U.S. Chamber Asks Supreme Court to Review EPA PM2.5 Air Rule

The U.S. Chamber of Commerce, several leading business organizations and 25 states asked the U.S. Supreme Court on Wednesday to review a D.C. Circuit decision upholding a Biden-era EPA rule that tightens the National Ambient Air Quality Standards (NAAQS) for fine particulate matter, or PM2.5.

The petition targets the EPA's 2024 rule, which lowered the annual PM2.5 standard through what the Chamber calls an abbreviated process. The business groups argue the rule will restrict or halt investment in manufacturing, energy production and critical infrastructure while worsening permitting bottlenecks already constraining companies across the country.

What are the stakes for business?

The stakes center on permitting. According to the Chamber, the new standard triggers new federal and state regulatory obligations, makes permitting more onerous, and imposes compliance burdens on communities and businesses nationwide. The Chamber's Global Energy Institute points to decades of improvement as evidence the tightening is unnecessary.

"The United States has some of the best air quality in the world, thanks to steady reductions in contributors to particulate matter emissions – by as much as 79 percent since 2010," said Chad Whiteman, Vice President of Environment and Regulatory Affairs at the Chamber's Global Energy Institute. "It is important to continue making progress, but the regulation would restrict or even stop investments in manufacturing and other critical infrastructure and exacerbate permitting challenges that are already limiting the ability of businesses to respond to changing market conditions and growing consumer demands."

Why do the petitioners say the science doesn't support the rule?

The emissions picture has shifted, the Chamber argues. More than 84 percent of particulate matter emissions now come from non-point sources such as wildfires, construction and road dust — factors the group describes as extremely difficult for individual regions and states to control. Only 16 percent come from industrial sources and power plants, with further reductions likely as new plants and emerging technologies come online.

That imbalance sits at the heart of the business challenge: regions can struggle to meet tighter standards even when local industry has already cut emissions sharply, because the dominant sources fall outside any single state's control.

What legal questions does the petition raise?

The petition argues the D.C. Circuit's decision presents questions of exceptional importance that necessitate Supreme Court review. It rests on two legal claims:

• Process: EPA may not revise national air-quality standards outside the Clean Air Act's normal five-year review cycle without first completing a thorough scientific review, as Congress required.
• Costs: EPA must consider the costs and consequences of exercising its authority before deciding to impose a new standard outside the normal review cycle.

"Congress established a clear process and EPA did not follow it," said Daryl Joseffer, President of the U.S. Chamber Litigation Center. "The agency bypassed important scientific review requirements and failed to account for the consequences of exercising its discretionary authority. The D.C. Circuit's decision empowers administrations of both parties to upend regulatory regimes in all fifty States without fully understanding the science or considering costs. The Supreme Court should hear this exceptionally important case and reaffirm the limits that Congress placed on EPA's power."

What happens next?

The Supreme Court must now decide whether to take the case. A grant of review would put the 2024 PM2.5 standard — and the broader question of how far the EPA can go outside its statutory review cycle — before a court that has increasingly scrutinized agency power. A denial would leave the tighter standard and its permitting consequences in place for businesses and states across the country.