Abstract: ObjectiveTo investigate the source and level of pollution of polycyclic aromatic hydrocarbons (PAHs) in PM2.5 in winter of Tianjin, and assess the health risk to urban and rural population. MethodsFrom December 2014 to February 2015, ambient PM2.5 samples were collected in Tianjin urban, suburb, and rural areas, separately. Concentrations of PM2.5 and 16 kinds of PAHs were detected by weighing method and gas chromatography mass spectrometry separately. Distribution characteristics and sources of PAHs were analyzed using ratio method. The health risk to population was evaluated by the model recommended by EPA, and further compared among different groups of population. ResultsA total of 117 samples were collected from urban, suburban, and rural areas (39 samples for each area) in winter of Tianjin. The concentrations of PM2.5 were (78.83±56.56) μg/m3, (117.42±91.43) μg/m3 , and (193.94±148.66) μg/m3 in urban, suburban, and rural areas, respectively (P＜0.01). The concentrations of PM2.5 in rural areas were higher than those in urban and suburban (both P＜0.01). There were 13 kinds of PAHs were detected in 16 species. There were statistically significant differences in the mass concentrations of 13 kinds of PAHs in the three areas (P＜0.01). The contents of 13 kinds of PAHs in rural areas were significantly higher than those in urban and suburban (both P＜0.01). It was found that coal combustion and petrol combustion were major sources of PAHs in the three areas in winter. The pollution sources of biomass burning were also found in suburban and rural areas in winter. The range of equivalent concentrations and total toxicity equivalent concentrations of PAHs in PM2.5 were 0.000-93.100ng/m3 and 7.624-143.569 ng/m3, respectively. Carcinogenic risks of atmospheric PM2.5 pollution induced by PAHs to adults and children were low in the urban, suburban, and rural areas. The carcinogenic risk was higher in rural area than that in urban and suburb. The carcinogenic risk to the adults was higher than that to the children in rural area (36.11×10-6 and 16.23×10-6, respectively). ConclusionThe main sources of PAHs pollution in PM2.5 were coal combustion and gasoline emission in winter in rural area of Tianjin. The carcinogenic risk of PAHs to population did not exist, but BaP could be health risk to rural population.