The U.S. Environmental Protection Agency announced on Sept. 30 that it would use the Clean Air Act to potentially regulate greenhouse gasses. Industry sources say the proposal, which applies to stationary sources that emit more than 25,000 tons of greenhouse gasses annually, could result in litigation and construction delays if it were to go into effect.

The same day, Sens. Barbara Boxer (D-Calif.) and John Kerry (D-Mass.) introduced legislation to address global warming in the Senate. The House of Representatives passed a global warming bill last spring, but the Senate has failed to move forward on a comparable bill until now.

The EPA says it will issue the proposal in an upcoming issue of the Federal Register in response to a 2007 Supreme Court decision, Mass. V. EPA, that left the door open to potential regulation of greenhouse gasses under the Clean Air Act. EPA administrator Lisa Jackson has said that she would prefer that Congress enact legislation addressing global warming, but that in the absence of congressional action, the agency would issue regulations.

Under the rule, facilities emitting more than 25,000 tons of greenhouse gasses annually would be required to obtain permits that demonstrate that they are using the best practices and technologies to minimize greenhouse gas emissions. Powerplants, refineries, industrial facilities and other large emitters would need to install greenhouse gas reduction controls when modified or expanded to increase emissions by more than 10,000 tons.

EPA estimates that under the proposed emission thresholds, 400 new sources and modifications to existing sources would be subject to review each year for greenhouse gas emissions. Approximately 14,000 large sources would need to obtain operating permits for greenhouse gas emissions. Small businesses would be exempted from the rule. “This is a common sense rule that is carefully tailored to apply to only the largest sources—those from sectors responsible for nearly 70% of U.S. greenhouse gas emissions sources,” EPA Administrator Lisa Jackson says.

But industry sources say the rule, if enacted, would result in construction delays and litigation. Former EPA Air Administrator Jeff Holmstead notes that the Clean Air Act requires any source emitting more than 250 tons of a major pollutant annually to be regulated. Although EPA is attempting to target the largest emitters by focusing on those that emit 25,000 tons per year, as opposed to 250 tons, the agency may face legal challenges for doing so. “Let’s hope it stands up in court, or anyone who wants to build anything in the U.S. will be facing more litigation and delay,” he says.

The National Association of Manufacturers Vice President for Energy Resources Policy Keith McCoy adds, “The EPA’s legal authority to exempt small manufacturers and businesses from permits mandated by the Clean Air Act is unclear at best.”

The Senate proposal unveiled Sept. 30 would call for cutting the nation’s greenhouse gas emissions by 20% of 2005 levels by 2020, compared to the 17% called for in the House bill.