Action” (NFA) letter—have had their NFA
reversed if the original investigation did
not assess VI potential. These sites may
face new requirements for VI investigation if the site contaminants and conditions represent a risk for VI exposure.
The additional VI investigation often
triggers the discovery of off-site impacts
and a potential third-party claim.
Notable litigation cases include the
Redfield, Colo., Department of Transportation and Brown Retail sites. Although the contaminated groundwater
plume at these sites had been reportedly
delineated, the vapor plume was found
(via direct indoor air sampling) to extend
more than two miles from the source
areas. Local residents filed a $380 million civil action for property diminution
in value (DIV) because of the required
installation of VI mitigation systems in
their homes. However, after a real estate
market analysis indicated no difference
in appraisal value at that time between
houses with and without mitigation systems, the amount awarded to the neighborhood residents was significantly
reduced. This noteworthy case demonstrates the need for a careful communication plan with the local community
and the difficulty in proving a claim for
DIV based on VI exposure.
Table 2. Comparison of Non-Residential Indoor Air Screening Levels
to Occupational Exposure Limits (µg/m3)
Table 3. ASTM Standard E2600-08 for Vapor Intrusion Assessment
Tier 1: Screening for potential
vapor intrusion condition (pVIC)
Search distance test
Chemicals of concern test
Tier 2: Screening using
Non-invasive-plume test/critical distance
determination or risk-based concentration test
Invasive—soil gas and groundwater sampling
Tier 3: Informational
Toolbox of approaches–follow appropriate/
applicable government guidance and regulation
Tier 4: Informational
Identifies general mitigation alternatives
Indoor air sampling is the
most direct method of
determining whether the
vapor intrusion pathway
is complete and whether
building occupants face a
long-term health risk.
jury’s sympathy for the ill child resulted
in a multi-million dollar award.
The subject of VI is a moving target.
States continue to issue VI guidance, although no national consensus exists on
sampling techniques, analytical methods,
and, more importantly, screening levels.
VI represents a real liability to site owners
based on potential significant costs for
required VI investigations, on- or off-site
VI mitigation system installations, and
potential third-party claims based on DIV
or exposure-related bodily injury.
Recent bodily injury claims due to
exposure to contaminant vapors have
presented significant legal defense challenges. In City of San Antonio v. Pollock,
a young child’s leukemia diagnosis was
allegedly the result of in utero exposure
to contaminant vapors emanating from
the adjacent landfill and entering the
Pollock home. Even though the plaintiff’s
experts were not able to demonstrate a
cause-and-effect relationship between
the vapor exposure and the disease, the
To learn more about the role of industrial hygienists in
VI investigations, see Parts I and II of “Vapor Intrusion:
Environmental and IAQ Challenge” in the February
and April 2007 issues of The Synergist.
Michelle Gillie, CIH, CPEA, is with Tetra Tech/
of the VI subcommittee of the AIHA Environmental
7660 or firstname.lastname@example.org.
Sandra Gaurin, ERM, LEED AP, is with Tetra Tech
Council’s Vapor Intrusion group.
American Petroleum Institute: Publication
4741, “A Practical Strategy for Assessing
the Subsurface Vapor-to-Indoor Air Migration Pathway at Petroleum Hydrocarbon
Sites.” November 2005.
U.S. Department of Defense: Vapor Intrusion Handbook, prepared by the Tri-Service
Environmental Risk Assessment Workgroup.
EPA: “Brownfields Technology Primer: Vapor
Intrusion Considerations for Redevelopment.” EPA 542-R-08-001. [Online] Available
at www.brownfieldstsc.org. March 2008.
EPA: Vapor Intrusion Database. [Online]
Available at http://iavi.rti.org.
EPA: Indoor Air Vapor Intrusion Mitigation
Approach. [Online] Available at www.epa.gov/
Interstate Technology & Regulatory
Council: Technical and regulatory guidance
supplement: “Vapor Intrusion Pathway: Investigative Approaches for Typical Scenarios” (ITRC VI-1A, 2007).
Information on New York State’s background database studies can be found at
April 2010 ; The Synergist