Some key research gaps in vapor intrusion for PFAS (Per- and Polyfluoroalkyl Substances) based on peer-reviewed research journals, particularly focusing on "no risk values," include the limited data on the volatility and vapor pressure of various PFAS compounds, which are crucial for understanding their potential for vapor intrusion. The mechanisms by which PFAS compounds migrate from subsurface sources to indoor air are not well understood, including the role of soil and groundwater in the transport process. Additionally, there is a lack of comprehensive indoor air sampling data for PFAS, which is necessary to assess the extent of vapor intrusion and its impact on indoor air quality. Effective remediation techniques for addressing PFAS vapor intrusion are still under development, necessitating research to identify and optimize methods for mitigating PFAS vapor intrusion. Furthermore, there is a need for clear regulatory guidelines and standards for assessing and managing PFAS vapor intrusion, including establishing acceptable indoor air concentration levels for various PFAS compounds. These research gaps highlight the need for further investigation to better understand and manage the risks associated with PFAS vapor intrusion.

Some relevant publications on this topic can be found

US EPA’s Science-Based Approach to Understanding and Managing .... https://www.epa.gov/sites/production/files/2020-09/documents/epa_pfas_rd_overview_complete_2020_09_25.pdf.

Occupational exposure to per- and polyfluoroalkyl substances: a scope .... https://www.nature.com/articles/s41370-023-00536-y.pdf.

Vapor Intrusion Potential of Select Per- and Polyfluoroalkyl ... - SSRN. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4548450.

A Critical Review and Meta-Analysis of Impacts of Per- and .... https://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2022.881584/full.

Frontiers | Per-and poly-fluoroalkyl substances (PFAS) effects on lung .... https://www.frontiersin.org/journals/toxicology/articles/10.3389/ftox.2024.1423449/full.

Comprehensive Review of Global Perspectives on Per- and ... - MDPI. https://www.mdpi.com/2073-4441/16/11/1583.

Fate and Transport of Per- and Polyfluoroalkyl Substances (PFAS). https://pfas-1.itrcweb.org/wp-content/uploads/2020/10/f_and_t_508_2020Aug.pdf.