Particulate Air Pollution Can Alter the Electrical Functioning in the Heart

Frank E. Speizer, M.D. and Diane R. Gold, M.D., M.P.H.
Harvard Medical School
NIEHS Grants P01ES009825 and P30ES000002

New research findings from NIEHS grantees at the Harvard University Department of Environmental Health suggests that exposure to fine particulate air pollution and black carbon particles can adversely effect the heart’s ability to conduct electrical signals in people with pre-existing coronary artery disease. The study conducted with 48 Boston-area heart patients, found changes in the ST-segment of the patient’s electrocardiograms, possibly indicating inadequate blood flow to the heart or inflamed heart muscle. 

The average 24-hour levels for all pollutants measured in the study were below accepted National Air Quality standards indicating the patients were breathing air considered healthy. Fine particulate matter and black carbon are combustion by-products and are generated in areas of heavy traffic.  The heart effects were highest within the first month after hospitalization, and for heart attack patients or those with diabetes. Previous studies have shown an association between exposure to road traffic and heart problems.

All the patients had undergone in-hospital procedures to examine or open blocked coronary arteries. The ST-segment changes observed in the study were asymptomatic, but the findings expand the evidence that air pollution can affect heart health, either through inflaming the heart muscle or through reducing blood flow to the heart.

The American Heart Association and the American College of Cardiology recommend that some heart patients, particularly those who have had a heart attack, avoid driving for two to three weeks after leaving the hospital because of the stress heavy traffic can create.  This study provides additional rationale to avoid or reduce heavy traffic exposure for people with heart conditions because of the potential exposure to elevated levels of air pollution particles. The study authors suggest additional research is necessary to determine whether the pollution-related ST-segment changes are due to increased heart inflammation, reduced blood flow, oxidative stress, or increased risk of arrhythmias.

Citation: Chuang KJ, Coull BA, Zanobetti A, Suh H, Schwartz J, Stone PH, Litonjua A, Speizer FE, Gold DR. Particulate air pollution as a risk factor for ST-segment depression in patients with coronary artery disease.Circulation. 2008 Sep 23;118(13):1314-20.