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Disclosures: One author reports he was an expert witness for the U.S. Department of Justice in cases involving violations of the Clean Air Act. The other authors report no relevant financial disclosures.
February 22, 2021
2 min read
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Long-term exposure to air pollutants confers CV, respiratory health risk

Disclosures: One author reports he was an expert witness for the U.S. Department of Justice in cases involving violations of the Clean Air Act. The other authors report no relevant financial disclosures.
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Long-term exposure to air pollutants may pose a significant risk to CV and respiratory health in the Medicare-age population, according to a study published in Circulation.

Mahdieh Danesh Yazdi

“Recent studies looking at the nonfatal health effects of air pollution have shifted their focus from short-term to long-term exposure. ... More studies are now exploring multiple air pollutants simultaneously in recognition of the fact that air pollution is a mixture of compounds with varying toxicities,” Mahdieh Danesh Yazdi, PharmD, MPH, PhD, environmental health research fellow at Harvard T.H. Chan School of Public Health, and colleagues wrote. “These changes suggest that current regulations may need to be amended.”

Air Pollution from stacks
Source: Adobe Stock

To examine the relationship between long-term exposure to fine particulate matter measuring 2.5 µm or less (PM2.5), nitrogen dioxide (NO2) and tropospheric ozone (O3) with CV and respiratory outcomes of MI, stroke, atrial fibrillation/flutter and pneumonia, researchers analyzed 63,006,793 Medicare beneficiaries.

“Our study is different in that it looked at long-term exposure to air pollution and included three different pollutants at the same time,” Yazdi told Healio. “Furthermore, we evaluated the change in risk on an additive scale; other studies usually use multiplicative models. This allowed us to directly estimate the absolute change in risk due to air pollution.”

Yazdi and colleagues found long-term exposure to PM2.5 was associated with increased risk for all study outcomes; stroke had the highest effect with a 0.0091% (95% CI, 0.0086-0.0097) increased risk for each 1 µm/m3 increase in annual PM2.5 levels, which translated to an additional 2,536 (95% CI, 2,383-2,691) stroke hospitalizations per year.

Further analysis showed NO2 was associated with increased risk for stroke (0.00059% increase per parts per billion [ppb]; 95% CI, 0.00039-0.00075) and AF (0.00129% increase per ppb; 95% CI, 0.00114-0.00148) as well as with a negative effect for MI and pneumonia hospital admissions.

Long-term exposure to O3 yielded mixed results. Researchers observed it was associated with increased probability of pneumonia (0.00413% per ppb; 95% CI, 0.00376-0.00447) but had no association with CV outcomes.

The pollutants were associated with elevated risk for all outcomes even at lower concentrations, according to the researchers.

“Long-term exposure to air pollution was found to be associated with an increased risk of hospitalization due to heart attacks, strokes, atrial fibrillation and pneumonia,” Yazdi told Healio. “There are two main things we can do to protect elderly patients from adverse health consequences. First, we must raise awareness of the serious risk that air pollution poses to human health among the general population as well as clinicians and policymakers. Second, we must advocate for better air quality across the United States. The results of this study suggest that even exposure to low levels may increase the risk of adverse health events; current regulations may not be sucient to protect human health.”

For more information:

Mahdieh Danesh Yazdi, PharmD, MPH, PhD, can be reached at mdaneshyazdi@hsph.harvard.edu.