Dirty atmosphere boosts heart attack risk

New York: Fatal heart attacks may be more likely among people who spend decades living in heavily polluted areas, Swedish researchers report.

While there was no association between people's exposure to various pollutants over a 30-year period and overall heart attack risk.

However, such exposure did appear to be associated with a greater risk of fatal heart attack, especially heart attacks occurring outside hospitals, Mats Rosenlund of the Stockholm County Council and colleagues report.

The researchers also found that people who had ever lived in pollution "hot spots" with particularly dirty air had a 23 per cent increased risk of heart attack, and a 40 per cent increased risk of fatal heart attack.

The health effects of short-term exposure to air pollution are fairly well understood, but it is much less clear how long-term pollution exposure affects health, Rosenlund and associates point out in the journal Epidemiology.

Pollution exposure could contribute to heart attack risk by causing chronic inflammation, speeding the progression of atherosclerosis (hardening of the coronary arteries) and altering heart function, they note.

To investigate, they reviewed information on pollution exposure for 1,397 men and women living in Stockholm County who had suffered heart attacks for the first time between 1992 and 1994 and 1,870 healthy controls.

The researchers estimated carbon monoxide, sulfur dioxide, particulate matter and nitrogen dioxide exposure by linking an individuals' address to historical data on emissions and atmospheric dispersion of the pollutants.

Overall, there was no link between pollution exposure and heart attack risk.

However, the risk of fatal heart attacks appeared to have some association with pollution exposure, especially among people who died outside the hospital.

This finding "implies that sudden death might be of special importance in relation to long-term air pollution exposure," Rosenlund and colleagues conclude.