This is Gwen Outen with the VOA Special English Health Report.

Researchers say people traveling in traffic are three times morelikely to suffer a heart attack whether driving in a car, riding abus or bicycling. They say the risk of a heart attack is greatestwithin an hour of being in traffic. Researchers believe the mainreason is polluted air.

The findings are based on a German study of almost seven hundredpeople who suffered heart attacks. The patients described theiractivities during the four days before their heart attack.Researchers found that those who had been in traffic were threetimes more likely to have a heart attack within one hour, comparedto those who had not been in traffic.

Most of those in the study had been traveling by car. But somehad been on bicycles and others were on buses. Women, people overthe age of sixty and those already at risk for heart problems weremost at risk.

Research shows that people in cars and buses are exposed to tentimes the amount of pollutants as people walking on the street. Thatis largely because they breathe in the particles and gasses releasedfrom the vehicles in front of them.

Over time, these small particles speed the buildup of a stickysubstance in the blood. This can cause blockages to form in thearteries around the heart and lead to a heart attack.

Earlier studies have linked traffic, air pollution and heartdisease. They found that people who live near major roads are atgreater risk of dying from heart and lung problems.

Other studies have also linked heart trouble to stress, similarto the kind that people face while driving in heavy traffic. But theresearchers of the latest study say they do not know whether theincreased heart attack risk was the result of stress or pollution.They suggest it may be a combination of stress, noise and pollution.

The study found that traffic was linked to eight percent of heartattacks. But experts note that the overall risk of having a heartattack after being in traffic is still very low.

Annette Peters led the research. She is with the NationalResearch Center for Environment and Health in Neuherberg, Germany.She said the research shows the need for cleaner vehicles and bettercity planning.

The research was done from nineteen ninety-nine to two thousandone. The study was published in the New England Journal of Medicine.

This VOA Special English Health Report was written by CynthiaKirk. This is Gwen Outen.