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Vapor Intrusion

EPA Technical Documents and Tools Prepared to Support Guidance Development

EPA has prepared several documents and tools, shown below, to support development of its Final Subsurface Vapor Intrusion Guidance. In addition, relevant research publications prepared by the EPA Office of Research and Development (see Related Links) will also be considered.

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.

EPA's Vapor Intrusion Database: Evaluation and Characterization of Attenuation Factors for Chlorinated Volatile Organic Compounds and Residential Buildings (PDF) (188 pp, 2.8MB,  About PDF).
This report presents technical information about sites in the U.S. that have been investigated for vapor intrusion. The primary focus of the report is the evaluation of concentrations of chlorinated VOCs in and underneath residential buildings based upon the U.S. EPA's vapor intrusion database as of 2010.  The technical information provided in this report may be useful for regulators, responsible parties, and others assessing and managing vapor intrusion investigation programs. An erratum was issued on July 3, 2012 to correct Table 10.

Conceptual Model Scenarios for the Vapor Intrusion Pathway (154 pp, 2.3MB, About PDF).
This report provides simplified simulation examples to illustrate graphically how subsurface conditions and building-specific characteristics determine (1) the distribution of vapor-forming chemicals in the subsurface, and (2) the indoor air concentration relative to a source concentration.  It was prepared to help environmental practitioners gain insights into the processes and variables involved in the vapor intrusion pathway and to provide a theoretical framework with which to draw inferences about and better understand the complex vapor fate and transport conditions typically encountered at actual, non-idealized contaminated sites. 

Indoor Air Vapor Intrusion Mitigation Approaches (PDF) (49 pp, 742K, About PDF).
The National Risk Management Research Laboratory has developed a technology transfer document regarding management and treatment of vapor intrusion into building structures. This document describes the range of mitigation technologies available. The document also provides information on selecting appropriate technologies in consultation with qualified engineering and risk management professionals.

Frequently Asked Questions about Vapor Intrusion (PDF) (56pp, 986K, About PDF).
EPA developed answers to a collection of Frequently Asked Questions (FAQs) about vapor intrusion at Superfund sites. These FAQs provide information and recommendations based on experiences garnered over the last few years in addressing vapor intrusion 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 vapor intrusion pathway and to help foster appropriate consistency in technical approach. Other Agency cleanup programs may find it helpful to consider parts of the FAQs for their own specific needs.

The VISL calculator contains macros and you must have an authorized copy of the Microsoft Excel® in order to open it. If you are interested in viewing or using it, EPA recommends that you first save it (rather than open it directly from the website) and use a file manager (e.g., Windows Explorer) to assign an .xlsm extension to the file, before opening it.

Vapor Intrusion Screening Levels
EPA developed a spreadsheet calculator (the Vapor Intrusion Screening Level (VISL) Calculator (XLSM) (618K) and VISL Users Guide (PDF) (11 pp, 560K,  About PDF) that: lists chemicals considered to be volatile and sufficiently toxic through the inhalation pathway; and 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.

Petroleum Hydrocarbons And Chlorinated Hydrocarbons Differ In Their Potential For Vapor Intrusion (13 pp, 709K, 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.

Some EPA Tools:

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