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Secondhand Smoke

Secondhand Smoke Facts

  • Secondhand smoke is tobacco smoke that is breathed in by someone who is not smoking themselves.
  • It occurs when a person is in the vicinity of a person who is smoking.
  • Secondhand smoke is a mixture of the smoke from the tobacco product itself (termed sidestream smoke) and exhaled smoke from the smoker (known as mainstream smoke).
  • The same chemicals, toxins, and cancer-causing substances are present in secondhand smoke as in active smoking; the person who inhales secondhand smoke is exposed to the same toxins as the smoker.
  • Secondhand smoke is known to carry definite health risks for both adults and children. An increased risk of lung cancer is just one of the hazardous health effects of secondhand smoke.

Secondhand Smoke Causes

Any tobacco product has the potential to cause dangers due to secondhand smoke, but cigarettes are the most common sources of secondhand smoke. Exposure to secondhand smoke can occur in the home, workplace, or in public places. Children exposed to secondhand smoke in the home are at particular risk for health problems related to tobacco smoke, as are nonsmokers who reside with smokers.

Secondhand Smoke Health Risks

Patient Comments
  • Secondhand smoke contains hundreds of harmful chemicals.
  • About 70 cancer-causing substances have been identified in secondhand smoke, and secondhand smoke has been classified as a "known human carcinogen" by the U.S. Environmental Protection Agency (EPA). A carcinogen is a chemical substance that has been proven to cause cancer.
  • Besides causing cancers, secondhand smoke carries multiple additional health risks for both adults and children. These risks are outlined in the following sections.
Last Reviewed 11/20/2017

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Patient Comments & Reviews

The eMedicineHealth doctors ask about Secondhand Smoke:

Secondhand Smoke - Patient Experience

Have you been diagnosed with a disease related to secondhand smoke? Please describe your experience.

Secondhand Smoke - Reducing Smoke Exposure

What measures have you taken to reduce your exposure to secondhand smoke?

Cigarette Smoking

Cigarette Smoking Risks

Compared to a nonsmoker, a smoker faces these risks:

  • fourteen times greater risk of dying from cancer of the lung, throat, or mouth;
  • four times greater risk of dying from cancer of the esophagus;
  • two times greater risk of dying from a heart attack; and
  • two times greater risk of dying from cancer of the bladder.

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