DALLAS, March 12 For the first time researchers have shown that air pollution negatively affects the blood vessels of healthy humans, according to a study in todays rapid access issue of Circulation: Journal of the American Heart Association.
In the study, 25 healthy people inhaled elevated concentrations of fine particles plus ozone for two hours. After exposure, volunteers blood vessels constricted between 2 percent and 4 percent on average. Their vessels did not constrict when they were exposed to ozone-free and particle-free air.
We have a wealth of epidemiological data saying that air pollution is associated with adverse respiratory and cardiovascular outcomes, but there is still a lack of understanding as to how the association occurs physiologically. These findings suggest a possible reason why the rate of heart attacks and other cardiovascular events increases with exposure to air pollution for people with known heart and blood vessel disease, says Robert D. Brook, M.D., study co-author and assistant professor of internal medicine in the division of hypertension and vascular medicine program at the University of Michigan, Ann Arbor.
There have been some suggestions in previous studies that people with atherosclerosis tend to respond with greater-than-normal constriction, or narrowing of blood vessels, in response to certain hormones in the body. Could it be that their blood vessels also have enhanced constriction in response to air pollution? Future studies will be needed to answer that question, Brook says.
The researchers focused on ozone and fine particulate matter. Fine particles are those with a diameter of less than 2.5 micrometers. Fine particles are emitted from burning fossil fuels, mostly from car engine exhaust, power generation and many industrial processes. Ozone and additional particulate materials are created when the sun shines on these emissions.