We all know that exerting yourself or even just trying to breathe when the air is polluted can be hard on your eyes, throat and lungs. But what's less obvious is the toll it can take on your heart.

Exposure to air pollution for even short periods has been linked to a higher risk of heart attacks and strokes. People who have heart disease, diabetes, or are older are especially susceptible.

The main culprit is a type of air pollution called particulate matter--small particles that you can see and some that you can't--that mix with moisture in the air.

These particles are thought to do their damage by constricting arteries, raising blood pressure, and making blood more likely to clot.

To reduce your exposure, check your local weather for the air quality index.

On days when the air is unhealthy, exercise indoors with the windows closed and the air conditioning on.

In the car, keep the windows closed, with the inside air recycled. Be sure to keep your car's air conditioning filter clean.

Even on days when the air isn't dangerous, try to do your outdoor activities in areas without heavy traffic or other sources of pollution. Your heart will be grateful for the exercise and the air.