Secondhand smoke drift: examining the influence of indoor smoking bans on indoor and outdoor air quality at pubs and bars.

Introduction: This study aimed to examine the influence of indoor smoking bans on indoor and outdoor air quality at pubs and bars and to assess whether secondhand tobacco smoke (SHS) drifts from outdoor smoking areas to adjacent indoor areas.

Methods: Data were covertly collected from a convenience sample of 19 pubs and bars that had at least 1 indoor area with an adjacent semi-enclosed outdoor eating/drinking area. Using TSI SidePak Personal Aerosol Monitors, concentrations of SHS (PM(2.5)) were measured concurrently in indoor and outdoor areas before and after implementation of the indoor smoking ban. Information was collected about the number of patrons and lit cigarettes and about the enclosure of outdoor areas.

Results: Indoor PM(2.5) concentrations reduced by 65.5% from pre-ban to post-ban (95% CI 32.6%-82.3%, p = .004). Outdoor exposure to PM(2.5) also reduced from pre-ban to post-ban by 38.8% (95% CI 3.2%-61.3%, p = .037). At post-ban, indoor concentrations of PM(2.5) were positively associated with outdoor concentrations. After adjustment for covariates, a 100% increase in geometric mean (GM) outdoor PM(2.5) was associated with a 36.1% (95% CI 2.4%-80.9%) increase in GM indoor PM(2.5) exposure (p = .035).

Discussion: Indoor smoking bans are an effective means of improving indoor and outdoor air quality in pubs and bars, although the air quality of smoke-free indoor areas may be compromised by smoking in adjacent outdoor areas. These findings require consideration in efforts to ensure adequate protection of the health of employees and patrons at hospitality venues.