EPA's 'Once In, Always In' May Be Officially on the Way Out
The EPA major source "Once In, Always In" rule may be on its way out. Major sources will now have the ability to reclassify as area sources.
EPA has proposed a rule that would officially eliminate the air regulations rule of “Once In, Always In” for major source hazardous air pollutant (HAP) emissions. As a result, EPA is estimating reduced regulatory burden for thousands of locations, and thousands of others could now have a better incentive to reduce air emissions.
⚡ TL;DR: EPA’s proposed rule eliminates “Once In, Always In,” allowing major HAP sources to reclassify as area sources once they reduce emissions. Estimated half of 7,920 major sources could qualify—saving $168.9M+ annually in compliance costs.
Background: Air Emissions Regs
Locations that emit one or more of the 187 named hazardous air pollutants above a certain threshold are classified as a “major source.” As a result, they become subject to a number of additional regulatory obligations. They are required to follow certain rules established by their related Maximum Achievable Control Technology (MACT) rules and are required to complete annual Title V Air Emissions permitting.
If locations have HAP air emissions below the stated threshold, they are classified as “area sources.” The regulatory requirements at this level are much less burdensome.
⚠️ What’s at stake: Major source classification locks facilities into perpetual Title V permitting, MACT monitoring, and annual compliance costs. But if this rule passes, smart operators can reclassify and cut regulatory burden dramatically—if they act fast.
What’s Once In, Always In?
EPA’s Once In, Always In policy stated that once a location reaches that major source classification, they were always going to be a major source, not matter what – even if the company took steps to reduce emissions below that threshold. It was developed in 1995 as a guidance memo and originally intended to only be in place until the agency could propose amendments, but it stayed in permanently.
As part of the 2017 Executive Order for agencies to review and reduce regulations, EPA looked at Once In, Always In. They determined the Clean Air Act really did not specify or support time limits. As a result, EPA issued its own interpretation memo saying there was no basis for major sources to have that classification permanently. These sources should have the ability to reclassify as area sources if they implemented the controls and reductions necessary to become area sources.
This new proposed rule is the formal step to make this interpretation final.
The Benefits
This rule will benefit companies that have already implemented technologies to control HAP emissions, and companies whose processes or operations have changed to the degree that they no longer emit or have the capabilities to emit HAPs above the thresholds.
EPA estimates that out of 7,920 major sources, approximately half will now be eligible to reclassify as an area source. Besides the lessened compliance burden, EPA estimates costs savings of $168.9 million in the first year, and $163-$183 million each year after.
Those companies who are still major sources will also now have a concrete incentive to make changes to operations that would further reduce HAP emissions.
If your facility is a major HAP source, the window to reclassify could be closing soon. Don’t wait for finalization—start modeling your HAP reduction strategy now. Contact iSi Environmental for an air emissions audit.
Public Comment
Find out more information about this rule here. EPA is also soliciting public comment at regulations.gov. They want to hear about all aspects of their proposal including their interpretation of Once In, Always In, requirements for establishing effective HAP limits, allowing limits issued by states/local/tribal agencies as effective as long as they are legally and practically enforceable, and ideas for safeguards to ensure emissions are not increased.
💰 The cost of non-compliance: Staying locked in as a major source costs $163M–$183M annually in compliance burden across the regulated community. Even a single facility can save six figures annually by reclassifying—if they have the emissions data to back it up.
Frequently Asked Questions
Q: What is EPA’s “Once In, Always In” rule for major sources?
The “Once In, Always In” rule is an EPA policy established in 1995 that classified facilities as permanent major sources of Hazardous Air Pollutants (HAPs) once they exceeded the major source threshold, regardless of subsequent emission reductions. Major sources must comply with Maximum Achievable Control Technology (MACT) standards and Title V annual air emissions permitting requirements, which are significantly more burdensome than area source requirements.
Q: What is the difference between a major source and an area source for hazardous air pollutants?
A major source emits one or more of EPA’s 187 named hazardous air pollutants above the regulatory threshold and must comply with MACT rules and Title V permitting. An area source falls below this threshold and has significantly less stringent regulatory requirements. Major source classification triggers substantial compliance costs and administrative obligations, while area sources have minimal regulatory burden.
Q: How does EPA’s proposed elimination of “Once In, Always In” benefit companies?
Eliminating “Once In, Always In” allows major sources that have implemented effective HAP emission controls or operational changes to reclassify as area sources. EPA estimated that approximately half of 7,920 major sources could be eligible for reclassification. This policy change creates an incentive for companies to invest in emission reduction technologies with potential cost savings of $168.9 million in the first year and $163-$183 million annually.
Q: What documentation is required to reclassify from major source to area source status?
Facilities seeking reclassification must demonstrate they have implemented effective controls and reductions to keep HAP emissions below the major source threshold, with requirements that limits be legally and practically enforceable. iSi Environmental recommends consulting EPA guidance on establishing effective HAP limits and recordkeeping documentation.
The “Once In” rule has held facilities hostage for decades. This proposed rule is your off-ramp—but only if you’re ready with data and emission controls.
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