Mobile sources are the greatest contributor to American air pollution.
By Roddy Scheer and Doug Moss

The U.S. Environmental Protection Agency (EPA) points to mobile sources (trains, planes and automobiles) as the greatest contributors to American air pollution, but industrial sources such as power plants and factories are not far behind. Photos: Tailpipe: JT/Environment Blog; Smokestack: Pascal Kammer
The main threats to local air quality across the United States (as well as almost everywhere else) remain smog and particulate pollution, which combined or acting alone trigger millions of hospital visits and health complications for people every year. The American Lung Association (ALA) has reported that almost half of all Americans live in counties where air pollution routinely reaches unhealthful levels and can therefore make people sick or exacerbate existing health conditions.
The U.S. Environmental Protection Agency (EPA) points to mobile sources (trains, planes and automobiles) as the greatest contributor to American air pollution, but industrial sources such as power plants and factories are not far behind. Regardless of which kind of pipe pollution comes out of, the result is consistently bad air quality in the nation’s 22 largest metropolitan areas and beyond.
“Ozone develops in the atmosphere from gases that come out of tailpipes, smokestacks and many other sources,” reported ALA. “When these gases come in contact with sunlight, they react and form ozone smog.” Breathing in smog, while inevitable in certain urban and industrial areas, can irritate the cardiovascular system and cause other health problems.
As for particulate pollution, it too comes from a wide range of both mobile and stationary sources. “Burning fossil fuels in factories, power plants, steel mills, smelters, diesel- and gasoline-powered motor vehicles (cars and trucks) and equipment generates a large part of the raw material for fine particles,” according to the ALA. “So does burning wood in residential fireplaces and wood stoves or burning agricultural fields or forests.” Chronic exposure to particulate pollution has been linked not only to cardiovascular issues but also to cancers and reproductive problems—and has been shown to contribute to premature death.
Fortunately, the Clean Air Act has gone a long way toward cleaning up the air we breathe across the U.S., reducing key air pollutants over all by a whopping 68 percent since the Act first became law in 1970. A recent study by EPA researchers showed that, in 2010 alone, the Clean Air Act prevented more than 160,000 premature deaths, 130,000 cases of heart disease and 1.7 million asthma attacks, not to mention 86,000 hospital admissions and millions of respiratory illnesses.
But even though four decades of Clean Air Act programs have already done a lot to improve our health, environmental leaders and public health advocates alike would like to see lawmakers put in place even more stringent rules to reduce pollution of all kinds and put our economy on a cleaner, greener path over all.
As for what you can do, ALA recommends protecting yourself and your family by checking air quality forecasts in your community and avoiding exercising or working outdoors when bad air quality is expected. Also, steps you can take to improve local air quality—driving less, using less electricity, turning the thermostat down, etc.—will have the positive side effect of helping mitigate global warming. Who knew that reducing your carbon footprint could actually also help you breathe more easily too?
Contacts: ALA, www.lung.org; EPA, www.epa.gov.
EarthTalk® is written and edited by Roddy Scheer and Doug Moss and is a registered trademark of E – The Environmental Magazine (www.emagazine.com).
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