Profiles of Neutral, Volatile Per- and Polyfluoroalkyl Substances (PFAS) in Residential Indoor Air and Particle Samples From the Indoor PFAS Assessment Campaign
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Per- and polyfluoroalkyl substances (PFAS) comprise >9,000 chemicals with a wide range of physicochemical properties. Many PFAS are used in building materials and consumer products, and thus, pose a potential exposure risk. However, PFAS levels and partitioning in indoor environments are not well understood. As part of UNC’s Indoor PFAS Assessment (IPA) Campaign, we measured PFAS in indoor air in 10 homes in North Carolina using PUF-XAD-PUF sandwich cartridges (72 h sampling duration, 5 L/min sampling flow rate), with and without an upstream quartz fiber filter (QFF). Total air (unfiltered) and gas-phase only (pre-filtered) samples were collected in each home at the beginning of the field campaign, and after 3 and 6 months. Samples were extracted and analyzed for eight neutral, volatile PFAS using gas chromatography/electron ionization-mass spectrometry (GC/EI-MS). The sum of neutral PFAS in total air samples ranged from 3-52 ng/m³. Concentration profiles varied strongly between and within homes, reflecting the dynamic nature of PFAS in indoor air. Most consistently, 6:2 and 8:2 fluorotelomer alcohol (FTOH) were found in all samples, accounting for 70-95% of measured neutral PFAS. Results for total air and gas-phase only samples were usually similar, indicating that neutral PFAS species are predominantly in the gas phase in indoor air. However, higher particle concentrations indoors were associated with larger differences between total air and gas-phase only samples. Analyses of QFFs placed upstream will be used to further assess the presence of neutral PFAS in airborne particles in homes. This will allow discussion of the dependence of PFAS profiles and partitioning on physicochemical properties, particle concentrations, and other factors.