Seasonal variation and inhalation health risk of atmospheric polyfluoroalkyl and perfluoroalkyl substances in a metropolitan city centre of southwest China

Fifty-six total suspended particle (TSP) samples, covering four seasons from April 2022 to January 2023, were collected from the centre of Chongqing, a metropolitan city of southwest China, using an aerosol sampler. The samples were analyzed for 20 targeted poly- and per-fluoroalkyl substances (PFAS) by HPLC-MS/MS. The concentrations of PFAS ranged from 125 pg/m3 to 200 pg/m3 and were dominated by perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), 2-perfluorohexyl ethanoic acid (6:2 FTCA) and perfluorooctane sulfonate (PFOS). Seasonal variations of PFAS were distinct, with the highest concentrations in winter, followed by autumn, and with lowest levels in summer. Positive matrix factorization (PMF) and a dry deposition model were used to apportion sources and to estimate the dry deposition fluxes of the 20 PFAS, respectively. PMF analysis indicated that, based on the annual average, paper packaging production (28.1%) and the degradation of precursor compounds and emissions from PFCA production (27.8%) were the two major sources, followed by electronic product manufacturing (24.0%) and textile production (20.1%), although there were significant differences in sources between seasons. The average annual dry deposition flux of PFAS was estimated to be 18.0 ng/m2/day. However, the wet deposition of PFAS was estimated to account for 82.2% of the total atmospheric deposition flux, suggesting it plays a more important role. Estimated daily intakes (EDI) and hazard quotients (HQ) were utilized to evaluate the risks to humans via exposure to PFAS through inhalation and were found to be insignificant (HQ << 1). This study provides important information on the contamination status and exposure risk for atmospheric PFAS in a mountainous megacity, and for similar urban centers across China.