Obama-era ozone standards that sparked years of litigation will largely remain in place after federal judges today rejected a variety of legal challenges.
The U.S. Court of Appeals for the District of Columbia Circuit upheld most of EPA's 2015 thresholds for ground-level ozone, which set 70 parts per billion as the highest acceptable level of the pollutant under the Clean Air Act.
A three-judge panel rejected claims from industry and conservative states that the National Ambient Air Quality Standards for ozone are impossible to achieve. But it ordered EPA to take a closer look at secondary public welfare standards aimed at protecting animals, crops and vegetation.
It also scrapped a grandfathering provision that allowed some sources in the middle of a permitting process to continue operating under an earlier, less stringent ozone threshold.
Critics of the 2015 standards waited years to make their case in court. The litigation was on hold while the Trump administration spent more than a year considering whether to scrap the Obama rule and revert to more lenient ozone limits.
It ultimately agreed to defend the 70 ppb cap, a decision that led to December's unlikely showdown between EPA lawyers and reliable Trump supporters like Murray Energy Corp (Greenwire, Dec. 18, 2019).
Murray, states and other opponents said the 2015 requirements are too hard to meet in light of background ozone that drifts across borders or forms from natural sources. They argued it's unfair for places with high levels of background ozone beyond their control to be classified as "nonattainment areas" and have to comply with stricter permitting requirements.
Some environmental groups, by contrast, criticized the Obama administration's 70 ppb threshold as not protective enough. The figure is the least stringent level of a range recommended by air pollution experts advising the agency.
Ozone contributes to smog, which can lead to severe breathing problems for children and people with asthma.
Environmentalists in the litigation also called for a stricter secondary ozone standard, which is also currently set at 70 ppb, to protect plants and animals. The D.C. Circuit today ordered EPA to revisit that threshold.
Reporter Sean Reilly contributed.