Warning over air pollution link to stroke: research

Air pollution, even at levels generally considered safe by federal regulations, increases the risk of stroke by 34 percent, Beth Israel Deaconess Medical Center researchers have found.

Pensioners living in cities may be more likely to suffer a stroke as study finds 'moderate' levels of car pollution increase risk by a third.

Writing in the Feb. 14, 2012 issue of the Archives of Internal Medicine, researchers who studied more than 1,700 stroke patients in the Boston area over a 10-year period found exposure to ambient fine particulate matter, generally from vehicle traffic, was associated with a significantly higher risk of ischemic strokes on days when the EPA's air quality index for particulate matter was yellow instead of green.

It was found that the chances of having a stroke on days when there was moderate pollution was 34 per cent higher than on good days.

The risk rose between 12 and 24 hours after the pollution level was increased.

Lead author Gregory Wellenius of the Centre for Environmental Health and Technology at Brown University, wrote: "In conclusion, these results suggest that particulate matter exposure increases the risk of ischemic stroke at levels below those currently considered safe under US regulations.

"These associations can be observed within hours of exposure and are most strongly associated with pollution from local or transported traffic emissions."

More evidence reveals that short- and long-term exposure to air pollution directly increases the likelihood of heart attack, stroke, or other cardiovascular problems, leading physicians to issue new recommendations to help people reduce their risk.

The new recommendations were released Monday by the American Heart Association (AHA) and singled out fine particulate matter as a cardiovascular risk factor.

Fine particulate matter becomes suspended in the air as a result of various human activities, including burning fossil fuels, cooking, and other indoor activities. Forest fires and biomass burning can also result in increased concentrations of fine particulate matter in the air. Of the different sizes of particles that can become suspended in air, fine particulate matter appears to be most strongly associated with adverse effects.

The research team says the current information suggests there is no safe level of particulate matter exposure and that particulate matter should be considered a modifiable risk factor for heart disease.

Based on their findings, the panel recommends:

Continued efforts to address other cardiovascular disease risk factors through smoking cessation, weight loss, exercise, and a healthy diet to mitigate susceptibility to air pollution.

Informing people with, or at high risk for, cardiovascular disease of the dangers associated with air pollution and the steps that can be taken minimize exposure.