Kentucky is taking its fight against tougher federal air-quality rules all the way to the U.S. Supreme Court, with Attorney General Russell Coleman arguing the Environmental Protection Agency overstepped its authority when it tightened the nation's soot pollution standard by 25%. Coleman filed the petition Friday, asking the justices to review a Biden-era rule that lowered the annual limit on fine particulate matter, commonly known as soot. The nation's highest court has not yet decided whether it will take up the case.
Coleman is co-leading a 25-state coalition with West Virginia Attorney General JB McCuskey, according to WLKY. The petition follows a June 26 ruling from the U.S. Court of Appeals for the District of Columbia Circuit, which upheld the EPA rule and rejected challenges from Kentucky, West Virginia, 23 other state attorneys general, and major industrial trade groups, per Justia Law. Kentucky argues the EPA did not have the authority to reopen the soot standard in the first place, and separately contends the agency failed to weigh the economic cost of the tighter rule before finalizing it.
“Together with attorneys general across the country, we're asking the Supreme Court to turn the page of President Biden's assault on common sense,” Coleman said. “This regulation was about politics, not public health.”
What the EPA Rule Actually Changed
The EPA finalized the regulation in February 2024, cutting the primary annual standard for fine particulate matter, or PM2.5, from 12.0 micrograms per cubic meter down to 9.0 micrograms per cubic meter, a 25% reduction, according to the Federal Register. PM2.5 refers to microscopic airborne particles measuring 2.5 microns or smaller, tiny enough to lodge deep in the lungs. Hoodline previously reported on the rule's rollout and its impact on Arizona compliance when it first took effect in 2024.
Federal officials projected at the time that meeting the new 9.0 µg/m³ standard by 2032 would prevent up to 4,500 premature deaths, 800,000 cases of asthma symptoms, and 290,000 lost workdays in 2032, per estimates reported by Reuters. Industry opponents, including the National Association of Manufacturers and the U.S. Chamber of Commerce, pushed back, while the EPA estimated that compliance could cost the U.S. economy up to $590 million annually and jeopardize air permits for new manufacturing and infrastructure projects, the same Reuters reporting noted.
A 25-State Coalition Challenges the EPA Rule
The coalition filing alongside Kentucky and West Virginia includes Alabama, Alaska, Arkansas, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Louisiana, Mississippi, Missouri, Montana, Nebraska, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, and Wyoming, according to WWNR Radio. The Supreme Court's 2001 decision in Whitman v. American Trucking Associations held that the EPA cannot consider economic compliance costs when setting National Ambient Air Quality Standards under the Clean Air Act, per Oyez.
The decision held that the EPA cannot consider economic compliance costs when setting air quality standards under the Clean Air Act. Coleman's petition follows a 2024 Kentucky lawsuit over soot standards, according to WKMS.
How Kentucky Tracks Soot Locally
Within Kentucky, the Division of Air Quality runs 24 ambient air monitoring stations spread across 23 counties, tracking fine particulate matter, per the agency's own data cited in coverage from a Facebook post by WLKY. Those stations are the on-the-ground tools that would need to show compliance with whatever standard ultimately survives this legal fight, whether that remains the 9.0 µg/m³ limit or a rolled-back figure closer to the old 12.0 µg/m³ threshold.
For context, even the current 9.0 µg/m³ standard is considerably looser than international guidance. The World Health Organization recommends an annual fine particulate threshold of just 5.0 µg/m³ to limit long-term health risks, according to Filterbuy. That gap has fueled arguments from public health advocates that even the rule Kentucky is now challenging does not go far enough.
Whether the Supreme Court agrees to hear Kentucky's petition remains an open question. The justices have given no indication of a timeline for deciding whether to grant certiorari, leaving the fate of the 25% soot reduction, and the cost-consideration debate underlying it, unresolved for now.
