Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air applies to all sites being evaluated under federal land cleanup statutes by EPA, other federal agencies, state and tribal governments, and brownfield grantees. Technical Guide for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites addresses any sites where vapor intrusion related to petroleum contamination from underground storage tanks is a concern.