Secondhand smoke levels in Scottish pubs: the effect of smoke-free legislation.

OBJECTIVE To compare levels of particulate matter, as a marker of secondhand smoke (SHS) levels, in pubs before and 2 months after the implementation of Scottish legislation to prohibit smoking in substantially enclosed public places. DESIGN Comparison of SHS levels before and after the legislation in a random selection of 41 pubs in 2 Scottish cities. METHODS Fine particulate matter <2.5 microm in diameter (PM2.5) was measured discreetly for 30 min in each bar on 1 or 2 visits in the 8 weeks preceding the starting date of the Smoking, Health and Social Care (Scotland) Act 2005 and then again 2 months after the ban. Repeat visits were undertaken on the same day of the week and at approximately the same time of the day. RESULTS PM2.5 levels before the introduction of the legislation averaged 246 microg/m3 (range 8-902 microg/m3). The average level reduced to 20 microg/m3 (range 6-104 microg/m3) in the period after the ban. Levels of SHS were reduced in all 53 post-ban visits, with the average reduction being 86% (range 12-99%). PM2.5 concentrations in most pubs post-ban were comparable to the outside ambient air PM2.5 level. CONCLUSIONS This study has produced the largest dataset of pre- and post-ban SHS levels in pubs of all worldwide smoke-free legislations introduced to date. Our results show that compliance with the Smoking, Health and Social Care (Scotland) Act 2005 has been high and this has led to a marked reduction in SHS concentrations in Scottish pubs, thereby reducing both the occupational exposure of workers in the hospitality sector and that of non-smoking patrons.