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THURSDAY, Dec. 6 (HealthDay News) -- As air pollution in the United States declines, it appears Americans are living longer, according to a new study.
Researchers from the Harvard School of Public Health have associated increased longevity with reductions in fine particulate matter. They noted this positive trend would continue if the country's air quality continues to improve.
"Despite the fact that the U.S. population as a whole is exposed to much lower levels of air pollution than 30 years ago because of great strides made to reduce people's exposure, it appears that further reductions in air pollution levels would continue to benefit public health," said study lead author Andrew Correia, a doctoral candidate in the department of biostatistics, in a Harvard news release.
Exposure to fine particle air pollution, or small particles with a diameter of 2.5 micrometers or less, has been linked to cardiopulmonary disease and death, the researchers explained. The study examined the health effects of fine particle air pollution on people living in more than 500 U.S. counties from 2000 to 2007.
Their work, published online Dec. 3 in the journal Epidemiology, expands on previous research published in 2009.
Although the reductions in air pollution have slowed in the United States over the past decade, the study revealed that a modest drop of 10 micrograms per cubic meter in the concentration of fine particulate matter was associated with an average increase of a little more than four months in life expectancy.
The researchers noted the link between declines in air pollution and increased life expectancy was stronger in more densely populated urban areas than rural counties. They suggested that differences in the composition of the particulate matter may explain this discrepancy. Women also benefited from the improved air quality more than men, the study revealed.
"Since the 1970s, enactment of increasingly stringent air-quality controls has led to improvements in ambient air quality in the United States at costs that the U.S. Environmental Protection Agency has estimated as high as $25 billion per year," said study senior author Francesca Dominici, professor of biostatistics at Harvard.
"However, the extent to which more recent regulatory actions have benefited public health remains in question," Dominici added. "This study provides strong and compelling evidence that continuing to reduce ambient levels of [fine particle air pollution] prolongs life."
The study found an association between improved longevity and cleaner air, but it did not prove cause-and-effect.
The U.S. Environmental Protection Agency provides more information on the health effects of air pollution.