NAM Fights EPA Air Rule at Supreme Court

The National Association of Manufacturers has taken its fight against a new Environmental Protection Agency air quality standard to the U.S. Supreme Court. The NAM, joined by a coalition of business groups, filed a petition asking the court to reverse a lower court's decision that allowed the EPA's rule on fine particulate matter, known as PM2.5, to stand.

NAM Chief Legal Officer Linda Kelly called the rule an unlawful regulatory shortcut. She argued it makes growing U.S. manufacturing and creating jobs more difficult. The consequences for investment and competitiveness are enormous, she stated.

Investment and Job Threats

A new analysis from the NAM quantifies the potential impact. The EPA lowered the National Ambient Air Quality Standard for PM2.5 from 12 micrograms per cubic meter to 9 in 2024. According to the NAM, this new standard jeopardizes at least 474 manufacturing projects announced in the United States since January 1, 2025.

The association claims these projects represent nearly $1 trillion in planned investment. They also support more than 122,000 American jobs. The potential scale of this disruption is a primary concern for industry leaders reviewing their fixtures and expansion plans.

A Contested Legal Pathway

The legal battle centers on how the EPA enacted the stricter standard. The Clean Air Act requires the agency to conduct a thorough review of air standards every five years. Following a complete review in 2020, the EPA retained the PM2.5 standard at 12 micrograms per cubic meter.

The previous administration later reopened that completed review. It then lowered the standard to 9 in 2024. The NAM and seven business groups challenged this move in the D.C. Circuit Court of Appeals. They argued the EPA lacked the authority to revise the standard through an "off-cycle reconsideration" without a new, thorough review.

In a significant shift, the EPA under the Biden administration reversed the federal government's position in November 2025. It asked the D.C. Circuit to vacate the rule, agreeing with the NAM that the previous administration had used an unlawful shortcut.

Despite this, the D.C. Circuit upheld the rule on June 26, 2026. The court concluded the EPA could revise standards outside the five-year review cycle without a full review. It relied on a Clean Air Act provision the previous administration had not used to defend the rule. The NAM calls this judicial rescue of an unlawful regulation improper.

Manufacturers now seek a Supreme Court review. They argue the standard threatens their ability to obtain permits, expand operations, and modernize facilities. The NAM is the largest manufacturing association in the U.S., representing companies in every industrial sector and all 50 states.