AHA 2008: Cardiovascular Effects of Air Pollution, Even in the Comfort of Home

Shelley Wood

November 14, 2008

November 14, 2008 (New Orleans, Louisiana) — Researchers who fitted study subjects with "air-pollution vests" to continuously monitor exposure to both indoor and outdoor air pollutants say that people are probably exposed to much higher levels of pollutants than community monitoring stations typically indicate and that this exposure affects both endothelial function and systolic blood pressure.

Dr Robert Brook (University of Michigan, Ann Arbor) and colleagues presented a poster with the results of their Detroit Exposure and Aerosol Research Study (DEARS) during the American Heart Association (AHA) 2008 Scientific Sessions. In an interview with heartwire , study coauthor Robert Bard said that the results should serve as a reminder to cardiologists, who tend to forget the extent to which air pollution can harm the heart.

"Cardiologists are really not aware of this as a risk factor," Bard said, despite a 2004 AHA scientific statement warning about the cardiovascular risks of air pollution. What's needed, Bard said, is "a greater awareness that air pollution is contributing to CVD."

Something in the Air

Brook, Bard, and colleagues enlisted 65 people--most of them women--between the ages of 19 and 80 living in three areas of Detroit. All subjects wore pollution-monitoring vests for 24 hours over five consecutive days in the summer and five consecutive days in the winter, only taking the vests off to shower or sleep, in which case they were instructed to keep the vests close to them, in the same room. As a result, Bard explained, the vests picked up not only communitywide pollutants but exposures in the home, as well as short-term exposures, when subjects walked past someone smoking or a bus pulling away from a curb and emitting a burst of exhaust.

Investigators found that mean personal exposure to fine particulate matter <2.5 µm (PM2.5), combining both indoor and outdoor exposures, was 21.9 µg/m3 but ranged up to 225.4 µg/m3--much higher than that being measured at community monitoring stations, which was a mean of 15.4 µg/m3 and a maximum of 41 µg/m3. Strikingly, a 10-µg/m3 increase in personal exposure in the study was associated with brachial blood vessel diameter narrowing within two days of the exposure and increased systolic blood pressure (by 1.6 mm Hg) after one day of exposure.

According to Bard, the main types of air pollutants detected by the vests were "by-products of combustion," namely motor-vehicle exhaust and second-hand cigarette smoke, despite the fact that all study participants were nonsmokers living in nonsmoking households. Smoking is still permitted, for example, in restaurants in Michigan, Bard noted.

"Air pollution is actually noted as the 13th leading cause of death worldwide," Bard reminded heartwire . "We already knew that air pollution is associated with adverse cardiovascular events, including increases in blood pressure, but the novel aspect here is that we were measuring pollution that people were directly exposed to and evaluating cardiovascular function. We found that the average person in our study had increased blood pressure and reduced endothelial function from the air they were exposed to in the previous 24 hours. And importantly, these results were shown despite levels of ambient air pollution that were at or below those recommended in the current EPA guidelines."

He continued: "Patients shouldn't panic, because these levels are still relatively low. But people need to be more aware of air pollution as a CVD contributor and to support clean-air initiatives. And if you have cardiovascular disease, you may need to try to avoid exposure to air pollution at peak times."

The complete contents of Heartwire , a professional news service of WebMD, can be found at www.theheart.org, a Web site for cardiovascular healthcare professionals.

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