Smog has effects on our blood

Air pollution reduces blood flow and interferes with the body’s natural ability to break up blood clots, researchers said Wednesday in a finding that may help explain why pollution can cause heart attacks. The study, published in the New England Journal of Medicine, also suggests that heart patients trying to shape up might do their exercising away from traffic.

The researchers tested 20 male volunteers, all heart attack survivors, who pedaled an exercise bike while breathing diluted fumes from the exhaust of an idling Volvo diesel engine. The exposure was comparable to the pollution levels found while driving in traffic.

Doctors already know that long-term exposure to air pollution increases the risk of heart problems. The World Health Organization has estimated that it causes 800,000 premature deaths worldwide each year.

The new study, by researchers at Britain’s Edinburgh University, looked at one particularly suspect element of air pollution -- diesel fumes -- and how it affected people over the short term.