Clean Air – Environmental and Energy Law Program

Regulatory Tracker

Once In Always In Guidance for Major Sources under the Clean Air Act

The Biden EPA rule requires facilities that reclassify from major sources of hazardous air pollutants to area sources to remain subject to the major source standards for 7 pollutants.

May 1, 2025

Regulatory Tracker

Clean Car Rules — Corporate Average Fuel Economy Standards/Greenhouse Gas Standards

The Biden administration approved the California waiver and promulgated rules to reduce vehicle emissions. On Mar. 12, 2025, EPA announced that it intends to roll back vehicle emissions regulations for model year 2027 and later light- and medium-duty vehicles, as well as greenhouse gas emissions standards for trucks.

April 18, 2025

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 14, 2025

Regulatory Tracker

Petroleum Refinery Sector Rule (NESHAPs / NSPS)

The Biden EPA amended the 2015 standards for refineries. On Mar. 12, the Trump administration slated these standards for rollback.

April 10, 2025

Regulatory Tracker

EPA VOC and Methane Standards for Oil and Gas Facilities

The Biden EPA finalized three rules regulating methane emissions from the oil and gas sector. One of the rules, the Waste Emission Charge, has been repealed under the Congressional Review Act. The Trump EPA included the other two, the methane emission reduction and GHG reporting rules, as slated for rollback.

April 10, 2025

Regulatory Tracker

Mercury and Air Toxics Standards

The Biden EPA strengthened mercury standards for coal-fired power plants, which industry challenged in the D.C. Circuit. The Trump EPA provided exemptions to 68 power plants and EPA has slated the rule for rollback.

April 8, 2025

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Clean Fuel Standard Directed Benefit Mechanisms to Promote Equity

New paper co-authored by Abby Husselbee looks at how CFS programs could be designed to direct public health, mobility, and economic benefits.

April 3, 2025

Regulatory Tracker

Municipal Solid Waste Landfill Air Pollution Emission Standards for Methane and Other Pollutants

MSW landfills are currently subject to EPA’s 2016 New Source Performance Standards and Environmental Guidelines. In October 2024, EPA requested comments in advance of a rulemaking. Comments are due by May 23, 2025.

March 21, 2025

Regulatory Tracker

Regional Haze Rule

EPA is reviewing Regional Haze state implementation plans. The Trump administration announced that it plans to restructure the Regional Haze Program.

March 20, 2025