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Vapor Intrusion/Vapor Encroachment: ASTM’s New Standard Guide

February 28th, 2011

Vapor Intrusion in the HomeBy Steve Wing

On June 14, 2010, ASTM International (formerly the American Society for Testing and Materials) issued E 2600-10, Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions. This document revises and supersedes ASTM E 2600-08, Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions, issued on March 3, 2008.1

Vapor intrusion – and/or vapor encroachment – from subsurface sources onto parcels of real estate and the resulting concerns with health hazards and potential liabilities have become an increasingly significant issue within the environmental consulting industry.2 ASTM published the 2008 Standard Practice to address these concerns, but, according to some observers, the 2008 Standard resulted in “confusion in the marketplace.”  For instance, real estate and environmental professionals wanted to know whether E 2600-08 was a screening standard or an assessment standard, and how the standard was related to ASTM’s Phase I Environmental Site Assessment (ESA) Standard (E 1527-05). ASTM therefore issued the 2010 Standard Guide.3

The Interstate Technology and Regulatory Council (ITRC) has defined vapor intrusion as “the migration of volatile chemicals from the subsurface into overlying buildings. Volatile chemicals may include volatile organic compounds, select semivolatile organic compounds, and some inorganic analytes, such as elemental mercury and hydrogen sulfide.”4

In the new standard guide, ASTM defines a vapor encroachment condition (VEC) as the presence or likely presence of vapors from chemicals of concern (COC) in the subsurface of a property caused by the release of vapors on or near the property.5

Anthony Buonicore, who chaired the ASTM work group on vapor intrusion, stated that the 2008 standard was criticized for going beyond the scope of its original intent, which had been as a screening tool. Mr. Buonicore stated that the new standard will be more streamlined, containing two tiers for determining whether a property has the potential for vapor intrusion rather than the four tiers included in the earlier version.6 Finally, Mr. Buonicore said that the revisions of the 2008 Standard were to improve “practicality, clarity and consistency.”7

The Environmental, Safety & Toxic Torts Group of Seyfarth Shaw, LLP, stated that the 2010 Standard appears to act as a screen for determining the possibility of vapor intrusion, while the 2008 Standard included an actual assessment of the presence of vapor intrusion and recommended actions to address this condition. Seyfarth Shaw stated further that the 2010 Standard is a guide that helps establish whether a VEC exists, likely exists, can be ruled out, or cannot be ruled out.8

Environmental Attorney Laurence Kirsch of Goodwin Proctor, LLP, concurred that the 2008 Standard was intended as a screening tool, and also stated that the 2008 Standard was considered too prescriptive and created confusion among the intended users, including insurers, lenders and buyers involved in property transactions. Environmental Attorney Larry Schnapf of Schnapf Law, LLC, said that vapor intrusion has become a source of lawsuits, and that it appears as though “it is becoming the new asbestos.” Mr. Kirsch and Mr. Schnapf served as co-chairs of the legal committee working on the Vapor Encroachment Screen Standard.9

Vapor intrusion

The new ASTM Standard Guide addresses the need for clarification in the vapor intrusion area. The Environmental Protection Agency’s (EPA) most recent substantive effort towards providing direction was a draft of an Office of Solid Waste and Emergency Response vapor intrusion guidance document released in 2002.10 This document provides technical and policy recommendations for evaluating subsurface vapor intrusion. It is notable that the document in still in draft form and to date has not been finalized.

There are indications that the EPA itself is dissatisfied with this 2002 draft document both because of its limitations of purpose and scope and outdated technical information. This is best demonstrated by the title of an Evaluation Report released on December 14, 2009 by the EPA’s own Office of Inspector General, Lack of Final Guidance on Vapor Intrusion Impedes Efforts to Address Indoor Air Risks.11 The EPA stated that it expects to issue a final version of its vapor intrusion guidance by November 2012, and recommends using “the 2002 draft and other available sound scientific information to address vapor intrusion in the interim.”12

In the meantime, other federal entities and a growing number of states have published their own vapor intrusion guidance documents. For example, in 2009 the U.S. Department of Housing and Urban Development’s (HUD) Guide to Multifamily Accelerated Processing (MAP Guide) added a vapor intrusion screen amendment to the Phase I ESA already required for multifamily housing loans.13 In January, 2009, the Tri-Service (Army, Navy, Air Force) Environmental Risk Assessment Work Group issued the Department of Defense Vapor Intrusion Handbook.14 A Vapor Intrusion Indoor Air Survey prepared for the Massachusetts Department of Environmental Protection in April, 2010, revealed that at the time of the survey 29 of the 50 U.S. states had specific vapor intrusion guidance policies.15

Finally, the ITRC Vapor Intrusion Team, composed of representatives from 19 state environmental agencies, 12 environmental companies, and 4 federal agencies, including the EPA, addressed this issue by developing two Vapor Intrusion Pathway documents, A Practical Guide (VI-1, 2007) and Investigative Approaches for Typical Scenarios (VI-1A, 2007).16

The large number and variety of guidance documents indicates that one of the advantages of the ASTM E2600-10 Standard Guide is that it provides a standardized methodology to evaluate the potential for vapor encroachment on properties.17

The new Standard features a two-tiered approach to vapor encroachment screening. Information collected during Tier 1 vapor encroachment screening is similar to that collected during a Phase I ESA investigation and includes such information as:

  • Federal, state, local, and tribal government records;
  • Chemical use records and prior use records of the property and the area of concern;
  • Soil, geological, and contaminant characteristics;
  • Contaminant plume migration and possible pathways;
  • Groundwater depth and flow; and
  • Property information data.

If a VEC cannot be ruled out by Tier 1 screening, the user may proceed to the Tier 2 process. Tier 2 requires a more refined screening that uses numeric data gained through evaluation of existing files and documents or collected by sampling the soil, soil gas, and/or groundwater of the property.18

When Tier 2 screening involves sampling, labs such as Columbia Analytical Services can provide analytical expertise and project management capabilities to support a variety of soil vapor intrusion and indoor air investigations.19

Anthony Buonicore, the chair of the ASTM Vapor Intrusion work group, anticipates that the screening under ASTM E 2600-10 will eventually become a routine part of an All Appropriate Inquiry-compliant Phase I ESA.20


  1. ASTM International. Standards. Vapor Encroachment Screening.
  2. Civil & Environmental Consultants, Inc. Jennifer A. Ewing, P.G. November 1, 2010.
  3. Environmental Protection. Vapor Intrusion and ASTM’s Revised Vapor Encroachment Standard. Dianne P. Crocker. December 6, 2010.
  4. Interstate Technology & Regulatory Council. Vapor Intrusion Webpage. Accessed on December 15, 2010.
  1. ASTM International. Standards. Vapor Encroachment Screening.
  2. Bureau of National Affairs. EPA Vapor Intrusion Guidance, ASTM Standard Forthcoming. May 20, 2010.\
  3. Pollution Engineering. A Smaller Intrusion. Anthony Buonicore, May 1, 2009.
  4. Seyfarth Shaw, LLP. ASTM Changes “Vapor Intrusion Assessment” into “Vapor    Encroachment Screening. Accessed on December 5, 2010.
  5. Bureau of National Affairs. EPA Vapor Intrusion Guidance, ASTM Standard Forthcoming. May 20, 2010.
  6. EPA. Vapor Intrusion Guidance. Updated on August 27, 2008. OSWER Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance)
  7. EPA Office of Inspector General. Vapor Guidance Evaluation Report. December 14, 2009.
  8. EPA OSWER Vapor Intrusion Page. Updated August 30, 2010
  9. HUD MAP Guide. Chapter 9. September 18, 2009
  10. EPA Contaminated Site Clean-up Information. Vapor Intrusion. January, 2009.
  11. Massachusetts Department of Environmental Protection. Vapor Intrusion Indoor Air Survey. April, 2010
  12. Interstate Technology & Regulatory Council. Vapor Intrusion Webpage. Accessed on December 15, 2010.
  13. Environmental Protection. Vapor Intrusion and ASTM’s Revised Vapor Encroachment Standard. Dianne P. Crocker. December 6, 2010.
  14. Civil & Environmental Consultants, Inc. Jennifer A. Ewing, P.G. November 1, 2010.
  15. Columbia Analytical Services, Inc. Subsurface Vapor Intrusion to Indoor Air
  16. Commonground. EDR. Anthony Buonicore. June 17, 2010
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