools-in-delhi-to-be-closed-till-sunday-manish-sisodia/articleshow/61560145.cms">school closures</a> and <a href="http://www.independent.co.uk/news/world/asia/united-cancels-flights-new-delhi-dangerous-smog-asia-environment-latest-a8050611.html">flight cancellations</a> in India’s capital and largest city. It has also been blamed for <a href="https://www.ndtv.com/delhi-news/delhis-toxic-smog-leads-to-24-car-accident-on-yamuna-expressway-1772758">highway accidents</a>.</p>
<p>Delhi is home to 20 million residents, and the city’s more than 10 million vehicles are a major contributor to air pollution. Industrial emissions are also to blame. Thirteen coal-fired <a href="https://www.oneindia.com/india/indias-air-pollution-a-crisis-beyond-delhi-2582028.html">power stations</a> operate within a 300 kilometre radius of the city. Conditions reach crisis level every winter, when the capital’s already poor air quality is further degraded by smoke from post-harvest burning in the neighbouring agricultural states of Haryana and Punjab.</p>
<p>The concentration of airborne particulate matter (PM2.5) recently reached <a href="http://www.reuters.com/article/us-india-pollution/new-delhi-pollution-hits-dangerous-level-putting-runners-at-risk-idUSKBN1D70QN">999</a> in parts of Delhi. This measurement was literally off the charts of maximum thresholds for air pollutants. The alarming fact is that Delhi is not even India’s smoggiest city. By one measure, four other Indian cities typically suffer even worse air <a href="http://www.telegraph.co.uk/travel/destinations/asia/india/articles/delhi-most-polluted-city-in-the-world/">pollution</a>.</p>
<p>There is little evidence that either the central or Delhi government has any effective policy strategy for air pollution. Now is the time for India to peer through the smog and learn how another major city, Beijing, is taking meaningful steps to stabilise its own air pollution crisis. While China still has progress to make, some lessons from the country’s capital are a useful guide for clearing Delhi’s air. </p>
<h2>China’s response</h2>
<p>According to the World Health Organisation, ten of the world’s 20 <a href="https://www.theguardian.com/cities/datablog/2017/feb/13/most-polluted-cities-world-listed-region">most polluted</a> cities are in India, and three in China. The two countries top the ignoble list of deaths related to air pollution, with more than <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)30884-X/fulltext">one million</a> each in 2015. The two are the world’s most populous countries and also have among the highest <a href="https://phys.org/news/2017-10-countries-highest-pollution-deaths-mortality.html">proportions</a> of deaths related to air pollution. </p>
<p>Nevertheless, China is making progress. The central government has taken a systematic and coordinated approach to managing air pollution. It has adopted a suite of policies that promote alternative energy and punish regulatory breaches. </p>
<p>The country is rapidly scaling back capacity for <a href="https://www.nytimes.com/2017/01/18/world/asia/china-coal-power-plants-pollution.html">coal-fired power</a> and <a href="https://www.reuters.com/article/us-steel-eu/china-to-cut-steel-capacity-but-excess-output-still-expected-eurofer-idUSKBN18703O">steel</a>, whose production is suspected of threatening <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5101733/">respiratory health</a>. China is also soliciting foreign investment in green energy <a href="https://www.wsj.com/articles/china-seeks-u-s-investment-in-green-projects-1465194173">technologies</a>, and has intensified <a href="http://www.scmp.com/news/china/policies-politics/article/2111434/china-send-over-100-pollution-inspection-teams-cities">inspections</a> of major polluters around Beijing. </p>
<p>In Beijing alone, <a href="https://www.theguardian.com/sustainable-business/2017/mar/31/china-beijing-air-pollution-smog-business-crackdown-fines-spot-checks">fines</a> for pollution topped USD$ 28 million in 2015. To combat vehicle exhaust smoke, which is responsible for one-third of Beijing’s emissions, an annual <a href="https://www.chinadaily.com.cn/cndy/2017-02_/06/content_28109609.htm">quota</a> of 150,000 new cars was established for 2017, with 60,000 allotted only to fuel efficient cars. Beginning in 2018, this quota will be <a href="http://www.chinadaily.com.cn/a/201712/15/WS5a33819aa3108bc8c6734ecb.html">reduced</a> by one third, to 100,000 annually. This will limit the total number of cars to around 6.3 million. </p>
<p>Beijing is also aiming to reduce <a href="https://www.reuters.com/article/us-china-coal/beijing-aims-to-curb-citys-use-of-coal-by-2020-idUSKBN1A406R">coal consumption</a> from the current 11 million tons per year to under 5 million by 2020. </p>
<p>There is some evidence that these measures are working. In the Beijing-Tianjin-Hebei region, PM2.5 levels <a href="https://www.ft.com/content/e971c3c2-c52e-11e7-a1d2-6786f39ef675">decreased</a> by 27% between 2013 and 2016.</p>
<h2>India’s apathy</h2>
<p>By comparison, India’s political inefficiency is making regional air pollution a nearly intractable problem. Although the states of Haryana and Punjab have <a href="https://www.ft.com/content/0ca99966-afca-11e7-aab9-abaa44b1e130">banned</a> farmers from burning straw, implementation has been minimal. Policy coordination is also weak across states governed by rival political parties. For example, the leaders of Delhi and Haryana have publicly <a href="http://www.financialexpress.com/india-news/delhi-pollution-cm-arvind-kejriwal-ml-khattar-take-smog-crisis-to-twitter-sparks-fly/931327/">clashed</a> about who is to blame for air pollution. They have also failed to hold discussions about the problem or to find feasible solutions. </p>
<p>Farmers constitute a significant voting base in Haryana and Punjab. This has led state governments to demand <a href="http://www.thehindu.com/news/cities/Delhi/delhi-smog-blame-game-over-pollution-begins/article20046362.ece">compensation</a> from central government for losses farmers incur by ceasing burning. Such focus on short-term political gain is distracting policymakers from collaborating on regional solutions. The consequences of territorial grandstanding are deadly.</p>
<p>Another difference between India and China is the level of apathy among the government and general public. In China, years of seething public anger prompted Prime Minister Li Keqiang to <a href="https://www.ft.com/content/5c9b4d18-a437-11e3-b915-00144feab7de">“declare war”</a> on pollution in 2014. </p>
<p>In India, public outrage over air pollution is still <a href="http://www.abc.net.au/news/2017-11-13/why-delhis-air-worsens-as-beijings-improves/9143090">“seasonal”</a> and rarely swells beyond social media. The central government has remained largely silent about pollution while state leaders indulge in meaningless inter-party squabbling and political theatre.</p>
<p>Amid this discouraging accountability vacuum, India’s Supreme Court recently assumed the mantle of leadership on air pollution. It banned <a href="https://www.nytimes.com/2017/10/12/world/asia/india-pollution-new-delhi-diwali.html?mtrref=www.google.com.sg">fireworks</a> in the capital during the Diwali festival and pushed for response focused <a href="http://cpcb.nic.in/final_graded_table.pdf">action planning</a>. While these are encouraging steps, bypassing the legislative process on such fundamental public health issues is hardly ideal or sustainable. </p>
<h2>Progress is needed</h2>
<p>India has made remarkable progress lifting millions of people out of poverty in recent years. It aspires to be a global superpower, but has singularly failed to curb air pollution. Central government must intervene to coordinate collaborative policy among states and hold officials accountable for inaction. Central government should also reinforce state-level <a href="https://www.nytimes.com/2017/11/12/opinion/air-pollution-smog-india-delhi.html">initiatives</a> to minimise burning and promote sustainable farming.</p>
<p>More broadly, it may be time to ask whether highly argumentative democratic models are always the best solution for problems that transcend city and provincial boundaries. Sensible and informed policy leadership is needed to solve environmental challenges. India must rise above petty politics, lest the country bicker its way into smoggy irrelevance.</p><img src="https://counter.theconversation.com/content/89378/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>While India struggles for answers to its urban air pollution crisis, Beijing is moving forward with strong resolve and effective policy.Asit K. Biswas, Distinguished visiting professor, University of GlasgowKris Hartley, Assistant professor, The Education University of Hong KongLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/703752016-12-13T18:12:23Z2016-12-13T18:12:23ZTake a deep breath – an expert explains the deadly dangers of air pollution<figure><img src="https://images.theconversation.com/files/149969/original/image-20161213-1596-4zoyxh.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/dbakr/9478479785/sizes/o/">dbakr/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><a href="http://www.scmp.com/news/china/society/article/2054230/smog-plagued-beijing-may-ban-coal-trucks-storage-tianjin-tackle">Beijing</a>, <a href="http://www.ibtimes.co.uk/london-mayor-sadiq-khan-issues-air-quality-alert-pollution-hits-high-levels-1594454">London</a>, <a href="http://www.nytimes.com/2016/06/14/world/americas/mexico-city-cars-pollution.html?_r=0">Mexico City</a>, <a href="http://www.sciencealert.com/new-delhi-s-air-is-now-so-toxic-schools-are-closing-and-expats-are-fleeing">New Delhi</a> and <a href="http://www.forbes.com/sites/ceciliarodriguez/2016/12/12/paris-cant-breath-worst-pollution-in-a-decade-has-city-scrambling-for-solutions/#1d9b2f946821">Paris</a> are among the cities that have drawn attention for their dangerously high air pollution levels in 2016 – but they’re not alone. The World Health Organisation (WHO) has confirmed that <a href="http://www.who.int/phe/health_topics/outdoorair/databases/en/">92% of the world’s urban population</a> now live in cities where the air is toxic.</p>
<p>In India, <a href="http://www.livemint.com/Science/Pru06soFtZXF5bipbF4axI/41-Indian-cities-have-bad-air-quality-survey-finds.html">a study</a> found that 41 Indian cities of more than a million people faced bad air quality on nearly 60% of the total days monitored. Three cities – Gwalior, Varanasi and Allahabad – didn’t even manage one good air quality day. </p>
<p>Over on the African continent, dirty air was <a href="http://www.oecd-ilibrary.org/development/the-cost-of-air-pollution-in-africa_5jlqzq77x6f8-en">identified</a> as the cause of 712,000 premature deaths – that’s more than unsafe water (542,000), childhood malnutrition (275,000) or unsafe sanitation (391,000). </p>
<p>In <a href="http://www.eea.europa.eu/highlights/stronger-measures-needed">Europe</a>, it was found that around 85% of the urban population are exposed to harmful fine particulate matter (PM2.5) which was responsible for an estimated 467,000 premature deaths in <a href="http://www.eea.europa.eu/highlights/stronger-measures-needed/table-10-1-premature-deaths">41 European countries</a>. </p>
<p>It’s not all bad news though: 74 major <a href="http://cleanairasia.org/wp-content/uploads/2016/08/China-Air-2016-Report-Full.pdf">Chinese cities</a> have seen the annual average concentrations of particulate matter, sulphur dioxide and nitrogen dioxide, decrease since 2014 although the Chinese government’s <a href="http://www.huffingtonpost.com/entry/china-air-pollution-2014_us_568e592ce4b0a2b6fb6ecb73">“war on air pollution”</a> has received criticism. </p>
<h2>Health risk</h2>
<p>The health impacts of air pollution are well documented; but now, new evidence suggests a link between air pollution and <a href="https://www.newscientist.com/article/2108773-dementia-risk-linked-to-air-pollution-and-lack-of-vitamin-d/">dementia</a> and <a href="https://www.theguardian.com/environment/2016/sep/05/toxic-air-pollution-particles-found-in-human-brains-links-alzheimers?CMP=share_btn_tw">Alzheimer’s disease</a>, with exposure to poor air quality equivalent to passively smoking <a href="http://nltimes.nl/2016/08/17/amsterdam-air-pollution-equal-smoking-6-cigarettes-per-day-environmental-group">six cigarettes</a> a day. Not only that, toxic air has been blamed for more <a href="http://www.telegraph.co.uk/science/2016/10/03/air-pollution-could-be-to-blame-for-hundreds-of-traffic-accident/">road traffic crashes</a> from pollutants distracting drivers, causing watery eyes and itchy noses.</p>
<p>It is often poor, young, old and disadvantaged people who are worst affected by poor air quality. Air pollution is responsible for the deaths of <a href="https://www.unicef.org/publications/index_92957.html">600,000 children</a> under the age of five every year. Ethnic minorities are more likely to be exposed to high pollution levels than other groups. In London, <a href="https://www.theguardian.com/environment/2016/oct/10/londons-black-communities-disproportionately-exposed-to-air-pollution-study?CMP=share_btn_tw">black, African and Caribbean people</a> were exposed to higher illegal nitrogen dioxide levels (15.3%) because of where they lived, compared to the rest of the city’s population (13.3%).</p>
<p>Air pollution also affects regional climate, which impacts on future <a href="http://link.springer.com/article/10.1007/s10584-016-1850-7">water availability</a> and ecosystem productivity. Black carbon is a particulate matter created through the burning of fossil fuels (such as diesel) and biomass. As well as effecting human health, it is responsible for <a href="http://www.nature.com/articles/ncomms12574">glacial melting</a> in the Himalayan and Tibetan Plateau. Black carbon deposits on snow and ice darkens surfaces, resulting greater absorption of sunlight and faster melting.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/149971/original/image-20161213-1594-rz03ir.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Black snow.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasa_goddard/6800507248/sizes/l">NASA Goddard Space Flight Center/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Research from the <a href="http://openknowledge.worldbank.org/handle/10986/25013">World Bank</a> estimated that the global economic cost of air pollution-related deaths to be US$225 billion in lost labour income (in 2013) and more than US$5 trillion in welfare losses. The <a href="https://www.oecd.org/environment/indicators-modelling-outlooks/Policy-Highlights-Economic-consequences-of-outdoor-air-pollution-web.pdf">OECD</a> predicted that global air pollution-related healthcare costs will increase from US$21 billion in 2015 to US$176 billion in 2060. And by 2060, the global annual number of lost working days that affect labour productivity is projected to reach 3.7 billion – it is currently around 1.2 billion.</p>
<h2>Air creative</h2>
<p>A number of creative ways of understanding and addressing the air pollution problem were seen throughout 2016. In London, <a href="http://www.pigeonairpatrol.com/">racing pigeons</a> took to the skies equipped with pollution sensors and a Twitter account, to raise awareness of the capital’s illegally dirty air. Amsterdam carried on the bird theme, with smart bird houses that light up to show the air quality status, while offering free <a href="http://treewifi.org">Treewifi</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"709432162324508672"}"></div></p>
<p>Other innovations included the development of an <a href="https://www.theguardian.com/environment/2016/sep/16/new-inhaler-protects-lungs-against-effects-of-air-pollution?CMP=share_btn_tw">inexpensive over-the-counter inhaler</a> that protects the lungs against air pollution, and the installation of a <a href="http://www.forbes.com/sites/ywang/2016/10/20/can-this-tower-solve-chinas-air-pollution-problem/#52c1470563d0">seven-metre tall tower</a> in Beijing, which sucks pollutants from filthy air.</p>
<p>Raising awareness of the causes and effects of air pollution is important, as we are not only victims, but also contributors to the problem. There have also been many air quality monitoring projects to engage citizens on air pollution issues such as <a href="http://www.flanderstoday.eu/innovation/citizen-study-shows-big-differences-air-pollution-street-level">“curious noses”</a>, which saw Antwerp residents measure traffic pollution and <a href="http://www.charlottefive.com/citizens-measuring-air-quality/">“clean air zones”</a> in North Carolina, US, where individuals measured particulate matter in real time.</p>
<p>We’ve also seen awareness lead to action, when the demand for clean air led to <a href="http://www.clientearth.org/major-victory-health-uk-high-court-government-inaction-air-pollution/">ClientEarth</a> taking legal action against government failure to tackle illegal air pollution. Meanwhile, <a href="https://www.theguardian.com/environment/2016/aug/16/young-londoners-launch-independent-air-pollution-billboard-campaign?CMP=share_btn_tw">artists</a> in London produced their own campaigns, aimed at warning young people about the effects of poor air quality. </p>
<h2>Change is in the air</h2>
<p>This year the UN’s <a href="http://habitat3.org/the-new-urban-agenda/">New Urban Agenda</a>, the <a href="http://sustainabledevelopment.un.org/sdgs">Sustainable Development Goals</a> and the <a href="http://breathelife2030.org/">Breathe Life Campaign</a> called for action to improve urban air quality and deliver social, environmental and economic co-benefits. </p>
<p>Meanwhile, Paris, Mexico City, Madrid and Athens have pledged to remove all <a href="https://theconversation.com/these-four-cities-are-cracking-down-on-diesel-vehicles-to-improve-air-quality-heres-how-69921">diesel vehicles</a> from their streets by 2025, while promoting walking and cycling infrastructure. In Asia, a <a href="http://cleanairasia.org/ccap/">city certification programme</a> is being piloted to encourage cities to make advances in air quality management.</p>
<p>If anything, 2016 has showed us that poor air quality is a scourge of the developed and developing world alike – and that it requires immediate action. The evidence is clear: we need to clean up our act, to protect human health and reap the benefits of clean air for all.</p><img src="https://counter.theconversation.com/content/70375/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gary Haq is a Senior Research Associate at the Stockholm Environment Institute and has previously received research funding from the European Union, Joseph Rowntree Foundation, UK Local authorities and the Swedish and UK governments, United Nations and Clean Air Asia. He is currently on secondment to the EC Joint Research Centre.</span></em></p>Will the evidence finally convince polluted cities to clean up their act?Gary Haq, SEI Associate, Stockholm Environment Institute, University of YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/598832016-05-27T23:11:17Z2016-05-27T23:11:17ZWhat is going on with India’s weather?<p>On May 19, India’s <a href="http://edition.cnn.com/2016/05/20/asia/india-record-temperature/">all-time temperature record was smashed</a> in the northern city of Phalodi in the state of Rajasthan. Temperatures soared to 51°C, beating the previous record set in 1956 by 0.4°C.</p>
<p>India is known for its unbearable conditions at this time of year, just before the monsoon takes hold. Temperatures in the high 30s are routine, with local authorities declaring heatwave conditions only once thermometers reach a stifling 45°C. But the record comes on the back of an exceptionally hot season, with several heatwaves earlier in the year. So what’s to blame for these scorching conditions?</p>
<p>Much of India is in the grip of a <a href="http://www.bbc.com/news/world-asia-india-36299778">massive drought</a>. Water resources are scarce across the country. Dry conditions exacerbate extreme temperatures because the heat energy usually taken up by evaporation heats the air instead. </p>
<p>The <a href="https://theconversation.com/el-nino-is-here-and-that-means-droughts-but-they-dont-work-how-you-might-think-47866">complex relationship between droughts and heatwaves</a> is an area of active scientific research, although we know a <a href="http://www.pnas.org/content/109/31/12398.short">preceding drought</a> can significantly amplify the intensity and duration of heatwaves.</p>
<p>India’s drought was a possible factor in the <a href="http://www.aljazeera.com/news/2016/04/concerns-grow-heat-wave-persists-india-160421093938511.html">earlier heatwaves in April</a> over central and southern India. However, Rajasthan, where 51°C was recorded, is always bone-dry in May. So the drought made no difference to the record temperature.</p>
<h2>The El Niño effect</h2>
<p>We have also experienced one of the <a href="http://www.nasa.gov/feature/goddard/nasa-studying-2015-el-nino-event-as-never-before/">strongest El Niño events on record</a>. While the current event has <a href="https://theconversation.com/el-nino-is-over-but-has-left-its-mark-across-the-world-59823">recently ceased</a>, its sting is certainly still being felt. </p>
<p>El Niño episodes are associated with <a href="http://www.carbonbrief.org/analysis-how-much-did-el-nino-boost-global-temperature-in-2015">higher-than-average global temperatures</a> and have also been a factor in some of India’s <a href="http://metnet.imd.gov.in/mausamdocs/16441.pdf">past heatwaves</a>. However, there is no direct connection to El Niño in Rajasthan, because its climate at this time of year is so dry anyway.</p>
<p>India also has an extreme air pollution problem. Caused largely by <a href="http://www.who.int/heli/risks/indoorair/indoorair/en/">domestic fuel and wood burning</a>, it kills <a href="http://timesofindia.indiatimes.com/india/Green-stoves-to-replace-chullahs/articleshow/5293563.cms?referral=PM">up to 400,000 people every year</a>. This pollution, made up of fine particles called aerosols, also has the effect of cooling the local climate by reflecting or absorbing sunlight before it reaches the ground, thus reducing the likelihood of the most extreme high temperatures. </p>
<p>So although India is no stranger to extreme heat at this time of year, the smog has kept record-breaking high temperatures at bay – until now. This is what makes the record in Phalodi remarkable.</p>
<h2>Longer-term heat extremes</h2>
<p>A <a href="http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50150/full">study published in 2013</a> analysed annual trends in extremes and found no significant change in the intensity of extreme Indian temperatures between 1951 and 2010. The high levels of local air pollution were probably behind the lack of change.</p>
<p>However, the study found a significant increase in the <em>frequency</em> of extreme temperatures and a remarkable trend in the <em>duration</em> of warm spells in India, as the map below shows. Warm spells, defined as at least six days of extreme temperatures relative to the location and time of year, increased by at least three days per decade over 1951-2010 – the largest trend recorded globally.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=551&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=551&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124272/original/image-20160527-883-ww6f9w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=551&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global trends in ‘warm spell duration index’, which shows that the duration of heatwaves in India has increased markedly relative to the 1961-90 average. Data are also available via www.climdex.org.</span>
<span class="attribution"><a class="source" href="http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50150/full">J. Geophys. Res.</a></span>
</figcaption>
</figure>
<p>It is worth keeping in mind that these trends are annual and are influenced by extremes all year round. However, monthly trends in the frequency of Indian temperature extremes for May, which can be found on the <a href="http://www.climdex.org/gewocs.html">CLIMDEX climate database</a>, show an increase over the past 60 years.</p>
<p>Based on local station data, the Indian Meteorological Department <a href="http://metnet.imd.gov.in/mausamdocs/16441_F.pdf">reported</a> that many northern states experienced an average of eight heatwave days each March-July between 1961-2010. Trends in “normal” and “severe” heatwaves increased over this time, and in particular over the last decade of the analysis. </p>
<p>Some Indian regions also tended towards longer and more intense heatwaves after an El Niño, and northwestern states of India, where Phalodi is located, tend to experience more intense events anyway. Trends in the intensity of extreme temperatures are less clear and vary across the country.</p>
<p>Different spatial and temporal scales and methods of quantifying extreme temperature hamper a direct comparison of the two studies described above. However, they both document an increase in the frequency of extreme temperatures over India, which is consistent with many other regions worldwide. Heatwave indices and the hottest yearly temperature have only increased significantly in a relatively small region of western India.</p>
<h2>What will the future bring?</h2>
<p>Most climate models do not do a great job of capturing observed trends in heatwaves over India, because large-scale models struggle to accurately represent the localised effect of aerosols. </p>
<p>It is therefore difficult to use them in great detail for future projections, particularly if pollution levels continue or even increase. However, if air pollution is reduced, temperatures will rise with a vengeance. We know this from experience over Europe, where summer temperature trends were virtually zero up to the 1980s and very strong afterwards, once air pollution was controlled.</p>
<p>Even though this is the hottest time of the year for the region, the recent weather should not be dismissed as regular. It is feasible that India’s pollution problem has been “hiding” extreme heat spikes. </p>
<p>While any clean-up activities will have many positive local health impacts, these are likely to cause more intense heatwaves in future. This will be amplified by background warming due to climate change, which is also likely to drive increases in the frequency of temperature extremes.</p>
<p>Last year <a href="https://en.wikipedia.org/wiki/2015_Indian_heat_wave">India</a> and neighbouring <a href="https://en.wikipedia.org/wiki/2015_Pakistan_heat_wave">Pakistan</a> suffered similarly atrocious conditions, killing thousands of people. This year’s death toll is <a href="http://www.dw.com/en/blistering-heat-wave-kills-hundreds-in-india/a-19227359">already in the hundreds</a>, with numbers sure to rise further. </p>
<p>India is already highly vulnerable to the health impacts of oppressive heatwaves and, as climate change continues, this vulnerability will grow. It is therefore imperative that heat plans are put in place to protect the population. That’s a difficult prospect in places that lack communications infrastructure or widespread access to air conditioning. </p>
<p>In the longer term, this episode shows that the global warming targets agreed in Paris have to be taken seriously, so that unprecedented heatwaves and their deadly impacts don’t become unmanageable in this part of the world.</p><img src="https://counter.theconversation.com/content/59883/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Perkins-Kirkpatrick receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Andrew King receives funding from the ARC Centre of Excellence for Climate System Science.</span></em></p><p class="fine-print"><em><span>Geert Jan van Oldenborgh receives funding from the following projects: European Climate Extremes: Interpretation and Attribution (EUCLEIA), and World Weather Attribution (WWA). </span></em></p>The city of Phalodi has set a temperature record for India, hitting 51°C. Until now, India’s smog problem has curbed extreme temperatures. But that could be about to change.Sarah Perkins-Kirkpatrick, Research Fellow, UNSW SydneyAndrew King, Climate Extremes Research Fellow, The University of MelbourneGeert Jan van Oldenborgh, Climate researcher, Royal Netherlands Meteorological Institute Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/593002016-05-20T01:05:32Z2016-05-20T01:05:32ZThe paradox of peak-based ozone air pollution standards<figure><img src="https://images.theconversation.com/files/122538/original/image-20160513-19307-n32ixc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Houston in 2002. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/10659106@N00/5751828942/in/photolist-jwGTT-dCVDGi-32dh5E-328Zf6-sPNXn-9LgCmw-b8zLCz-6Rcx6B-b6WTeX-aApWyE">Michael Bludworth/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p><em>“And when she was good, she was very, very good,</em></p>
<p><em>But when she was bad she was horrid.”</em></p>
<p>Henry Wadsworth Longfellow’s <a href="http://www.bartleby.com/360/1/120.html">poem</a> may have befit Houston’s air around 1999, when the city briefly <a href="https://news.google.com/newspapers?nid=1683&dat=20000908&id=o74aAAAAIBAJ&sjid=VjkEAAAAIBAJ&pg=5770,6511288&hl=en%22%22">ranked</a> as the “New U.S. Smog Capital.” Back then, leaks and flares from local petrochemical plants too often contributed to <a href="http://onlinelibrary.wiley.com/doi/10.1029/2002JD003070/full">ozone spikes</a> that could fairly be described as “horrid.” Texas Air Quality Studies in <a href="http://www.tceq.state.tx.us/assets/public/implementation/air/am/contracts/reports/da/TexAQS2000_NOAA_Data_Analysis.pdf">2000</a> and <a href="http://www.tceq.state.tx.us/assets/public/implementation/air/texaqs/doc/rsst_final_report.pdf">2006</a> illuminated how industrial and urban emissions interacted to cause these pollution spikes.</p>
<p>Emission control efforts informed by those studies have made Houston smog episodes far less frequent and far less “horrid.” The efforts have been so successful that, averaging in days when our air is “very, very good,” Houston now has lower average ozone levels than most of the country. The city also meets all EPA standards for far deadlier particulate matter (PM) pollution, though <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4624091/">benzene</a> and other air toxics remain a concern in some neighborhoods. </p>
<p>Yet Houston ranks sixth smoggiest among U.S. cities in the American Lung Association (ALA) <a href="http://www.stateoftheair.org/2015/city-rankings/most-polluted-cities.html">ozone rankings</a>, and likely remains over a <a href="http://www.chron.com/local/gray-matters/article/Is-it-even-possible-for-Houston-and-Dallas-to-hit-6660561.php">decade</a> away from attaining EPA’s recently tightened ozone standards, which were <a href="https://theconversation.com/why-new-us-ozone-standards-arent-enough-to-protect-health-and-the-environment-48552">introduced in October 2015</a>.</p>
<p>Why does a city with such clean average air quality remain stuck on lists of smoggiest cities and regions that fail to meet air quality rules? Houston does have some unique air quality conditions. But its situation illustrates a paradox in how we use peak pollution levels to rank cities on air quality and set national ozone standards. </p>
<h2>Progress</h2>
<p>ALA rankings and EPA regulations focus on days with the worst ozone each year. By those measures, Houston is indeed far too polluted. When hot stagnant conditions set in, emissions uniquely concentrated in Houston’s petrochemical industry combine with typical big-city vehicle exhaust to form unhealthful levels of ozone. On such days, monitors downwind of the urban core and the Houston Ship Channel may measure ozone levels exceeding EPA standards.</p>
<p>Just four days per year above 70 parts per billion (ppb) at a single monitor is enough to bring an entire region into nonattainment of EPA’s recently tightened <a href="https://www3.epa.gov/ttn/naaqs/standards/ozone/s_o3_index.html">standard</a>. Some portion of the Houston region <a href="https://www.tceq.texas.gov/cgi-bin/compliance/monops/ozone_summary.pl">surpasses</a> this limit anywhere from 12 to 36 days each year. Ozone at these levels has been shown to impair lung function and trigger other adverse health outcomes.</p>
<p>From 2013-2015, areas in the U.S. with the fourth-worst ozone level, measured over eight-hour periods, at the region’s most polluted monitor (EPA’s basis for determining attainment) was <a href="https://www.tceq.texas.gov/cgi-bin/compliance/monops/8hr_attainment.pl">80 ppb</a> when averaged over three years. That’s far lower than levels at the turn of the century (Figure 1), but still 10 ppb above EPA’s new limit.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=182&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=182&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=182&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=229&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=229&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122540/original/image-20160513-10679-1wxtoc2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=229&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Figure 1. Fourth highest annual May-September 8-hour ozone concentration in 2000-2002 (left) and 2013-2015 (right).</span>
<span class="attribution"><span class="source">Data from EPA</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Ideally no days would exceed 70 ppb. However, complexities of atmospheric chemistry along with background pollution cause ozone to be relatively insensitive to changes in emissions of its precursors, nitrogen oxides and hydrocarbons. Ozone forms when sunlight drives chemical reactions of these gases. </p>
<p>Greater than 50 percent reductions in nitrogen oxide emissions – which come mostly from vehicle and industrial sources – may be needed to cut peak ozone by a mere 10 percent, and may do little to improve ozone on nonpeak days when biogenic hydrocarbons from trees are less abundant. The response of ozone to emissions changes is less than one-to-one because some ozone originates from background sources upwind, and because the chemistry is nonlinear.</p>
<p>Also, the focus of EPA and ALA on peak day ozone ignores the fact that air quality affects health year-round, not just when the standard is exceeded. <a href="http://www.ncbi.nlm.nih.gov/pubmed/16581541">Epidemiologists</a> find that health continues to improve as ozone falls far below regulated levels. Regulating just the peaks detracts attention from influences on average ozone conditions.</p>
<h2>Air quality duality</h2>
<p>Few Houstonians realize our abundance of “good” air days on EPA’s <a href="https://airnow.gov/index.cfm?action=aqibasics.aqi">Air Quality Index</a>. The cleanest days occur when gulf breezes bring in air with very little ozone and other pollutants. Even in the summer “ozone season,” we enjoy many days with ozone levels less than a third of the EPA limit. </p>
<p>Though scientists are still <a href="https://www.tceq.texas.gov/assets/public/implementation/air/am/committees/pmt_set/20151019/20151019_OverPredictionFromTheGulf_Smith.pdf">grappling</a> with the halogen chemistry and other factors that cause gulf air to be so clean, Houston monitors unequivocally show clean air even on many hot summer days. Those clean-air days help Houston rank lower than most cities and even many rural parts of the country for our average ozone levels (Figure 2).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=185&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=185&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=185&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=232&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=232&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122541/original/image-20160513-10663-1i711t8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=232&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Figure 2. Average annual May-September 8-hour ozone concentration in 2000-2002 (left) and 2013-2015 (right).</span>
<span class="attribution"><span class="source">Data from EPA</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The duality of Houston as a “smog capital” and “clean air haven” is illustrated by contrasting the city’s high peak ozone levels with its unusually clean average conditions (Figure 3). This helps explain why Houston fails to attain peak-based ALA targets and EPA standards yet has relatively low rates of ozone-induced premature mortality, which EPA <a href="https://www3.epa.gov/ttn/naaqs/standards/ozone/data/20140829healthreasummary.pdf">assumes</a> to be linked primarily to average conditions.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=206&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=206&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=206&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=259&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=259&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122542/original/image-20160513-10670-1bs3cgm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=259&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Figure 3. Average (blue) and fourth highest (red) 8-hour ozone concentrations in U.S. cities, May-September 2013-2015.</span>
<span class="attribution"><span class="source">Data from EPA</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This difference between peak versus average has public health implications. </p>
<p>Our analysis of EPA data shows that ozone trends across the country look very different on average and peak-day bases. Ozone has been trending down nationwide far more quickly on peak days than for average conditions, as <a href="http://pubs.acs.org/doi/abs/10.1021/es504514z">shown</a> by EPA scientists and confirmed by our figures. Many cities have shown no significant improvement in clean-day or average ozone conditions despite substantial reductions in peaks, though Houston averages have improved.</p>
<p>Here in Houston, while more improvements are still needed, we should breathe easier knowing that our “horrid” smog days are behind us as a result of more stringent emissions controls. With our relatively low average ozone and PM levels, Houston can set aside its outdated moniker as a smog capital. </p>
<p>Nationally, focusing on peak-day ozone too narrowly could constrain us from the broader perspective needed to holistically address our biggest air and climate challenges. Although ozone is harmful, particulate matter (PM) is a deadlier pollutant and climate change poses the greatest environmental challenge to society. Reducing our reliance on fossil fuels overall, rather than exclusively targeting ozone-forming gases, will be needed to jointly address these challenges.</p><img src="https://counter.theconversation.com/content/59300/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Cohan has received research funding from NASA, US EPA, and the Texas Commission on Environmental Quality. </span></em></p><p class="fine-print"><em><span>Beata Czader and Rui Zhang do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>U.S. states need to put in place new ozone air quality standards, but how they are measured – based on peak ozone – doesn’t always best reflect a city’s overall air quality.Daniel Cohan, Associate Professor of Environmental Engineering and Faculty Scholar at Baker Institute for Public Policy, Rice UniversityBeata Czader, Research Scientist in atmospheric modeling and chemical mechanisms, Rice UniversityRui Zhang, Postdoctoral Research Associate, Rice UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/508342015-11-23T19:18:33Z2015-11-23T19:18:33ZFeeding ‘Godzilla’: as Indonesia burns, its government moves to increase forest destruction<figure><img src="https://images.theconversation.com/files/102768/original/image-20151123-18264-1nrx9tp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Drought and deforestation have proved to be a volatile combination in Indonesia.</span> <span class="attribution"><span class="source">David Gilbert/Greenpeace</span>, <span class="license">Author provided</span></span></figcaption></figure><p>In the midst of its worst fire crisis in living memory, the Indonesian government is taking a leap backward on forest protection. The recently signed <a href="http://www.thestar.com.my/News/Nation/2015/11/22/KL-Jakarta-form-council-of-palm-oil-producing-countries/">Council of Palm Oil Producing Nations</a> between Indonesia and Malaysia, signed at the weekend in Kuala Lumpur, will attempt to wind back palm oil companies’ pledges to end deforestation. </p>
<p>This is despite Indonesia’s efforts to <a href="http://news.mongabay.com/2015/11/jokowi-turning-over-a-new-leaf-for-indonesia-on-haze-but-details-still-foggy/">end fires and palm oil cultivation</a> on peatlands. </p>
<p>If successful the move will undo recent attempts to end deforestation from palm oil production, and exacerbate the risk of future forest fires. </p>
<h2>Forests on fire</h2>
<p>Since August, forest and peatland fires have become so widespread across Indonesia that, in satellite images, the nation has looked like an over-lit Christmas tree. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=315&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=315&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=315&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=395&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=395&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102684/original/image-20151121-404-1d161af.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=395&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fires detected in Indonesia during a single week in October.</span>
<span class="attribution"><span class="source">Global Forest Watch</span></span>
</figcaption>
</figure>
<p>The fires have been so bad that carbon emissions from peatland burning alone (forgetting about the many thousands of additional forest fires) have equalled those <a href="http://news.mongabay.com/2015/10/carbon-emissions-from-indonesias-peat-fires-exceed-emissions-from-entire-u-s-economy/">produced by the entire United States</a></p>
<p><a href="http://www.abc.net.au/news/2015-09-15/malaysia-closes-schools-as-indonesia-smoke-haze-worsens/6777508">Schools</a> and <a href="http://atwonline.com/airports-routes/smoke-haze-forces-malaysian-indonesian-airport-closures">airports</a> have been repeatedly closed across large expanses of Southeast Asia. To reduce their risks, residents have been told to stay indoors.</p>
<p>Some 500,000 people have so far suffered <a href="http://www.economist.com/news/international/21677629-el-ni-o-leaves-much-south-east-asia-choking-smog-burning-questions">respiratory distress</a>. Nearby Singapore has threatened legal action against <a href="http://www.abc.net.au/news/2015-09-26/singapore-moves-against-indonesian-firms-over-haze/6807258">several Indonesian companies</a> whose activities have been linked to the fires, provoking a serious diplomatic spat between the two nations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102686/original/image-20151121-442-13awzn.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">Residents struggling with dense haze in central Indonesian Borneo.</span>
<span class="attribution"><span class="source">REUTERS/Sigit Pamungkas</span></span>
</figcaption>
</figure>
<p>Recent rains have dampened things somewhat. But climatologists tell us the <a href="https://theconversation.com/godzilla-el-nino-time-to-prepare-for-mega-droughts-46673">“Godzilla” El Niño</a> that worsened the fires this year will likely continue for several months more. </p>
<h2>Good news, then bad</h2>
<p>In the wake of the alarming fire crisis, Indonesian president Joko Widodo recently <a href="http://news.mongabay.com/2015/11/jokowi-turning-over-a-new-leaf-for-indonesia-on-haze-but-details-still-foggy/">banned peatland fires and the planting of peatlands with palm oil</a>. </p>
<p>The president must be lauded for this crucial action. Although belated, it’s central to efforts to staunch the present fire crisis and to limit future crises.</p>
<p>But we’re not out of the haze yet.</p>
<p>Between them, Indonesia and Malaysia produce around <a href="http://www.straitstimes.com/asia/se-asia/jakarta-kl-to-set-green-standards-for-palm-oil">85% of the world’s palm oil</a>. Palm oil is <a href="https://theconversation.com/palm-oil-plantations-are-bad-for-wildlife-great-and-small-study-33632">intimately linked to forest loss and burning</a>. For example, most of the peatland fires have occurred because deep channels were carved into the peat swamps, so they drain out and become dry and easy to burn. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102683/original/image-20151121-442-kv9nwa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Heavy machines channel and drain peat forest in western Indonesian Borneo.</span>
<span class="attribution"><span class="source">Edy Pumomo/Greenpeace</span></span>
</figcaption>
</figure>
<p>While oil palm plantations can be established on cleared lands, many legally and <a href="https://eia-international.org/wp-content/uploads/Permitting-Crime.pdf">illegally</a> involve deforestation, because it allows them to <a href="http://www.cifor.org/publications/pdf_files/articles/aobidzinski1301.pdf">use timber revenues to help offset the costs of plantation establishment</a>.</p>
<h2>The deforestation revolution</h2>
<p>The <a href="https://theconversation.com/palm-oil-continues-to-destroy-indonesias-wildlife-31831">destructive impacts of oil palm on rainforests and peatlands</a> is a key reason why palm oil corporations have come under heavy fire in recent years to clean up their environmental acts. </p>
<p>And this has fomented a true revolution. Under growing public and consumer pressure, many of the world’s biggest palm oil producers, as well as many large multinationals (such as <a href="http://us.pg.com/sustainability/environmental_sustainability/policies_practices/palm_oil">Procter & Gamble</a>, <a href="http://www.nestle.com/csv/rural-development-responsible-sourcing/responsible-sourcing/deforestation">Nestlé</a> and <a href="http://www.cargill.com/news/cargills-un-deforestation-pledge-how-it-happened/index.jsp">Cargill</a>) that buy and use palm oil, have adopted <a href="https://theconversation.com/how-global-forest-destroyers-are-turning-over-a-new-leaf-22943">“no-deforestation” agreements</a>. This has all happened in the last two years and it’s been one of the most remarkable environmental advances of the last decade.</p>
<p>But just as the no-deforestation agreements are starting to yield real benefits, Indonesia and Malaysia are moving actively to destroy them. <a href="http://www.reuters.com/article/2015/10/14/indonesia-palm-ipop-idUSL3N12E22820151014">One of the aims</a> of the new council is to pressure corporations working in their nations to drop their no-deforestation pacts. </p>
<p>They argue that the pledges are an <a href="http://www.reuters.com/article/2015/10/14/indonesia-palm-ipop-idUSL3N12E22820151014">affront to sovereignty</a>, in being driven by Western consumers, and <a href="http://www.indonesia-investments.com/news/todays-headlines/indonesia-to-stop-complying-with-european-union-s-palm-oil-standards/item6025">disadvantage smaller palm-oil producers</a>. However the coalition coordinating no-deforestation efforts among Indonesian producers — known as the <a href="http://www.palmoilpledge.id/">Indonesia Palm Oil Pledge</a> — is working to help smaller firms and community producers achieve no-deforestation <a href="http://www.reuters.com/article/2015/10/14/indonesia-palm-ipop-idUSL3N12E22820151014">compliance</a>.</p>
<h2>Another smokescreen?</h2>
<p>In my view, the arguments by Indonesia and Malaysia are just another smokescreen to expand palm oil production.</p>
<p>For instance, Indonesia is planning to convert <a href="http://news.mongabay.com/2014/08/indonesian-govt-reiterates-plan-to-clear-14m-ha-of-forest-by-2020/">14 million hectares</a> of degraded forest to plantations and other resources, which will likely involve deforestation. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102687/original/image-20151121-389-1fefvkg.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">A seemingly endless sea of oil palm in central Sumatra, Indonesia.</span>
<span class="attribution"><span class="source">William Laurance</span></span>
</figcaption>
</figure>
<p>The new council also plans to <a href="http://www.indonesia-investments.com/news/todays-headlines/indonesia-to-stop-complying-with-european-union-s-palm-oil-standards/item6025">lobby China and India</a>, both massive palm oil consumers who’ve so far shown little interest in anything other than buying large amounts of palm oil as cheaply as possible, to accept its new palm oil scheme.</p>
<p>While the council has promised <a href="http://www.thestar.com.my/News/Nation/2015/11/22/KL-Jakarta-form-council-of-palm-oil-producing-countries/">sustainable palm oil and to limit forest fires</a>, it is unclear how this will be achieved with a massive expansion of the palm oil industry. </p>
<h2>Don’t feed Godzilla</h2>
<p>The fires and dense haze that have plagued Southeast Asia this year are certainly not a one-off event. In fact, they’ve been an <a href="http://www.thejakartapost.com/news/2015/09/21/your-letters-annual-smoke-indonesia.html">annual occurrence for many years</a>, albeit worsened this year by an intense fire-breathing El Niño drought that we’ve long known was coming. </p>
<p>Indonesia is destroying its rainforests <a href="http://www.theguardian.com/environment/2014/jun/29/rate-of-deforestation-in-indonesia-overtakes-brazil-says-study">faster than any other tropical nation</a>, and it is at the heart of the recurring air-pollution crisis in Southeast Asia. Its policies will have a huge impact on forests, biodiversity and the global climate. President Widodo’s recent pledge to halt peatland fires is an essential initiative and one that should be heartily applauded.</p>
<p>But if the newly formed council holds sway, any benefits from Widodo’s peat-burning ban could be overwhelmed by increasing forest destruction in some of the biologically richest real estate on the planet. </p>
<p>And I predict that any corporation rash enough to backslide on its hard-won no-deforestation pledge will be quickly targeted by environmental groups and, hopefully, punished by consumers.</p><img src="https://counter.theconversation.com/content/50834/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bill Laurance receives funding from the Australian Research Council and other scientific and philanthropic organisations. He is director of the Centre for Tropical Environmental and Sustainability Science (TESS) at James Cook University, and founder and director of ALERT--the Alliance of Leading Environmental Researchers & Thinkers.
</span></em></p>While Indonesia has taken steps to address the worst forest fires in living memory, a new palm oil alliance with Malaysia threatens to take a giant leap back.Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/485522015-10-06T10:09:48Z2015-10-06T10:09:48ZWhy new US ozone standards aren’t enough to protect health and the environment<figure><img src="https://images.theconversation.com/files/97338/original/image-20151006-29248-52c9ja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ground-level ozone levels in US lag other countries' guidelines for air quality. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/30003006@N00/530910048/in/photolist-NV44w-9dmtMw-5y3UJ-o1oJsW-yWzUF-pMxwKs-p8nQV-7XAjDH-3nff21-o73WAs-oedY-jiedz1-e7dzx1-7FK4Hm-xsUjvH-jtSnYu-jaguU-9uhdfy-5WjdXB-nmTpTD-5WwVkA-4VhCaS-xsLNrZ-ckajYY-rykHgu-fcSEdx-sgbfyH-nZvsR-aRMuXc-p1twH6-4t2G52-4FMNkz-aQEWnM-5DFQT5-ee6kY1-4EjNgb-s5Vvz-788cgF-ysAd-8pu59P-8pxghU-47PGd3-33FCNQ-rSypxQ-aFNN8T-8pUg3k-nk5bJN-bZo8D-pDxhZx-obnEY">urbanfeel/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>On October 1, the US Environmental Protection Agency announced <a href="http://www3.epa.gov/ozonepollution/actions.html">new standards</a> for ground-level ozone. Much of the <a href="http://www.nytimes.com/2015/10/02/us/politics/epa-to-unveil-new-limit-for-smog-causing-ozone-emissions.html">discussion</a> around the new regulations has centered either on whether they are protective enough of health or on how much implementation will cost.</p>
<p>The US is not the only country taking action to restrict ground-level ozone – and from a health perspective, even the new, lower US limit is still higher than guideline levels in other countries. </p>
<p>Industry in the US has resisted tighter controls on ozone because they would require upgrades to air quality equipment at power plants, industrial activity and vehicles. However, a true accounting of the costs and benefit should include the health and ecological benefits of stricter controls. </p>
<h2>Damaging impact</h2>
<p>Wherever it comes from, ground-level ozone can cause <a href="http://www3.epa.gov/ozonepollution/health.html">substantial damage to human health</a>, including respiratory problems, asthma attacks, and premature mortalities. Ozone impacts the environment, too, by <a href="http://www.ars.usda.gov/Main/docs.htm?docid=12462">harming plant growth</a> and lowering agricultural crop yields. Ozone can also act as a <a href="https://www.ncdc.noaa.gov/monitoring-references/faq/greenhouse-gases.php">greenhouse gas</a>, contributing to warming of the climate.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/97341/original/image-20151006-29251-oovagc.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">Higher ozone levels can impact crop yields as well as damage human health.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/scania/2869182255/in/photolist-5nxiVz-jbFPK1-pMxoH-8Lsd1k-5BSjNP-9XdSSB-8YCUDw-rjXnb-9XgKkJ-5VHAzt-4wuwPN-5akdR7-59tSzt-HPdPk-7zsQtg-iUKE8K-4iBXSS-6Joq61-5xbWJP-dQMNDD-3pL1Bj-fQC2rq-9bd3TX-itwiz-9oEoMa-7HwcMx-3Qtz4-hW2Cb-2tiQsD-5ZTfxL-7AdcQF-ePTPMk-24f2V-9duYsL-aHHNo-5uaWE8-5uiurM-axCfjX-4bAbEJ-8wwHnZ-dQZQ3a-4pLNpd-5JnJYH-5Jnajr-5JrSmL-3nzwSV-9uLe8U-5ZU4bU-dHjyzW-2EsRiN">Scania</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>While ground-level ozone is primarily a regional issue, pollutants that can contribute to ozone formation also travel across continents. For example, emissions from Asia contribute to local ground-level ozone problems in the United States.</p>
<p>Much discussion of the new EPA rule has focused on the issue of compliance costs, with <a href="http://www3.epa.gov/ozonepollution/pdfs/20151001numbersfs.pdf">very</a> <a href="http://thehill.com/blogs/congress-blog/energy-environment/255508-epa-ozone-rule-costly-duplicative-unnecessary">different</a> estimates of the economic implications of meeting the new standard. </p>
<p>However, the health and ecological impacts of ozone have an economic cost as well – and these can add up. In the US, for example, the EPA estimates that strengthening the standards could lead to <a href="http://www3.epa.gov/ozonepollution/pdfs/20151001numbersfs.pdf">US$2.9-5.9 billion in benefits</a> from improved health.</p>
<h2>Comparing numbers</h2>
<p>The new ambient air quality standard was reduced from a level of 75 parts per billion (ppb) of allowed ground-level ozone in air to 70 ppb. This is at the top end of the range – 60 to 70 ppb – <a href="http://www3.epa.gov/ttn/naaqs/standards/ozone/data/20140829pa.pdf">recommended by the scientific advisory committee</a> tasked with informing EPA about this issue.</p>
<p>A concentration of 70 ppb is still a high level of ozone when compared with targets set by other countries around the world. Ozone concentrations are often averaged over eight hours. As ozone forms from chemical reactions that include sunlight and temperature, the maximum level usually occurs in the afternoons.</p>
<p>The World Health Organization’s <a href="http://apps.who.int/iris/bitstream/10665/69477/1/WHO_SDE_PHE_OEH_06.02_eng.pdf">health-based guideline</a> (a recommendation only - the WHO is not a regulatory body) for all its member states is equivalent to 50 ppb. The European Union (EU) aims for a long-term objective to protect health that corresponds to <a href="http://ec.europa.eu/environment/air/quality/standards.htm">60 ppb</a>, and Canada’s standard is <a href="http://ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=9EBBCA88-1">63 ppb</a>. Research has also shown that the negative <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1440776/">health effects of ozone can occur at concentrations far below these levels</a>.</p>
<p>However, it is difficult to compare regulations directly, as both the form and the enforcement capacity differ. </p>
<p>The US regulation allows the set level to be exceeded up to four times per year, before deeming an area to be violating the standard. The EU’s level represents a long-term objective – in the near term, concentrations can exceed the target level up to <a href="http://ec.europa.eu/environment/air/quality/standards.htm">25 times, averaged over three years</a>. Canada’s standard, while measured similarly to the US, is essentially a voluntary target, with little enforcement capacity.</p>
<p>In practice, both in the US and elsewhere, ozone concentrations frequently fail to meet the standards. Based on 2012-2014 data, <a href="http://ozoneairqualitystandards.epa.gov/OAR_OAQPS/OzoneSliderApp/index.html">241 counties</a> in the US had concentrations that exceeded the new standard. In the summer of 2014, the EU did not meet its long-term objective at <a href="http://www.eea.europa.eu/highlights/ozone-pollution-in-europe-fewer">80% of measurement stations</a>.</p>
<p>In other parts of the world ozone is an even more widespread problem. High levels of industrial and traffic emissions in Asia lead to high ozone concentrations there that can <a href="http://www.atmos-chem-phys.net/11/3511/2011/acp-11-3511-2011.pdf">far exceed</a> levels in North America and Europe.</p>
<h2>Connection to greenhouse gases</h2>
<p>Regulatory actions aren’t the only factor in controlling ozone levels. Because ozone is produced in the atmosphere, its formation can also be affected by meteorological conditions. </p>
<p>In many areas in the US – in particular, densely populated areas where people live such as the East, Midwest, and South – it is projected that <a href="http://www2.epa.gov/cira/climate-action-benefits-air-quality">climate change can make ozone worse</a>, because changes like increasing temperature can increase ozone formation.</p>
<p>By 2050, it has been estimated that the global health costs from ozone could reach <a href="http://iopscience.iop.org/article/10.1088/1748-9326/4/4/044014/meta">$580 billion</a>, considering both climate and future emissions changes. Also, because both increasing temperatures and ozone can reduce crop yields, climate change and air pollution acting together are projected to <a href="http://news.mit.edu/2014/climate-change-air-pollution-will-combine-curb-food-supplies-0727">cause substantial crop damage worldwide</a> in the future. </p>
<p>The other general point to be made is that the sources that contribute to ozone formation – such as vehicles and power plants – also emit other pollutants that, in turn, also contribute to atmospheric particulate matter and climate change. Yet current regulations often deal with pollutants in isolation. Coordinated strategies could lead to greater benefits and, at the same time, save money. </p>
<p>For example, <a href="http://www.unep.org/publications/ebooks/slcf/">controlling methane, a greenhouse gas, can help mitigate ozone damages</a> at the same time as benefiting the global climate. Carbon policies, similar to those proposed under the Clean Power Plan, can also <a href="http://www.nature.com/nclimate/journal/v5/n6/full/nclimate2598.html">improve</a> <a href="http://www.nature.com/nclimate/journal/v4/n10/full/nclimate2342.html">ozone air quality</a> across the US.</p>
<p>A truly healthy atmosphere would contain substantially less ozone than 70 ppb. Fully implementing the new standard, and taking advantage of innovative and coordinated strategies to reduce greenhouse gases and traditional air pollutants, could help the US lead the way in addressing this global challenge.</p><img src="https://counter.theconversation.com/content/48552/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Noelle Eckley Selin has received funding from the U.S. Environmental Protection Agency for research on air quality. </span></em></p>The US has stricter ozone rules but the limits lag guidelines set by some other countries and more coordination in regulation is needed to address air pollution globally.Noelle Eckley Selin, Associate Professor of Data, Systems, and Society and Atmospheric Chemistry, Massachusetts Institute of Technology (MIT)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/482962015-09-29T20:44:54Z2015-09-29T20:44:54ZThe not-so-invisible damage from VW diesel cheat: $100 million in health costs<figure><img src="https://images.theconversation.com/files/96679/original/image-20150929-30999-1rpqnzq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Smog over car-heavy Los Angeles. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/bobtravis/431927416/">bobtravis/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Cheating is not a victimless crime. The recent revelations that Volkswagen rigged in-vehicle software to defeat emissions tests are but the latest example of efforts to evade regulations that protect human health and the environment. </p>
<p>In crimes against the environment, it’s sometimes difficult to calculate who is affected and how substantial the damages are. However, it is possible to estimate the damages, based on our understanding of the atmosphere and of how pollutants affect human health.</p>
<p>My analysis shows that Volkswagen’s deception – which resulted in emissions 30-40 times allowable levels when driving – could exceed US$100 million in economic costs from health damages. This staggering sum hints at the scope of the consequences of just one case of corporate cheating.</p>
<h2>What air pollutants are we talking about?</h2>
<p>The pollutants that Volkswagen failed to effectively control are nitric oxide (NO) and nitrogen dioxide (NO<sub>2</sub>), which are collectively known as NOx. NO<sub>2</sub> is a dangerous air pollutant in its own right, as it can cause respiratory damages. But combined with other atmospheric pollutants, NOx can form even more dangerous pollutants: ozone and particulate matter.</p>
<p>US Environmental Protection Agency (EPA) regulations for diesel engines limit the amount of NOx that can be emitted per mile traveled. Volkswagen classified its vehicles as meeting so-called <a href="http://www.csmonitor.com/Business/In-Gear/2015/0922/VW-diesel-emissions-recall-widens-10-things-you-need-to-know">Tier II/Bin 5</a> emission standards, which means that they were allowed to emit <a href="http://www3.epa.gov/otaq/standards/light-duty/tier2stds.htm">0.07 grams of NOx</a> for every mile traveled over the lifetime of the vehicle. Actual emissions from affected cars were reported to be <a href="http://www3.epa.gov/otaq/cert/documents/vw-nov-caa-09-18-15.pdf">10-40 times higher</a> – as discovered by a <a href="https://theconversation.com/how-volkswagen-got-caught-cheating-emissions-tests-by-a-clean-air-ngo-47951">US nongovernmental organization working with researchers from West Virginia University</a>.</p>
<p>In practice, the total amount of excess pollution from each tailpipe will depend on the driving conditions – for example, whether vehicles were driven on highways or city streets – as well as how many miles were driven by these cars, and under what conditions and temperatures. With more than 480,000 cars affected, estimates have ranged from <a href="http://www.theguardian.com/business/ng-interactive/2015/sep/23/volkswagen-emissions-scandal-explained-diesel-cars">10,000 to 40,000 tons</a> of extra NOx released in the United States. </p>
<p>The order of magnitude of this number makes sense: if each car traveled 15,000 miles per year and emitted 2.8 grams of NOx per mile instead of 0.07 grams per mile, the total amount of excess NOx would be over 10,000 metric tons.</p>
<p>To calculate the ozone and particulate matter formed as a result of this additional NOx, it is necessary to know where and when this NOx was released. Then an atmospheric model can be used to calculate how pollutants travel and the chemical reactions they undergo. </p>
<p>A number of previous studies have <a href="http://pubs.acs.org/doi/abs/10.1021/es304831q">examined</a> the <a href="http://www.sciencedirect.com/science/article/pii/S1352231013004548">ozone and particulate matter formation</a> from on-road sources of NOx, so good estimates exist of how much ozone and particulate matter would be formed on average per ton of NOx, and how these estimates vary with space and time.</p>
<h2>What are the health impacts of this excess pollution?</h2>
<p>Ozone and fine particles are known to cause serious human problems. Particles smaller than 2.5 micrometers in size, small enough to be inhaled deep into the lungs, are of most concern for health and are referred to as PM<sub>2.5</sub>. <a href="http://www3.epa.gov/pm/health.html">Negative health effects</a> from PM<sub>2.5</sub> include heart attacks, decreased lung function, bronchitis and aggravated asthma. <a href="http://www3.epa.gov/ozonepollution/health.html">Ozone can cause respiratory symptoms</a>, such as coughing, shortness of breath and inflammation, and can worsen lung diseases such as asthma or emphysema. Both of these pollutants can lead to premature deaths.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/96680/original/image-20150929-30970-158z696.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Air pollutants linked to NOx emissions can cause asthma and other respiratory illnesses.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/30912734@N04/3631079012/in/photolist-6wSehy-7cNP1a-8K2EBL-8Dch8M-po49tK-6DtYim-6DpPXX-8DcgGt-bXh2Ug-gMQcjo-dFZiox-tRnHxG-9Frwrh-8ZKokY-8DfozU-8Us4bh-JBVDE-9m6KWc-nusAXK-m5KpY4-6DtYdN-6DpQ5P-wiiDCj-2XV9Uo-78dxDx-2XV9H9-8Dfo2h-4URrnm-7HLzTa-ejmLKW-9VDNVm-9qMECF-8ZKmvy-85pknQ-2XVWgL-8pAw9q-8DfoT5-8Dcgvk-8Dfpbd-8DcgJc-8DcgyZ-8Dcgqr-8Dfoi1-8DfnW9-5vMrJi-9FrxSW-9Fry8h-abteNg-9Fry4b-9FrxVQ">KristyFaith/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p><a href="http://www.nytimes.com/2015/09/29/upshot/how-many-deaths-did-volkswagens-deception-cause-in-us.html">Different methods of calculating</a> the lives lost from the scandal have been discussed in the media. One way of calculating the human toll is to look at populations exposed to more or less pollution and differences in their health. Epidemiologists can derive statistical relationships between pollutant concentrations and health impacts like heart attacks and deaths. Models use this information to estimate the health damage of any given unit of pollution. For example, the EPA’s <a href="http://www2.epa.gov/benmap">BenMAP software</a> is an open-source program that estimates the health impacts from changes in air quality compared with a baseline. </p>
<p><a href="http://www.sciencedirect.com/science/article/pii/S0160412012001985">An EPA study</a> using BenMAP recently estimated that one ton of on-road NOx can be expected to lead to <a href="http://www2.epa.gov/sites/production/files/2014-10/documents/sourceapportionmentbpttsd.pdf">0.00085 deaths</a>, based on a <a href="http://scientificintegrityinstitute.net/Krewski052108.pdf">commonly used function</a> associating PM<sub>2.5</sub> with mortality rates. That means that for the amount of NOx estimated from the Volkswagen scandal (10,000-40,000 tons), we’d expect eight to 34 deaths.</p>
<h2>How do regulators assess the economic costs of health impacts?</h2>
<p>In proposing regulations on air quality, EPA conducts an analysis that assesses the cost and benefit of air quality improvements. The benefits of regulation can be thought of as the inverse of the pollution damages. If reducing a unit of pollution saves us money, then adding a unit of pollution would cost us.</p>
<p>Many economic researchers have studied how to express health damages from air pollution and other environmental risks in dollar terms. One approach would be to quantify the “<a href="http://yosemite.epa.gov/ee/epa/eed.nsf/dcee735e22c76aef85257662005f4116/e9e1a924cc59306485257662005f97bf!OpenDocument">cost of illness</a>” – that is, add up the cost of treating an illness as well as the lost work time resulting from that illness. <a href="http://www2.epa.gov/benmap/how-benmap-ce-estimates-health-and-economic-effects-air-pollution">Another approach</a> would be to assess the “willingness to pay,” which incorporates both these direct costs as well as the value people would attribute to the pain and suffering caused by the illness.</p>
<p>While efforts to monetize health impacts can be controversial, the EPA has used the concept of <a href="http://link.springer.com/article/10.1023/A:1025598106257">Value of Statistical Life (VSL)</a> to take into account the economic implications of health burdens, which measures people’s willingness to pay in order to avoid risks of dying. The current estimate for VSL, which is adjusted every year, is about $9 million. </p>
<p>BenMAP uses these assumptions to come up with <a href="http://www2.epa.gov/benmap/how-benmap-ce-estimates-health-and-economic-effects-air-pollution">monetary estimates of the health burden of air pollution</a>. The EPA study noted above used BenMAP to value the health burden per ton of NOx emitted from on-road sources at <a href="http://www2.epa.gov/sites/production/files/2014-10/documents/sourceapportionmentbpttsd.pdf">$7,300</a> using its VSL estimates. Even at the low end of estimates of tons of excess NOx emitted by the Volkswagen scandal (15,000 tons), a $7,300/ton health burden would exceed $100 million in damages.</p>
<h2>How does this number compare?</h2>
<p>It’s difficult to attach a precise figure to health damage caused by the Volkswagen scandal. But what we know about NOx in the atmosphere is clear: every excess ton emitted can have detrimental effects on people’s health, and those illnesses have a cost to individuals and society.</p>
<p>To compare these numbers with another high-profile case, the recent large-scale recall of defective air bags led to <a href="http://money.cnn.com/2015/06/21/news/companies/eighth-takata-airbag-death/">eight known deaths</a>. While health impact analysis can’t identify specific affected individuals, the people whose lives were cut short because of Volkswagen’s actions – as well as the numerous others whose health was impaired – are the real victims of this crime. </p>
<p>Any delay on the part of Volkswagen to address this issue costs additional lives each year. The good news is that as soon as these cars are fixed, air pollution and our health will rapidly get better.</p>
<p><em>This article has been updated to correct the level of NOx emissions allowed by EPA rules and the estimate of grams emitted by car.</em></p><img src="https://counter.theconversation.com/content/48296/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Noelle Eckley Selin has received funding from the U.S. Environmental Protection Agency for her research on air quality issues. </span></em></p>Volkswagen’s emissions cheat didn’t just anger owners and regulators; the cost to human health from violating air quality rules exceeds US$100 million.Noelle Eckley Selin, Associate Professor of Data, Systems, and Society and Atmospheric Chemistry, Massachusetts Institute of Technology (MIT)Licensed as Creative Commons – attribution, no derivatives.