We all know that doing exercise is one of the keys to good health. However, air pollution and exercise is a bad mix. Outdoor air pollution can come from sources such as motor vehicle traffic, wind-blown dust, burning wood, construction sites and agricultural operations. The exposure to pollution from such sources may already cause risk to any individual but when you exercise amid such air pollution, the potential health risks are increased. The main reason for this increased risk is due to the fact that during aerobic activities, you usually inhale more air and breathe it in more deeply into your lungs. Since you are also more likely to breathe deeply through your mouth during exercise, the air you breathe in generally bypasses your nasal passages, which normally filter airborne pollution particles. Research has also found that exercising in air polluted areas regularly causes an increase in the risk of dying from heart diseases as the exhaust fumes can cause a significant reduction in blood flow to the heart. It is therefore advisable to always monitor air pollution levels and avoid doing exercise near high-pollution areas such as busy roads. It is also good practice to do exercise out of peak traffic hours. If you have any lung or heart condition, do consult with your doctor before starting a new exercise regime.