Secondhand Smoke

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Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Secondhand smoke refers to tobacco smoke that is passively breathed in by people in the vicinity of a person who is smoking. Terms that have been used to refer to secondhand smoke are passive smoking, involuntary smoking, or environmental tobacco smoke (ETS). 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).

When a nonsmoker inhales secondhand smoke, he or she is exposed to the same toxins and chemicals, including nicotine, as the smoker.

Exposure of children to secondhand smoke also increases their health risks; and children are especially vulnerable to the effects of environmental tobacco smoke. About 35% of U.S. children live in homes where smoking occurs regularly. Research has shown that 50% to 75% of children in the U.S. have detectable levels of cotinine (the breakdown product of nicotine) in their blood, so even children who do not live with smokers may be at risk for adverse effects of secondhand smoke. Chemicals from tobacco smoke inhaled by a nursing mother are also known to reach breast milk.

Cigarettes are the most common sources of secondhand smoke, followed by cigars and pipe smoke. People can be exposed to environmental tobacco smoke anywhere - in their homes, in the workplace, and in recreational settings.

Secondhand smoke carries many health risks. At least 250 harmful chemicals have been identified in secondhand smoke, including at least 50 carcinogens (chemicals that are known to cause cancer). Just some of the dangerous chemicals present in secondhand smoke include vinyl chloride, cadmium, benzene, arsenic, and ethylene oxide.

Secondhand smoke is known to cause cancer. It has been classified as a "known human carcinogen" by the U.S. Environmental Protection Agency (EPA). It is also associated with cardiovascular and respiratory diseases as well as other serious health conditions; several are listed below.