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The concentrations of ambient fine particulate matter (PM2.5) and its compositions in urban Taiyuan, China during a typical winter and summer time period in 2017 were measured to investigate the pollution characteristics, source apportionment and health risks assessment of PM2.5 pollution. The results demonstrated that the mean daily mass concentration of PM2.5 in winter (102.6 ± 6.2 μg/m3) was higher than that in summer (65.0 ± 17.2 μg/m3) during sampling. The relatively high concentrations of heavy metals (Zn, Pb, Cu, As, Ni, Cr and Cd), anion (SO42−, NO3−, Cl− and F−) and high-molecular-weight PAHs in PM2.5 were observed. The enrichment factors (EFs) values, special diagnostic ratios like ratios of NO3−/SO42− and individual PAHs concentration ratio showed that coal combustion and vehicle emissions were the major sources of PM2.5 pollution. Health risk assessment illustrated that mean hazard indices for non-cancer and cancer risk of all analyzed metals were within the safe range. However, inhalation exposure to PM2.5-bound PAHs had carcinogenic risk, while not indicating non-carcinogenic risk. Taken together, although PM2.5 pollution was alleviated to some extent, PM2.5 pollution in 2017 was still serious and PM2.5 was mainly originated from coal burning, especially, in which PM2.5-bound PAHs in Taiyuan may pose a potential health risk. [ABSTRACT FROM AUTHOR]

We reported the discovery and identification of emerging sulfur-containing polycyclic aromatic hydrocarbons, namely polycyclic aromatic sulfur heterocycles (PASHs), in PM 2.5 collected from two typical regions of China, Taiyuan and Guangzhou. Until now, there is no research on contamination status, sources and potential health risks of this unexpected group of organic contaminants in PM 2.5. High atmospheric concentrations (ng m−3) and significant time-dependent variations were determined in PM 2.5 of Taiyuan from 2017 to 2018. Coal combustion/secondary formation and traffic emission/secondary formation were apportioned as possible pollution sources for the PM 2.5 -bound PASHs in Taiyuan and Guangzhou, respectively. Dithiothreitol and cell viability assays were applied for evaluations of PASH-induced reactive oxygen species (ROS) production and cell toxicity based on the determined real exposure levels for adults. The results illustrated that PASHs in PM 2.5 possibly caused oxidative stress and inhibition of human bronchial epithelial cells in seriously polluted regions such as Taiyuan, suggesting that the pollutant-induced health concerns may need more investigations. This study provides new insights into PM 2.5 pollution, and is beneficial for the development of effective contamination control strategies and reduction of risks on public health. [Display omitted] • Detailed contamination levels of PM 2.5 -bound PASHs were firstly studied. • Different pollution sources were identified in Taiyuan and Guangzhou. • The PM 2.5 -bound PASHs possessed potential health risks for human inhalation. [ABSTRACT FROM AUTHOR]