Abstract: Objective To study the oxidative stress damages induced by soot on rat pulmonary cells.Methods The rat pulmonary cells were pretreated with anti-oxidative N-ace tylcysteine(NAC)for 30 minutes,then they were exposed to the soot extracts for 24 hours.MTT assays and ethidium bromide fluorescence assays(EFA)were applied to detect the cyto to xicity and DNA cross-links.Results The results showed that NAC could reduce the cytotoxicity and DNA cross-links of rat pulmonary cell caused by soot.Conclusion It was sugg ested that the soot can lead too xidat ive stress on cells.