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reviewed 7/24/2018

Secondhand smoke: True or false?

Even though fewer people are lighting up nationwide, most of us still know someone who smokes. And if you're exposed to their secondhand smoke, you're breathing in more than 7,000 chemicals, including arsenic, ammonia and carbon monoxide. Just how dangerous is this smoke? Test your knowledge now.

True or false: Though it can cause lung irritation, secondhand smoke is unlikely to cause cancer.

False. Even if you don't smoke yourself, you can still get lung cancer by inhaling secondhand smoke. In fact, the U.S. surgeon general estimates that living with a smoker increases a nonsmoker's risk of lung cancer by up to 30 percent. Secondhand smoke may also raise the risk of breast cancer in women and brain cancer and leukemia in children.

True or false: Smoking and nonsmoking sections of restaurants are effective protection for nonsmokers.

False. Separating smokers from nonsmokers in a restaurant can't completely eliminate exposure to secondhand smoke. And there's no safe level of secondhand smoke. Even low levels can be harmful.

True or false: It's especially important to protect children from secondhand smoke.

True. Babies who breathe in secondhand smoke have a greater risk of sudden infant death syndrome (also known as SIDS). And older children whose parents smoke tend to get sick more often—and they're more likely to get pneumonia. Secondhand smoke can also trigger asthma attacks in kids.

True or false: Opening a car window is enough to protect nonsmokers from secondhand smoke.

False. Even exhaling out the car window does little, if anything, to reduce smoke exposure. So if you smoke—but haven't been able to quit yet—never light up in a car with other people.

True or false: Secondhand smoke can cause heart attacks.

True. Even a brief exposure to secondhand smoke can damage the lining of blood vessels. It can also cause your blood platelets to become stickier. And these changes can trigger a deadly heart attack.

Secondhand smoke can contribute to lung cancer even in nonsmokers.

Learn more about lung cancer

Sources: American Academy of Family Physicians; American Cancer Society; Centers for Disease Control and Prevention

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