Secondhand smoke exposure in the nonsmoking section: how much protection?

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.

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.

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.

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.