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Particulate matter (PM) adsorbed by air purifiers, normally used in residential buildings, was collected and analysed by this study. The concentrations of eight heavy metals and 16 poly-aromatic hydrocarbons (PAHs) in PM were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and gas chromatography-mass spectroscopy (GC-MS). The health risk of heavy metals and PAHs was assessed using the health assessment model recommended by the US Environment Protection Agency (EPA). The results showed that the total concentrations of heavy metals during the heating period and non-heating period were 771.27 mg/kg and 441.10 mg/kg, respectively. The carcinogenicity and non-carcinogenicity of chemicals found are higher during the heating period than the non-heating period. The exposure of children was higher than that of adults. Eight heavy metals would pose non-carcinogenic risks for children, but four of these would pose carcinogenic risks for adults and children. The total concentrations of 16 PAHs during the heating period and non-heating period were 106.69 μg/kg and 68.72 μg/kg, respectively. Total toxicity equivalents (TEQs) were 16.37 μg/kg and 9.20 μg/kg, respectively. Among them, 4-rings PAHs accounted for the highest proportion, followed by 5-rings PAHs and 6-rings PAHs. The proportion of 2-rings and 3-rings PAHs were the lowest. 16 PAHs could pose a high carcinogenic risk to adults and children during the heating period, and there was a potential carcinogenic risk during the non-heating period.

Due to the low winter temperatures in rural areas of Northeast China, biomass fuels are widely used for heating and cooking, resulting in increased concentrations of PAHs in rural indoor areas during the heating period and threatening human health. Therefore, exploring the pollution characteristics, source localization, and risk assessment of indoor PAHs in rural Northeast China is of great significance for improving rural indoor air quality. In this study, PAHs were collected from a residential building in rural Northeast China for one consecutive year (January 2020–December 2020), and their concentrations were determined to explore the distribution patterns and sources of PAHs to further assess the carcinogenic risk of PAHs to humans. The results of the study showed that the average concentration of indoor PAHs in rural areas during the heating period (93.02 ng/m3) was about 1.81 times higher than that of the non-heating period (51.26 ng/m3). The main sources of PAHs were mixed combustion of biomass and coal, motor vehicle emissions, and domestic waste combustion. The level of indoor PAHs pollution has posed a carcinogenic risk to the health of the rural population in the Northeast.

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