[CPEO-BIF] EPA Vapor Intrusion Guidance

[Lenny Siegel <lennysiegel@gmail.com>]

Lack of Final Guidance on Vapor Intrusion Impedes Efforts to Address 
Indoor Air Risks

U.S. EPA Office of the Inspector General
December 14, 2009

[To view the full report, go to
www.epa.gov/oig/reports/2010/20091214-10-P-0042.pdf]

What We Found

EPA's efforts to protect human health at sites where vapor intrusion 
risks may occur have been impeded by the lack of final Agency guidance 
on vapor intrusion risks. EPA's 2002 draft vapor intrusion guidance has 
limited purpose and scope, and the science and technology associated 
with evaluating and addressing risk from vapor intrusion is evolving. 
EPA's draft also contains outdated toxicity values for assessing risk to 
humans from chemical vapors in indoor air.

EPA's draft guidance does not address mitigating vapor intrusion risks 
or monitoring the effectiveness of mitigation efforts. The draft 
guidance also does not clearly recommend that multiple lines of evidence 
be used in evaluating and making decisions about risks from vapor 
intrusion. The draft guidance is not recommended for assessing vapor 
intrusion risks associated with petroleum releases at Underground 
Storage Tank sites. EPA's outdated toxicity values allow for the use of 
widely different, nonfederal toxicity values and have caused delays in 
work to address possible risks.

EPA has not finalized its guidance, according to EPA managers and staff, 
because the 2007 Interstate Technology Regulatory Council guidance 
addressed many issues that EPA would have addressed in a final guidance, 
and because finalizing EPA's guidance would take a long time in light of 
the emerging scientific issues in the field. Also, previous 
administrative review requirements for Agency guidance were perceived as 
barriers to issuing timely guidance in a rapidly changing environment. 
These requirements were revoked by the current Administration, but 
significant guidance remains subject to some administrative review.

Seven years later, EPA is developing a roadmap of technical documents 
that will update its draft guidance. However, technical documents may 
not be effective for conveying and representing Agency policy. EPA has 
also made some progress in updating toxicity values for some 
contaminants most frequently associated with vapor intrusion.

What We Recommend

We recommend that EPA issue final guidance to establish current Agency 
policy on the evaluation and mitigation of vapor intrusion risks. The 
Agency should also finalize toxicity values for trichloroethylene and 
perchloroethylene - common contaminants associated with vapor intrusion. 
The Agency agreed with our recommendations and provided milestones.

--


Lenny Siegel
Executive Director, Center for Public Environmental Oversight
a project of the Pacific Studies Center
278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org



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