Air pollution tied to higher heart attack risk

Breathing in dirty air may be linked to a higher chance of suffering a heart attack in the next few days, suggests a fresh look at past studies undertaken by French researchers.

While it's well established that people who spend years living in polluted cities or near major highways are at increased risk of heart problems, the new findings suggest even short-term exposure to pollution can be harmful.

"If you put together the evidence, clearly day-to-day changes in particle concentration do make a very small but significant difference in terms of increasing susceptibility for cardiovascular events" such as heart attacks, said Dr. Sanjay Rajagopalan, who studies pollution and cardiovascular health at The Ohio State University in Columbus.

"This seems to be particularly so for individuals with pre-existing heart disease," Rajagopalan, who wasn't involved in the new study, told Reuters Health.

Researchers led by Dr. Hazrije Mustafic from the Paris Cardiovascular Research Center found 34 studies that compared the risk of suffering a heart attack at various levels of industrial and traffic-related air pollutants including carbon monoxide, nitrogen dioxide and very small soot-like particles.

Those reports included anywhere from about 400 to more than 300,000 people, with heart attacks confirmed in hospital records and disease and death registries.

The combined findings showed that heart attacks were slightly more common at high levels of every main pollutant except ozone, Mustafic's team reported in the Journal of the American Medical Association.

The differences in heart risks were small. For most of the pollutants, an increase in concentration of 10 micrograms per cubic meter of air -- the typical standard used to assess harm, and barely noticeable to a person breathing the air -- was associated with a one to three percent increase in the chance of having a heart attack in the next week.

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