Oct. 1--Facilities that produce large amounts of global warming gases will, for the first time, be regulated under federal clean air laws.

On Wednesday, the Environmental Protection Agency said who will be affected by the new rules. That encased dozens of businesses in Oregon, from Oregon Health & Science University in Portland to Ash Grove's cement plant in Baker County, whose annual output of carbon dioxide and other so-called greenhouse gases exceeds the proposed threshold.

That means those facilities will be forced to better track their emissions, but more significantly, any new large source of greenhouse gases -- such as a new power plant, or a significant modification to an older facility -- would have to prove it was doing everything possible to limit the heat-trapping gases that most scientists agree are altering the Earth's climate.

"The businesses it will affect will be ones that are energy-intensive businesses, things that have big boilers. That's wood products, pulp and paper, cement plants -- just basic industry," said John Ledger, vice president of Associated Oregon Industries, a lobbying group.

The problem then becomes identifying what emission reductions will satisfy regulators.

"There will certainly be litigation over that question," said Jeffrey Holmstead, former EPA assistant administrator for air issues and an attorney at a Washington, D.C., firm that represents many industries affected by the proposed rule.

In essence, the EPA is proposing to treat six greenhouse gases the same way it does traditional air pollutants, like lead, under the Clean Air Act.

"That's really important, and it's a huge change from the previous administration," said Janette Brimmer, an attorney with the environmental law firm Earthjustice.

But the notion drew fire Wednesday from some industry groups.

"Today's proposal highlights the perils of forcing greenhouse gas regulations into the Clean Air Act," Charles Drevna, president of the National Petrochemical & Refiners Association, said in a statement.

That landmark environmental law applies to facilities that annually emit 250 tons of certain pollutants. But literally millions of places, from schools to farms, release that much carbon dioxide, the leading greenhouse gas. So the EPA settled on a threshold for greenhouse gases of 25,000 tons per year.

"This is a common-sense rule that is carefully tailored to apply to only the largest sources -- those from sectors responsible for nearly 70 percent of U.S. greenhouse gas emissions sources," EPA Administrator Lisa Jackson said in a statement.