In an article on an Inspector General report evaluating the process that led to EPA's greenhouse gas endangerment finding, the Washington Post states:

The investigation did not examine the scientific evidence underpinning the EPA finding of a connection between human activity and global warming over the past half-century.

However, [Sen. James] Inhofe said, the IG's conclusions raised the question of whether the administration should have concluded that carbon dioxide and other greenhouse gases qualify as pollutants under the Clean Air Act.

In fact, the IG did not question whether greenhouse gases are pollutants. And there's some other important information missing here. It was the Supreme Court, not the Obama administration, that decided greenhouse gases “fit well within the Clean Air Act's capacious definition of 'air pollutant.'” From the 2007 ruling:

The Clean Air Act's sweeping definition of “air pollutant” includes "any air pollution agent or combination of such agents, including any physical, chemical ... substance or matter which is emitted into or otherwise enters the ambient air ... ." §7602(g) (emphasis added). On its face, the definition embraces all airborne compounds of whatever stripe, and underscores that intent through the repeated use of the word “any.” Carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons are without a doubt “physical [and] chemical ... substance[s] which [are] emitted into ... the ambient air.” The statute is unambiguous.

Both Obama and EPA Administrator Lisa Jackson have said they prefer a legislative approach to climate change. But in the absence of Congressional action, the Clean Air Act requires EPA to regulate greenhouse gases if they pose a danger to public health and welfare, according to the Supreme Court ruling.

Six months after the ruling, EPA sent the White House a draft endangerment finding, stating: “The Administrator proposes to find that the air pollution of elevated levels of greenhouse gas (GHG) concentrations may reasonably be anticipated to endanger public welfare.” The White House reportedly refused to open the email containing the document, which was not made public until October 2009.

Then-EPA Administrator Stephen Johnson told President Bush in a January 2008 letter made public earlier this year that “a finding is still required by the Supreme Court case, and the state of the latest climate change science does not permit a negative finding, nor does it permit a credible finding that we need to wait for more research.” Johnson went on to say that greenhouse gases could be regulated in a way that is “responsible, cost-effective and practical” and “it is in the Administration's best interest to move forward with this plan in the next few weeks.”

Instead, the Bush administration decided to launch a comment period, punting the obligation to respond to the Supreme Court to the next administration. After assessing the state of climate science, EPA determined in December 2009 that greenhouse gas emissions endanger public health and welfare. Its finding drew from peer-reviewed synthesis reports on climate change, which in turn were based on peer-reviewed research, and it “underwent a technical review by 12 federal climate change experts, internal EPA review, interagency review, and a public comment period.”

But the recent IG report, which was requested by Inhofe, says that it should have been subjected to further peer review procedures under Office of Management and Budget guidelines created (controversially) by the Bush administration. OMB disagrees with the IG's conclusion, saying EPA “reasonably determined” that the finding did not fit a classification requiring an even more extensive process.

Ultimately, the IG made some procedural recommendations for the future and concluded that “EPA met statutory requirements for rulemaking and generally followed requirements and guidance related to ensuring the quality of the supporting technical information.”

None of this addresses the status of greenhouse gases as an air pollutant and the Washington Post should have said so.