The U.S. Supreme Court on Monday declined to take up industry’s challenge to a federal court ruling that upheld the Bush administration’s air quality standard for ozone. 

The high court’s denial leaves intact the D.C. Circuit’s July 2013 decision upholding the Environmental Protection Agency’s (EPA’s) last revision of its National Ambient Air Quality Standards (NAAQS) for ozone, which in 2008 set the health-based (primary) standard at 75 parts per billion (ppb). States and industry groups had challenged the 2008 standard, arguing that the EPA improperly justified a reduction in the NAAQS based on “distorted science.”

Notably, in that decision, the D.C. Circuit rejected the EPA’s attempt to set the secondary (environmental-based) ozone NAAQS at the same level as the primary ozone NAAQS, concluding that the EPA could not merely “compare the level of protection afforded by the primary standard to possible secondary standards and find the two roughly equivalent.”

The D.C. Circuit’s ruling prompted the Utility Air Regulatory Group to file a petition with the Supreme Court for a writ of certiorari earlier this year. The group, whose members include power and mining companies, called on the nation’s highest court to decide whether the lower court’s refusal to require the EPA to justify the revised 2008 NAAQS as being “not lower or higher than is necessary” conflicts with a previous Supreme Court decision.

But the Supreme Court denied the petition without explanation on Monday.

As POWER notes in a recent regulatory update, the EPA is working to propose an even stricter primary and secondary NAAQS for ozone.

Before the EPA could finalize a rule proposed in 2010 to set a NAAQS of between 60 ppb and 70 ppb, President Obama in 2011 scuttled the rule to reduce regulatory burdens and uncertainty. But a California federal judge this April ordered the EPA to propose primary and secondary NAAQS for ozone by Dec. 1, 2014, and finalize them by October 2015.

An August 2014–released EPA final policy assessment provides “strong support” for revising the standard within the range of 60 ppb to 70 ppb.

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)