Study Population Selection

This evaluation focused only on workers in establishments defined by the D.C. Official Code as a “club,” “brew pub,” “nightclub,” or “tavern.” In May 2005 a Yellow Pages search with these descriptors identified 273 sites, and 1,950 bartenders. We excluded 11 bars that had enforced restricted smoking policies prior to the ban, or that were exempt. One hundred eighty-four (71%) of the 262 eligible sites from six high-density areas where adult customers congregated seven days a week were selected. Because of time and resource restraints, we could not include 78 small neighborhood bars distributed throughout the city. Using a Power = 0.80, alpha = 0.05, a one-tailed test, and effect size of > 50% in cotinine levels based on employee ETS research, we needed > 35 sites/employee pre-ban and post-ban assessments. We randomly selected 41 bars.

Site and Employee Recruitment

Letters were sent and calls made to the randomly selected sites to describe the study and to seek permission of managers to approach employees. These were ineffective. We then trained 12 volunteer staff (MPH students) to approach managers from December 2 to December 21, 2006, to seek permission to conduct the study and recruit employees prior to the ban (O1). Participants had to be (1) a nonsmoker, (2) not using other forms of tobacco, (3) did not live with a smoker, or the smoker did not smoke indoors, and (4) employed > 20 hours/week at the site.

Fifty-two (78%) employees identified themselves as bartenders. Other staff categories, 6 servers, 3 barbacks, 3 managers, one owner, and one host, were recruited who met all screening criteria and served customers. After consent, staff collected baseline information, saliva samples, ETS exposure, and respiratory and sensory symptom reports, and attitudes on the ban (O1). Employee assessment procedures (O2) were replicated from February 1 to February 21, 2007, after the ban.

Impact Measurement: Salivary Cotinine

Our primary impact measure was employee cotinine levels: the major proximal metabolite of nicotine present in a person’s body fluids. A coti- nine half-life of 18 hours makes it a valid measure for ETS exposure. This study used a recommended < 10 ng/mL cutoff for nonsmoking self-reports. Saliva samples were collected using a Salivette sample vial and frozen < 3 hours. In < 7 days after assessment, samples were thawed, centrifuged and shipped in dry ice to the Pharmacology Laboratory at San Francisco General Hospital/Univeristy of California, San Francisco, for analysis. Saliva cotinine was measured using tandem liquid chromatography-mass spectrometry (LC-MS/MS). This analysis has a minimum detectable level = 0.05 ng/mL, is the most sensitive type of cotinine measurement, and has “excellent” specificity.

Self-reported Symptoms

After screening, a questionnaire elicited descriptive information, respiratory and sensory symptoms, and smoking ban attitudes. Respiratory symptoms questions in the past four weeks were from a validated form used in comparable hospitality-bar employee assessment studies: International Union Against Tuberculosis and Lung Disease (IUATLD) Bronchial Symptoms Questionnaire.

Statistical Analysis

Analyses of changes were restricted to employees with O1 and O2 assessments, who were cotinine-confirmed nonsmokers, and were employed at the same bar during both collection periods. Salivary coti- nine levels and symptom data were analyzed by computing O1 and O2 difference. Respiratory and sensory symptoms were analyzed by change in the number of symptoms. Analyses were completed with the SAS System 8.02.


Of the 102 employees approached at the 41 bars, one did not understand enough English to give consent. One worked in a bar with ETS restrictions. Of the 100 remaining, 17 (17%) were smokers: 17 nonsmoking employees (17%) refused to participate. Between December 2, 2006, and December 21, 2006, staff recruited 66 eligible employees who had worked at least two hours at the time (> 8:00 p.m.) of baseline data collection. Of the 66 assessed, 16 were not eligible for follow-up. Two reported smoking, and 14 were ineligible due to a change of job (6), bar closing (6), bar exemption (1), or death (1). This left 50 eligible participants. Only three eligible participants were lost to follow-up, unreachable at work or by phone. Only one employee refused the O2 assessment. Thus, follow-up data were collected on 46 of 50 (94%) eligible employees


Two employee samples at O2 were below levels of laboratory quantification. We imputed O2 cotinine levels to be 0.05 ng/mL. Six samples did not have sufficient volume for analysis at either O1 or O2. We imputed their cotinine values, assuming, conservatively, no O1 or O2 changes.


baseli ne mean



p value


Saliva Cotinine

2.37 ng/mL

0.49 ng/mL

< 0.0001

< 79.3%

# hrs at work: < week

35 (25-40 hr.)

35 (25-50 hr.)



# hrs ETS work:

30 (18-40 hr.)

0 (0-1 hr.)

< 0.0010

< 100%

Cotinine levels: As noted in Table 3.12, the cotinine levels of the 46 employees declined significantly, by 79.3%: O1 = 2.37 ng/mL and O2 = 0.49 ng/mL.

Self-reported ETS levels: As noted in Table 3.12, the number of hours reported working did not change significantly between O1 and O2, nor did reported hours of ETS exposure outside of work. The hours exposed to ETS at work declined from a median of 30hr/wk at O1 to 0hr/wk at O2

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