© 2008 American Thoracic Society
Particulate Air Pollution in Irish Pubs Is Grossly UnderestimatedFrom the Authors:In their letter, Drs. Travers and Lee correctly identify some differences between the levels of particles as observed in our study and those published in other studies. They state that, to measure secondhand tobacco smoke (SHS) specifically, a conversion factor needs to be applied to the Aerocet instrument. To our knowledge, no such conversion factor has been established and published in the peer-reviewed literature. Where authors have reported calibration of optical instruments to tobacco smoke, there seems to be no standardized way of doing this. Most reports measure smoldering cigarettes, not when a cigarette is actually smoked, nor the different types of cigarette. This clearly highlights the need for some level of uniformity in the approach to calibration to SHS that reflects the real situation encountered in pubs. On the other hand, we did not set out to measure SHS. Our study was designed to measure PM2.5, PM10, and benzene levels in a range of public houses, pre– and post–smoking ban (1). We assumed that if there is a total ban on smoking in a venue, and it is obeyed, then the level of SHS should be zero. We wished to measure the effect of a smoking ban in pubs on the atmosphere, accepting that there are other sources of pollution in pubs. We wished to show that, when environmental tobacco smoke (ETS) is removed, whether it comes from SHS, side stream smoke, or smoldering cigarettes in ashtrays, the pollution load is significantly reduced. We were aware that the instrument as configured could not measure SHS exclusively, nor did we report our results as SHS. We claimed that the observed reduction in PM2.5 was most likely due to a reduction in ETS. The PM instrument was used according to the manufacturer's instructions. Our primary objective was to determine the change in levels, pre- and postban, where we observed an 83.6% reduction in PM2.5, virtually identical to that reported by Travers and colleagues (2), and an 80% drop in benzene, both highly statistically significant, while at the same time we did not observe any significant change in indoor PM10, or ambient outdoor PM2.5, or PM10. Apart from the issue of a conversion factor to specifically convert our PM2.5 values to SHS, there are other design differences that may influence the observed measurement levels. We measured levels in 42 pubs for a minimum of 3 hours in each venue on each occasion, both before and after the ban. Repace and colleagues (3) measured levels in seven bars, selected because of visible smoking, and measured for an average of 43 minutes per venue. Similarly, Travers and colleagues measured in 22 venues, 7 of which were bars and 6 bar/restaurants, again for a median time of 38 minutes. Edwards and colleagues (4) measured in 64 pubs in four groups, selected on socioeconomic grounds, monitoring for 30 minutes on average in the "busiest" room, where they showed the marked variation both between pubs and also within individual pubs, as we reported. We also suggest that the composition of the cigarettes available in the different countries may be different, and produce variable amounts of combustion products. The surprising outcome from the various studies where there has been a comprehensive workplace smoking ban is that the relative reduction in measured particle levels seems remarkably consistent.
Research Institute for a Tobacco Free Society
Dublin Institute of Technology FOOTNOTES Conflict of Interest Statement: Neither author has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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