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Reduced Secondhand Smoke Exposure After Implementation of a Comprehensive Statewide Smoking Ban --- New York, June 26, 2003--June 30, 2004
Secondhand smoke (SHS) causes premature disease and death in nonsmokers, including heart disease and lung cancer (1). 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 (1). 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 (1--5). To assess changes in indoor SHS exposure in a general population, the New York State Department of Health analyzed data on observations of indoor smoking by respondents to the New York Adult Tobacco Survey (NYATS) and measured levels of cotinine* in saliva among nonsmoking NYATS respondents before and after implementation of the 2003 New York state ban on smoking in indoor workplaces and public places. This report describes the results of that analysis, which determined that reports of indoor smoking among restaurant and bar patrons decreased significantly after the law took effect; moreover, saliva cotinine levels in nonsmoking NYATS participants decreased by 47.4% over the same period. These findings suggest that comprehensive smoking bans can reduce SHS exposure among nonsmokers.
NYATS is an ongoing, quarterly, random-digit--dialed telephone survey of approximately 2,000 state residents aged >18 years designed to generate state and regional estimates of tobacco-use behaviors and related attitudes and beliefs among adults living in residential households. Initial NYATS data collection began on June 26, 2003, less than 1 month before implementation of the statewide law on July 24, 2003.
To assess levels of indoor smoking in restaurants, bars, and workplaces, all NYATS participants were asked three questions: "The last time you went to a restaurant in your community in the past 30 days, did you see someone smoking indoors?" "The last time you went to a bar in your community in the past 30 days, did you see someone smoking indoors?" and "In the past 7 days, has anyone smoked in your work area?" To assess smoking status, NYATS participants were asked, "Do you now smoke cigarettes every day, some days, or not at all?" Nonsmokers were defined as those who answered "not at all."
All nonsmokers who participated in NYATS during June 26, 2003--June 30, 2004, and who lived outside New York City and Nassau County were eligible to participate in a saliva cotinine study and were invited to submit a saliva sample through the mail for cotinine analysis. Saliva cotinine has been determined to be an accurate and reliable measure of SHS exposure (1), and saliva cotinine samples remain stable when submitted by mail (6). Residents of New York City and Nassau County were excluded because those jurisdictions had implemented comprehensive local smoking bans in March 2003; as a result, their residents might have already experienced declines in SHS exposure. Participants who agreed to provide a saliva sample were mailed a packet that included a consent form, a vial, instructions for providing the sample, a $10 incentive check, and a postage-paid return mailer. Eligible NYATS participants who did not submit a sample within 2 weeks were mailed postcard reminders. The 296 respondents whose samples were too small for analysis were not asked to provide an additional sample. The 96 respondents whose samples yielded cotinine values >15 ng/mL were excluded from the analysis because those values are associated with active smoking (1).
The concentration of cotinine in the saliva samples was determined using liquid chromatography with tandem mass spectrometry. This method has a limit of detection (LOD) of 0.05 ng/mL. For participants with a cotinine level below the LOD, values were imputed by applying an expectation-maximization regression model to the log-transformed cotinine levels that were above the LOD (7). This method generates estimates of values below the LOD to replicate the true distribution of the sample (i.e., the distribution that would have been observed had there been no LOD). The method is recommended when the proportion of samples with values below the LOD exceeds 40% to provide the best estimate of the true shape of the distribution while avoiding distortions that result from assigning a single value to samples with cotinine levels below the LOD (7,8).
Response rates for NYATS, calculated according to the Council of American Survey Research Organizations formula, averaged 22% (range: 21%--24%) for the quarterly surveys conducted during June 26, 2003--June 30, 2004. Response rates for the cotinine study, calculated as the number of participants submitting saliva samples divided by the number of eligible participants, averaged 33% (range: 27%--41%). NYATS data regarding both reported indoor smoking and cotinine levels were weighted to account for nonresponse, demographics, and geographic location. Participants in the cotinine study were similar to all nonsmoking NYATS participants in terms of age group, education level, race/ethnicity, and self-reported health status, with two exceptions. A greater proportion of participants in the cotinine study had college degrees and were non-Hispanic white than the nonsmoking NYATS participant population overall (Table 1).
Reports of Indoor Smoking
The percentages of NYATS respondents reporting exposure to SHS in restaurants and bars decreased significantly after the law took effect, from 19.8% (during June 26--July 23, 2003) to 3.1% (during April 1--June 30, 2004) among restaurant patrons and from 52.4% to 13.4% among bar patrons over the same period (Table 2). The percentage of respondents reporting exposure to SHS in workplaces, which had been 13.6% before implementation of the smoking ban, did not change significantly after implementation of the law. This finding likely is attributable to local smoke-free air laws and voluntary workplace smoking restrictions that were in place before implementation of the state law.
Nonsmoker Levels of Cotinine
Of the 6,152 NYATS participants who were eligible to submit saliva samples, 3,053 agreed, and 2,008 (33%) submitted samples. The analysis described in this report is based on the 1,594 saliva samples that contained sufficient saliva to test for cotinine, had a cotinine level of <15 ng/mL, and were accompanied by a signed consent form. Saliva samples were analyzed at the New York Department of Health Wadsworth Laboratory.
The geometric mean level of salivary cotinine among nonsmoking NYATS participants who submitted saliva samples decreased by 47.4%, from 0.078 ng/mL during June 26--July 23, 2003, before the state law took effect, to 0.041 ng/mL during April 1--June 30, 2004 (Table 3). The proportion of respondents with cotinine levels below the LOD (0.05 ng/mL) increased from 32.5% to 52.4% when comparing the same periods.
Reported by: U Bauer, PhD, H Juster, PhD, New York State Dept of Health; A Hyland, PhD, Roswell Park Cancer Institute, Buffalo, New York. M Farrelly, PhD, M Engelen, D Weitzenkamp, RTI International, Research Triangle Park, North Carolina. J Repace, MSc, Repace Associates, Bowie, Maryland. S Babb, MPH, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.
Revised Healthy People 2010 objectives call for reducing the proportion of nonsmokers aged >4 years who are exposed to SHS to 63% (objective 27-10), increasing the proportion of indoor workers covered by smoke-free air workplace policies to 100% (objective 27-12), and implementing laws making indoor workplaces and public places smoke-free in all 50 states (objective 27-13). The proportion of the U.S. population exposed to SHS has decreased substantially during the past 20 years as the prevalence and strength of local and state smoke-free air laws and voluntary workplace smoking restrictions have increased and adult smoking prevalence has decreased (1,9,10). However, approximately 126 million nonsmokers in the United States remain exposed to SHS (1).
Studies have determined that laws prohibiting smoking in hospitality venues such as restaurants and bars are associated with rapid reductions in self-reported respiratory and sensory symptoms and improvements in objective measures of pulmonary function among nonsmoking hospitality workers (1,3--5). However, this is the first report of a biologically validated population-level reduction in SHS exposure among nonsmokers after implementation of a comprehensive state smoke-free air law. The substantial reduction in saliva cotinine levels observed in this study likely indicates a substantial reduction in SHS exposure, which should result in reductions in morbidity and mortality from heart disease and lung cancer among nonsmoking adults over time (1).
The findings in this report are subject to at least two limitations. First, the average quarterly response rates for both NYATS (22%) and the saliva cotinine study (33%, for a cumulative rate of 7%) were low; in addition, the number of preban respondents in the cotinine study (80) was approximately one fourth to one fifth the number of respondents in each of the postban samples (range: 337--425). Although respondents in NYATS and the cotinine study might not be representative of the state's general populations of adults and adult nonsmokers, respectively, 2004 NYATS participants were similar to respondents in the 2004 New York state Behavioral Risk Factor Surveillance System survey in age group, education level, race/ethnicity, and self-reported health status. Moreover, an examination of age group, education level, and race/ethnicity demonstrated that cotinine study participants were similar to all nonsmoking NYATS participants, with two exceptions. Neither of these differences should negate the findings described in this report, although the low response rates do increase the possibility for error resulting from response bias. Second, a substantial proportion of respondent cotinine levels were below the LOD, and this proportion increased over time (likely because of the protection from SHS afforded by the new law). This required estimation of the values below the LOD to calculate the geometric means; although validated, this estimation is subject to error.
Additional research is needed to confirm the findings of this study. 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.
This report is based, in part, on contributions by T Pechacek, PhD, R Kaufmann, PhD, A Trosclair, MS, and R Caraballo, PhD, Office on Smoking and Health, National Center for Chronic Disease Prevention and Health Promotion; and S Caudill, PhD, Div of Laboratory Sciences, National Center for Environmental Health, CDC.
* Cotinine, which can be measured in serum, urine, or saliva, is a metabolite of nicotine and a biomarker for both active smoking and SHS exposure.
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Date last reviewed: 7/18/2007