PM2.5 particles were collected by high volume samplers in the most polluted area of the Czech Republic-Ostrava region (localities Bartovice, Poruba and Karvina) and in the locality exhibiting a low level of air pollution – Trebon – a small town in the non-industrial region of Southern Bohemia. PM2.5 particles were extracted (extractable organic matter – EOM) and c-PAHs contents in the EOMs were determined. As markers of genotoxic potential, DNA adduct levels and oxidative DNA damage levels (8-oxo-7,8-dihydro-2′-deoxyguanosine, 8-oxodG) induced by EOMs in an acellular assay of calf thymus DNA coupled with 32P-postlabeling (DNA adducts) and ELISA (8-oxodG) in the presence and absence of microsomal S9 fraction were employed. Twofold higher DNA adduct levels (17.20 adducts/108 nucleotides/m3 vs. 8.49 adducts/108 nucleotides/m3) were induced by EOM from Ostrava–Bartovice (immediate proximity of heavy industry) compared with that from Ostrava–Poruba (mostly traffic emissions). Oxidative DNA damage induced by EOM from Ostrava–Bartovice was more than fourfold higher than damage induced by EOM from Trebon (8-oxodG/108 dG/m3: 0.131 vs. 0.030 for Ostrava–Bartovice vs. Trebon, respectively). c-PAH contents in EOMs are the most important factors relating to their genotoxic potential (Topinka et al., 2011).