Life expectancy up when cities clean the air

Study shows people live longer after fine-particulate air pollution reduced

Americans can breathe easier, thanks in part to a decrease in air pollution in recent years, according to a new analysis in the Jan. 22 New England Journal of Medicine.

The study evaluated changes in life expectancy and changes in the amount of fine-particulate air pollution in the United States over two decades. By the year 2000, Americans were living an average of 2.7 years longer than in 1980. About five months of that increase was linked to improvements in air quality, the study shows.

“For a policy maker this says, ‘Yeah, when you clean up the air, people live longer, and that’s important across the country,’ ” comments Joel Schwartz, an environmental epidemiologist at the Harvard School of Public Health in Boston.

Fine-particulate air pollution — made of particles smaller than or equal to 2.5 microns in diameter — results from burning things such as gasoline, diesel and coal, or from high temperature processes used in manufacturing products such as steel, explains C. Arden Pope of Brigham Young University in Provo, Utah, who led the new study.

These small particles have been implicated in cardiovascular and cardiopulmonary diseases. In 1997, the Environmental Protection Agency tightened standards on the amount of particulate matter allowed per cubic meter of air across the United States.

“This is good news,” says Pope. “We’ve been putting a lot of effort into cleaning up our air and there’s been debate about the effect. These results suggest that it is paying off with improved public health.”

The findings suggest that the payoff comes quickly, says Schwartz. The new work confirms earlier studies by Schwartz and others showing that death rates dropped soon after cities cleaned up their air. “If you clean up the air, people live longer and you don’t have to wait an exceedingly long time for that to happen,” Schwartz says.

The research team analyzed air pollution data gathered in 61 U.S. cities from 1979 to 1983 by the Environmental Protection Agency’s Inhalable Particle Monitoring Network. The network stalled after 1983 until new national air quality standards kicked in, prompting more monitoring. The team used data gathered in 1999 and 2000, which had samples from 51 cities analyzed from earlier years. The team also assessed life expectancy using national mortality statistics and U.S. census data.

In determining how air quality and life expectancy were related, the team accounted for factors such as decreased number of cigarette smokers, changes in income, people relocating and access to better heath care. In more polluted cities that cleaned up their air the most, such as Pittsburgh, the increase in life expectancy associated with air pollution was about 10 months.

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