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Secondhand Smoke

Secondhand smoke is tobacco smoke that affects a nonsmoker. Secondhand smoke can come directly from a cigarette or other lit tobacco; it may also be exhaled by a person smoking.

Secondhand smoke is sometimes referred to as environmental tobacco smoke (ETS), involuntary smoking, or passive smoking.

Secondhand smoke contains the same cancer-causing and lung-damaging chemicals that affect smokers. Repeated exposure to secondhand smoke over many years can cause damage to a nonsmoker's lungs that is similar to that of a smoker's.

Secondhand smoke is the most important risk factor for cancer among nonsmokers, far greater than other known cancer-causing substances. Secondhand smoke is most harmful to:

  • Children and spouses of smokers, or anyone who lives with a smoker.
  • People who spend most of their time in confined areas that are filled with tobacco smoke.
By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Michael Seth Rabin, MD - Medical Oncology
Last Revised September 12, 2012

WebMD Medical Reference from Healthwise

Last Updated: September 12, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.