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Vapor Intrusion


In June 2015, EPA issued the OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor AirAdobe PDF Logo as well as the Technical Guide For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank SitesAdobe PDF Logo. Together, these guides supersede and replace EPA's 2002 Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils. In addition to these two guidance documents, EPA has published numerous documents focusing on various aspects of vapor intrusion. Other federal agencies such as the Agency for Toxic Substances and Disease Registry (ATSDR) within the Center for Disease Control (CDC) and the Department of Defense (DoD) have also developed guidance and resource documents addressing vapor intrusion. Non-governmental entities such as the Interstate Technology Regulatory Council (ITRC) and the American Petroleum Institute (API) have also published guidance on vapor intrusion.

Guidance documents are grouped by the following:


Adobe PDF LogoOSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air
U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI), 2015.

Guide describes a recommended framework for assessing vapor intrusion that relies upon collecting and evaluating multiple lines of evidence to support risk management decisions. It also provides technical recommendations about monitoring and terminating building mitigation systems.

Adobe PDF LogoTechnical Guide for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites
U.S. EPA Office of Underground Storage Tanks, 2015.

The Petroleum Technical Guide provides technical information to regulatory personnel from EPA and state, tribal, and local agencies for investigating and assessing petroleum vapor intrusion at sites where petroleum hydrocarbons (PHCs) have been released from underground storage tanks (USTs). The second part, "Supporting Technical Information," provides detailed technical information supporting the guide's recommendations.

Technical documents intended to facilitate consideration of the recommendations in the Technical Guide can be found in EPA's Petroleum Vapor Intrusion (PVI) Compendium.

Vapor Intrusion Screening Level (VISL) Calculator
U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI). Updated February 2018.

The U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI) developed an online tool that: (1) lists chemicals considered to be volatile and sufficiently toxic through the inhalation pathway; and (2) provides VISLs for groundwater, soil gas and indoor air, which are generally recommended, media-specific, risk-based screening-level concentrations. The primary purpose of the VISL calculator is to assist Superfund site managers and risk assessors in determining, based on an initial comparison of site data against the VISLs: whether chemicals found in groundwater or soil gas can pose a significant risk through vapor intrusion; and, if so, whether a site-specific vapor intrusion investigation is warranted. Other Agency cleanup programs may also find it helpful to consider the VISLs for their own specific needs. VISL Users Guide

Adobe PDF LogoPetroleum Hydrocarbons And Chlorinated Hydrocarbons Differ In Their Potential For Vapor Intrusion
U.S. Environmental Protection Agency, 13 pp, September 2011.

Discusses and compares petroleum vapor intrusion (PVI) and chlorinated solvent vapor intrusion with respect to processes that influence whether and how vapors can migrate through vadose zone materials into buildings and other confined spaces as well as some implications for addressing PVI.

Indoor Air Vapor Intrusion Mitigation Approaches
Science Applications International Corporation. Engineering issue: Indoor Air Vapor Intrusion Mitigation Approaches. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-08/115. 49 pp. 2008.

Engineering Issue Paper explains the range of soil and groundwater vapor intrusion mitigation technologies available. It also provides information on selecting appropriate technologies in consultation with qualified engineering and risk management professionals. It provides information for making appropriate selections and evaluating the recommendations of mitigation contractors and engineers.

Assessing Protectiveness at Sites for Vapor Intrusion: Supplement to the "Comprehensive Five-Year Review Guidance"
OSWER Directive 9200.2-84, 12 pp, November 2012.

This brief supplemental guidance provides recommendations for assessing VI remedy protectiveness at private and federal facility Superfund sites during the review process described in EPA's 2001 Comprehensive Five-Year Review Guidance. It also contains recommendations for assessing protectiveness at sites where a VI remedy has not been implemented and (1) the VI pathway was never adequately characterized, or (2) changes in site conditions since the last 5-year review have potentially led to a complete VI pathway.

Adobe PDF LogoEvaluation Of Empirical Data To Support Soil Vapor Intrusion Screening Criteria For Petroleum Hydrocarbon Compounds
Hers, I. and R.S. Truesdale. EPA 510-R-13-001, 144 pp, 2013.

This report presents an evaluation of empirical data and select modeling studies of the behavior of petroleum hydrocarbon (PHC) vapors in subsurface soils at petroleum release sites and how these vapors can affect subsurface-to-indoor air vapor intrusion. Specifically, the report develops an inclusion distance approach for screening petroleum release sites for vapor intrusion that should improve the efficiency of petroleum release site investigations and help focus resources on the sites of most concern for petroleum vapor intrusion (PVI).

Adobe PDF LogoOperational and Functional Determination and the Transfer of Fund-lead Vapor Intrusion Mitigation Systems to the State (OSWER 9200-2.72)
U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI) 4 pp, April 9, 2009.

Directive presents the Office of Superfund Remediation and Technology Innovation's guidance for making the operational and functional determination for vapor intrusion mitigation systems when these systems transfer to the state agency for operation and maintenance.


EPA Region 5

Adobe PDF LogoVapor Intrusion Handbook
U.S. EPA Region 5 Superfund and Emergency Management Division, March 2020.

The VI Policy Workgroup prepared this handbook for the Superfund and Emergency Management Division (SEMD), particularly On-Scene Coordinators (OSC) and Remedial Project Managers (RPM). Other programs, agencies, and individuals, such as Brownfields Project Managers (BPM) and state environmental programs, may find this document useful.

Vapor Intrusion ToolBox
On Scene Coordinator Response - EPA Region 5

This Vapor Intrusion Toolbox is used to post documents and resources for On-Scene Coordinators (OSCs) and Remedial Project Managers (RPMs) to use in addressing vapor intrusion at sites.


Other Federal Agencies

Center for Disease Control (CDC)

Adobe PDF LogoEvaluating Vapor Intrusion Pathways
Agency for Toxic Substances and Disease Registry (ATSDR), Center for Disease Control (CDC). 2016.

This is a technical supplement to the January 2005 ATSDR Public Health Assessment Guidance Manual. The document provides ATSDR health assessors with guidance on evaluating the public health implications of vapor intrusion.

Department of Defense (DoD)

Adobe PDF LogoContinuous Monitoring for Vapor Intrusion (Fact Sheet)
Naval Facilities Engineering Systems Command, Environmental Restoration and BRAC (NAVFAC ERB), 4 pp. 2021.

This fact sheet discusses the assessment of vapor intrusion (VI) which are complicated by a high degree of spatial and temporal variability. The fact sheet focuses on recent applications of a continuous monitoring (CM) technology that provides quantitative measurements of vapor concentrations in the field. CM can help to address site-specific building conditions that influence the VI pathway over time.

Adobe PDF LogoNAVFAC/ Navy and Marine Corps Public Health Center (NMCPHC) Guidance for Communicating Vapor Intrusion at Environmental Restoration Sites
Naval Facilities Engineering Command and Navy and Marine Corp Public Health Center. 46 pp. October 2014.

Provides RPMs with recommendations for notifying and relaying information regarding VI investigations to Base personnel and potentially affected occupants of industrial, office, or residential buildings.

Adobe PDF LogoNAVFAC Interim Final Guidance for Environmental Background Analysis Volume IV: Vapor Intrusion Pathway
User's Guide-2091-ENV. 163 pp. April 2011.

Reviews methodologies for assessing potential background sources to indoor air as a part of the assessment of the VI pathway.

Tri-Service Environmental Risk Assessment Workgroup: Vapor Intrusion Fact Sheets

A series of fact sheets has been prepared by DoD's Tri-Service Environmental Risk Assessment Workgroup to update and supplement the DoD Vapor Intrusion Handbook (2009). Begun in 2017, this fact sheet series covers sampling and assessment techniques that allow for an improved understanding of VI given temporal variability and the potential for the presence of background sources of VOCs. The 2019 fact sheet update presents a matrix for selecting VI investigation technologies and ranks the various technologies to facilitate selection of an effective approach. Selection is based on the specific investigation objectives, including characterization of subsurface sources, evaluation of vadose zone vapor migration pathways, and investigation of a building's sub-slab region and interior. The following fact sheet updates have been posted:

View the fact sheets on the DENIX VI web page at

Adobe PDF LogoPassive Sampling for Vapor Intrusion Assessment
Technical Memorandum TM-NAVFAC EXWC-EV-1503. 20 pp. July 2015.

Describes the basics of passive sampler theory and design, the available types of passive samplers, the advantages and limitations of passive samplers, and important considerations when implementing a passive sampling program. In addition, results from two VI case studies are highlighted.

Adobe PDF LogoDoD Vapor Intrusion Handbook
Prepared by the Tri-Service Environmental Risk Assessment Workgroup, 172 pp, January 2009.

The handbook was developed as a tool to assist DoD installations with evaluating and investigating the vapor intrusion pathway at sites conducting response actions under the Defense Environmental Restoration Program (DERP). DoD facilities should evaluate the vapor intrusion pathway when volatile chemicals are present in soil, soil gas, or groundwater underlying existing structures and a complete human exposure pathway may be present, consistent with DERP and DERP management guidance.

Adobe PDF LogoNavy/Marine Corps Policy on Vapor Intrusion
5 pp, April 29, 2008.

Adobe PDF LogoInterim Final Guidance for Environmental Background Analysis, Volume IV: Vapor Intrusion Pathway
User's Guide UG-2091-ENV. 153 pp. April 2011.

Reviews methodologies for assessing potential background sources to indoor air as a part of the assessment of the VI pathway.

Adobe PDF LogoA Quantitative Decision Framework for Assessing Navy Vapor Intrusion Sites
Venable, P., T. Chaudhry, D. Caldwell, I. Rivera-Duarte, C. Lutes, L. Lund, and K. Hallberg.
Navy Environmental Sustainability Development to Integration (NESDI) Program, NESDI #476, TR-NAVFAC-EXWC-EV-1603, 581 pp, 2015.

This decision framework is focused on chlorinated hydrocarbon sources, which represent a large potential Navy VI source. Petroleum hydrocarbon information is included in the database only as found commingled with CVOCs.

Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol
McHugh, T. and L. Beckley. ESTCP Project ER-201505, 2018.

This technical information can help practitioners develop more accurate conceptual site models about conduit vapor intrusion, Project objectives were to (1) develop and validate an effective protocol to determine the presence or absence of a sewer/utility tunnel preferential pathway during a VI investigation (i.e., is a sewer/utility transporting VOCs from a subsurface source causing unacceptable buildings impacts?); (2) apply the validated protocol at VI sites to evaluate how often sewer/utility preferential pathways play a role in VOC transport into buildings; and (3) use the results to develop a detailed conceptual model for preferential pathways that identifies the types of sites at risk and the key mechanisms and processes involved in VOC transport through preferential pathways. The following reports were completed: Investigation Protocol (27 pp)Adobe PDF Logo; Conceptual Model (20 pp)Adobe PDF Logo; Final Report (790 pp)Adobe PDF Logo; Executive Summary (26 pp)Adobe PDF Logo


Non-Governmental Agencies and States

Individual States

Several state environmental agencies offer additional guidance documents on various aspects of vapor intrusion. To find the latest guidance and requirements for state environmental programs, consult the appropriate state agency website.

Interstate Technology and Regulatory Council (ITRC)

Petroleum Vapor Intrusion, Fundamentals of Screening, Investigation, and Management
Interstate Technology & Regulatory Council (ITRC), Vapor Intrusion Guidance Document PVI-1., 2014.

ITRC has developed a guidance document that provides and 8-step process for assessment and management of vapor intrusion at petroleum contaminated sites. Methods for screening as well as tools and strategies for evaluating the vapor intrusion pathway are provided.

Technical Resources for Vapor Intrusion Mitigation
Interstate Technology & Regulatory Council (ITRC) Vapor Intrusion Mitigation Team, Report No: VIM-1, 2021.

ITRC has developed nine fact sheets and one technology information sheet for emerging technology to summarize the latest science, practices, and new approaches for vapor intrusion mitigation. The documents are designed for state and federal environmental staff, and others (including stakeholders, project managers, and decision-makers), to gain a working knowledge of vapor mitigation and practice. While every effort was made to keep the information accessible to a wide audience, it is assumed the reader has some basic technical background in chemistry, environmental sciences, risk assessment, and vapor intrusion.


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