Objective Through the comparative study of the acute toxic effects of PM2.5 in nickel-contaminated area in rats to explore the possible mechanism of acute toxicity of PM2.5.Methods A nickel-contaminated area and a control area were selected,the air quality of the two areas was monitored and the concentration of nickel in the collected PM2.5 was determined. Forty two male Wistar rats(SPF Grade)were randomly divided into three groups,including one saline control group and two experimental groups,the nickel-polluted group and the non-polluted group,in each.There were three subgroups.PM2.5 were administered to rats by intratraeheal instillation at doses of 1.6 mg/kg,8.0 mg/kg and 40.0 mg/kg respectively.The rats were sacrificed 24 hours after treatment and the brochoalveolar tavage fluid(BALF)were collected,the phagocytic function of alveola macrophages of rats were tested.Results There was no significant difference between the level of environmental quality in the two areas,the concentration of Ni in PM2.5 in the nickel-polluted area was 48.75 times of that in the non-polluted control area.The phagocytic function of alveola macrophages of rats in the experimental groups decreased significantly(P