The Environmental Protection Agency today handed down a decision that could have a major impact on air quality in Texas.

The EPA decision – not an unexpected one – was to disapprove what the state environmental agency calls the “qualified facilities exemption” rule. Essentially, the rule for years has allowed Texas industries – power plants, chemical plants, refineries and others – to circumvent some portions of the federal Clean Air Act.

EPA officials and environmental activists said the decision will have far-reaching effects: Industries, in negotiation with the EPA and Texas Commission on Environmental Quality, will have to figure out how to comply with clean-air provisions. The public will have more chance to comment when polluting industries modify their facilities. And, within the next few years, the state’s air quality could substantially improve.

“Today’s action improves transparency by requiring companies that modify their operations to notify the public and will assure that all air emitting sources are properly permitted under the Clean Air Act,” Al Armendariz, the EPA’s Region 6 administrator, said in a press release. “Improved public review will better inform our communities about the environmental conditions where they live.”

The Qualified Facilities exemption rule was part of the State Implementation Plan submitted by TCEQ to show what Texas is doing to comply with federal clean-air regulations. Last September the EPA gave notice that it was proposing to disallow the exemption rule. The move means that industrial facilities in Texas that have been operating below federal standards no longer have any federally recognized permits to operate their facilities — they will not have to shut down their facilities, but will be subject to review by the EPA.

Ilan Levin, senior attorney for the Environmental Integrity Project, said that EPA will now need to unveil its plan for getting the state and the plants back into compliance.

“TCEQ hasn’t really responded to EPA’s concerns, and so EPA really has no choice but to disapprove this submittal by the state,” he said. “I think in the next couple of days we’ll see additional announcements on EPA’s program going forward. I expect we’ll know what that program is by the end of the week.”

Under the Qualified Facilities program, plants that are responsible for large sources of air pollution were exempt from strict clean air rules, and have been incrementally brought up to state regulatory standards. The problem with the program, environmentalists say, it’s been a very weak and lax program, and TCEQ hasn’t enforced the rules very well.

Levin speculated that over the in the next couple of years, some of the biggest polluters in the state will have to redo their air pollution permits.

“This is not just power plants — refineries, chemical plants, cement kilns and others,” he said. “Ultimately this is going to be a negotiation that will take 18 months to two years. But at end of day we’ll see permits in Texas that look vastly different than they do today.”

What this should mean for Texas, he said, is huge reductions in pollution across the board in soot, smog pollutants, and toxic emissions such as mercury and lead. Just as important, he said, polluting plants will be governed by enforceable permits that are transparent and understandable.

“We’re going to have monitoring of those facilities so we know how much they’re actually emitting,” he said. “We lack that right now.”