A federal appeals court ruled Tuesday that the Environmental Protection Agency was justified in not establishing a new air quality standard for acid rain.
The EPA decided in 2012 after a lengthy rulemaking proceeding that it needed further scientific study before it could set a new air quality standard for oxides of nitrogen and oxides of sulfur.
Environmental groups claimed that EPA's failure to issue a new multi-pollutant rule violated the Clean Air Act.
In a 3-0 decision, the U.S. Court of Appeals for the District of Columbia Circuit said it was turning aside the environmental groups' petition for judicial review because the EPA could not form a reasoned judgment as the Clean Air Act requires.
"EPA did not simply leave in place the old standard," said appeals judge A. William Randolph. "Although it did not promulgate a new standard, it identified the data gaps that prevented it from doing so and initiated a data-collection program designed precisely to fill those gaps and facilitate future regulation."
Once EPA found that the two current standards were inadequate with respect to acid rain, the agency sought to determine what new multi-pollutant standard would be appropriate, the judges said. EPA recognized that a new national ambient air quality standard would necessarily be more complex than those set historically for just one pollutant, the court wrote.