Passive smoking is the inhalation by individuals other than the smoker of tobacco smoke, called second-hand smoke, passive smoke (SHS) or environmental tobacco smoke (ETS). It occurs when tobacco smoke diffuses into the surrounding atmosphere as an aerosol pollutant, which leads to its inhalation by nearby bystanders within the same environment. Exposure to passive tobacco smoke causes many of the same health effects caused by active smoking, although at a lower prevalence due to the reduced concentration of smoke that enters the airway. According to a World Health Organization (WHO) report published in 2023, more than 1.3 million deaths are attributed to passive smoking worldwide every year. The health risks of passive smoke are a matter of scientific consensus, and have been a major motivation for smoking bans in workplaces and indoor venues, including restaurants, bars and night clubs, as well as some open public spaces. Concerns around passive smoke have played a central role in the debate over the harms and regulation of tobacco products. Since the early 1970s, the tobacco industry has viewed public concern over passive smoke as a serious threat to its business interests. Despite the industry's awareness of the harms of passive smoke as early as the 1980s, the tobacco industry coordinated a scientific controversy with the purpose of stopping regulation of their products.
Terminology Fritz Lickint created the term "passive smoking" ("Passivrauchen") in a publication in the German language during the 1930s. Terms used include "environmental tobacco smoke" to refer to the airborne matter, while "involuntary smoking" and "passive smoking" refer to exposure to second-hand smoke. The term "environmental tobacco smoke" can be traced back to a 1974 industry-sponsored meeting held in Bermuda, while the term "passive smoking" was first used in the title of a scientific paper in 1970. The Surgeon General of the United States prefers to use the phrase "second-hand smoke" rather than "environmental tobacco smoke", stating that "The descriptor 'second-hand' captures the involuntary nature of the exposure, while 'environmental' does not." Most researchers consider the term "passive smoking" to be synonymous with "second-hand smoke". In contrast, a 2011 commentary in Environmental Health Perspectives argued that research into "thirdhand smoke" renders it inappropriate to refer to passive smoking with the term "second-hand smoke", which the authors stated constitutes a pars pro toto. The term "sidestream smoke" is sometimes used to refer to smoke that goes into the air directly from a burning cigarette, cigar, or pipe, while "mainstream smoke" refers to smoke that a smoker exhales.
Health effects
Passive smoke causes many of the diseases of direct smoking, including cardiovascular diseases, lung cancer, and respiratory diseases. These include:
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