PFAS Sampling and Analysis of Indoor Air and Soil Gas
The risk assessment of per- and polyfluoroalkyl substances (PFAS) is complex, with an increasing number of compounds and environmental matrices being identified. Human exposure to PFAS typically occurs through food and drinking water, with exposure levels commonly compared to the tolerable weekly intake (TWI) established by the European Food Safety Authority (EFSA, 2020) for PFAS4 — comprising PFOS, PFOA, PFNA, and PFHxS — set at 4.4 ng/kg body weight/week. In addition to dietary sources, indoor air may represent a significant exposure pathway, as individuals spend approximately 90% of their time indoors. PFAS are frequently detected in indoor environments, and inhalation is increasingly recognized as an important exposure route, particularly for children (Morales-McDevitt et al., 2021).
PFAS volatility varies widely across compounds. Legacy PFAS, such as the PFAS4, are generally polar and charged, exhibiting low volatility. These compounds are therefore primarily associated with airborne particulate matter (ASTM D8560-24). In contrast, neutral compounds such as fluorotelomer alcohols (FTOHs), fluoroalkyl sulfonamides (FASAs), and fluoroalkyl sulfonamide ethanols (FASEs) can also be found in the gas phase.
Concentrations reported in the literature for indoor environments (homes, schools, offices) typically range from 1 to 100 ng/m³. Gas-phase PFAS are often dominated by 6:2 and 8:2 FTOHs, a pattern also confirmed in internal testing conducted by Eurofins. In soils contaminated by aqueous film-forming foams (AFFF), Eurofins has detected 6:2 FTOH in the gas phase of 6:2 FTAB-dominated soils. A U.S. EPA report (2023) reported sub-slab air and soil gas concentrations up to 18,000 µg/m³ at a PFAS production site. Regulatory frameworks are still evolving. A 2023 compilation by the Interstate Technology & Regulatory Council (ITRC) shows state-level guideline values ranging from 4 to over 10,000 ng/m³, depending on the specific PFAS compound and exposure duration.
In collaboration with the Eurofins European PFAS Competence Centre, Eurofins Pegasuslab has developed a comprehensive sampling concept for indoor air, sub-slab air, and soil gas. Building on our experience with active (pumped) PAH sampling, our method offers two major advantages:
- The ability to sample both neutral PFAS (e.g. FTOHs ranging from 6:2 to 12:2) and ionic PFAS (e.g., PFAS4) using a single sampler.
- The integration of both gas-phase and particulate-phase sampling for indoor air environments.
Two types of samplers are available, both XAD-2 based. The OVS-type sampler also includes a filter to capture particulate-bound PFAS. This approach allows for the detection of a wide range of PFAS compounds with low limits of quantification (LOQs), typically between 0.2 and 1 ng/m³ (based on a 1 m³ sample volume). Two analytical packages are offered:
- A targeted package based on experience from Eurofins studies, covering 16 analytes including FTOHs, FASAs/FASEs (e.g., EtFOSE, MeFOSE), and PFAS4.
- A screening package covering over 60 analytes.
This concept is suitable for investigating PFAS contamination in both buildings and soils, and for assessing occupational exposure. Sampling has been tested in various settings such as homes, offices, fire station and exercise sites, AFFF storage room and wastewater treatment plants. An overview is provided in our information sheet. Sampling instructions, including recommended pump flow rates and sampling durations, are available in a separate document. Eurofins Pegasuslab offers rental of calibrated pumps and soil gas sampling equipment (e.g. iron spears). Additionally, PFAS analysis in dust samples is available to support assessments of overall exposure and intake.
For more information on our sampling packages, equipment rentals, and analytical services, please visit our website or contact us at: info.pegasuslab@etn.eurofins.com, tel: 010-490 82 50