Jan. 21, 2009 -- Steps to curb air pollution in the United States are paying off, helping to dramatically increase average life spans, a new study says.
Researchers at Brigham Young University and the Harvard School of Public Health report in the Jan. 22 issue of the New England Journal of Medicine that the average life expectancy in 51 U.S. cities increased nearly three years over recent decades.
"Such a significant increase in life expectancy attributable to reducing air pollution is remarkable," says C. Arden Pope III, PhD, a BYU epidemiologist and lead author of the study. "We find that we're getting a substantial return on our investments in improving our air quality."
The scientists looked at pollution data, collected by the U.S. Environmental Protection Agency, for 51 cities and compared it to health statistics from 1980 to 2000.
The researchers say in a news release they found that cleaner air added approximately 10 months to the average resident's life in cities that had previously been the most polluted but had been cleaned up.
Americans were living 2.72 years longer, on average, at the end of a two-decade study period. Up to five months of that was because of reduced air pollution.
"There is an important positive message here that the efforts to reduce particulate air pollution concentrations in the United States over the past 20 years have led to substantial and measurable improvements in life expectancy," says study co-author Douglas Dockery, ScD, of the Harvard School of Public Health.
The EPA used work of Dockery and Pope as the basis for guidelines in the 1997 tightening of air pollution standards.
The researchers say they found gains in life expectancy even in cities that initially had relatively clean air, but which had recorded improvements.
"Our findings provide evidence that improvements in air quality have contributed to measurable improvements in human health and life expectancy," the authors say.
Dockery has received grant support from the Health Effects Institute, an independent nonprofit group, but says there is "no other potential conflict of interest."