Industrial facilities that emit large amounts of hazardous air pollution during non-routine events -- such as start-ups, shutdowns and equipment malfunctions -- must fully account for such discharges under the Clean Air Act, a federal appeals court ruled today.

In a split ruling, a three-judge panel of the U.S. Circuit Court of Appeals for the District of Columbia vacated U.S. EPA's so-called "SSM" rule for industrial facilities. The rule was first implemented by the Clinton administration as part of the Clean Air Act's Title V permitting program.

In 2003, the Bush administration loosened some requirements for SSM, including removal of a requirement that plans be written into facilities' Title V permits. Under the new rules, industrial plants would not have to submit the plans to EPA for review, nor could the public review such plans without a "specific and reasonable request" from a permitting authority.

EPA argued that Section 112 of the Clean Air Act, which governs hazardous air emissions, allowed a loosening of the SSM rules if the EPA administrator believed such changes were warranted.

The Sierra Club and other environmental groups challenged the rule, leading to today's 2-1 opinion, which held that Congress did not grant such discretionary authority to the Section 112 standards. "Congress was explicit when and under what circumstances it allowed for such discretion," Judge Judith Rogers wrote for the majority, adding that EPA's argument that it held such authority "belies the text, history and structure of Section 112."

Environmental groups welcomed the ruling, saying it closes "a gaping air pollution loophole" created by the Bush administration for operators of refineries, chemical plants and other industrial facilities to violate the Clean Air Act without repercussion.

"Under this notorious EPA exemption, industrial facilities have been allowed to operate like a fleet of junk cars parked in neighborhoods while spewing blue smoke, misfiring, backfiring, stalling and chugging," said Marti Sinclair, who chairs the Sierra Club's Clean Air Team.

Officials with EPA were not immediately available for comment, nor were officials with the American Chemistry Council, which joined as an intervenor in the case.

Judge A. Raymond Randolph dissented from the majority on two grounds.

First, he said, the Sierra Club's petition for review was not timely, since the original SSM rule was adopted in 1994 and EPA's subsequent actions did not amount a re-promulgation of the original rule.

Second, Randolph said, the majority opinion relied on legal arguments not raised by either the plaintiffs or EPA. While plaintiffs' arguments were built around Section 112 of the Clean Air Act, the SSM provision's broader legality rests with another part of the act, Section 302, that was not subject to the petition.

Randolph accused the majority of attempting "to shoehorn" its opinion to fit a legal framework that allowed for the provision to be struck down.