Distributions and partitioning of airborne Per- and Polyfluoroalkyl Substances (PFAS) in urban atmosphere of Northern New Jersey

This study collected gas-phase and particulate samples, wet deposition, and total deposition from the urban atmosphere in Northern New Jersey to determine the atmospheric characteristics of airborne ionic Per- and Polyfluoroalkyl Substances (PFAS). The results showed higher PFAS concentrations in the gas phase (197.7 ± 47.9 pg·m⁻³) compared to the particulate samples (48.3 ± 47.9 pg·m⁻³), indicating higher inhalation risks to human health. Short-chain alternative PFAS, such as perfluoroheptanoic acid (PFHpA), had higher concentrations in the gas-phase than the US EPA-regulated PFAS (e.g., PFHpA reached 142.6 ± 28.0 pg·m⁻³). Additionally, PFHpA had the lowest rain-air partition coefficient, suggesting its preferential distribution in the gas phase. In contrast, perfluorohexanoic acid (PFHxA) exhibited the highest levels of both the total deposition rate (12.4 ± 29.0 μg·m⁻² yr⁻¹) and wet deposition rate (40.2 ± 76.0 μg·m⁻² yr⁻¹) among the 24 PFAS analyzed in this study. Most PFAS had higher wet deposition fluxes than total deposition fluxes, indicating they may predominately accumulate at the water-air interfaces and could re-enter the atmosphere. Legacy perfluorooctanoic acid (PFOA) still had the highest concentrations (12.3 ± 8.5 pg·m⁻³) in particulate samples, ranking second in both gas-phase and total deposition samples and third in wet deposition samples. The results reveal that airborne PFAS in urban environments could pose negative impacts on human health and the natural environment.