Atmospheric concentrations of per- and polyfluoroalkyl substances in Michigan's ambient air using passive sampling

As a part of Michigan's efforts to identify and address per- and polyfluoroalkyl substances (PFAS) contamination statewide, more knowledge of atmospheric PFAS concentrations is needed to better understand their atmospheric transport and impact on other environmental media. This research aimed to measure atmospheric concentrations of PFAS in Michigan's ambient air using low-cost and easy-to-use passive samplers and identify relationships with environmental factors. Passive samplers, consisting of polyurethane foam (PUF) discs and sorbent-filled polyethylene tubes (radiello-XAD samplers), were deployed for a month at 27 sites across Michigan and analyzed for both ionic and volatile, neutral PFAS. Short chain perfluorocarboxylic acids (PFCAs), specifically perfluoropropanoic acid (PFPrA) (d.f. 60 %) and perfluorobutanoic acid (PFBA) (d.f. 96 %), and perfluorooctane sulfonic acid (PFOS) (d.f. 63 %) were the most frequently detected compounds, with the ∑₃PFAS ranging from non-detect to 15.5 pg/m³ for the PUFs and from non-detect to 248 pg/m³ in the radiello-XAD samplers. 6:2 fluorotelomer alcohol was also frequently detected (d.f. 45 %) and had a positive correlation with both population density (r = 0.52, p < .05) and industrial sites' density (r = 0.48, p < .05). Detection of specific compounds on each type of sampler provided insight into the preferential transport pathway of atmospheric PFAS. For example, PFOS was observed mostly in the gas-phase, predominantly captured by the radiello-XAD samplers, while PFBA was mostly in the particle-phase, predominantly captured by the PUFs. This study highlights the importance of developing detection tools for measuring atmospheric PFAS across a vast geographic area to identify contributing factors to ambient concentrations.