Secondhand smoke is the combination of smoke from the burning end of a cigarette and the smoke exhaled by smokers. You can be exposed to secondhand smoke in homes, cars, the workplace, and public places, such as bars, restaurants, and recreational settings.
In the United States, the source of most secondhand smoke is cigarettes, followed by pipes, cigars, and other tobacco products. Secondhand smoke contains more than 7,000 chemicals. Hundreds of the chemicals are toxic and about 70 are known to cause cancer.
There is no safe exposure to secondhand smoke. When you are around a person who is smoking, you inhale the same dangerous chemicals as the smoker. Breathing even a little secondhand smoke can be dangerous.
Inhaling secondhand smoke can cause lung cancer in nonsmoking adults. In the United States, approximately 3,000 adults die each year due to lung cancer from secondhand smoke exposure. According to the U.S. Surgeon General, living with a smoker increases a nonsmoker’s chances of developing lung cancer by 20% to 30%.
Exposure to secondhand smoke can also cause coronary heart disease and have negative effects on your blood and blood vessels, increasing your risk of a heart attack. Heart disease caused by secondhand smoke kills approximately 46,000 nonsmokers every year. People who already have heart disease are at an especially high risk of suffering negative effects from breathing secondhand smoke and should avoid even brief exposure to it.
Because studies show that laws banning smoking in public places help improve worker and customer health, many states and communities have laws making workplaces, public places, restaurants, and bars smoke-free. But millions of children and adults still breathe secondhand smoke in their homes, cars, workplaces, and in public places.
Pregnant women who breathe secondhand smoke are more likely to have lower birth weight babies than women who do not breathe secondhand smoke. Once born, babies who are around cigarette smoke are more likely to:
Secondhand smoke can cause serious health problems in children, including:
For these reasons, women who are pregnant are advised to avoid environments where heavy concentrations of secondhand smoke linger.