Particle Concentrations Inside a Tavern Before and After Prohibition of Smoking: Evaluating the Performance of an Indoor Air Quality Model.

Abstract

Measurements were made of respirable suspended particles (RSP) in a large sports tavern on 26 dates over approximately two years in which smoking was allowed, followed by measurements on 50 dates during the year after smoking was prohibited. The smoking prohibition occurred without warning when the city government passed a regulation restricting smoking in local restaurants and taverns. Two follow-up field surveys, consisting of 24 and 26 visits, respectively, were conducted to measure changes in RSP levels after smoking was prohibited. No decrease in tavern attendance was evident after smoking was prohibited. During the smoking period, the average RSP concentration was 56.8 |ig/m3 above the outdoor concentrations, but the average abruptly dropped to 5.9 ug/m3 above outdoor levels-a 90% decrease- on 24 visits in the first two months immediately after smoking was prohibited (first follow-up study). A second set of 26 follow-up visits (matched by time of day, day of the week, and season to the earlier smoking visits) yielded an average concentration of 12.9 jig/m3 above the outdoor levels, or an overall decrease in the average RSP concentration of 77% compared with the smoking period. During the smoking period, RSP concentrations more than 100 ug/m3 above outdoor levels occurred on 30.7% of the visits. During the 50 nonsmoking visits, 92% of the RSP concentrations were less than 20 u,g/m3 above outdoor levels, and no concentration exceeded 100 ug/m3 on any nonsmoking visit. The data show there was a striking decline in indoor RSP concentrations in the tavern after smoking was prohibited. The indoor concentration observed in the nonsmoking periods (9.1 u.g/m3 average for all nonsmoking visits) was attributed to cooking and resuspended dust. A mathematical model based on the mass balance equation was developed that included smoking, cooking, and resuspended dust. Using cigarette emission rates from the literature, the tavern volume of 521 m3, and the air exchange rate measured in the tavern under conditions regarded by the management as "typical," the model predicted 42.5 ug/m3 for an average smoking count of 1.17 cigarettes, which compared favorably with the average concentration of 43.9 ng/m3 observed in the tavern. A regression analysis indicated that the active smoking count explained over 50% of the variation of the RSP concentrations measured on different dates. The mathematical model can be used to estimate RSP concentrations from smoking in other similar taverns under similar conditions.