Diesel Fumes, Heart Disease a Bad Mix
Study May Hold Clues About Link Between Air Pollution and Heart Attacks
Sept. 12, 2007 -- Men who've had heart attacks might want to exercise away
from traffic, based on a new study of air pollution and heart disease.
The study included 20 men who'd had a heart attack more than six months
earlier and whose coronary artery disease was in stable condition.
In the researchers' lab, the men used a stationary bike for 15 minutes,
rested for 15 minutes, biked for another 15 minutes, and rested for 15 more
minutes while their hearts were closely monitored.
The men took the test once while breathing clean, filtered air and again on
another day while breathing air that contained diesel fumes from a car. They
had blood tests six hours after exposure to the filtered air or the diesel
When the men exercised in the polluted air, their hearts were more stressed
and produced less of a clot-busting chemical called tPA (tissue plasminogen
The men didn't report any symptoms during or after the tests, and it's not
clear if the findings apply to people without heart disease. Also, air
pollution is a jumble of chemicals, not just diesel exhaust, and the
researchers don't yet know which chemicals drove the study's results.
Still, the study may help explain why air pollution is associated with
cardiovascular events such as heart attacks, write the researchers, who
included Nicholas Mills, MD, of the Centre for Cardiovascular Science at
Scotland's University of Edinburgh.
An editorial published with the study urges people not to get the wrong
The issue isn't about exercising -- it's about air pollution, according to
editorialist Murray Mittleman, MD, DrPH, of the Cardiovascular Epidemiology
Research Unit at Boston's Beth Israel Deaconess Medical Center.
"Considering the unequivocal benefit of habitual exercise ... the risk
benefit ratio may be optimized if people exercise away from traffic when
possible," writes Mittleman.
(Does pollution affect your exercising? Tell us about it on WebMD's
Heart Disease Support Group message board.)