Highlights

EPA releases a new technical report: Background Indoor Air Concentrations of Volatile Organic Compounds in North American Residences (1990 – 2005): A Compilation of Statistics for Assessing Vapor Intrusion PDF (67 pp, 812K, About PDF). This 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. Similar compilations have been previously published, but these have been based on generally older data or limited statistical information.

The Office of Underground Storage Tanks has developed a communications paper. Petroleum Hydrocarbons And Chlorinated Hydrocarbons Differ In Their Potential For Vapor Intrusion (PDF), (13 pp, 362K,  About PDF). This document describes how petroleum and chlorinated hydrocarbons behave differently in the subsurface and how these differences can influence whether there is a potential for vapor intrusion to occur. This version addresses public comments that OUST solicited in July 2011.

EPA is working toward a proposed rulemaking to add a new screening component to the Hazard Ranking System (HRS) which would allow sites with subsurface intrusion contamination to be evaluated for placement on the Superfund National Priorities List (NPL). The addition would enable the HRS to directly consider the human exposure to contaminants that enter building structures through the subsurface environment.

Guidance Documents

In 2002, EPA released the OSWER Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance) - This document presents technical and policy recommendations of the Office of Solid Waste and Emergency Response for evaluation subsurface vapor intrusion. EPA expects to issue a final version of its vapor intrusion guidance by November 2012 and we recommend use the 2002 draft and other available sound scientific information to address vapor intrusion in the interim.

In August 2010, EPA released its Review of the 2002 Draft OSWER Subsurface Vapor Intrusion Guidance PDF (7 pp, 79K, About PDF).

EPA to Issue Final Subsurface Vapor Intrusion Guidance

EPA is planning to issue final Subsurface Vapor Intrusion Guidance by November 30, 2012. A request for public input was announced in the Federal Register on March 17, 2011 (76 FR 14660 PDF) (2 pp, 188K, About PDF). The comment period ended on May 14, 2011, all comments that were received will be considered in the development of the on the developed of final guidance. Comments can be viewed at Regulations.gov EPA-HQ-RCRA-2002-0033.

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