原文：Smoke-free laws reduce exposure to second-hand tobacco smoke
The International Agency for Research on Cancer concluded: “there is sufficient evidence that implementation of smokefree policies substantially decreases second-hand smoke exposure” (46).
Studies of the effects of smoke-free policies consistently show that these policies decrease exposure to second-hand tobacco smoke by 80–90% in high-exposure settings, and that they can lead to overall decreases in exposure of up to 40% (47). People who work in places that are smoke-free are exposed to 3–8 times less second-hand tobacco smoke than other workers (48). Non-smoking adults who live in communities with comprehensive smoke-free laws are 5–10 times less likely to be exposed to second-hand tobacco smoke than those who live where there is no smoke-free legislation (49). Ireland provides strong evidence of the effects of reducing exposure to second-hand tobacco smoke. Following the country’s implementation of smoke-free legislation in 2004, ambient air nicotine and particulate matter concentrations in monitored indoor environments decreased by 83%, and there was a 79% reduction in exhaled breath carbon monoxide and an 81% reduction in salivary cotinine* among bar workers. Bar workers’ exposure to second-hand tobacco smoke plunged from 30 hours per week to zero (50, 51).
These findings were confirmed in numerous other places that enacted comprehensive smoke-free legislation. In Toronto, Canada, a complete smoke-free law for bars implemented in 2004 led to a reduction of 68% in the level of urinary cotinine* of bar workers in one month, while bar workers of a control community without smoke-free legislation did not experience any significant change in the level of urinary cotinine levels (52). In Scotland, comprehensive smoke-free legislation enacted in 2006 resulted in an 86% decrease in the concentration of airborne particulate matter in pubs (53) and a 39% reduction in salivary cotinine levels among adult non-smokers (47).
In New York State, salivary cotinine levels in non-smoking adults decreased 47% in the year after enactment of a comprehensive smoking ban in 2003 (54); in New Zealand, comprehensive smokefree legislation enacted in 2004 appears to have reduced exposure of bar patrons to second-hand tobacco smoke by about 90% (55); and in Finland, a nationally implemented smoke-free law resulted in a reduction in second-hand tobacco smoke exposure in workplaces covered by this law, from 51% of workers reporting exposure before the law to 12% reporting exposure three years after the law became effective (56).
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