Shijie Liu

Per- and polyfluoroalkyl substances (PFASs) are a global concern because of their toxicity and persistence, yet seasonal dynamics, pollution-level dependencies, and inhalation risks of PM_2.5-bound PFASs in haze-prone industrial cities remain underexplored. This study investigated 163 PM_2.5 samples collected from December 2023 to November 2024 in Jinan—a typical industrial city—and quantified 17 PFASs via LC-MS/MS. The results showed that total concentrations (∑PFASs) rank winter (133.8) > autumn (123.6) ≈ summer (123.5) > spring (97.1 pg·m⁻³). In summer and autumn, PFAS concentrations were numerically higher on clean days than on slightly polluted days. This may suggest that good air quality does not necessarily guarantee low PFAS levels. Spearman correlation analysis showed no significant monotonic relationships between ΣPFASs and individual meteorological variables. However, compound-specific responses to temperature, humidity, and wind speed exhibited chain-length dependence. Inhalation-risk evaluation of the 15 assessable PFASs showed that PFOA and short-chain PFCAs co-dominated estimated daily intake (73.1%), whereas PFOA dominated estimated risk (95.6%). Several compounds (e.g., PFHxA, PFOS) showed numerically higher risk values on clean or slightly polluted days than on polluted days. This suggests the need for species-specific evaluation. This study provides critical evidence of PFASs’ atmospheric behavior in haze-affected industrial settings and provides a scientific basis for prioritizing control species.

Enhanced ozone (O₃) pollution has emerged as a pressing environmental concern in China, particularly for densely populated megacities and major city clusters. However, volatile organic compounds (VOCs), the key precursors to O₃ formation, have not been routinely measured. In this study, we characterize the spatial and temporal patterns of VOCs and examine the role of VOCs in O₃ production in five cities (Dongying (DY), Rizhao (RZ), Yantai (YT), Weihai (WH), and Jinan (JN)) in the North China Plain (NCP) for two sampling periods (June and December) in 2021 through continuous field observations. Among various VOC categories, alkanes accounted for the largest proportion of VOCs in the cities. For VOCs, chemical reactivities, aromatic hydrocarbons, and alkenes were dominant contributors to O₃ formation potential (OFP). Unlike inland regions, the contribution to OFP from OVOCs increased greatly at high O₃ concentrations in coastal regions (especially YT). Model simulations during the O₃ episode show that the net O₃ production rates were 27.87, 10.24, and 10.37 ppbv/h in DY, RZ, and JN. The pathway of HO₂ + NO contributed the most to O₃ production in JN and RZ, while RO₂ + NO was the largest contributor to O₃ production in DY. The relative incremental reactivity (RIR) revealed that O₃ formation in DY was the transitional regime, while it was markedly the VOC-limited regime in JN and RZ. The O₃ production response is influenced by NOx concentration and has a clear daily variation pattern (the sensitivity is greater from 15:00 to 17:00). The most efficiencies in O₃ reduction could be achieved by reducing NOx when the NOx concentration is low (less than 20 ppbv in this study). This study reveals the importance of ambient VOCs in O₃ production over the NCP and demonstrates that a better grasp of VOC sources and profiles is critical for in-depth O₃ regulation in the NCP.