Abstract: Objective To investigate DNA damage induced by inhalable particulate matter (PM10) and its mechanisms in HepG2 cells.Methods DNA strand breaks induced by extractable organic matter of PM10 was assessed by single cell gel electrophoresis (SCGE) assay.Intracellular generation of reactive oxygen species (ROS),expression of 8-hydroxydeoxyguanosine (8-OHdG) and protein expression of NF-κB p65 were estimated by 2,7-dichlorofluorescein (DCFH),immunocytochemistry staining and Western blot,respectively.Results Significant differences in percent of tail DNA induced by the extractable organic matter of PM10 were revealed between samples collected in summer and winter seasons and from different monitoring sites.The percent of tail DNA in HepG2 cells significantly increased in a dose-dependent manner after exposure to 7.5-30μg/mL extractable organic matter of PM10 for 1hr.After exposure to extractable organic matter of PM10 for 1hr,intracellular ROS increased significantly.The 8-OHdG was positive in the HepG2 cells treated with extractable organic matter of PM10.The protein expression of NF-κB p65 significantly increased in HepG2 cells after treatment with 30μg/mL extractable organic matter of PM10 for 24 hr.Conclusion The extractable organic matter of PM10 induces DNA strand breaks in HepG2 cells.Significant differences in percent of tail DNA relates to PM10 samples collected at different times and locations.The extractable organic matter of PM10 exerts DNA damage effects in HepG2 cells probably through oxidative DNA damage induced by intracellular ROS,increase of 8-OHdG formation and the expression of NF-κB p65.