While aerobic activity is one of the keys to a healthy lifestyle, air pollution and exercise can be an unhealthy combination. This is especially true if you have asthma, diabetes, heart or lung conditions, or lower respiratory disease. Even when you're not exercising, exposure to air pollution can cause health problems. But with the combination of air pollution and exercise, the potential health problems are increased. One reason for this increased risk may be that during aerobic activity, you usually inhale more air and breathe it more deeply into your lungs. And because you're likely to breathe mostly through your mouth during exercise, the air you breathe in generally bypasses your nasal passages, which normally filter airborne pollution particles. Health problems that air pollution is associated with include: Damage to airways of the lungs, Increased risk of asthma development, Worsening of existing asthma or other lung conditions , Increased risk of heart attacks and strokes, Increased risk of death from lung cancer and cardiovascular disease. What's not clear with air pollution and exercise is how much exposure is a danger, or how long you have to be exposed. And because exercise has clear health benefits, don't give up on exercise entirely, unless your doctor has instructed you to. Instead, focus on ways to minimize the risks of the air pollution and exercise combination. To limit the effects of air pollution and exercise: Monitor air pollution levels. , , Avoid high-pollution areas. , Exercise indoors. . If you have asthma, diabetes or another condition, check with your doctor about when it's safe for you to exercise.