BMC Public Health 2006, 6:42 http://www.biomedcentral.com/1471-2458/6/42 Table 1: Fine particle (PM2.5) levels by pub category in µg/m3 Affluent food-serving pubs (n = 16) Affluent non food pubs (n = 16) Deprived food-serving pubs (n = 17) Deprived non food pubs (n = 15) All affluent pubs (n = 32) All deprived pubs (n = 32) All food-serving pubs (n = 33) All non food pubs (n = 31) Mean (95% CI) 188.1 (128.1 to 248.1) 186.6 (118.9 to 254.3) 399.4 (177.7 to 621.2) 365.7 (195.6 to 535.7) 187.4 (144.8 to 229.9) 383.6 (249.2 to 518.0) 293.6 (172.1 to 415.2) 277.3 (189.8 to 364.8) 10.50 pm,); affluent non food-serving 9.17 pm (range 7.50 to 10.40 pm); deprived food-serving 8.55 pm (range 7.45 to 10.25 pm); deprived non food-serving 9.08 pm (range 7.36 to 10.20 pm); and all affluent 9.08 pm (range 7.15 to 10.50 pm) and all deprived 9.01 pm (range 7.36 to 10.25 pm). Figure 1 shows a typical plot from a single night's moni- toring. It shows the dramatic increase in fine particle levels seen as we moved from the external ambient air and entered each pub. It also shows the variability in levels between pubs with the highest levels seen on this evening in the third pub, which was a non food-serving pub from a deprived area. The mean level of PM2.5 across all venues was 285.5 (95% CI 212.7 to 358.3) µg/m3. Levels were highest on Thurs- days (mean PM2.5 = 356.7 µg/m3) and lowest on Tuesdays (mean PM2.5 = 187.3 µg/m3). Mean levels varied by order of visit as follows: 287.3 µg/m3 for the first, 209.5 µg/m3 for the second, 311.6 µg/m3 for the third, and 333.4 µg/ m3 for the final visit. Table 1 shows the mean, median and range of PM2.5 levels by pub category. Figure 2 shows these data graphically. The geometric mean for time weighted averages of PM2.5 were higher in pubs in deprived communities (245.2 µg/ m3, 95%CI 169.9 to 353.9 µg/m3) than in pubs in more affluent areas (151.2 µg/m3; 95%CI 116.4 to 196.4 µg/ m3), p = 0.03. There was little difference in levels between food and non food-serving pubs (difference in geometric means = 2.4 µg/m3, p = 0.96). Discussion The English Public Health White Paper proposed to exempt non food-serving pubs and bars from the smoke- free legislation. This study was designed to investigate air quality in pubs in relation to this proposal, and the degree to which air quality varied by deprivation. This is the first such investigation that we are aware of in the UK or else- where. We found that levels of fine particles were about twice as high in pubs situated in more deprived areas, but Median 160.3 163.7 329.8 290.3 161.3 312.4 166.7 216.6 Range 59.3–424.4 14.9–497.4 54.1–1395.1 23.5–1226.6 14.9–497.4 23.5–1395.1 54.1–1395.1 14.9–1226.6 there was little difference between food and non food- serving pubs. Our measurements spanned a range of days and times, and included relatively quiet times early on in midweek evenings. We excluded Saturday nights, when occupancy and hence smoking levels are likely to be at their greatest. Despite this four pubs still had extremely high levels of PM2.5. Fine particle levels have been used in previous studies of air quality in the workplace, including in the hospitality trade [11,12]. We found extremely high levels of PM2.5 in these hospitality venues, of the same order as those found in similar studies of 20 hospitality venues from New York (mean 324 µg/m3), [11] and eight hospitality venues from Delaware (mean 231 µg/m3) [12]. Levels of PM2.5 observed were much higher than seen in heavily trafficked urban areas. For example, mean ambi- ent PM2.5 levels in central London (Marylebone Road) in September 2005 were 23.5 µg/m3, 24.6 µg/m3 between 7 and 12 pm. [13] In the UK, there is no air quality standard for PM2.5, though one may be introduced soon. In the USA, the Environmental Protection Agency (EPA) uses an air quality standard for ambient air, one component of which is the mean PM2.5 level over a 24 hour period [14]. Levels over 65, 150 and 250 µg/m3 are labelled by the EPA as 'unhealthy', 'very unhealthy' and 'hazardous' respec- tively [15]. Direct comparisons are only a rough guide as the EPA Air Quality Index refers to time weighted averages over a 24 hour period. However, using the EPA categorisa- tion, air quality was unhealthy or worse in 57 out of 64 (89%) of the pubs, and was hazardous in 26 (41%). Of the pubs with hazardous levels (> 250 µg/m3), 19 were in deprived areas. All the pubs with very high levels – two 500–999 µg/m3and four > 1000 µg/m3 – were in deprived areas. A limitation of the study was the lack of information on ventilation in the participating pubs. However, the data represent current figures from real world settings and should therefore be representative of air quality experi- enced by customers and staff across a range of UK pubs. As Page 4 of 6 (page number not for citation purposes)