Studies link air pollution to increased risk of strokes and dementia

Published: Wednesday, Feb. 15 2012 7:00 p.m. MST

The unhealthy air covering Utah County. Looking north from Provo. Feb. 20, 2008 Photo by Stuart Johnson

Stuart Johnson, Deseret News

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SALT LAKE CITY — Three new studies that underscore the link between bad air quality and significant health risks such as stroke, heart attacks and dementia suggest there is no safe level of air pollution and that more needs to be done to control the problem.

While the effects of air pollution have long been blamed for increased incidences of heart disease, the new scientific research unveiled greater risks of stroke, heart attack and cognitive degeneration — with long-term exposure to pollution said to "age" the mind by as many as two years.

Dr. Brian Moench, president of Utah Physicians For a Healthy Environment, said the studies should be a wake-up call for residents and public policy makers to get serious about the grave effects of air pollution on the everyday lives of Utahns.

"We are seeing that most of the health effects of air pollution do not have a threshold," he said. "The smallest amount of air pollution will have a corresponding amount of health impact. There is no such thing as an exposure of air pollution that will not affect you."

Two of the studies were published Monday in the Archives of Internal Medicine. Brown University's Gregory A. Wellenius, an associate professor of epidemiology, was lead author of a study that looked at 1,705 Boston-area patients hospitalized for stroke.

When controlling for other factors such as hypertension, the study found that the risk of stroke jumped 34 percent on days when traffic pollutants were classified by federal regulators as "moderate," defined as a minimal danger to health.

"These results suggest that exposure to PM2.5 levels generally considered safe by the US EPA increase the risk of (stroke onset) within hours of exposure," the study concluded. PM2.5 is fine particulate matter 2.5 micrometers or smaller.

The study looked at a hospital's admission records for stroke victims from 1999 to 2008 and cross-checked them against the exact time of the medical incident to the EPA's air quality index in the hours and days preceding each event. The increase in risk, the study found, was greatest within 12 to 14 hours of exposure to the particulate matter and strongly associated with traffic-related pollution.

Another study published in the same journal tracked nearly 20,000 U.S. women ages 71 to 80 for about a decade. It found that long-term exposure to air pollution "typically experienced by many individuals in the United States is associated with significantly worse cognitive decline in older women."

Moench said studies already have shown that the air quality along the Wasatch Front shaves two years off a person's life and this latest research demonstrates that mental  acuity is at risk as well.

"We have 40 to 50 studies in our back pocket that support the conclusions," he said. "These studies are getting a lot of play, a lot of attention because they come from well known, well-respected teams."

He added that the one study's suggestion that federal air quality standards do not go far enough reinforce what the EPA's own expert committee of scientists have been arguing for years.

"The studies clearly indicate that current air quality standards do not protect health. Virtually every major medical organization in the country has been calling on the EPA to make those standards stricter."

A third study published in the Journal of the American Medical Association looked at short-term exposure to air pollution and its link to heart attacks. In that research, French scientists actually tapped the particulate information compiled in a Utah study as part of its data set.

Dr. Benjamin Horne, director of cardiovascular and genetic epidemiology at the Intermountain Heart Institute, said the journal study clearly demonstrates the increased risk of having a heart attack within a few days after a spike in air pollution — anywhere from 1 percent to 3 percent.

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