Second-hand smoke (also referred to as environmental tobacco smoke) causes disease and death. No scientific authority or regulatory health body in the world has established a safe level of exposure to second-hand smoke.

Second-hand smoke contains over 4000 chemicals, of which more than 50 are known or suspected carcinogens. Second-hand smoke has been classified as a known human carcinogen by the International Agency for Research on Cancer (an agency of the World Health Organization), the U.S. National Toxicology Program, and the U.S. Environmental Protection Agency.

Scientific evidence of the adverse health effects of second-hand smoke was available beginning in the 1970's. Within the past decade, several rigorous and independent reviews of the literature on the health effects of second-hand smoke have been published. These included reports of the U.S. Environmental Protection Agency, the Australian National Health and Medical Research Council, the California Environmental Protection Agency, the United Kingdom Scientific Committee on Tobacco and Health, the World Health Organization, the U.S. National Toxicology Program, and the International Agency for Research on Cancer. These studies all reached the conclusion that second-hand smoke is a serious health hazard.

Exposure to second-hand smoke causes about 425 deaths in Ontario annually, not including exposure in the workplace. Second-hand smoke also causes the following diseases and conditions.

In adults:

• Heart disease
  Exposure to second-hand smoke increases the risk of an acute coronary heart disease event by 25-35 per cent.
• Lung cancer
  Never-smoking spouses of smokers have an increased risk of lung cancer of between 20% (for women) and 30 per cent (for men). Risks to highly exposed groups such as hospitality workers may be much greater.
• Nasal sinus cancer
• Respiratory symptoms such as bronchitis and wheezing chronic obstructive pulmonary disease
• Eye and nasal irritation

In children:

• Low birth-weight
• Sudden Infant Death Syndrome (SIDS)
• Bronchitis, pneumonia and other respiratory tract infections
• Induction and worsening of asthma symptoms
• Middle ear infections

Other diseases and conditions thought to be linked to exposure to second-hand smoke:

• Miscarriages
• Cervical cancer
• Breast cancer
• An adverse impact on cognition and behaviour in children
• Exacerbation of cystic fibrosis
• Decreased lung function

Makomaski Illing, E.M & Kaiserman, M.J. (2004). Mortality attributable to tobacco use in Canada and its regions, 1998. Canadian Journal of Public Health, 95(1), 38-44.

International Agency for Research on Cancer, World Health Organization. IARC Monographs (Vol. 83) Tobacco Smoke and Involuntary Smoking, IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, Lyon, France;June 11-18 2002.

Ontario Tobacco Research Unit. Protection from Second-hand Smoke in Ontario: A Review of Evidence Regarding Best Practices [PDF]. Toronto, ON: May 2001.

United States Environmental Protection Agency. Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders. Office of Research and Development, EPA/600/6-90/006F, Washington, USA, December 1992.

National Health and Medical Research Council. The health effects of passive smoking. Australia, November, 1997.

California Environmental Protection Agency. Health Effects of Exposure to Environmental Tobacco Smoke. Office of Environmental Health Hazard Assessment, September, 1997.

Department of Health. Report of the Scientific Committee on Tobacco and Health. The Stationery Office. London, United Kingdom, March, 1998.

World Health Organization. Tobacco-Free Initiative. International Consultation on Environmental Tobacco Smoke (ETS) and Child Health: Consultation Report. WHO Technical Document Number WHO/TFI/99.10. 1999.

U.S. Department of Health and Human Services, Public Health Service. Report on Carcinogens, Eleventh Edition. 2005.

National Toxicology Program (2000). 9th Report on Carcinogens. U.S. Department of Health & Human Services, National Institute of Environmental Health Sciences, Research Triangle Park, NC.

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