The University of Toronto has one of only a few facilities in the world currently using human volunteers that is capable of concentrating outdoor urban air particles to a desired pollution level, then piping them into a special air chamber for experiments such as this one, he says.
In this study, the researchers used ultrasound to measure the diameter of the volunteers brachial artery which runs from the shoulder to the elbow before and after two hours of exposure to a concentrated mixture of ozone and fine particles. The level of concentration (150 micrograms per cubic meter) was about twice the EPA-suggested level for 24 hours of exposure (65 micrograms per cubic meter). Brook described that exposure as similar to those found in urban areas during peak air pollution times such as rush-hour traffic.
At least two days before or after the pollutant exposure, subjects underwent the same measurements after being exposed to air that was filtered to remove the pollutants.
The volunteers arteries showed no change in response to breathing filtered air, but constricted from 2 percent to 4 percent in response to the polluted air.
Researchers measured the width, or dilation, of the brachial artery. Before exposure to fine particles, brachial artery dilation was 3.92mm; after exposure to pollution it was 3.82mm. For the filtered air, dilation was virtually unchanged (3.89mm vs. 3.90mm).
Although the degree of constriction in and of itself is unlikely to produce significant problems in healthy individuals, such a constriction could con
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Contact: Carole Bullock
carole.bullock@heart.org
214-706-1279
American Heart Association
11-Mar-2002