Second-Hand Smoke

There is no safe level of exposure to second-hand smoke, also called passive, involuntary or environmental tobacco smoke.1 Read more about second-hand smoke...


Nicotine, carcinogens and toxic chemicals found in tobacco smoke are inhaled when people breathe in second-hand smoke.2

Similar to smokers, non-smokers exposed to second-hand smoke have an increased risk of lung cancer, coronary heart disease and respiratory illnesses.1

Infants whose mothers smoked during pregnancy and those exposed to second-hand smoke after birth have an increased risk of sudden infant death syndrome (SIDS).1

Infants and children exposed to second-hand smoke have a higher risk of developing severe acute and chronic respiratory illnesses as well as ear infections. More frequent and more severe asthma attacks may occur among children with asthma who are briefly exposed to second-hand smoke.1

Research has shown that, in 2002, exposure to second-hand smoke alone caused 831 deaths in Canada, including 579 deaths from heart disease and 252 lung cancer deaths.3

These health warning messages for cigarettes and little cigars address second-hand smoke exposure:

A little girl coughing inside a vehicle because of tobacco smoke
Little boy wearing an oxygen mask

What is second-hand smoke?

Second-hand smoke is the combination of smoke coming directly from a burning tobacco product and the smoke exhaled by a smoker. Many of the chemicals in tobacco smoke 4,5 are present in second-hand smoke.

Cotinine, a chemical produced when nicotine degrades in the body, can be detected in body fluids and is a good indicator of exposure.1 A recent Canadian study found that 14% of non-smokers aged 6 to 79 had measurable amounts of cotinine in their urine - indicating that they had been exposed to second-hand smoke in the previous few days.6

How does second-hand smoke increase the risk of health problems?

Some of the chemicals in second-hand smoke cause, initiate or promote cancer while some affect the heart and the lungs.

Exposure to some of the chemicals in tobacco smoke 4,5 alter the development of an infant's brain and the lungs. This in turn affects how an infant breathes and may be responsible for SIDS.7,8

How can I reduce my risk from second-hand smoke?

Cleaning or filtering the air, increased ventilation or segregated areas (non-smoking sections) cannot completely eliminate exposure to second-hand smoke nor the health risks associated with this exposure.1

The only solution to protect non-smokers is to eliminate smoking in all enclosed spaces such as restaurants, homes, and automobiles.


1. U.S. Department of Health and Human Services. The Health Consequences of Involuntary Exposure to Tobacco Smoke. A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services, Centres for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking an Health; 2006. Available from:

2. International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: Tobacco Smoke and Involuntary Smoking. Vol. 83. Lyon (France): International Agency for Research on Cancer, 2004.

3. Rehm J, Baliunas D, Brochu S, Fischer B, Gnam W, Patra J, et al. The costs of substance abuse in Canada 2002. Ottawa: Canadian Centre on Substance Abuse; 2006.

4. Rodgman, A., Perfetti, T.A. The chemical components of tobacco and tobacco smoke. (2009). CRC press, Florida, USA. ISBN 978-1-4200-7883-1.

5. Hecht SS. Research Opportunities Related to Establishing Standards for Tobacco Products Under the Family Smoking Prevention and Tobacco Control Act. Nicotine & Tobacco Research.

6. Health Canada. Report on Human Biomonitoring of Environmental Chemicals in Canada (Cat. H128-1/10-601E). Ottawa, Canada: Health Canada, 2010.

7. Anderson HR, Cook DG. Passive smoking and sudden infant death syndrome: review of the epidemiological evidence. Thorax 1997; 52:1003-1009.

8. Sawnani H, Olsen E and Simakajomboon N. The Effect of In Utero Cigarette Smoke Exposure on Development of Respiratory Control: A Review. Pediatric Allergy, Immunology, and Pulmonology 2010; 23(3):161-6.

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