Second-Hand Smoke

About Second-Hand Smoke

Second-hand smoke is a mixture of particles and gases released from burning cigarettes or other tobacco products and exhaled smoke. It contains many known carcinogens, including benzene, formaldehyde, arsenic, cadmium and chromium.

Second-hand smoke causes lung cancer and heart disease, and worsens allergic reactions and asthma. There is some evidence it may cause laryngeal and pharyngeal cancers [1].

CAREX Canada estimates that approximately 418,000 Canadians are exposed to second-hand smoke at work [2].

Burden of Cancer Results

Approximately 130 lung cancers, and possibly 20 suspected laryngeal cancers and 35 suspected pharyngeal cancers among non-smokers are attributed to occupational second-hand smoke exposure each year, based on 2011 cancer statistics. This amounts to 0.6% of all lung cancers, 1.6% of all laryngeal cancers, and 2.4% of all pharyngeal cancers diagnosed annually in Canada. The cost of the newly diagnosed lung cancers alone is approximately $129 million.

Most second-hand smoke-related cancers occur among workers in the manufacturing and trade sector (see pie chart).

Exposure Reduction

Smoking bans are the most effective way of reducing second-hand smoke exposure [3]. Significant progress has been made to reduce exposure to second-hand smoke in workplaces through legislation, as well as increased awareness of health effects and population-wide changes in smoking behaviour [4].

Despite this progress, exposure to second-hand smoke still occurs in some workplaces, such as sales and services, trades, and transportation [5]. Further efforts are needed to strengthen and enforce smoke-free workplace legislation, especially in outdoor workplaces, and to promote smoking cessation programs to workers in all sectors.


  1. International Agency for Research on Cancer. IARC Monographs Volume 100E: Personal habits and indoor combustions (2012).
  2. CAREX Canada. Second-Hand Smoke Occupational Exposures Profile.
  3. McNabola A, Gill LW. The Control of Environmental Tobacco Smoke: A Policy Review. Int J Environ Res Public Health. 2009;6(2):741-758.
  4. Ontario Tobacco Research Unit. Smoke-Free Ontario Strategy Monitoring Report.
  5. Statistics Canada. Canadian Tobacco Use Monitoring Survey (CTUMS). February to December 2012. Public use data. 2013.