Even short-term exposure to air pollution is enough to increase the risk of heart attack, according to a study in the Journal of the American Medical Association as quoted by media reports Wednesday.

In the study, French researchers analyzed the results of 34 studies that compared the risk of heart attack and short-term exposure to air pollutants including ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter.

The results showed that heart attacks were slightly more common at high levels of every main pollutant except ozone

For most of the pollutants, an increase in concentration of 10 micrograms per cubic meter of air was associated with a one to three percent increase in the chance of having a heart attack in the next week, according to the study.

Explaining the possible reasons behind the association between air pollution and heart attack, researchers said on the one hand, when people inhale polluted air, small particles can reach the tiny sacs in the lungs and be carried in the bloodstream to the heart.

On the other hand, the research showed that exposure to air pollution may increase the heart rate and may make the blood more likely to form potentially dangerous clots.

Another report published on Monday in the Archives of Internal Medicine linked long-term exposure to air pollution with faster cognitive decline in older women.