A new study published in JAMA finds that long-term exposure to slightly elevated levels of ambient air pollution can be linked to accelerated development of lung damage similar to smoking, even among people who have never smoked.

In this study conducted between 2000 and 2018 that included 5780 participants in 6 US metropolitan regions followed up for a median of 10 years, there was a statistically significant association between baseline ambient concentrations of ambient ozone (O3), fine particulate matter (PM2.5), oxides of nitrogen (NOx), and black carbon with greater increases in emphysema assessed quantitatively using computed tomographic (CT) imaging. Concentrations of O3 and NOx, but not concentrations of PM2.5, over study follow-up were also associated with increases in emphysema. Baseline ambient O3 was significantly associated with a faster decline in forced expiratory volume in the first second (FEV1). The study looked at the health effects of breathing in various pollutants, including ground-level ozone, the main component of smog.

The researchers found that people in the study who were exposed for years to higher-than-average concentrations of ground-level ozone developed changes to their lungs similar to those seen in smokers. The study involved adults living in six U.S. cities: Chicago, Los Angeles, Baltimore, St. Paul, Minn., New York City, and Winston-Salem, N.C. Generally, people in the study were exposed to annual average concentrations of between 10 and 25 parts per billion of ground-level ozone outside their homes. For more details on this Ambient Air Pollution Exposure Study, please click here.