Ethics in Medicine

The Heavy Health Toll of Air Pollution: Recent studies

Kristen Sparrow • February 17, 2012

Not that we needed any more evidence of the negative effects of pollution, but three studies this week found that higher levels of air pollution not only increased risk of stroke, but of heart attacks and cognitive decline. A previous post on pollution here . There is a very disturbing trend on the conservative side to defund public transit which is abominable given these recent statistics on the health toll of traffic pollutants, let alone the threats from climate change. Info on the practice here.

February 15, 2012, 10:31 am
Air Pollution Linked to Heart and Brain Risks
Keith Meyers/The New York TimesA layer of smog rests over Lower Manhattan.

It may be time to start paying more attention to those local air pollution alerts.

That is the message of three new studies this week that found, collectively, that people exposed to higher levels of air pollution have a greater risk of stroke, heart attacks and cognitive deterioration.

The impact of pollution on the heart and brain was seen over both the short and the long term. One nationwide study that followed nearly 20,000 women over a decade found that breathing in levels of polluted air like those commonly found in most parts of the country greatly accelerates declines in measures of memory and attention span. Another study in Boston found that on days when concentrations of traffic pollutants went up, so did the risk of stroke. The odds climbed by more than 30 percent even on days classified by the federal air quality index as “moderate” pollution days, which is intended to correspond to a minimal danger to health.

“At levels that the Environmental Protection Agency says are safe, we’re seeing real health effects,” said Gregory A. Wellenius, an associate professor of epidemiology at Brown University and lead author of the study linking pollution to stroke. “We saw these effects within 12 to 14 hours of when pollution levels went up…”.

After controlling for age, hypertension and a slew of other risk factors for stroke, the researchers found a 34 percent higher risk at times when pollution levels climbed from “good” to “moderate.” (In the Boston area, where the study was conducted, pollution levels rarely climb very high, Dr. Wellenius said.) The effect was particularly strong when the researchers looked at levels of so-called black carbon and nitrogen dioxide, two markers of pollution from traffic.

Reducing air pollution levels by just 20 percent, an “achievable” goal, Dr. Wellenius said, “would have prevented about 6,000 of the 184,000 hospitalizations for stroke in the Northeast region” in 2007 alone, he said. The results were published this week in The Archives of Internal Medicine.

In a separate report published Tuesday in The Journal of the American Medical Association, scientists at the University Paris Descartes in France helped bolster the link between short-term exposure to air pollution and cardiovascular disease. They found that a variety of common pollutants — carbon monoxide, nitrogen dioxide, sulfur dioxide and others — raised a person’s immediate risk of having a heart attack...