A federal appeals court ruled Friday that the Environmental Protection Agency (EPA) is not required to adopt carbon monoxide standards to mitigate global warming, and that its current standards are sufficient to protect public health.
Environmental groups had challenged the EPA's 2011 decision that it does not have to adopt carbon monoxide secondary standards — meant to protect the environment — and that its existing primary standards — meant to protect health — are sufficient.
The court also sided with the EPA's science.
"Petitioners have not presented a sufficient showing that carbon monoxide emissions ... will worsen global warming," the judges said.
The court also found the agency "acted reasonably" in keeping primary standard levels at 9 parts per million in an eight-hour average, or 35 parts per million in a one-hour average.
The groups had argued that the EPA ignored some studies on the health effects of carbon monoxide, used flawed studies to justify its decision and didn't give proper weight to its scientific advisory board.
"No toxicology or clinical studies show that carbon monoxide emissions at the levels of the primary standards caused adverse health effects," the court said.
WildEarth was disappointed with the decision.
"We're very concerned with EPA disregarding studies that clearly indicated a lower carbon monoxide standard was needed," said Jeremy Nichols, director of WildEarth’s climate program. "Obviously, the D.C. Circuit didn’t agree with us."
Nichols called the ruling on standing "a technicality," but promised to keep fighting for better carbon monoxide standards. The EPA must review all of its air quality rules every five years, so WildEarth will be active in that process.
"Despite this setback, we’re going to come back hard on EPA," Nichols said. He did not comment on whether the group might seek a review at the Supreme Court.
"The EPA is pleased with this decision and committed to reducing air pollution to protect public health," agency spokeswoman Alisha Johnson said.
EPA first set its carbon monoxide standard in 1971, and it documented an 83 percent drop in carbon monoxide levels from 1980 to 2012.