Americans are living nearly three years longer than they were only two decades ago, and they owe up to five months of that longevity to cleaner skies, a study shows.
"It is a good-news story," says Brigham Young University's C. Arden Pope, author of the study in today's New England Journal of Medicine, which included 51 metropolitan areas in the USA and more than 200 countries. "Our efforts to clean up our air appear to be worth it."
All cities got a boost from cleaner air, including areas where air was relatively clean at the beginning of the study, the results show.
On average, cities reduced their pollution levels by one-third, cutting the level of small particles from 21 micrograms per cubic meter to 14 micrograms per cubic meter, the study says. At the same time, life expectancy increased by an average of 2.7 years.
Residents of Pittsburgh and Buffalo, which made the biggest gains against pollution, also increased their life spans the most. People there gained almost 3 1/2 extra years, although life expectancy in both cities remains slightly below average.
Pope says those results were "stunning," considering that he included other factors that could explain the longer life expectancies, including changes in smoking habits.
The results also are in line with earlier findings about the damage caused by air pollution, the University of Ottawa's Daniel Krewski wrote in an accompanying editorial in the medical journal. The World Health Organization estimates that 1.4% of all deaths are a result of air pollution.
Yet the findings may be seen as "provocative rather than conclusive," says the American Cancer Society's Michael Thun.
Other factors -- such as new medical practices or laws that protect people from secondhand smoke -- also could have helped people live longer, he says.
He notes that earlier studies by Pope and his colleagues have withstood rigorous scrutiny in the past.
Although this kind of study can't prove that cleaner air adds five months of life, it provides strong scientific reasons to continue cleaning the air -- even if those efforts are expensive, says Norman Edelman, chief medical officer for the American Lung Association.
Thun notes that the same pollution that causes heart attacks and lung disease contributes to global warming -- providing additional reasons to clear the air.
"The solutions to one problem may help to address the other," Thun says.
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