Passive smoking

Passive smoking (also known as environmental tobacco smoke (ETS), involuntary smoking or secondhand smoke) occurs when the exhaled and ambient smoke from one person's cigarette is inhaled by other people. Non-smokers exposed to secondhand smoke are at greater risk for many of the health problems associated with direct smoking. In 1992, the Journal of the American Medical Association published a review of the evidence available from epidemiological and other studies regarding the relationship between secondhand smoke and heart disease and estimated that passive smoking was responsible for 35,000 to 40,000 deaths per year in the United States in the early 1980s.

Non-smokers living with smokers have about a 25 per cent increase in risk of death from heart attack and are also more likely to suffer a stroke, and some research suggests that risks to nonsmokers may be even greater than this estimate. One recent study in the British Medical Journal found that exposure to secondhand smoke increases the risk of heart disease among non-smokers by as much as 60 percent.

Passive smoking is especially risky for children and babies and can cause low birth weight babies, sudden infant death syndrome (SIDS), bronchitis and pneumonia, and middle ear infections.

Some controversy has attended efforts to estimate the specific risk of lung cancer related to passive smoking. The US Environmental Protection Agency (EPA) in 1993 issued a report estimating that 3,000 lung cancer related deaths in the US were caused by passive smoking every year. Tobacco industry lobbyists, such as the Alexis de Tocqueville Institution, and industry-funded researchers, such as S. Fred Singer, aggressively attacked the EPA study as "junk science". In 2002, a 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 reviewed all significant published evidence related to tobacco smoking and cancer. It concluded its evaluation of the carcinogenic risks associated with involuntary smoking, with second-hand smoke also being classified as carcinogenic to humans. An earlier World Health Organization epidemiology study also found "weak evidence of a dose-response relationship between risk of lung cancer and exposure to spousal and workplace ETS". The fact that the evidence was described as "weak" has been interpreted by the tobacco industry and its supporters as evidence that the ETS-lung cancer link has been "disproven". More precisely, the "weakness" of the evidence stems from the fact that the risk of ETS for individuals is small relative to the very high risk of actually smoking, making it more difficult to quantify through epidemiology. In addition to epidemiology, moreover, several other types of scientific evidence (including animal experiments, chemical constituent analysis of ETS, and human metabolic studies) support the WHO and EPA conclusions.

Most experts believe that moderate, occasional exposure to secondhand smoke presents a low cancer risk to nonsmokers, but the risk is more likely to be significant if non-smokers work in an environment where cigarette smoke is prevalent. For this reason, many countries (such as Ireland) and jurisdictions (like New York State) now prohibit smoking in public buildings. Many office buildings contain specially ventilated smoking areas; some are required by law to provide them.

See also Oxidized assault.