Microscopic air pollution may lead to decreased heart function, researchers in Boston, Massachusetts reported in the journal Circulation: Journal of the American Heart Association.

More exactly, the researchers found that pollution particles impair the heart’s signaling pathways, thus leading to inadequate blood flow to the heart and inflammation of the heart muscle.

For the study, Diane R. Gold, MD, MPH, senior author of the study and an associate professor of medicine and environmental health at Harvard University, and colleagues monitored 24 patients, all of whom had coronary artery disease. The researchers used 24-hour Holter monitors to examine electrocardiograms for the conductivity change called an ST-segment depression, which may indicate inadequate blood flow to the heart or inflamed heart muscle.

“We found that an elevation in fine particles, from non-traffic as well as traffic sources, and black carbon, a marker for traffic, predicted ST-segment depression,” Gold said.

The findings add to previous research showing that exposure to road traffic can trigger heart attacks and that particulate air pollution increases the risk for cardiac death or heart death. In fact, the American Heart Association and the American College of Cardiology recommend that patients suffering from heart disease, especially those who have had a heart attack, delay driving for two to three weeks after leaving the hospital and avoid driving in heavy traffic because of the stress it creates.

"Our study provides additional rationale to avoid or reduce heavy traffic exposure after discharge, even for those without a heart attack, since traffic exposure involves pollution exposure as well as stress," Gold said.