The ITRC Vapor Intrusion Toolkit replaces, combines, and updates three previous ITRC vapor intrusion (VI) documents: Vapor Intrusion Pathway: A Practical Guidance (VI-1, 2007), Petroleum Vapor Intrusion: Fundamentals of Screening, Investigation, and Management (PVI 1, 2014), and Technical Resources for Vapor Intrusion Mitigation (VIM-1, 2021).

The Toolkit includes:

  • Vapor Intrusion Technical and Regulatory Guidance
  • Fact Sheets
  • Technology Information Sheets
  • Checklists
  • Training Resources

Permission is granted to refer to or quote from this publication with the customary acknowledgment of the source. The suggested citation for this document is as follows:

ITRC (Interstate Technology & Regulatory Council). January 2026. Vapor Intrusion Toolkit. Washington, D.C.: Interstate Technology & Regulatory Council, Vapor Intrusion Update Team.
https://itrcweb.org/vapor-intrusion-toolkit/

For more information, read the full ITRC Disclaimer at https://itrcweb.org/terms-and-conditions/#disclaimer.

Vapor Intrusion Technical and Regulatory Guidance

The Vapor Intrusion Technical and Regulatory Guidance document includes 11 Chapters and 12 Appendices. It provides regulators, practitioners, responsible parties, and community members with consensus information based on empirical data and recent research to support VI decision-making under different regulatory frameworks.

Note: The Technical and Regulatory Guidance includes Bookmarks to Chapters, Sections, and Appendices to assist with navigation. These Bookmarks can be viewed by enabling the Bookmarks option or the Document Outline view in your PDF software.

Technical and Regulatory Guidance

Acknowledgments

Glossary

Acronyms

Appendix A: Summary of State Vapor Intrusion Practices

Fact Sheets

The Toolkit includes 36 Fact Sheets that provide supplemental information and details on VI topics introduced in the Technical and Regulatory Guidance document.

Active VI Mitigation Systems

Approaches for Vapor-Forming Chemical Source Determination

Attenuation Factors

Background Sources of Indoor Air

BioVapor Model

Building Characteristics

Common Mistakes in VI Evaluations, Investigations, and Mitigation

Conceptual Site Model for VI Mitigation

Data Quality & Adequacy

Design and Implementation Considerations for VI Mitigation Approaches

Direct Volatilization to Indoor Air

Flux Chambers and Other Flux Measurement Devices

General Concepts of Mass-Flux-Based Screening

High Volume Soil Vapor Sampling

Johnson and Ettinger (J&E) Model

Model Sensitivity Analysis

Multiple Lines of Evidence

Passive VI Barriers

Passive VI Mitigation Systems (VIMS)

Petroleum Vapor Intrusion

Pressure Monitoring and Building Pressure Control

Quality Assurance Considerations

Rapid Response and Ventilation for VI

Real-Time Monitoring

Screening Levels

Soil Vapor Probe Installation Toolbox

Tracers for Determination of Attenuation Factors and Ventilation Rates

Units and Unit Conversions

Vapor-forming Per- and Polyfluoroalkyl Substances (PFAS) and the VI Pathway

VI Preferential Pathways

VI Remediation and Institutional Controls

VIMS Construction Quality Assurance

VIMS Curtailment & Shutdown

VIMS Operation, Maintenance, and Monitoring

VIMS Post-Installation Verification

VI Screening Levels Calculator

Technology Information Sheets

The Toolkit includes 17 Technology Information Sheets that provide descriptions and considerations about the use of several VI mitigation technologies.

Preferential Pathway Sealing and Ad Hoc Ventilation

Indoor Air Treatment

Heating, Ventilation, and Air Conditioning (HVAC) Modification

Soil Vapor Extraction (SVE)

Multiphase Extraction (MPE)

Institutional Controls (ICs)

Sub-Slab Depressurization (SSD)

Crawl-Space Ventilation (SCV)

Aerated Floor Void Space Systems (VSS)

Composite Membranes

Single-Sheet Membranes (SSM)

Epoxy Floor Coatings (EFCs)

Aerobic Vapor Migration Barrier (AVMB)

Building Design for Passive VI Mitigation

Sub-Slab Ventilation (SSV)

Sub-Membrane Depressurization (SMD)

Passive SSV

Checklists

The Toolkit includes 7 Checklists that provide supplemental information and details on VI topics introduced in the Technical and Regulatory Guidance document. Checklists are fillable PDFs to further decision making for VI situations.

Active Mitigation

Indoor Air Quality & Building Inventory

Passive Mitigation

Regulator Checklist for Soil Vapor Samples

VIMS Operation, Maintenance, and Monitoring

Post-Installation VIMS

VI Mitigation Conceptual Site Model

Training Resources

Vapor Intrusion Training (Live and Archived Webinars)

ITRC continues to host trainings on Vapor Intrusion topics.

ITRC Vapor Intrusion YouTube Playlists

ITRC created a curated set of Vapor Intrusion‑focused playlists featuring both ITRC‑produced videos and content from other organizations. The playlists include:

  • Vapor Intrusion 101: This collection of videos explain the basics of VI.
  • Vapor Intrusion – Sampling & Analysis: This playlist features videos that provide general demonstrations on how to collect samples for investigation of VI as well as demonstrations of various specific available sampling and analysis technologies.
  • Vapor Intrusion – Mitigation: The mitigation playlist features videos from state agencies, private companies, and other organizations, ranging from two minutes to 2 hours.
  • Petroleum Vapor Intrusion (PVI): This playlist features short videos that summarize the PVI assessment process, explain ITRC’s recommended “bottoms-up” approach, and highlight screening methods and best practices for sites where standard screening distances do not apply.
  • Vapor Intrusion – Community Education: This collection of videos explains VI from the perspective of a non-practitioner and may be useful tools during community engagement to educate the public about VI and its potential risks.
  • Vapor Intrusion – Advanced Topics: These videos are more than one hour in length and provide in-depth analyses on academic and industry research on VI investigation and mitigation.

Topic(s): Indoor Air, Vapor Intrusion