Clean Air – Page 2 – Environmental and Energy Law Program

Regulatory Tracker

Air Transport Rules: Cross-State Air Pollution Rule/Good Neighbor Plan Rule

The Clean Air Act’s Good Neighbor provision requires upwind states to ensure that their instate sources do not contribute to downwind states’ attainment of the NAAQS. On Mar. 12, 2025, EPA announced its plan to roll back the Biden administration’s Good Neighbor Plan, which the Supreme Court stayed in June 2024.

April 27, 2026

Regulatory Tracker

National Ambient Air Quality Standards (NAAQS) for Particulate Matter (PM)

The CAA requires EPA to review and set primary and secondary standards for PM NAAQS every 5 years. The Biden EPA strengthened the standard in March 2024. On November 25, 2025, EPA requested the D.C. Circuit vacate the 2024 rule.

April 24, 2026

Quick Takes

EPA’s Proposal to Rescind Ethylene Oxide Emissions Standards for Commercial Sterilizers

A look at EPA’s four main rescissions and the agency’s rationale.

April 21, 2026

Quick Takes

EPA Finalizes Weakened Standards for OOOO Rules

Rule loosens requirements for flares and vent gas. EPA states the revisions are intended to provide flexibility to oil and gas operators.

April 10, 2026

Legal Analysis

EPA’s Final Rule Rescinding 2024 MATS Rule and Reinstating 2012 Standards

The legal foundations, regulatory history, and contested cost-benefit rationale behind EPA’s repeal of the 2024 MATS rule.

March 18, 2026

Quick Takes

EPA Rejects Colorado’s Regional Haze Plan Over Disputed Coal Plant Closure

A quick take on the disapproval, including a look at some of the legal arguments raised by commenters.

March 18, 2026

Regulatory Tracker

Ethylene Oxide (EtO) Emissions Standards for Commercial Sterilizers

In March 2026, EPA proposed rolling back many of the 2024 rule’s more stringent emissions limits.

March 17, 2026

Regulatory Tracker

Implementation of 2015 Ozone National Ambient Air Quality Standards (NAAQS)

Under the Trump executive order Regulatory Freeze Pending Review, the Biden administration’s final rule setting deadlines for states to submit SIPs for nonattainment areas did not go into effect. On June 3, 2025, EPA announced its plans to reconsider the rule.

March 9, 2026

Post

‘The Clean Air Act is the bedrock of U.S. climate regulation, but it cannot do the job alone.’

Jody Freeman in Yale Environment 360: Now is the time to develop climate strategies that can be pursued when the political balance shifts.

March 3, 2026