Objective:To investigate the characteristics,sources and health risk of polycyclic aromatic hydrocarbons(PAHs)pollution in atmospheric PM2.5 in Wujin District of Changzhou City.Methods:From 2017 to 2022,monthly atmospheric PM2.5 samples in Wujin District of Changzhou were collected,and PAHs mass concentration in PM2.5 was measured with high performance liquid chromatography and PAHs source was analyzed with molecular diagnostic ratios(MDRs)to assess the possible health risks of PAHs.Results:A total of 521 valid samples were collected from 2017 to 2022.The average annual atmospheric PM2.5 concentration in Wujin District of Changzhou City ranged from 39 to 56 μg·m-3,showing a decreasing trend and the difference was statistically significant(P＜0.05).The total average annual concentration of 16 PAHs ranged from 1.08 to 5.54 ng·m-3,showing a decreasing trend with statistical significance in different years(P＜0.05),and the performance of PAHs monomer was higher in winter and spring than that in summer and autumn.Among the 16 PAHs,mainly 4 to 5 rings,the concentration of benzo[b]fluoranthene was the highest.The hazard quotient(HQ)of benzo[a]pyrene was between 0.02 and 0.37,and the excess cancer risk(ECR)of PAHs was 1.68 × 10-6,1.63 × 10-6,1.06 × 10-6,6.11 × 10-7,2.34 × 10-7 and 1.98 × 10-7,respectively.The ECR value is lower than 1 × 10-6 in spring,summer and autumn,and higher than 1 × 10-6 in winter.Conclusion:From 2017 to 2022,the concentration of PAHs in atmospheric PM2.5 in Wujin District of Changzhou shows a decreasing trend in general,and the main sources are biomass and coal combustion,fossil fuel combustion,petroleum combustion and motor vehicle emissions.The non-carcinogenic risk could be ignored,and the carcinogenic risk is higher in winter and in people over 16 years old than that in children.
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