Short-term exposure to such irritants not only can impair performance, but also can cause wheezing, coughing, headaches and nausea. Chronic exposure, moreover, may increase the risk of pulmonary problems such as bronchitis, emphysema and even pneumonia.
To avoid these risks:
1. Run as early or as late in the day as possible. Pollutants generally escalate during the day as cars and industry crank out airborne antagonists.
2. Run where the grass is greener. If you can run in a park or along a river or creek, or in an area that's open and windy, by all means do so. The farther you get from car exhaust and the closer to oxygen-producing trees, the better.
3. Know what you're getting into. You can't always assess pollution levels just by looking or smelling, because some irritants are invisible and odorless. Check your local newspaper for air-quality readings. When the Pollutant Standards Index is greater than 200, consider an indoor workout.
4. Don't play hero. If you experience uncommon fatigue or painful symptoms such as tightness in the chest or nausea, finish your run early. And if you suffer from heart disease, asthma, allergies or any other chronic lung problem, don't run in polluted environments without checking first with your doctor.
5. Call in the reinforcements. Substantial evidence shows that the antioxidants vitamin C, vitamin E and beta-carotene prevalent in fruits and vegetables may help protect cells from damage caused by pollutants.