MARY LOUISE KELLY, HOST:
To new evidence now that long-term exposure to air pollution, especially ground-level ozone, can speed up the development of emphysema, even in nonsmokers. NPR's Allison Aubrey reports ground-level ozone is the primary ingredient in smog and is linked to climate change.
ALLISON AUBREY, BYLINE: It's long been known that for people who have lung disease due to cigarette smoking or asthma, air pollution can make it worse. But this new study suggests that many more of us are vulnerable. Study author Joel Kaufman of the University of Washington says he and his collaborators found that living in a community with slightly elevated concentrations of ground-level ozone can speed up the progression of lung damage.
JOEL KAUFMAN: We found that an increase of about three parts per billion outside your home was equivalent to smoking a pack of cigarettes a day for 29 years.
AUBREY: The study included about 7,000 adults living in a bunch of different cities, including Los Angeles, Baltimore, St. Paul and Winston-Salem. But Kaufman says people in communities all over the U.S. can be exposed to similar concentrations of ground-level ozone. So these results are bad news.
KAUFMAN: That was a very large surprise to us to see that the effects were in the same magnitude as cigarette smoking, which is the best-established and most well-recognized cause of emphysema.
AUBREY: To track changes in the lungs, all of the participants in the study had up to five CT scans over a decade, which give a 3D picture of the lungs.
Emily Brigham is a pulmonologist at Johns Hopkins University. She was not involved in this study, but she explains what you can see at the early stages of respiratory disease.
EMILY BRIGHAM: What we're able to see is this loss of normal structure. And when that happens and the airways get damaged and narrowed, it's harder for air to move in and out of the lung, and air gets trapped.
AUBREY: She says at the early stages, people may not notice much. But over time, emphysema symptoms develop.
BRIGHAM: What patients typically start to feel when their damage reaches a certain point is breathlessness, and it does tend to get worse over time if you continue the exposures.
AUBREY: And the changes are generally believed to be irreversible. Brigham says these findings help to answer a very important question - what explains so many cases of COPD, which is an umbrella term for several respiratory diseases, including emphysema.
BRIGHAM: A significant proportion of the U.S. population who has COPD actually are never smokers. So what is causing their underlying lung disease? And I think this gives us a partial answer.
AUBREY: Now, overall, levels of air pollution in the U.S. have been declining, but ground-level ozone, or smog, has been harder to control. That's because it's formed when pollution released from sources such as cars and smokestacks bake in the sunlight. And on very hot days, the conditions are favorable to produce more smog.
BRIGHAM: And so as climate change progresses, we expect that these vulnerable populations and even healthy populations are going to see increased effects.
AUBREY: Which may mean more people at risk of developing respiratory disease.
Allison Aubrey, NPR News.
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