Analyzing data from tens of thousands of ultrasound tests of the carotid arteries, which supply blood to the brain, NYU Langone researchers found a worrisome relationship—air pollution may increase the risk of stroke. They report in a new study that long-term exposure to a form of air pollution called PM 2.5, or fine particulate matter smaller than 2.5 microns in diameter, is associated with a greater chance of narrowing in the carotids. “Findings like these point to the possibility that lowering levels of fine particulates, which originate mostly from combustion engines, would reduce the risk of carotid artery stenosis and stroke,” says coauthor Jeffrey S. Berger, MD, assistant professor of medicine.
The study, published in a recent issue of the Journal of the American Academy of Cardiology, is based on ultrasounds performed on over 300,000 New York, New Jersey, and Connecticut residents from 2003 to 2008. Segregating the data by patients’ zip codes and adjusting for demographic and socioeconomic factors, the researchers found that those people in the quartile of zip codes with the highest average PM 2.5 levels during the testing period were about 24 percent more likely to have stenosis—defined as a narrowing by at least half—in either of the two internal carotid arteries that supply the brain.
NYU Langone researchers found a worrisome relationship—air pollution may increase the risk of stroke.
The analysis also showed that even a modest increase in the average PM 2.5 level, by just 10 micrograms per cubic meter, was associated with a near doubling of carotid stenosis risk.
“If you’re in very good health, the levels of air pollution that we see in most of the U.S. probably don’t pose a significant risk, but for the very young, the elderly, and people with other health problems like diabetes, air pollution might be a very important source of risk,” says NYU Langone cardiologist Jonathan D. Newman, MD, MPH, a clinician–scientist with NYU Langone’s Center for the Prevention of Cardiovascular Disease and the lead author of the study.