Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Lung Disease & Respiratory Health Center

Font Size

Air Pollution May Raise Risk of Stroke

Researchers Say Breathing Polluted Air May Contribute to Ischemic Stroke

WebMD Health News

Oct. 27, 2005 -- Breathing dirty, polluted air may increase your risk of suffering the most common type of stroke, according to a new study.

Air pollution has already been linked to a higher risk of heart attack and other heart-related problems such as heart failure. But researchers say this is the first study to link air pollution with an increased risk of ischemic stroke. Ischemic strokes are caused by a blood clot that blocks blood flow to the brain.

Researchers found the number of ischemic strokes reported in nine major U.S. cities was 1% higher on days that air pollution levels were high compared with days when air pollution levels were relatively low.

Although a 1% increase may seem minor, researchers say the impact of air pollution on stroke rates may be substantial because air pollution is so widespread.

The researchers write that although the relative increase is small, given the large number of people simultaneously at risk for ischemic stroke and exposed to urban pollution, even a small risk may be of significant public health interest. "Especially," notes researcher Gregory Wellenius, ScD, "when you realize that someone in the United States has a stroke every 45 seconds." Wellenius is a postdoctoral fellow in cardiology at Beth Israel Deaconess Medical Center in Boston.

Air Pollution Linked to Stroke

Researchers say previous studies have shown that exposure to air pollution raises the risk of heart attack, heart failure, and irregular heartbeat. While the mechanism remains unclear, the researchers suggest that exposure to particulate air pollution may change blood vessel function, leading to increased blood clotting and blood flow.

Some studies have suggested that air pollution may increase the risk of stroke, but most of these studies did not distinguish between ischemic and hemorrhagic stokes, which are caused by a ruptured blood vessel.

In this study, published in Stroke: Journal of the American Heart Association, researchers looked at the association between daily air pollution levels and hospital admissions among Medicare recipients for both types of strokes in nine major U.S. cities (Birmingham, Ala., Chicago, Cleveland, New Haven, Conn., Detroit, Minneapolis, Minn., Pittsburgh, Salt Lake City, and Seattle).

Specifically, they looked at daily Environmental Protection Agency levels of particles in the air smaller than 10 micrometers in diameter, which includes particles released by motor vehicles, power plants, and other sources for more than 37,000 days in the nine cities.

Today on WebMD

man coughing
You may not even know you have it.
blood clot
Signs of this potentially fatal complication.
man coughing
When a cold becomes bronchitis.
human lungs
Causes behind painful breathing, fluid buildup.

chest x-ray
Bronchitis Overview
Copd Myth Fact Quiz
Energy Boosting Foods

woman coughing
Lung xray and caduceus