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Worldwide burden of disease from exposure to second-hand smoke: a retrospective analysis of data from 192 countries [FREE FULL TEXT] 

Jump to full article: The Lancet, 2010-11-26


Exposure to second-hand smoke is still one of the most common indoor pollutants worldwide. On the basis of the proportions of second-hand smoke exposure, as many as 40% of children, 35% of women, and 33% of men are regularly exposed to second-hand smoke indoors. We noted wide regional variations of exposure, ranging from 13% or less in Africa to 50% or more in the western Pacific or eastern Europe. These differences can be mostly explained by the stages of the tobacco epidemic of a country because second-hand smoke is closely related to active smoking rates where no robust and extensive smoke-free indoor policies exist.

We have estimated that second-hand smoke caused 603 000 deaths and 10·9 million DALYs worldwide in 2004, corresponding to 1·0% of all deaths and 0·7% of the worldwide burden of disease in DALYs in this year. These deaths should be added to the estimated 5·1 million deaths31 attributable to active smoking to obtain the full effect of both passive and active smoking. Smoking, therefore, was responsible for more than 5·7 million deaths every year in 2004. Worldwide, children are more heavily exposed to second-hand smoke than any other age-group, and they are not able to avoid the main source of exposure—mainly their close relatives who smoke at home. Furthermore, children are the group that has the strongest evidence of harm attributable to second-hand smoke. These two factors should form the basis of public health messages and advice to policy makers.

Almost two-thirds of all deaths in children and adults and a quarter of DALYs attributable to exposure to second-hand smoke were caused by ischaemic heart disease in adult non-smokers. Smoke-free laws banning smoking in indoor workplaces rapidly reduce numbers of acute coronary events.35, 36 Therefore, policy makers should bear in mind that enforcing complete smoke-free laws will probably substantially reduce the number of deaths attributable to exposure to second-hand smoke within the first year of its implementation, with accompanying reduction in costs of illness in social and health systems.

The largest effects on deaths occurred in women. . . .

Information about the magnitude and distribution of the burden of disease caused by second-hand smoke is particularly pertinent to policy makers because the harm done by second-hand smoke is eminently preventable. There are well documented and effective interventions to reduce exposure to second-hand smoke in public and private places. For example, by the end of 2007, 16 countries had passed national smoke-free legislation covering all workplaces and public sites,39 and many other countries have state or local government ordinances that restrict smoking. In a review of the effectiveness of legislation of this type, exposure to second-hand smoke in high-risk settings (such as bars and restaurants) was typically reduced by about 90%, and the exposure of adult non-smokers in the general population to second-hand smoke cut by as much as 60%.13

Most epidemiological studies have been done in developed countries. Conditions in developing countries can differ from those in high-income countries, and, in particular, exposure to second-hand smoke in the home is often not well characterised by the presence or absence of parents or spouses who smoke. . . .

Previously reported national estimates of the burden of disease caused by second-hand smoke are generally similar to those reported here. Variations result from differences in the burden from active smoking, the active and passive smoking rates used, and the methods used (eg, whether or not active smokers are deemed susceptible). The size of the relative risk estimates used did not generally vary across studies of health effects from exposure to second-hand smoke.

This assessment shows that second-hand smoke poses a substantial health risk and disease burden for children and adult non-smokers worldwide. The findings are relevant to health policy decisions and public health strategies in all regions.

Only 7·4% of the world population lives in jurisdictions with comprehensive smoke-free laws at present, and the enforcement of these laws is robust in only a few of those jurisdictions. . . .

Policy makers should also take action in two other areas to protect children and adults. First, although the benefits of smoke-free laws clearly extend to homes, protection of children and women from second-hand smoke in many regions needs to include complementary educational strategies to reduce exposure to second-hand smoke at home. Voluntary smoke-free home policies reduce exposure of children and adult non-smokers to second-hand smoke, reduce smoking in adults, and seem to reduce smoking in youths.13 Second, exposure to second-hand smoke contributes to the death of thousands of children younger than 5 years in low-income countries. Prompt attention is needed to dispel the myth that developing countries can wait to deal with tobacco-related diseases until they have dealt with infectious diseases. Together, tobacco smoke and infections lead to substantial, avoidable mortality and loss of active life-years of children.

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