Introduction: Secondhand smoke (SHS) exposure continues to be a problem in bars and restaurants where smoking is permitted. This study measures the relative SHS exposure reduction in nonsmoking sections of establishments that allow some smoking.
Methods: Measurements were conducted simultaneously in the smoking and nonsmoking sections of 14 Minnesota hospitality venues. All of the 16 two-hr visits included photometer measurements of fine particles (PM2.5) and 12 of the visits also included measurements of 4 gas-phase tracers of SHS.
Results: The median ratio of nonsmoking/smoking section PM2.5 concentrations was 0.65 with an interquartile range (IQR) of 0.49-0.72. Measurements conducted after implementation of a smoking ban at 13 of the venues resulted in a smoking section PM2.5 post-ban/pre-ban ratio of 0.06 (IQR = 0.02-0.16). The median nonsmoking/smoking section ratios for gas-phase compound were 0.67 (IQR = 0.35-0.78) for pyridine, 0.52 (IQR = 0.30-0.70) for pyrrole, 0.43 (IQR = 0.35-0.84) for 3-EP, and 0.27 (IQR = 0.16-0.47) for nicotine. These results are consistent with the expectations of differential removal: the lowest ratios are for the least volatile, most strongly sorbing gases and the highest ratios for less sorbing gases and PM2.5.
Conclusions: Designated nonsmoking sections in establishments that allow some smoking resulted in a median PM2.5 reduction of 35% compared with a 94% reduction after a smoking ban. The only adequate protection from cigarette smoke exposure is to eliminate smoking in indoor spaces.