NEW ORLEANS — Brief inhalation of dilute diesel exhaust at levels comparable to those encountered curbside along city streets promotes myocardial ischemia in patients with coronary heart disease, Dr. David E. Newby reported at the annual meeting of the American College of Cardiology.
He presented the first-ever study in which patients with known CHD were deliberately exposed to air pollution. The purpose was to pinpoint the mechanisms underlying the well-established epidemiologic association between air pollution and increased cardiovascular morbidity and mortality.
“Not everybody believes that air pollution is linked to cardiovascular disease, particularly pressure groups backed by the automobile industry. So we felt it was very important to show what the mechanisms are,” explained Dr. Newby, professor of cardiology at the University of Edinburgh.
He and his coinvestigators in Edinburgh and at Umeå (Sweden) University briefly exposed 20 Swedish patients with prior MI to either dilute diesel exhaust at a concentration of 300 mcg/m
Exposure to diesel exhaust caused a threefold increase in the magnitude of exercise-induced ST-segment depression: a mean 49 mcV of ST depression, compared with 17 mcV of ST depression while breathing filtered air during exercise.
In addition, blood levels of tissue plasminogen activator—a potent endogenous clot dissolver—declined significantly after patients were exposed to diesel exhaust, providing a second specific mechanism to explain the oft-described link between air pollution and cardiovascular events.
In a prior study conducted in healthy volunteers, Dr. Newby and colleagues showed that brief exposure to real-world levels of diesel exhaust caused impairment of arterial vasodilation.
Dr. Newby noted that the World Health Organization has estimated that nearly 1 million deaths per year are attributable to inhalation of polluted air.
His study was funded by the British Heart Foundation.
Nearly 1 million deaths per year may be due to inhalation of polluted air. PhotoDisc, Inc.