Environmental tobacco smoke exposure among non-smoking waiters: measurement of expired carbon monoxide levels.

CONTEXT Exposure to environmental tobacco smoke is a health risk that is of concern to patrons and of particular concern to employees of restaurants and bars. OBJECTIVE To assess environmental tobacco smoke exposure (using expired carbon monoxide levels) in non-smoking waiters before and after a normal day's shift and to compare pre-exposure levels with non-smoking medical students. DESIGN An observational study. SETTING Restaurants with more than 50 tables or 100 places in São Paulo. SUBJECTS 100 non-smoking restaurant waiters and 100 non-smoking medical students in São Paulo, Brazil. MAIN MEASUREMENTS Levels of expired carbon monoxide, measured with a Smokerlyser (Bedfont EC 50 Scientific), before and after a normal day's work. RESULTS Waiters' pre-exposure expired carbon monoxide levels were similar to those of medical students, but after a mean of 9 hours exposure in the workplace, median levels more than doubled (2.0 ppm vs. 5.0 ppm, P <0.001). Post-exposure carbon monoxide levels were correlated with the number of tables available for smokers (Kendall's tau = 0.2, P <0.0001). CONCLUSIONS Exposure to environmental tobacco smoke is the most likely explanation for the increase in carbon monoxide levels among these non-smoking waiters. These findings can be used to inform the ongoing public health debate on passive smoking.