EPA has defended itself against a recent OIG report that faulted the Agency for failing to follow OMB requirements in peer reviewing the scientific data used to support its GHG endangerment finding. Specifically, the reviewers' findings were not publically reported, and one of the 12 reviewers was an EPA employee. The endangerment finding, published on December 15, 2009, provided the legal basis for EPA's regulation of GHG emissions. Climate change skeptic Sen. James Inhofe (R-OK) asked OIG to determine whether EPA complied with federal regulations in developing and reviewing the Technical Support Document ("TSD") used to support the endangerment finding.    

In a statement issued on September 28, 2011, EPA stated it "disagree[s] strongly with the Inspector General's findings and followed all the appropriate guidance in preparing [the endangerment] finding." In an effort to head off further controversy over the scientific basis for its endangerment finding, EPA clarified that the OIG report only questioned EPA's compliance with procedural requirements, and did not evaluate the validity of the scientific information or the merits of EPA's endangerment finding.

EPA and OIG disagree over whether the TSD should be considered "influential scientific information" or a "highly influential scientific assessment." If the latter, additional peer review was required. The OMB peer review bulletin defines a "highly influential scientific assessment" as an evaluation of scientific or technical knowledge that could have a potential impact of more than $500 million/year in either the public or private sector, or involves a novel, controversial, or precedent setting issue. EPA argued that the TSD was only a summary of other assessments, and not an assessment itself. The OIG concluded otherwise, pointing out that EPA reviewed individual studies not considered in the assessments and placed limited weight on these studies. OMB's position fell somewhere in between – that EPA reasonably interpreted its bulletin in concluding that the TSD did not meet the definition of a highly influential scientific assessment.

While it did not question the validity of the science that formed the basis of EPA's decision to regulate GHGs, the OIG report provides ammunition to climate change skeptics and others critical of the GHG regulations. Arguably, EPA should have followed the peer review procedures required for highly influential scientific assessments before promulgating such a significant expansion of the Clean Air Act.