Secondhand smoke exposure is a risk factor for having a heart attack. Breathing secondhand smoke can cause the cells in your blood that are responsible for clotting (platelets) to become stickier, making your blood more likely to clot. This can cause a clot to form that may block an artery, causing a heart attack or stroke.

Secondhand smoke also causes endothelial dysfunction, which makes the arteries unable to dilate. This condition is associated with many forms of cardiovascular disease.

Chemicals in secondhand smoke also irritate the lining of your arteries, causing them to swell (inflammation). This inflammation can narrow your arteries, increasing your risk of having chest pain related to your heart (angina) and even a heart attack.

Many studies have found that heart attack rates go down in areas after smoke-free laws are passed.

To avoid secondhand smoke, try:

• Avoiding the smoke others exhale
• Avoiding places others are smoking, even open spaces
• Explaining to smokers that their smoke may be harmful to you and others
• Encouraging smokers you're around regularly to smoke in outdoor areas that reduce the amount of secondhand smoke others will breathe
• Encouraging smokers you're often around to quit smoking

It's especially important to avoid secondhand smoke if you have had a previous heart attack or have been diagnosed with heart disease.

If you smoke, the best way to reduce your heart attack risk is to quit.