When the world’s top athletes competed this summer at the Beijing 2008 Olympic Games, some faced a challenge that tested more than their athletic abilities: heavy pollution. This is the same kind of pollution that many city dwellers face every day during a lunch-hour run, for example.

“Not only will [Olympic] athletes have irritated eyes, but a good portion may have decreased potential to be competitive,” says Timothy Craig, MD, chair of the American Academy of Allergy, Asthma & Immunology Sports Medicine Committee. “Exercise can enhance the adverse effects air pollutants have. Rigorous exercise combined with pollutants can stimulate an asthma attack.”

If you wheeze, cough or have prolonged shortness of breath or chest pain/tightness within 5 to 20 minutes after exercise, you could have exercise-induced asthma (EIA), which affects 7% of Americans and as many as 20% of top athletes, including 15% of all Olympic athletes.

Even people without asthma or reactive airways can suffer from EIA. Bad air, (including the pollutants ozone, sulfur dioxide, nitric oxide and others) or even humidity and the temperature of the air are what’s called asthmagenic, meaning they can inflame your airways to the point of asthma attack.

Here’s how it happens: When you’re resting, you breathe through your nose, which warms and humidifies the air like the oxygen already in your lungs. When you’re exercising, you force air in and out of your mouth, so the air is colder and drier when it hits your sacs. The contrast between the warm air in your body and the cold air rushing in can trigger an attack.

If you experience these symptoms after exercising, see your healthcare provider. Prescription medications, including controller and rescue inhalers and medications, can treat EIA. You can also try warming up before exercising and staying hydrated to minimize your risk.

Even if you have EIA, it shouldn’t stop you from striving to achieve your personal best. Dr. Craig says 30% of 1996 Olympians from the U.S. who had asthma or who took asthma medicines during the events won team or individual medals in their competitions—faring as well as their symptom- and medication-free colleagues who also earned spots on the podium.