Characteristics and human inhalation exposure of ionic per- and polyfluoroalkyl substances (PFASs) in PM of cities around the Bohai Sea: Diurnal variation and effects of heating activity.

Atmospheric PM (particulate matter with aerodynamic diameter <10 μm) samples were collected in the cities along the Bohai Sea Rim during heating and non-heating periods, and ionic per- and polyfluoroalkyl species (PFASs) in the PM were measured. The total concentration of ionic PFASs ranged from 21.8 to 87.0 pg/m, and the mean concentration of ionic PFASs during the day (42.6 pg/m) was slightly higher than that at night (35.1 pg/m). Generally, diurnal variations in the levels of ionic PFASs were consistent with those in the PM concentrations. Perfluorooctanoic acid (PFOA, 23.5-33.7%), perfluoropentanoic acid (PFPeA, 28.3-39.9%) and perfluorobutyric acid (PFBA, 17.1-20.1%) accounted for the dominant compositional contributions. Significant positive correlations (p < 0.05) between the main components of PFASs and O implied that oxidative degradation (O served as the main oxidant) in the period of non-heating may affect the short-chain PFASs. The clustering analysis of a 72-h backward trajectory indicated that cross-provincial transport contributed to ionic PFASs at the sampling sites. Compared with ingestion via daily diet, the inhalation of PM exhibited an insignificant contribution to the estimated average daily intakes (ADIs) of PFASs by different age groups. In addition, the calculated hazard ratios (HRs) for the non-cancer respiratory risk, based on the air concentrations of PFOA and perfluorooctane sulfonate (PFOS), also manifested lower non-cancer risk through inhalation exposure. CAPSULE: The effects of heating and non-heating activity and diurnal variation on the concentrations of PFASs, dominated by PFOA, PFPeA, and PFBA in PM, were determined, and atmospheric trans-provincial input served as an important source.