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.