Traffic Pollution Could Raise Heart Risks

Living near a freeway associated with artery damage, study finds

MONDAY, July 16, 2007 (HealthDay News) -- People who regularly breathe in fumes from heavy traffic are more likely to get the hardening of the arteries that boosts heart attack risk, a German study finds.

"It's not limited to freeways," said lead researcher Barbara Hoffmann, head of the unit of environmental epidemiology at the University of Duisburg-Essen. "We see it in inner-city dwellings on heavily traveled streets as well."

Her team published the findings in the July 17 issue of Circulation.

The damage to the arteries seen in such people is similar to that produced by inhaling secondhand tobacco smoke, "although the effect we see here in this study is even larger than that caused by secondhand smoke," Hoffmann said.

Most of the blood vessel damage is due to high levels of particulate pollutants in vehicle exhaust fumes, Hoffmann speculated, although there might be other contributing factors, such as the constant noise of heavy traffic "which can contribute to high blood pressure."

The journal report is based on data from a continuing study done in three cities in the industrialized Ruhr area of Germany. Hoffmann and her colleagues got the home addresses of almost 4,500 adults to determine the distance of their living quarters from heavy traffic. They were also assessed for cardiovascular risk factors such as diabetes and smoking.

A technology called electron-beam automated tomography was then used to measure the degree of vessel calcification -- the buildup of calcium deposits that cause arteries to harden and become more vulnerable to blockages.

The amount of calcification was found to be related directly to the distance of living quarters from heavy traffic. Compared to participants living more than 200 meters (642 feet) from heavy traffic, calcification was 63 percent higher for those living less than 50 meters (160 feet) from heavy traffic, 34 percent higher for those whose distance was 51 to 100 meters (164 to 328 feet) and 8 percent higher for those whose distance was 100 to 200 meters (328 to 642 feet).

This is the first study to show such a relationship between traffic-based air pollution and damage to the arteries, Hoffmann said. The participants will be followed to see whether the traffic-related damage worsens and whether it is associated with a higher incidence of heart attack and other cardiovascular problems.

"The follow-up data will be important to have," said Dr. Sidney Smith, professor of medicine at the University of North Carolina and a former president of the American Heart Association.

Smith was a member of a committee of experts assembled by the association in 2004 to review the literature on air pollution and cardiovascular disease. Among the committee's recommendations was that people at high risk of cardiovascular disease limit outdoor activities when air pollution is high.

However, Smith said, "this current study is incomplete, because it just looks at calcification." He added, "The follow-up, which will look at the incidence of [cardiovascular] events, will provide important information."

The only immediate protective action that can be taken by people living close to heavy traffic is increased attention to known cardiac risk factors, such as obesity and high blood pressure, Hoffmann said. Over the longer run, community action is needed, she and Smith agreed.

For example, "When they build roads, communities should consider the location of residential buildings and schools," Hoffmann said.

"There is increased concern about environmental pollutants worldwide, and I don't think we should neglect opportunities to reduce this as a global risk factor," Smith said. "Communities need to look at how to reduce ambient pollution levels."

More information

There is more on air pollution at the U.S. National Library of Medicine.

SOURCES: Barbara Hoffmann, M.P.H., head, unit of environmental epidemiology, University of Duisburg-Essen, Germany; Sidney Smith, M.D., professor, medicine, University of North Carolina, Chapel Hill; July 17, 2007, Circulation
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