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Don't Jog in the Smog

Two studies published online at  news@nature found that there is a link between smog and death. In particular, they cite heart attacks and strokes as being risks of exposure to diesel smog. We all know the benefits of exercise, such as jogging, but according to cardiologist David Newby at the University of Edinburgh in the UK, “The message we’re trying to promote is please exercise, it’s good for your heart and your health. But if it’s a bad [air] day, you should think twice.”

According to the World Health Organization, in 2000 nearly 800,000 people worldwide died from causes due to air pollution, mostly through stroke and heart attacks. Newby tested patients exposed to diesel exhaust made by a Volvo tractor engine, which is close to the pollution one would receive on a smoggy day in London. After two 15 minute tests on an exercise bike inhaling sooty air, patients who had had a previous heart attack suffered measurable clotting effects and strain and less blood made it to the heart muscles. Also, “levels of a protein tPA which responds to blood clots, were lowered. After the experiment was conducted, the factors returned to normal.” Said Newby in the New England Journal of Medicine, “This sort of backup mechanism [to clotting] is lost when you’re exposed to diesel, and therefore it makes a clot form a lot more likely to be successful and a heart attack to occur.”

In another study, physician Gokhan Mutlu of Northwestern University’s Feinberg School of Medicine in Chicago found that mice exposed to dirty air didn’t bleed as long as mice that breathed clean air. The tests suggest that the immune response to particles in the lungs causes inflammation and can lead to blood clots, according to an article in the  Journal of Clinical Investigation.  

Published: September 24, 2007