Outdoor Tobacco Smoke Exposure

Abstract

An increasing number of cities and countries have implemented outdoor smoking restrictions at building entrances. The purpose of this study was to determine outdoor tobacco smoke (OTS) exposure as a function of distance from the smoking source. The outcomes can lead to recommendations of the appropriate distance to minimize the influence of outdoor smoking. Outdoor concentrations of ambient particulate matter smaller than 2.5 μm in aerodynamic diameter (PM2.5) were measured at four different distances (1, 3, 6, and 9 m) from a simulated smoking source. Wind speed and direction were measured using a wind meter. A smoking doll was used to provide tobacco smoking for approximately 3 min. One smoking experiment consisted of 13 min (5 nonsmoking min, 3 smoking min, and 5 more nonsmoking min). The difference between mean PM2.5 concentrations during smoking versus nonsmoking conditions was taken as the OTS exposure. A novel peak analysis was used to accurately assess the acute outdoor tobacco exposure. Average peak concentration and peak frequency were used for the analysis. The OTS levels were 72.7 µg/m3, 11.3 µg/m3, 4.1 µg/m3, and 2.6 µg/m3 at 1 m, 3 m, 6 m, and 9 m, respectively. The OTS levels decreased with increasing distance from the smoking source, although detectable OTS levels were measured even at 9 m. The OTS levels were significantly higher than zero at all distances. The OTS levels were highly associated with wind direction. Although the OTS levels were higher downwind of the source, the OTS levels were not significantly different directly downwind versus at an angle to the wind direction. The OTS levels were negatively associated with wind speed. The peak frequencies and average peak concentrations during smoking conditions were significantly greater than those under nonsmoking conditions. More frequent peaks of high concentration were observed at 9 m from the smoking source. To prevent OTS exposure, the minimal distance from a smoking source should be at least 9 m.