The Life-Saving Bonus from Greenhouse Gas Emission Cuts: Better Air Quality

Climate change mitigation is often portrayed as a burden, with any long-term benefits far in the future. That’s a misleading and inaccurate picture, as emission cuts can produce many benefits right out of the gate. Chief among those is the potential for improved air quality. When we burn less of the oil, coal and gas that produce heat-trapping gases such as carbon dioxide, there’s also an immediate reduction in the witch’s brew of other compounds that these fuels add to our atmosphere. Cutting this pollution could pay phenomenal benefits in public health, saving hundreds of thousands of lives. In the year 2013, outdoor air pollution was connected to about 2.9 million deaths globally, and about 80,000 deaths in the U.S., according to a 2016 study carried out by the University of British Columbia as part of the Global Burden of Disease project. The global toll was even larger when considering both indoor and outdoor air pollution: more than 5.5 million premature deaths. Two of the worst culprits are coal plants in China and indoor cookstoves in India, according to the report.



Figure 1. Pupils cover their noses after school in heavy smog on December 23, 2015, in Binzhou, China. According to the Ministry of Environmental Protection of the People's Republic of China, more than 50 cities, including Beijing, Tianjin, Shanghai and Guangzhou, were affected by severe air pollution. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

Clean Air Act has made a big impact in the United States
The U.S. has already made great progress in cutting back on some of our worst air pollutants. Lead--a terrible health hazard that still plagues water in cities around the nation, including Flint, Michigan--was once an airborne scourge as well: it poured into the atmosphere every time we pumped leaded gasoline into our vehicles. But a federally mandated switch to unleaded gas has almost eliminated unsafe levels of lead in the atmosphere, with reductions of more than 90% since 1980. More recently, updates to the Clean Air Act have led to big cuts in the emissions of nitrogen oxides (NOx) and volatile organic compounds (VOC), which team up in the presence of sunlight to produce dangerous ground-level ozone. From 2004 to 2014, U.S. fossil-fuel emissions of NOX dropped 13%, and VOC a whopping 42%, according to EPA data.


Figure 2. Juxtaposed with the growth in many other indices of our industralized society--including carbon dioxide emissions--the United States has made noteworthy progress since 1970 in reducing the combined emissions of six common pollutants: carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide. Image credit: EPA, courtesy American Lung Association.


Particulates are a particular concern
It’s been harder to cut down on the tiny airborne solids and liquids called aerosols, or fine particulate matter. These are produced by fossil fuel burning as well as wildfires and natural sources. Particulates smaller than 2.5 microns in diameter (0.0001 inch) can accumulate in the lungs and cause both short- and long-term trouble. This includes asthma, lung cancer, and other respiratory ailments, as well as cardiovascular disease, an air-pollution threat that’s gone from obscurity to infamy in the last 20 years. You may be surprised to learn that, according to the WHO, roughly 80% of the deaths related to outdoor air pollution in 2012 were from heart disease or stroke.


Figure 3. Particulates that enter our atmosphere from fossil fuel burning, wildfires, and other sources can be less than 2.5 microns (0.0001 inch) in diameter--smaller in diameter than beach sand or a human hair. These particles are small enough to enter the bloodstream and contribute to cardiovascular disease. Image credit: EPA, courtesy American Lung Association.

How many people does pollution kill?
Why is it that air pollution episodes that kill thousands of Americans don't receive the media attention that, say, hurricanes get? It’s because "premature deaths" caused by air pollution are only partly attributable to breathing bad air, while drowning in a hurricane's storm surge is entirely due to the hurricane, and is a much more dramatic event. Nevertheless, a great many children die of pollution-induced asthma attacks who would not have died otherwise, and the mortality due to air pollution in the general U.S. population is in the tens of thousands each year. The only way to see air pollution deaths is to analyze death rate statistics for multiple years, carefully filtering out other influences such as weather extremes. Over two thousand studies have been published in the scientific literature documenting the link between air pollution and higher death and hospitalization rates. Most of these studies concern fine particulate matter; recent studies have also documented higher death rates from ozone pollution.

Cutting emissions could prevent nearly 300,000 U.S. air pollution deaths by 2030
The startlingly large death toll related to pollution means there is great potential to save lives. A February 2016 study published in Nature Climate Change, "Climate and health impacts of US emissions reductions consistent with 2 °C", found that reducing U.S. emissions in the energy and transport sectors could prevent almost 300,000 early deaths caused by air pollution in the U.S. between 2015 and 2030, or about 20,000 per year. The reductions in pollution would also lead to about 29,000 fewer asthma attacks per year in children under 18 requiring emergency room visits, and save 15 million lost adult work hours per year. These benefits would require a reduction of air pollution emissions averaging 2.7% per year beginning in 2015, consistent with the U.S. pledge made at the Paris Climate Summit in 2015 to keep global warming less than 2 °C above pre-industrial levels. The researchers estimated that the saved lives and reduced health care costs would benefit the U.S. economy by $250 billion per year, and estimated that "benefits seem to outweigh costs by at least a factor of 5–10." Once you include the benefits of emissions cuts for reducing global climate change, these economic gains “roughly quintuple”, they said.

When one adds in the huge health and environmental costs associated with fossil-fuel extraction--such as oil spills, mountaintop removal for coal mining, and failures of coal ash ponds--the benefits of switching away from fossil fuel energy sources are even more dramatic.

How climate change could shape the face of U.S. air pollution
In case we need still more motivation to cut back on fossil fuels, there is also evidence that climate change itself may exacerbate certain types of air pollution. In the U.S., urban air pollution appears to be getting “spikier,” with heat waves, droughts, and wildfires worsening the worst episodes even as many cities experience cleaner air overall. In its 2016 State of the Air report, the American Lung Association noted that most of the cities plagued with high year-round particulate levels made real progress in 2015. Los Angeles had its record-lowest number of unhealthy days for both ozone and particulates. Yet seven cities saw their highest-ever number of days with unhealthy short-term levels of particulates. California’s Central Valley was the epicenter of this syndrome, with persistent high pressure, record heat, and a fourth year of drought gripping the region for much of 2015.


Figure 4. A view of the Los Angeles city skyline as heavy smog shrouds the city on May 31, 2015. Image credit: Mark Ralston/AFP/Getty Images.


More perspective comes from a major report released by the Congressionally-chartered U.S. Climate Change Research Program in April, The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment. The report covers a wide range of health impacts, from heat and cold waves to vector-borne disease. Among the key findings in the chapter on air quality:

• Climate change will make it harder for any given regulatory approach to reduce ground-level ozone pollution in the future as meteorological conditions become increasingly conducive to forming ozone over most of the United States [Likely, High Confidence]. Unless offset by additional emissions reductions, these climate-driven increases in ozone will cause premature deaths, hospital visits, lost school days, and acute respiratory symptoms [Likely, High Confidence].

• Wildfires emit fine particles and ozone precursors that in turn increase the risk of premature death and adverse chronic and acute cardiovascular and respiratory health outcomes [Likely, High Confidence]. Climate change is projected to increase the number and severity of naturally occurring wildfires in parts of the United States, increasing emissions of particulate matter and ozone precursors and resulting in additional adverse health outcomes [Likely, High Confidence].

• Changes in climate, specifically rising temperatures, altered precipitation patterns, and increasing concentrations of atmospheric carbon dioxide, are expected to contribute to increasing levels of some airborne allergens and associated increases in asthma episodes and other allergic illnesses [High Confidence].

Check out WU’s Air Quality Awareness Week website
The U.S. Environmental Protection Agency (EPA) has designated the week of May 2-6, 2016, as Air Quality Awareness Week. Check out our special WU website with more background on AQAW, including the major pollutants tracked by EPA as well as safety tips to help reduce the risk of health impacts from outdoor and indoor pollution affecting you and others around you.

Jeff Masters and Bob Henson