Comprehensive Smoking Bans May Decrease Secondhand Smoke Exposure

Laurie Barclay, MD

July 20, 2007

July 20, 2007 — Comprehensive smoking bans may decrease secondhand smoke exposure, according to a report in the July 20 issue of the Morbidity and Mortality Weekly Report. Following the 2003 New York state ban on smoking in indoor workplaces and public places, reports of indoor smoking and saliva cotinine levels decreased in nonsmoking participants in the New York Adult Tobacco Survey (NYATS).

"Secondhand smoke (SHS) causes premature disease and death in nonsmokers, including heart disease and lung cancer," write U. Bauer, PhD, from the New York State Department of Health, and colleagues. "The Surgeon General has concluded that no risk-free level of SHS exposure exists; the only way to fully protect nonsmokers is to completely eliminate smoking in indoor spaces. Studies have determined that levels of airborne particulate matter in restaurants, bars, and other hospitality venues and levels of SHS exposure among nonsmoking hospitality employees decrease substantially and rapidly after implementation of laws that prohibit smoking in indoor workplaces and public places."

The New York State Department of Health analyzed data (from June 26, 2003 – June 30, 2004) on observations of indoor smoking by NYATS, as well as cotinine saliva levels in nonsmoking NYATS respondents. The study period began before and ended after implementation of the 2003 New York state ban on smoking in indoor workplaces, restaurants, bars, and other public places.

After the ban took effect, reports of indoor smoking declined significantly, from 19.8% (during June 26 – July 23, 2003) to 3.1% (during April 1 – June 30, 2004) for restaurant patrons, and from 52.4% to 13.4% for bar patrons during the same period. However, the proportion of respondents reporting exposure to SHS in workplaces did not change significantly from 13.6% before implementation of the no-smoking law.

Liquid chromatography with tandem mass spectrometry was used to measure concentration of cotinine in saliva samples that nonsmoking NYATS participants sent in by mail. Mean salivary cotinine decreased by 47.4%, from 0.078 ng/mL during June 26 to July 23, 2003, before the smoking ban was implemented, to 0.041 ng/mL during April 1 to June 30, 2004. During the same periods, the proportion of respondents with cotinine levels below the limit of detection (LOD) of 0.05 ng/mL increased from 32.5% to 52.4%.

"These findings suggest that comprehensive smoking bans can reduce SHS exposure among nonsmokers," the authors write.

An accompanying editorial note states the study limitations of low average quarterly response rates for both NYATS (22%) and the saliva cotinine study (33%, for a cumulative rate of 7%) and an error involved in estimating cotinine values below the LOD to calculate the geometric means.

"Additional research is needed to confirm the findings of this study," the editorial concludes. "However, the results suggest that comprehensive smoke-free air laws can substantially reduce SHS exposure to nonsmokers, even in jurisdictions with a high prevalence of existing smoking restrictions. Even greater reductions in SHS exposure might be expected in jurisdictions that had fewer smoking restrictions in place before implementing a statewide smoke-free air law."

MMWR Morb Mortal Wkly Rep. 2007;56(28):705–708.

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