Inhaling a heart attack: How air pollution can cause hea...(g the elderly and people with coronary a...)

Identifying harmful pollutants

Researchers are trying to find out which pollutants are harmful and how the harmful pollutants work to damage the cardiovascular system. They have focused on smaller, microscopic particles that can get into the lungs and may gain entrance to the blood stream. (The upper airway filters out larger particles that are in smog and other air pollutants before they can cause a problem.)

In addition, researchers have focused on air pollutants, including:

• ozone
• nitrates
• sulfates
• metals
• aldehydes

One intriguing statistic is that the risk of heart attack increases in parallel with time spent in traffic the previous day. In animal experiments, Dr. Bhatnagar has found that aldehydes -- a toxic class of chemicals found in most forms of smoke, including cigarette smoke and car exhaust -- increase blood cholesterol levels and activate enzymes that cause plaque in the blood vessels to rupture. When plaque ruptures, it can cause a blood clot, which may block an artery and lead to a heart attack.

Much of Robert Brook's research has centered on the relationship between air pollution and hypertension. Fine- and ultra-fine particles that get into the lung may make their way into the blood vessels. Within 15 minutes of inhaling pollutants, there is a very rapid increase in blood pressure, he said.

Blood vessels react to the pollutants by producing an inflammatory response to attack the foreign matter. However, the inflammatory response itself can set off a complex physiological reaction that is harmful to the blood vessels, Dr. Brook said.

Lessons learned

If you live in an area where pollution levels may be high, you can take steps to reduce the risk of air pollution, Dr. Brook
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