Effect of per and polyfluoroalkyl substances (PFAS) molecular properties on aerosolisation and size resolved distributions

Per and polyfluoroalkyl substances (PFAS), a class of toxic compounds often referred to as “forever chemicals”, are increasingly detected in the atmosphere. Aerosolisation from contaminated aqueous reservoirs has been proposed as a pathway for atmospheric PFAS, drawing analogy to sea-spray processes and supported by their elevated concentrations reported near sewage treatment facilities (Kizhakkethil et al., 2025). However, aerosolisation and particle formation in anthropogenically impacted waters differ fundamentally from marine systems, and the physico chemical controls governing PFAS aerosolisation outside the marine context remain poorly understood.

The aim of this work was to investigate the effect of PFAS molecular properties, including carbon chain length and functional groups, on aerosolisation from contaminated aqueous solutions. Experiments were conducted in the Chamber for Aerosol Modelling and Bio-aerosol Research (ChAMBRe), Italy. Twenty five PFAS, covering short, medium and long chain perfluoroalkyl carboxylic acids, perfluoroalkane sulfonates, fluorotelomer sulfonates and emerging alternatives representative of wastewater impacted environments were investigated. The role of bioaerosol seed particles commonly present in such environments was also assessed, as they could act as sinks or carriers for highly surface active PFAS and thereby influence their aerosol phase distribution.

Aerosol mass size distributions revealed a strong dependence on molecular structure, indicating compound-specific particle-phase behaviour. The presence of biological particles did not systematically alter PFAS size-resolved distributions, suggesting that the studied PFAS exhibited limited interaction with bioaerosols and remained predominantly in the submicron size range under the investigated conditions, which may favour their atmospheric persistence and long-range transport.

Overall, these findings indicate that primary aerosol formation from contaminated aqueous systems represents a chemically selective pathway for introducing PFAS into the organic aerosol, with size-resolved characteristics governed primarily by molecular properties and aerosol formation processes.

Reference: Kizhakkethil, J. P., Shi, Z., Bogush, A., and Kourtchev, I.: Measurement report: Per- and polyfluoroalkyl substances (PFAS) in particulate matter (PM10) from activated sludge aeration, Atmos. Chem. Phys., 25, 5947–5958, https://doi.org/10.5194/acp-25-5947-2025, 2025.