The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General, U.S. Department of Health and Human Services

What Is Secondhand Smoke?

• Secondhand smoke is composed of sidestream smoke (the smoke released from the burning end of a cigarette) and exhaled mainstream smoke (the smoke exhaled by the smoker).



• While secondhand smoke has been referred to as environmental tobacco smoke (ETS) in the past, the term “secondhand” smoke better captures the involuntary nature of the exposure.



• The 2006 Surgeon General’s report uses the term “involuntary” in the title because most nonsmokers do not want to breathe tobacco smoke. The term “involuntary” was also used in the title of the 1986 Surgeon General’s report on secondhand smoke.



• Cigarette smoke contains more than 4,000 chemical compounds.



• Secondhand smoke contains many of the same chemicals that are present in the smoke inhaled by smokers.
• Because sidestream smoke is generated at lower temperatures and under different conditions than mainstream smoke, it contains higher concentrations of many of the toxins found in cigarette smoke.


• The National Toxicology Program estimates that at least 250 chemicals in secondhand smoke are known to be toxic or carcinogenic.



• Secondhand smoke has been designated as a known human carcinogen (cancer-causing agent) by the U.S. Environmental Protection Agency, the National Toxicology Program, and the International Agency for Research on Cancer, and an occupational carcinogen by the National Institute for Occupational Safety and Health.



• Secondhand smoke contains more than 50 cancer-causing chemicals.
• When nonsmokers are exposed to secondhand smoke, they inhale many of the same cancer-causing chemicals that smokers inhale.

The Surgeon General has concluded that:

• There is no risk-free level of exposure to secondhand smoke: even small amounts of secondhand smoke exposure can be harmful to people’s health.
• Many millions of Americans continue to be exposed to secondhand smoke.
• A smoke-free environment is the only way to fully protect nonsmokers from the dangers of secondhand smoke. Separating smokers from nonsmokers, cleaning the air, and ventilating buildings cannot eliminate exposure of nonsmokers to secondhand smoke.

Information contained on this highlight sheet has been taken directly from The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. For more information, please refer to the Resources and How to Protect Yourself and Your Loved Ones from Secondhand Smoke highlight sheets. Additional highlight sheets are also available at www.cdc.gov/tobacco.

Last revised: January 4, 2007