New ASTM Standard for Assessment of Vapor Intrusion: More Harm Than Good?

May 23, 2008Articles The Bureau of National Affairs, Inc. Environment Reporter

Reprinted with permission from BNA, Inc's Environment Reporter, Vol. 39, No. 21, 05/23/2008 -


Recent increased attention to the migration of volatile chemicals from subsurface soil or groundwater contamination into buildings has raised concern about the evaluation of vapor intrusion in the process of buying and selling real property. In response, ASTM International’s Subcommittee on Real Estate Assessment and Management developed a standard practice, released March 3, to be used as a tool to evaluate vapor intrusion in that context. The author of this article is the sole member of subcommittee E 50.02 whose negative vote was not withdrawn after the final ballot in December 2007. In this article, he explains how this standard undermines ASTM Phase I standard E 1527-05 on all appropriate inquiries and directs environmental professionals to speculate about unacceptable risks in indoor air of inhabited buildings.

New ASTM Standard for Assessment of Vapor Intrusion: More Harm Than Good?

Vapor intrusion is the migration of volatile chemicals from subsurface soil or groundwater contamination into overlying buildings. The chemicals volatilize from the impacted soil or groundwater and migrate as soil gas through pore spaces in soil toward areas of lower pressure and chemical concentration (usually toward the surface). The soil gas can enter buildings through cracks in foundations and utility conduits. The chemicals that enter a building have the opportunity to accumulate and cause human exposures to a degree they would not if dispersed in open, ambient air.

At least three things are true about the potential for volatile contaminants to migrate into buildings as vapors (vapor intrusion):

1. Vapor intrusion is subject to growing scrutiny.

2. Vapor intrusion determinations are complex and are not made easily.

3. Vapor intrusion determinations inherently are high stakes because they are determinations about unacceptable health risks in the breathing air of building inhabitants.

With these truths as backdrop, ASTM International, through its Committee E50 and Subcommittee E50.02, set out to develop a tool for evaluating vapor intrusion issues in the context of the purchase and sale of real estate. The result is E 2600-08, Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions (VI Standard Practice). Unfortunately, the VI Standard Practice does not adequately take into account items two and three above.

Moreover, in issuing this VI Standard Practice, Committee E50 decided it needed to "clarify" its own Standard Practice for Environmental Assessments: Phase I Environmental Site Assessment Process (E 1527-05). E 1527-05, of course, has been deemed by the Environmental Protection Agency to satisfy ‘‘all appropriate inquiries’’ under the federal superfund law1 and the regulations promulgated thereunder.2 ASTM E 1527-05 provides the guidelines for the Phase I environmental site assessments performed everyday. This clarification of the existing standard is unfortunate as well as being unnecessary and unjustified.

Emergence, Character of Vapor Intrusion Issue

Concerns about vapor intrusion, as discussed here, have arisen out of the context of the investigation, assessment, and cleanup of contaminated soil and groundwater under the federal superfund and hazardous waste laws as well as comparable state statutes. Assessment of the vapor intrusion pathway is part of conducting a human health risk assessment where the contamination at issue involves volatile chemicals.

There is no question vapor intrusion is the subject of growing scrutiny. For example, as noted by E 50.02 in the materials that accompany the VI Standard Practice, more than 26 states have developed or adopted vapor intrusion guidance in the last few years. EPA requires the indoor air pathway to be addressed in its environmental indicators evaluations3 and issued its current draft guidance in November 2002.4 The Interstate Technology and Regulatory Council (ITRC), a coalition led by state and federal regulatory personnel, issued Vapor Intrusion Pathway: A Practical Guide in January 2007.5 California passed legislation in 2007 requiring consideration of the vapor intrusion pathway in cleanups there.6 At the federal level, Sen. Hillary Rodham Clinton (DN. Y.) introduced legislation (S. 1911) Aug. 1, 2007, aimed at vapor intrusion risks, especially risks related to trichloroethylene (TCE).7

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