There is no question that EPA’s 2002 draft vapor intrusion guidance has significant limitations. It contains a number of outdated toxicity values for assessing risk to humans from chemical vapors in the indoor air. It does not address how to mitigate vapor intrusion risks or monitor the effectiveness of mitigation efforts. It does not clearly recommend a multiple lines of evidence approach, the current-state-of-the-art in the field, to assessing vapor intrusion, and it does not respond to assessing vapor intrusion risks associated with petroleum releases at underground storage tank sites.

On EPA's defense, the Agency has on numerous occasions stated that the 2007 ITRC guidance addresses many of the issues that EPA would have addressed in a final guidance. Moreover, more than half the states have issued their own vapor intrusion guidance, along with the Army, Navy and Air Force. Even the Post Office has its own vapor intrusion guidance. In responding to mitigation questions, EPA often references the New York and New Jersey vapor intrusion guidance documents.

Notwithstanding, OIG, in a report issued in December, recommended, among other things, that EPA needs to: (1) identify the portions of their 2002 draft guidance that are still valid and those that need to be updated; and (2) issue final vapor intrusion guidance that includes updated toxicity values, the need for a multiple lines of evidence approach, addresses petroleum hydrocarbon vapors, identifies when or whether pre-emptive mitigation is appropriate, and addresses what O&M is appropriate for mitigation systems and when institutional controls and deed restrictions are appropriate. EPA OSWER in response to these recommendations indicated that (1) should be completed this summer and (2) by the fall of 2012. Progress at last!