This is the VOA Special English ENVIRONMENT REPORT.
New evidence suggests that air pollution found in many American cities may be linked to heart attacks. Researchers say the risk of heart attacks rises on days with high levels of pollution from cars and industry.
The problem is believed to be caused by particulates -- very small pieces of a carbon substance called soot. Particulates are released by vehicles and factories. Increasing evidence suggests that breathing these particles can be harmful.
Researchers say changes in the beating of a person’s heart may take place after breathing particle pollution. Healthy people may not be affected. But the effects may be dangerous for older people and people with heart disease.
Earlier studies have shown that particulates may cause long-term heart disease. The new study is the first to examine short-term effects on the heart.
The latest study was done in Boston, Massachusetts, a city with generally clean air. But researchers say the risks could be greater in cities where pollution levels are higher. These include Houston, Texas; Los Angeles, California and New York City.
Doctors at the Beth Israel Deaconess Medical Center questioned almost eight-hundred heart attack patients. They found that a person’s heart attack risk was sixty-two percent higher on days with the highest levels of air pollution, compared to days when air pollution was low.
Researchers say particle pollution appears to interfere with the ability of the heart to pump blood. Breathing these particles causes the lungs to release chemicals in the blood that are carried to the heart. The chemicals may interfere with the beating of the heart. The particles also may cause the blood to thicken and restrict the flow of blood to and through the heart. Studies suggest that people may die quickly after there is an increase in harmful particles in the air.
Particulates may also be dangerous because they may include metals such as iron. But some researchers believe it is the small size of the particles, not what is in them, that causes the harm.
Experts say particulate pollution may cause about ten-thousand deaths a year in the United States. They say the latest study could be used to urge federal environmental officials to consider stronger air pollution restrictions.
This VOA Special English Environment Report was written by Cynthia Kirk.