U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

For more information on Vapor Intrusion, please contact:

Michael Adam
Technology Integration and Information Branch

PH: (703) 603-9915 | Email: adam.michael@epa.gov

Vapor Intrusion

Policy and Guidance

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In June 2015, EPA issued the OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air as well as the Technical Guide For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites. Together, these guides supersede and replace EPA’s 2002 Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils.

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

The Technical Guide presents EPA's current recommendations for how to identify and consider key factors when:

  • Assessing vapor intrusion in both residential and nonresidential buildings.
  • Making risk management decisions.
  • Implementing mitigation.

It 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.

The Technical Guide is intended for use at any site being evaluated by EPA pursuant to CERCLA or RCRA corrective action, EPA's brownfield grantees, or state agencies acting pursuant to CERCLA or an authorized RCRA corrective action program where vapor intrusion may be of potential concern. Although the Technical Guide is intended for use at any site subject to federal statutes, regulations, and rules, it is not intended to alter existing requirements, guidance, or practices among OSWER's programs about circumstances for reviewing past risk management and cleanup decisions. Section 121 of CERCLA requires remedy reviews when hazardous substances remain on site. EPA's other land restoration programs (e.g., RCRA corrective action, brownfield redevelopment) will continue to rely upon their existing, respective practices to address the need, if any, for periodic reviews of cleanup decisions, including consideration of the vapor intrusion pathway.

Adobe PDF LogoTechnical Guide For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites
U.S. EPA, Office of Underground Storage Tanks.
U.S. EPA Office of Underground Storage Tanks (OUST), 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.

The Petroleum Technical Guide focuses on releases of petroleum-based fuels (e.g., gasoline and diesel), including both PHCs and non-PHC fuel additives, from underground storage tanks (USTs) regulated under Subtitle I of the Solid Waste Disposal Act of 1984, which are typically located at gas stations. The guide applies to new and existing releases of PHCs and non-PHC fuel additives from leaking USTs and to previously closed sites where the implementing agency has reason to suspect that there may be a potential for PVI. Although EPA developed the Petroleum Technical Guide based on data from typical UST sites, this technical guide may also be helpful when addressing petroleum contamination at comparable non-UST sites. Petroleum contamination at sites that are not comparable to UST sites (such as refineries, petrochemical plants, terminals, aboveground storage tank farms, pipelines, and large scale fueling and storage operations at federal facilities), or sites with releases of non-petroleum chemicals including comingled plumes of petroleum and chlorinated solvents regardless of the source, should be addressed under OSWER's Technical Guide above.

Technical documents intended to facilitate consideration of the recommendations in the Technical Guide For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites (EPA 2015b) can be found in EPA's Petroleum Vapor Intrusion (PVI) Compendium.

Vapor Intrusion Screening Level (VISL) Calculator (MS Excel)
U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI), 2015

The U.S. EPA Office of Superfund Remediation and Technology Innovation (OSRTI) developed a spreadsheet 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 GuideAdobe PDF Logo

Adobe PDF LogoEPA's Vapor Intrusion Database: Evaluation and Characterization of Attenuation Factors for Chlorinated Volatile Organic Compounds and Residential Buildings
Dawson, H.E. and R.B. Kapuscinski.
EPA 530-R-10-002, 188 pp, 2012.

This report provides updated information about the design, structure, and content of EPA's vapor intrusion database, which supersedes EPA's 2008 preliminary report on the database. Technical information is presented about sites in the United States that have been investigated for vapor intrusion. The primary focus is the evaluation of concentrations of chlorinated VOCs in and beneath residential buildings based on EPA's vapor intrusion data as of 2010. This report was peer reviewed under a different working title: U.S. EPA's Vapor Intrusion Database: Preliminary Evaluation of Attenuation Factors.

Adobe PDF LogoConceptual Model Scenarios for the Vapor Intrusion Pathway
Abreu, L. and H. Schuver.
EPA 530-R-10-003, 154 pp, 2012.

The simulation results presented in this document illustrate how different site and building conditions might influence both the distribution of VOCs in the subsurface and the indoor air quality of structures in the vicinity of a soil or groundwater VOC source. This information can help practitioners develop more accurate conceptual site models, design better sampling plans, and better interpret the results of site investigations.

Adobe PDF LogoSuperfund Vapor Intrusion FAQs
56 pp, February 2012.

A team of Headquarters and Regional EPA staff developed answers to a collection of Frequently Asked Questions (FAQ) about VI at Superfund sites. These FAQs provide information and recommendations based on experiences garnered over the last few years in addressing VI at Superfund remedial and removal sites and cleanups undertaken using other statutory authorities. The primary purpose of this document is to help Superfund site managers understand some of the key concepts related to assessment and mitigation of the VI pathway and to help foster appropriate consistency in technical approach. Other OSWER cleanup programs may find it helpful to consider parts of the FAQs for their own specific needs.

Petroleum Hydrocarbons And Chlorinated Hydrocarbons Differ In Their Potential For Vapor IntrusionAdobe PDF Logo
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.

Adobe PDF LogoBackground Indoor Air Concentrations of Volatile Organic Compounds in North American Residences (1990-2005): A Compilation of Statistics for Assessing Vapor Intrusion
(EPA 530-R-10-001)
EPA, 67 pp, June 2011.

Technical report presents a summary of indoor air studies that measured background concentrations of VOCs in the indoor air of thousands of North American residences and an evaluation and compilation of the statistical information reported in these studies. The objective of this compilation is to illustrate the ranges and variability of VOC concentrations in indoor air resulting from sources other than vapor intrusion.

Indoor Air Vapor Intrusion Mitigation Approaches
49 pp, October 2008.

Engineering Issue Paper explains the range of 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.

OSWER Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils
178 pp, November 2002.

OSWER draft guidance provides technical and policy recommendations on determining if the vapor intrusion pathway poses an unacceptable risk to human health at cleanup sites. The guidance is intended to aid in evaluating the potential for human exposure from this pathway given the state-of-the-science at this time. EPA is continuing to explore this area in an effort to improve the state-of-the-science of this complex exposure pathway. An updated and final guidance on vapor intrusion is targeted for November 2012.

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. This guide lists factors relevant to VI that should be considered for each of the three major questions in the 2001 guidance: (A) Is the remedy functioning as intended by the decision documents? (B) Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives used at the time of the remedy selection still valid? (C) Has any information come to light that could call into question the remedy's protectiveness?

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)
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 state for operation and maintenance.

Region 2

Vapor Intrusion Frequently Asked Questions

Region 5

Vapor Intrusion Guidebook Adobe PDF Logo
323 pp, October 2010.

On-Scene Coordinator Vapor Intrusion ToolBox

Region 6

Adobe PDF LogoDraft Interim EPA Region 6 Corrective Action - Vapor Intrusion Frequently Asked Questions (FAQs)
10 pp, January 3, 2011.

Region 7

Fact Sheet: What You Should Know About Vapor Intrusion
February 2010.


In addition to EPA guidance, guidance on vapor intrusion investigation and mitigation has been prepared by the Interstate Technology and Regulatory Council, the Association of State and Territorial Solid Waste Officials, and many of the state environmental regulatory agencies.

Interstate Technology and Regulatory Council

In 2007, the Interstate Technology & Regulatory Council (ITRC)─ a coalition of states, the District of Columbia, tribal and industrial representatives, and several federal partners─published Vapor Intrusion Pathway: A Practical Guideline, which is a framework intended for use with existing state and federal guidance or policy. This framework incorporates multiple lines of evidence and follows a 13-step approach to evaluating the potential for vapor intrusion. This guidance also provides detailed information on site investigation and mitigation approaches. ITRC’s companion document,Vapor Intrusion Pathway: Investigative Approaches for Typical Scenarios, walks users through using the guidance for varying scenarios, such as different contaminated properties and different receptors.

Petroleum Vapor Intrusion: Fundamentals of Screening, Investigation, and Management
387 pp, October 2014.

Vapor Intrusion Pathway: A Practical GuideAdobe PDF Logo
172 pp, January 2007.

Vapor Intrusion Pathway: Investigative Approaches for Typical Scenarios Adobe PDF Logo
52 pp, January 2007.

Association of State and Territorial Solid Waste Managers Officials

The Association of State and Territorial Solid Waste Managers Officials (ASTSWMO) developed this document to provide state federal facilities managers with a compendium of available EPA, DoD, and state regulations, policies, and guidance materials. It provides a basic understanding of available guidance and policies that aid in the incorporation of this pathway to the overall site remediation conceptual model.

Vapor Intrusion Pathway: A Guide for State and Territorial Federal Facilities Managers Adobe PDF Logo
90 pp, July 2009.

Individual States

State guidance, where it exists, supersedes the existing EPA guidance documents. State guidance documents range in scope and address varying issues related to vapor intrusion. Several state documents base their approach to assessing vapor intrusion on the 2002 draft OSWER guidance, but have modifications. Therefore, it is recommended that relevant state agencies be contacted concerning vapor intrusion issues to ensure appropriate guidance is followed. As more states address vapor intrusion and the science and technology behind it continues to improve, new documents are likely to be published soon and existing ones replaced. Therefore, stakeholders should contact appropriate state agencies to ensure that the most up-to-date and appropriate guidance is followed.

Available Guidance as of January 2011


No vapor intrusion guidance available at this time.

Department of Defense

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

Navy/Marine Corps Policy for Vapor Intrusion, Adobe PDF Logo
5 pp, April 29, 2008.

Interim Vapor Intrusion Policy for Environmental Response Actions Adobe PDF Logo
Department of the Army, 7 pp.  November 6, 2006.

Guide for the Assessment of the Vapor Intrusion Pathway Adobe PDF Logo
U.S. Air Force, Institute for Operational Health, IOH-RS-BR-SR-2006-OOO1, 64 pp, February 2006.

Guidance for Environmental Background Analysis, Volume IV: Vapor Intrusion PathwayAdobe PDF Logo
Naval Facilities Engineering Command (NAVFAC), UG-2091-ENV, 153 pp, April 2011.


Guidance on Site Characterization for Evaluation of Soil Vapour Intrusion into BuildingsAdobe PDF Logo
Hers, I. and J. Southwood.
Science Advisory Board for Contaminated Sites in British Columbia (SABCS), 232 pp, 2011

This guidance describes the framework, approach, and methods for sampling, chemical analysis, and data interpretation recommended for consideration by the SABCS when undertaking characterization programs at sites in British Columbia with the potential for hazardous soil vapor to migrate into indoor air.

Petroleum Hydrocarbon Vapour Intrusion Assessment: Australian GuidanceAdobe PDF Logo
Wright, J.
Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, 143 pp, 2013

This document provides a clear decision framework for the conduct of petroleum vapour intrusion (PVI) assessments. Drawing on guidance/science from Australia and other jurisdictions relating to the current understanding of PVI, this document outlines approaches that should be considered in the assessment of acute hazards and chronic risks, on the basis of a screening or more detailed level of assessment (as appropriate).


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