Particulates Can Cause Heart Attacks

By Cat Lazaroff

(ENS)-As few as two hours after being inhaled, tiny, invisible airpollutants can penetrate the lungs’ natural defenses and trigger aheart attack, says a recent report in Circulation: Journal of theAmerican Heart Association.

Previous studies have shown that long-term exposure to airparticulates can initiate a chain of events that trigger a heartattack in individuals with cardiovascular disease or cardiovascularrisk factors. The current study is the first to examine short-termeffects of air pollution on the risk of heart attack.

Between January 1995 and May 1996, researchers interviewed 772Boston-area heart attack patients about four days after their heartattack to establish when their symptoms began. Researchers comparedthe times heart attack symptoms began with daily air pollutionmeasurements, paying special attention to levels of the smallerpollutants.

“These tiny particles are known as PM2.5 because they measure lessthan 2.5 micrometers in diameter,” explained study coauthor Dr.Douglas Dockery, professor of environmental epidemiology at theHarvard School of Public Health. “They are so small that they can getpast the normal defense mechanisms in the lungs and penetrate deeplyinto the air exchange regions, or alveoli.”

The study concluded that there was a 48 percent higher risk of heartattack when PM2.5 concentrations increased by 25 micrograms per cubicmeter of air in the two hours before symptoms began. Fine particulateair pollution is produced primarily by automobile engines, powerplants, refineries, smelters and other industries. Larger, morereadily noticed particles of airborne dust and debris from farming,construction work and mining are less likely to trigger heart attack.