Ls Running Outside Toxic?

By Tom DiChiara

If you're like me, the prospect of running outside on a wooded trail with the wind in your face is considerably more appealing than the idea of chugging away on a treadmill, where the air is stagnant and the scenery is either an episode of Friends you've seen 27 times or your own sweaty reflection in the gym mirror. Even so, many people opt for the treadmill -- or simply skip running altogether -- because they're afraid that exercising outdoors will expose them to air pollutants that can cause lung problems (at the very least) or take years off their life (at the very worst). Are these fears founded, or are they a load of hot air?

The Rumor: Running outside exposes you to air pollution that can be hazardous to your health

There's no denying that breathing in carbon-monoxide-laden air on a regular basis is a superb way to develop inflamed lungs, exacerbate asthma and increase the risk of heart attack, stroke, chronic obstructive pulmonary disease, cancer and (by extension) death. Conventional wisdom holds that the potential for these health problems only increases with outdoor exercise, and as Mayo Clinic's Dr. Edward R. Laskowski points out, there's a physiological reason for that. During periods of aerobic activity, says Laskowski, people inhale more air than they do when they're at rest, breathe it more deeply into their lungs and gulp it mostly through their mouths -- bypassing the nasal passages, which normally filter out the dangerous pollution particulates that cars, trucks and buses spew into the atmosphere.

The Verdict: If you're smart about when and where you exercise, running outside is fine and even counteracts the negative effects of air pollution

While Laskowski makes a pretty compelling argument for why you shouldn’t run outside, he admits that it's not the whole story. "What's not clear with air pollution and exercise is how much exposure is a danger, or how long you have to be exposed," he writes. "Because exercise has clear health benefits, don't give up on exercise entirely, unless your doctor has instructed you to."

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