EPA Files Motion To Vacate Unlawful Biden-Era Air Quality Rule In Multi-State Lawsuit
By Matthew Holloway |
The U.S. Environmental Protection Agency (EPA) has filed a motion in a federal appeals court to vacate a Biden-era rule on fine particulate matter air quality standards, which was set to affect air quality regulations in Arizona.
In the motion filed in the U.S. Court of Appeals for the D.C. Circuit, Department of Justice attorneys representing the EPA told the D.C. Circuit that the agency’s 2024 rule change on fine particulate pollution standards is both legally and scientifically flawed and must be vacated. The motion noted that the “supplement” to the EPA’s 2019 Assessment of the NAAQS, or National Ambient Air Quality Standards, for particulate matter, “did not represent [a] full multidisciplinary evaluation of evidence’ for the underlying air quality criteria.” It added that the agency “lacks statutory authority to revise standards absent a thorough review.”
The PM 2.5 rule, finalized on December 15, 2024, was purported to strengthen protections against fine particulate matter pollution, which the EPA stated was linked to respiratory and cardiovascular health risks. Implementation was set to begin in 2025, with full compliance deadlines extending to 2031. The final rule revising the NAAQS lowered the annual primary PM 2.5 standard from 12.0 micrograms per cubic meter to 9.0 micrograms per cubic meter. The rule also established a new 24-hour PM 2.5 standard of 35 micrograms per cubic meter. The rule remains in effect until the court comes to a decision.
The consolidated lawsuits involved petitioners including the Commonwealth of Kentucky, et al., the Arizona Legislature, and the Arizona Chamber of Commerce, along with 21 other states and business groups against the U.S. Environmental Protection Agency, et al. The states and business groups challenged the rule, arguing it would impose billions in compliance costs on states like Arizona, potentially halting construction projects and job growth in areas struggling to meet the stricter standards.
The petitioners contended that the new limits would classify more areas as being in a state of nonattainment, leading to economic restrictions under the Clean Air Act. Oral arguments in the case were heard on December 16, 2024.
Arizona Senate President Warren Petersen hailed the EPA’s motion on X on November 26, 2025, crediting EPA Administrator Lee Zeldin with what he called a “BIG WIN FOR ARIZONA!” He added that the EPA, “just filed a motion in federal court to throw out Biden’s unlawful PM 2.5 rule that made it nearly impossible for parts of Arizona to ever meet clean-air standards — a rule that would have crushed jobs, construction, and our economy with billions in costs. The AZ Legislature & the AZ Chamber sued the Biden admin to stop this job-killing regulation. Our lawsuit helped bring about this reversal. Thank you, President Trump, for keeping your promise to cut red tape and protect Arizona families!”
Adam R.F. Gustafson, Principal Deputy Assistant Attorney General, and Sarah I. Zafar, Trial Attorney in the DOJ Environment and Natural Resources Division, filed the EPA’s motion for vacatur. They wrote in part, “Implementation of the NAAQS is a complex process, which generates significant costs and reliance interests among States, local governments, and regulated parties.”
The DOJ attorneys also argued that the EPA, “should at least have considered the distinct costs associated with revising the NAAQS mid-cycle. EPA’s disregard of this relevant factor was arbitrary and capricious because it was unreasonable for EPA to read an exercise of discretionary authority as an invitation to ignore a relevant factor like cost.”
The case remains ongoing in the U.S. Court of Appeals for the D.C. Circuit.
Matthew Holloway is a senior reporter for AZ Free News. Follow him on X for his latest stories, or email tips to Matthew@azfreenews.com.