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New Study Traces Harm to Health From Polluted Air


A new study appears to confirm what many doctors have long asserted: long-term exposure to air pollution significantly increases the risk of dying of lung cancer or heart disease. The study, published this week in the Journal of the American Medical Association, is being called the most definitive research to date on the health effects of air pollution.

Researchers say the study is compelling because it involved hundreds of thousands of people in many cities across the United States who were followed for almost two decades. Michael Thun, a population expert with the American Cancer Society in Atlanta, Georgia, says, "What we found was that living in the city with the highest air pollution was approximately equal to the risk of secondhand smoke… being a non-smoker married to a smoker. And to put that in perspective, the active risk for a smoker is a about twenty times larger than the increase that we saw with the most polluted city compared with the least polluted city."

The study followed the health of a half million adults taking part in a long term American Cancer Society lifestyle study. The investigators controlled for things such as diet, smoking and weight, and looked at the level of air pollution in different cities.

Researchers at a number of academic institutions analyzed data on the health of nearly all of participants living in cities across the United States for from about 1980 to 2000.

Dr. Thun acknowledges that in some of the world's most polluted cities - Mexico City, New Delhi, Beijing - there are infinitely more pressing health priorities. But the study also demonstrated regulation to control pollution works. "The good news is the air pollution levels in these cities are being reduced in these cities by about a third over that twenty-year interval," he said.

But the study's authors note despite clean air regulations set by the U.S. government in 1997, most major American cities continue to exceed the standard for small particulate pollution.

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