Personal exposures to PM2.5 and polycyclic aromatic hydrocarbons and theirrelationship to environmental tobacco smoke at two locations in Greece

In the context of a large-scale molecular epidemiology study of biomarkers of genotoxicity of air pollution, 24-h mean personal exposures to airborne PM2.5 (particulate matter < 2.5 mum) and associated polycyclic aromatic hyd rocarbon (PAHs) were measured in 194 non-smoking technical institute studen ts living in the city of Athens, Greece (an area with moderately high level s of air pollution) and the nearby small town of Halkida anticipated to hav e lower pollution levels. Extensive information relevant to the assessment of long-term and recent exposure to PAH was obtained from questionnaires as well as a time-location-activity diary (TLAD) which was kept by all subjec ts during a 4-day observation period. During the last 24 h of this period, subjects underwent personal exposure monitoring for PM2.5 and PAH, while a sample of blood was donated at the end of this period. All subjects were mo nitored in this way twice; once during a winter season (October-February) a nd once during the following summer season (June-September). Nine subjects with plasma cotinine levels above 20 ng/ml were considered as unreported sm okers and excluded from the study. Winter PM2.5 exposures were lower in Ath ens (geometric mean 39.7 mug/m(3)) than Halkida (geometric mean 56.2 mug/m( 3)) (p < 0.001),while there was no significant location difference during t he summer (Athens: geometric mean 32.3 mug/m(3), Halkida: geometric mean 32 .9 mug/m(3); P = 0.79). On the other hand, PAH exposures (sum of the eight carcinogenic PAHs) were significantly higher in Athens than in Halkida duri ng the winter (Athens: geometric mean 8.26 ng/m(3), Halkida: geometric mean 5.80 ng/m(3); P < 0.001) as well as during the summer (Athens: geometric m ean 4.44 ng/m(3), Halkida: geometric mean 1.48 ng/m(3); P < 0.001). There w as a significant difference in the profile of the PAH exposures at the two locations, the proportion of lighter PAH (benzo [a]anthracene, chrysene [CH RYS], benzo [k] fluoranthene, and benzo [b] fluoranthene) being higher, and that of heavier PAH (benzo [ghi] perylene [BPer] and indeno [ 1,2,3,cd] py rene) lower, in Halkida than in Athens, regardless of season. This differen ce appeared to be related to individual exposure to environmental tobacco s moke (ETS), as indicated by (a) the correlation at the individual level bet ween the CHRYS/BPer ratio and declared time of recent exposure to ETS as we ll as plasma cotinine levels, especially during the winter; (b) the paralle l variation of he mean levels of all three markers (declared ETS exposure, cotinine levels, CHRYS/BPer ratio) among three subgroups of subjects (Athen s subjects who had lowest levels of all three markers; Halkida subjects oth er than those living in the institute campus area; and Halkida subjects liv ing in the institute campus area who had the highest levels of all three ma rkers). This demonstrates that ETS can have a distinctive affect on the PAH exposure profile of subjects exposed to relatively low levels of urban air pollution.