Passive smoking (also known as environmental tobacco smoke (ETS), involuntary
smoking or second hand smoke) occurs when the exhaled and ambient smoke from one
person's cigarette is inhaled by other people. Non-smokers exposed to second
hand 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 second hand 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 non-smokers may be even greater than this
estimate. One recent study in the British Medical Journal found that exposure to
second hand 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, 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 WHO 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.
Many experts believe that moderate, occasional exposure to second hand smoke
presents a low cancer risk to non-smokers, 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.
