Promoting the design of future indoor environmental to improve air pollution: Based on the analysis of hazardous substances in indoor PM2.5 pollution in cold regions

People spend about 90% of their day indoors and are at increased risk of exposure to metal elements (MEs), water-soluble ions (WSIs) and polycyclic aromatic hydrocarbons (PAHs) contained in indoor PM2.5. Therefore, firstly this study investigated indoor PM2.5 pollution to explore the distribution characteristics of MEs, WSIs and PAHs. Secondly, the carcinogenic risk of MEs and PAH to the population was analyzed using health risk assessment models. Finally, the sources of MEs and PAHs were identified using statistical analyses. The results of the study show that PM2.5 concentrations fluctuate between spring and winter, with the most significant fluctuations reaching around 100 mu g/m3 in March and January. Concentrations of most MEs, WSIs and PAHs during the heating season are twice as high as during the non-heating season. The main sources of MEs and PAHs are industrial, coal-fired emission sources, vehicle exhaust and metallurgical chemical emission sources. The non-carcinogenic and carcinogenic risks of metallic elements to the population are mainly due to Co, which contribute up to 80% in both adults and children. The carcinogenicity risk indices of the six monomeric PAHs, BaP, DbA, Bbf, Bkf, Inp and BaA, were greater than 10-6, indicating a potential carcinogenic risk.