The Oregon Department of Environmental Quality has updated its guidance for evaluating
vapor intrusion at environmental cleanup, leaking underground storage tank, and heating oil tank sites. Vapor intrusion is the movement of contaminant vapors from spills or releases into buildings and is one of the most common ways that contamination from the environment impacts peoples' health. Vapor intrusion contaminants present ongoing potential health risks to all people who breathe impacted air in their homes or workplaces. Certain members of the population are more susceptible to vapor intrusion risks, such as children, older adults, unborn infants, people with disabilities, and those who live in areas impacted by multiple sources of pollution.
Final revised guidance, 2025
Oregon's final revised vapor intrusion guidance is available at the link below. If you would like assistance interpreting or implementing the revised guidance, please email the
Vapor Intrusion Workgroup at
VIWorkgroup@deq.oregon.gov. For project specific questions, please contact your DEQ project manager.
More information
The 2025 revision is the first update since DEQ's 2010 Vapor Intrusion Guidance. It includes substantial revisions to align with current science, standards of practice, and the U.S. Environmental Protection Agency's vapor intrusion screening levels. The revisions reflect internal and external review and feedback, including listening sessions and an informal public review period from March to June 2024. The revised guidance will improve DEQ's ability to protect people in Oregon, especially those most at risk, from health risks associated with vapor intrusion.
For a high-level overview of the vapor intrusion guidance, please review the executive summary in the guidance document or the slides from the listening sessions below. To request a recording of the listening sessions, please email the
Vapor Intrusion Workgroup at
VIWorkgroup@deq.oregon.gov.
Updated screening levels
DEQ uses screening levels called Risk Based Concentrations to make decisions about what is needed to address vapor intrusion health risks. The updated RBCs in the revised guidance incorporate EPA's vapor intrusion attenuation factors and the latest toxicity information, resulting in lower soil vapor and groundwater screening levels. Additionally, DEQ is no longer using soil RBCs to screen out risk from vapor intrusion because the latest scientific evidence shows that soil data does not reliably predict VI risk. DEQ also no longer considers the urban residential exposure scenario separately from residential exposure and is now using one set of vapor intrusion RBCs to evaluate all residential exposures. DEQ will update the vapor intrusion RBCs annually to remain consistent with the latest science from EPA's regional screening level updates. DEQ updated its vapor intrusion RBCs in June 2023 and issued its first annual update in March 2024. In March 2025, DEQ made the second annual update to the vapor intrusion RBCs.
The updated RBCs are also available on the Risk-Based Decision Making for the Remediation of Contaminated Sites web page.