DNA damage. (A) SCGE assay. BEAS-2B cells were exposed to 7.5 μg/cm2 of winter PM2.5 for 3 h. NAC, Thio and α-NF were used to determine the role of ROS and CYP enzymes, respectively. DNA damage is expressed as % of tail intensity (% DNA in tail). (B) DNA adduct formation in BEAS-2B cells exposed to 7.5 μg/cm2 of PM organic extract and 15 μM BaP for 3 and 24 h measured by 32P-postlabelling. Total bulky adducts (RAL, relative adduct labelling) were measured across the DRZ, diagonal radioactive zone of the TLC autoradiogram. (C) γH2AX expression measured by flow cytometry. BEAS-2B cells were exposed to 7.5 μg/cm2 of winter PM2.5 and organic extract for 3 h, and 15 μM of BaP for 24 h. The results are reported as fluorescence arbitrary units. (D) Formation of 8-oxodG. BEAS-2B cells were exposed to 7.5 μg/cm2 of winter PM2.5 and organic extract, and to 15 μM of BaP for 3 h. The results are reported as 8-oxodG in nM. All data are expressed as mean ± SEM of 3 independent experiments. * Statistically significant difference from untreated cells (control), P < 0.05.