The U.S. Environmental Protection Agency (EPA) recently issued draft final versions of two separate vapor-intrusion guidance documents. The first is the OSWER (Office of Solid Waste and Emergency Response) Final Guidance for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Sources to Indoor Air, which applies to actions under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA). According to the guide, “EPA has broad authority to assess and, if warranted, mitigate vapor intrusion in residential and nonresidential settings arising from subsurface contamination by hazardous chemicals.”

Meanwhile, a second document, titled “Guidance for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites,” which is produced by EPA’s Underground Storage Tank Program, focuses on underground storage tanks and petroleum vapor intrusion, which may not be subject to either CERCLA or RCRA. Both drafts describe various approaches to identifying, monitoring and mitigating vapor-intrusion risks.