Power plants in Pennsylvania must be prepared to meet the ozone and fine particulate emissions standards established by the newly reinstated Clean Air Interstate Rule (CAIR) as of Jan. 1, the Pennsylvania Department of Environmental Protection (PDEP) said Monday.

The commonwealth said it would move ahead with plans to implement the federal rule after the U.S. Court of Appeals for the District of Columbia last week reversed its July 11 decision to vacate the regulation in its entirety.

The court on Dec. 23 ordered the U.S. Environmental Protection Agency (EPA) to fix flaws in CAIR, but it did not set a deadline. The PDEP said that a federal implementation plan would govern power plants until the EPA approves the commonwealth’s CAIR state implementation plan.

CAIR’s purpose was to reduce sulfur dioxide (SO2), nitrogen oxide (NOx), and smog emitted by power plants in 28 Midwestern and Eastern states to lessen their impact on downwind areas. When it issued the rule in 2005, the EPA had anticipated that CAIR would result in the “largest pollution reductions and health benefits of any air rule in more than a decade.”

The agency had planned reductions would be achieved via an interstate cap-and-trade program, which would be implemented in two phases. The first phase for NOx reductions would have begun next year, and reductions for SOx in 2010. The second reduction phase for each pollutant was set to begin in 2015.

But on July 11, the federal appeals court unanimously struck down the rule because it had “several fatal flaws” and the EPA had adopted the rule as “one, integral action.” The court then had ordered the EPA to come up with a new rule consistent with that opinion.

The court’s decision (PDF) on Dec. 23 came in response to a petition filed with the court by the EPA in September requesting a rehearing in the case. Pennsylvania and other states had also recommended that CAIR not be vacated, arguing that though the rule’s cap-and-trade process to reduce air pollution was flawed, the short-term benefits of reducing air pollution using the first phase of the program weighed in favor of leaving it in place while the EPA reworked the rule.

“The parties’ persuasive demonstration, extending beyond short-term health benefits to impacts on planning by states and industry with respect to interference with the states’ ability to meet deadlines for attaining national ambient air quality standards for PM2.5 and 8-hour ozone, shows that the rule has become so intertwined with the regulatory scheme that its vacatur would sacrifice clear benefits to public health and the environment while EPA fixes the rule,” explained Circuit Judge Judith Rogers in the per curiam decision.

The federal court declined setting a definitive deadline without providing a concrete reason, though it reminded the EPA that it did not “intend to grant an indefinite stay of the effectiveness of [its] decision."

Pennsylvania is the first state to issue a timeframe for its CAIR-related plans. “The court’s decision is a positive outcome for Pennsylvania’s air quality, as it will allow residents of the commonwealth to benefit from the CAIR emission reductions while EPA addresses the flaws the court identified with the rule,” said Acting Environmental Protection Secretary John Hanger.

“The decision will allow Pennsylvania to move forward with our state implementation plans to meet ozone and fine particulate standards and to improve visibility while reducing regional haze.”

Sources: PDEP, U.S. Court of Appeals, District of Columbia, EPA