On March 12, 2025, EPA announced the “Biggest Deregulatory Action in U.S. History.” EPA’s press release referenced “31 historic actions in the greatest and most consequential day of deregulation in U.S. history.”

The press releases came out so fast and furious that CNN chief climate correspondent Bill Weir joined CNN host Kaitlan Collins on “The Source” later than evening and claimed the EPA was moving so fast it was making mistakes and incorrectly pointed to OOOOb/c in the title of one of the press releases as being typo or a placeholder. Instead, OOOOb/c was an informal reference to EPA’s standards under 40 CFR Part 60 Subparts OOOOb and OOOOc regulating crude oil and natural gas development.

So, what exactly did EPA promise to do? And now that a few months have passed, what progress has EPA made on their announcements?

This article focuses on EPA actions that are either directly or indirectly related to the air program, which covers nearly all of EPA’s actions. EPA’s actions can be broken down into four basic categories:

• Greenhouse Gas (GHG) Regulations
• 2024 amendments to New Source Performance Standards (NSPS) and National Emission Standards for Hazardous Air Pollutants (NESHAP)
• 2024 PM₅ National Ambient Air Quality Standard (NAAQS)
• Internal changes to EPA’s organization structure to align with its priorities

Greenhouse Gas Regulations

If you have been in the environmental protection business for a long time, you may remember a time when GHGs were not regulated under the Clean Air Act. It all started in 2007, when the U.S. Supreme Court in Massachusetts v. EPA ruled in a 5-4 decision that EPA could regulate GHG emissions in motor vehicles under Section 202(a)(1) of the Clean Air Act if EPA first determined that the GHG emissions from motor vehicles endangered public health or welfare. In 2009, EPA did so in a rule known as the Endangerment Finding. Then, in 2010 EPA finalized the Light-Duty Vehicle GHG Standards (LDV Rule), which triggered the regulation of GHGs at stationary sources.

Now, EPA is attempting to unravel all of this and using multiple pathways to do so. On July 29, 2025, EPA proposed to rescind the 2009 GHG Endangerment Finding. The Endangerment Finding is a prerequisite for regulating emissions from new motor vehicles and new motor vehicle engines. Absent this finding, EPA lacks statutory authority under Section 202 of the Clean Air Act to prescribe standards for GHG emissions. In this same proposed rule, separate from the rescission of the Endangerment Finding, EPA proposed to repeal all GHG emission standards for motor vehicles on the alternative bases that no requisite technology for vehicle and engine emission control can address the global climate change concerns identified in the findings without risking greater harm to public health and welfare. The public comment period ended on September 22, 2025.

Separate and independent from the Endangerment Proposal, on June 17, 2025, EPA proposed to repeal all GHG emissions standards for fossil fuel-fired power plants. EPA is also proposing, as an alternative, to repeal a narrower set of requirements that includes the emission guidelines for existing fossil fuel-fired steam generating units, the carbon capture and sequestration/storage (CCS)-based standards for coal-fired steam generating units undertaking a large modification, and the CCS-based standards for new base load stationary combustion turbines. The public comment period ended on August 7, 2025.

On September 16, 2025, EPA announced a proposed rule to end the GHG Reporting Program (GHGRP) that would result in up to $2.4 billion in savings. The GHGRP requires 47 source categories, covering over 8,000 facilities and suppliers in the U.S. to calculate and submit their GHG emissions reporting annually. EPA proposed that there is no requirement under the CAA to collect GHG emission information from businesses nor is continuing the ongoing costly data collection useful to fulfill any of the agency’s statutory obligations. The public comment period ends on November 5, 2025.

2024 Amendments to NSPS and NESHAP

There are several federal rules that were adopted in 2024 that were reconsidered by the new administration. These rules, and the actions taken by the new administration are as follows:

• 90 FR 35966 – Interim Final Rule July 31, 2025 extends the compliance deadlines for 40 CFR 60 Subpart OOOOb and Subpart OOOOc for crude oil and natural gas development. The public comment period ended September 2, 2025.
• 90 FR 25535 – Proposed Rule June 17, 2025 for 40 CFR 63 Subpart UUUUU, commonly known as the Mercury and Air Toxics Standards for coal- and oil-fired EGUs, that would repeal from the May 2024 rule, the revised PM standard for existing coal-fired EGUs; the revised PM standard compliance demonstration requirements; and the revised Hg standard for lignite-fired EGUs. The public comment period ended August 11, 2025.
• Under the Congressional Review Act (CRA) Congress passed a CRA resolution (H.J. Res. 61) disapproving the amendments to 40 CFR 63 Subpart XXXX for Rubber Tire Manufacturing (89 FR 94886; November 29, 2024), and President Trump signed it into law on May 23, 2025, as Public Law 119‑14. As a result, the November 2024 rule amendment is legally nullified and has no enforceable effect. An interesting aspect of the CRA is that a rule subject to an enacted joint resolution of disapproval may not be reissued in substantially the same form in the future.
• On July 17, 2025, President Trump, under the authority of Section 112(i)(4) of the Clean Air Act, issued a Proclamation granting a 2-year compliance extension for the “National Emission Standards for Hazardous Air Pollutants: Ethylene Oxide Emissions Standards for Sterilization Facilities Residual Risk and Technology Review” (89 FR 24090; April 5, 2024) in 40 CFR 63 Subpart O.
• On July 17, 2025, President Trump, under the authority of Section 112(i)(4) of the Clean Air Act, issued a Proclamation granting a 2-year compliance extension for the “New Source Performance Standards for the Synthetic Organic Chemical Manufacturing Industry and National Emission Standards for Hazardous Air Pollutants for the Synthetic Organic Chemical Manufacturing Industry and Group I & II Polymers and Resins” (89 FR 42932; May 16, 2024).
• On July 17, 2025, President Trump, under the authority of Section 112(i)(4) of the Clean Air Act, issued a Proclamation granting a 2-year compliance extension for the “National Emission Standards for Hazardous Air Pollutants: Taconite Iron Ore Processing” (89 FR 16408; March 6, 2024).
• On July 31, 2025 (90 FR 35966), EPA published an Interim Final Rule revising 2025 and 2026 compliance deadlines to April 3, 2027, based on technical and feasibility concerns raised by industry regarding the “National Emission Standards for Hazardous Air Pollutants: Integrated Iron and Steel Manufacturing Facilities Technology Review” (89 FR 23294; April 3, 2024). The initial public comment period was extended to October 2, 2025.
• On July 8, 2025 (90 FR 29997) EPA published an Interim Final Rule extending compliance dates for several provisions, including fenceline monitoring, leak controls, and emission standards, deferring enforcement to July 5, 2027 regarding the “National Emission Standards for Hazardous Air Pollutants for Coke Ovens: Pushing, Quenching, and Battery Stacks, and Coke Oven Batteries; Residual Risk and Technology Review, and Periodic Technology Review” (89 FR 55684; July 5, 2024). The initial public comment period was extended to October 6, 2025.

2024 PM_2.5 NAAQS

On February 7, 2024, EPA lowered the annual PM_2.5 NAAQS to 9.0 micrograms per cubic meter. In Kentucky et al. v. EPA (D.C. Circuit Case No. 24-1050), a coalition of states and industry groups challenged the PM_2.5 NAAQS. On February 25, 2025, the court granted a motion to hold the litigation in abeyance allowing new EPA leadership to review. In EPA’s March 12 announcement, they noted they had heard serious concerns regarding the rule from across the country. EPA also announced it would release guidance to increase flexibility on NAAQS implementation, reforms to New Source Review, and direction on permitting obligations. However, not much has happened publicly since then. EPA is required by law to notify states concerning any intended modifications to their nonattainment recommendations (also known as 120-day letters) by October 9, 2025, so something could be announced very soon.

Internal Changes to Align Priorities

EPA was not required to propose any rules or solicit public comments to make these changes since EPA has the authority to reorganize as they see fit in order to accomplish their priorities. As such, EPA has already made these changes to their organization.

• EPA Reorganization has reduced the workforce by about 3,700 employees, or about 23%, to employment levels near when Ronald Reagan was President.
• EPA terminated its Environmental Justice (EJ) and Diversity, Equity, and Inclusion (DEI) arms of the agency.
• EPA created the Office of State Air Partnerships. EPA stated in the announcement that: “This office will be focused on working with, not against, state, local and tribal air permitting agencies to improve processing of State Implementation Plans (SIPs) and resolving air permitting concerns.”
  • SIPs are critical for developing the detailed implementation requirements regarding Regional Haze, Interstate Transport, regulation of Startup/Shutdown/Malfunction issues, and other issues.
  • These state, local and tribal agencies do most of the implementation of the air quality programs through permitting, compliance, and SIP development. In the past, there has been much inefficiency created by EPA not providing timely guidance to these partner agencies or second guessing their decision making, sometimes long after the initial decision has been made.

What Should Air Permitted Sources Do?

Air permittees looking for assistance with upcoming permit applications or guidance in navigating these fast moving EPA changes, please contact your local Trinity Consultants office.