Tobacco Free Initiative (TFI)

Frequently asked questions about second hand smoke

How many people are passive smokers?

This is a worldwide phenomenon since people in all countries and cultures are exposed to SHS. This exposure occurs in everyday life, at home, work, in public transport, restaurants, bars, etc. It is estimated that over fifty percent of children worldwide are exposed to SHS in their homes (International Consultation on Environmental Tobacco Smoke and Child Health WHO/NCD/TFI/99.11)

What are the Effects of SHS on adults' health?

Carcinogenic effects of SHS

In June 2002, a scientific working group of 29 experts from 12 countries convened by the Monographs Programme of the International Agency for Research on Cancer (IARC) of the World Health Organization, Lyon, France, reviewed all significant published evidence related to tobacco smoking and cancer, both active and involuntary. Its conclusions confirmed the cancer-causing effects of active smoking. It also concluded its evaluation of the carcinogenic risks associated with involuntary smoking and classified second-hand smoke as carcinogenic to humans(1).

There is clear scientific evidence of an increased risk of lung cancer in non-smokers exposed to SHS. This increased risk is estimated at 20% in women and 30% in men who live with a smoker (2). Similarly, it has been shown that non-smokers exposed to SHS in the workplace have a 16 to 19% increased risk of developing lung cancer (3). The risk of presenting lung cancer increases with the degree of exposure. The Californian Environmental Protection Agency (Cal EPA) estimates that SHS causes 3000 deaths each year due to lung cancer in non-smokers.

Other health effects of SHS

It has also been shown that non-smokers exposed to SHS have a 25 to 35% increased risk of suffering acute coronary diseases (4). Chronic respiratory conditions are also more frequent in non-smokers exposed to SHS (5). There is evidence linking SHS to other adverse effects in adults including exacerbation of asthma and reduced lung function.

What are the effects of SHS on children’s health?

Small children whose parents smoke at home have an increased risk of suffering lower tract respiratory infections and otitis media (6,7). SHS has also been linked to an increase in the number and severity of asthma episodes in asthmatic children (8). There is also evidence that SHS increases the risk of Sudden Infant Death Syndrome (SIDS) (9).

How to protect the passive smoker?

  • Recognise that everyone has the right to breathe air not contaminated with tobacco smoke
  • Recognize that all workers have the right to work in places where they are not exposed to the harmful effects of SHS
  • Increase consciousness that smoking harms not only the person who smokes but also those around him/her. This is especially important to protect people from exposure to SHS at home, where legislation has no effect
  • Legislate in favour of an individual’s right to a smoke-free environment. Governments can legislate to protect people from involuntary exposure to tobacco smoke by establishing smoke-free public places and workplaces.



1. International Agency for Research on Cancer. IARC Monographs on the evaluation of carcinogenic risk of chemicals to humans - Tobacco smoking and tobacco smoke. Vol.83 (2002)

2. Hackshaw AK, Law MR, Wald NJ. The accumulated evidence on lung cancer and environmental tobacco smoke. British Medical Journal 1997, 315: 980–8.

3. Fontham et al. JAMA 1994; 271(22): 1752–1959.

4. Law MR, Morris JK, Wald NJ. Environmental tobacco smoke exposure and ischaemic heart disease: an evaluation of the evidence. British Medical Journal 1997, 315:973–80.

5. US Department of Health and Human Services. The health consequences of smoking: chronic obstructive pulmonary disease. A Report of the Surgeon General. Washington, DC: US Government Printing Office, 1984.

6. Strachan DP, Cook DG. Parental smoking and lower respiratory illness in infancy and early childhood. Thorax 1997, 52:905–14.

7. California Environmental Protection Agency and Office of Environmental Health Hazard Assessment. Health effects of exposure to environmental tobacco smoke. California Environmental Protection Agency, 1997.

8. Cook DG, Strachan DP. Parental smoking and prevalence of respiratory symptoms and asthma in school age children. Thorax 1997, 52:1081–94.

9. Anderson HR, Cook DG. Passive smoking and sudden infant death syndrome: review of the epidemiologic evidence. Thorax 1997, 52(11): 1003–9.