A federal appeals court largely upheld a decision to tighten the 2015 ozone air standards.
In a key part of the decision by the U.S. Court of Appeals for the District of Columbia Circuit, the court said the Environmental Protection Agency isn’t required to consider the economic, social and energy sector effects when setting air quality standards.
At issue was a 2015 EPA decision to tighten the primary and secondary ozone National Ambient Air Quality Standard to 70 parts per billion from 75 ppb.
The appeals court on Aug. 23 generally rejected claims by a group of states led by Arizona and the oil and natural gas industry that the new standards were too tough. Environmental groups argued the ozone limits didn’t go far enough.
The court rejected arguments the EPA failed to provide a “reasoned explanation” when it set the revised primary ozone standard.
“EPA has adequately explained why on the record before it the revised standard is requisite to protect the public health,” the court said in its unanimous decision.
In revising the standard, the EPA administrator considered the entire body of available scientific evidence, including clinical studies, epidemiologic evidence, human exposure and health risk assessments, a scientific advisory panel’s recommendations and more than 430,000 public comments, the court said.
At the same time, the court dismissed environmental groups’ arguments the decision was flawed because it would allow ozone levels to exceed 70 ppb on some days and could hurt sensitive populations.
The court dismissed an argument that the EPA should have set the ozone standard at a level as low as 60 ppb, a level recommended by the EPA’s Clean Air Scientific Advisory Committee.
The EPA considered the CASAC’s policy recommendation and set the ozone limit within a range recommended by the panel, according to the court.
The court agreed with environmental groups by remanding to the EPA its secondary ozone standard, which is designed to protect public “welfare,” including plants and wildlife.
The EPA erred when the agency decided to use a three-year average instead of a single-year, cumulative measurement of ozone exposure as a benchmark to gauge the protectiveness of its standard, the court said.
“We therefore remand this issue for EPA to either lower the standard to protect against unusually damaging cumulative seasonal exposures that will be obscured in its three-year average, or explain its conclusion that the unadjusted average is an appropriate benchmark notwithstanding CASAC’s contrary advice,” the court said.
Pointing to previous decisions, the court rejected arguments the EPA must consider implementation costs when it sets air quality standards.
The court also dismissed arguments the EPA failed to adequately consider “background” ozone, such as ozone from wildfires or other countries, when it set the new standards.
The Clean Air Act doesn’t give the EPA leeway to consider background ozone when setting its standards but does allow the agency to grant states exemptions on a case-by-case basis, according to the court.
Finally, the court vacated the EPA’s decision to allow parties who completed applications for pre-construction permits before the tougher standards were adopted to meet the previous standards. Grandfathering the permits violates the Clean Air Act, the court said.
The next ozone air quality standard is due in 2020, and the EPA has said it is working to meet that deadline.
When the EPA was considering revising the ozone standard in 2015, the American Public Power Association urged the agency keep the standard unchanged, saying it was strong enough to protect the public’s health.
Also, a revised standard shouldn’t include background ozone, which is beyond a state’s control, according to comments filed by the Association on the proposed change. The EPA needs to provide additional regulatory relief in cases when non-compliance with the standard is driven by background ozone.
The EPA’s proposal failed to explain how the agency decides what is an unacceptable health risk, the Association said.