Dear EarthTalk: Is air quality in the United States improving or getting worse? Is it cleaner in some parts of the country than in others? — K. Gould, Sherman Oaks, CA
Air quality across the United States has improved dramatically since 1970 when Congress passed the Clean Air Act in response to growing pollution problems and fouled air from coast to coast. According to data from the U.S. Environmental Protection Agency (EPA), levels of all major air pollution contaminants (ozone, nitrogen oxides, carbon monoxide, sulfur dioxide, particulate matter and lead) are down significantly since 1970; carbon monoxide levels alone dropped by more than 70 percent.
And that’s good news for everyone. A 2009 study published in the New England Journal of Medicine found that efforts to reduce fine particle pollution from automobiles, diesel engines, steel mills and coal-fired power plants have added between four and eight months to the average American’s life expectancy in recent years. Overall, Americans are living some two and three-quarter years longer than during the 1980s. Changes in smoking habits and improved socioeconomic conditions are the biggest reasons why, but cleaner air is also a big factor. “It’s stunning that the air pollution effect seems to be as robust as it is,” Arden Pope, the Brigham Young University epidemiologist who led the study, told reporters.
Pope and his team analyzed life expectancy, economic, demographic and pollution data from 51 metropolitan areas, and found that when fine-particle air pollution dropped by 10 micrograms per cubic meter, life expectancy rose by 31 weeks—such as in Akron, Ohio and Philadelphia. Where fine particle counts dropped even more—by 13 to 14 micrograms, such as in New York City, Buffalo and Pittsburgh—people lived some 43 weeks longer on average.
But according to the American Lung Association (ALA), even though air quality around the country is improving overall, some 175 million Americans—58 percent of the population—still live in places where pollution levels can cause breathing difficulties or worse. The group’s “State of the Air: 2010” report looks at levels of ozone and particle pollution found in monitoring sites across the United States in 2006, 2007, and 2008, and compares them to previous periods.
The biggest improvement was found in year-round (annual) particulate levels, which the ALA attributes to recent efforts to clean up major industrial air pollution sources. “However, the continuing problem demonstrates that more remains to be done, especially in cleaning up coal-fired power plants and existing diesel engines.” the group reports. ALA also found, by overlaying census data with pollution maps, that Americans with the lowest incomes face higher risks of harm from air pollution, underscoring what environmental justice advocates have been saying for years.