EPA’s “Once In, Always In” Policy Declared Dead Under CRA

If you’ve ever worked in environmental compliance, you know there are two kinds of rules: the ones you read in the Federal Register,
and the ones that live rent-free in your facility manager’s head. EPA’s “Once In, Always In” concept has been bothpart legal doctrine,
part campfire story (“and then… you’re a major source foreverrrrr”).

But in the latest plot twist, Congress used the Congressional Review Act (CRA) to nullify EPA’s 2024 “once in, always in”-style
rule on major-source reclassification for hazardous air pollutants (HAPs). The CRA joint resolution became law on June 20, 2025,
and EPA followed up by amending the regulations effective January 2, 2026 to remove the 2024 provisions and restore the 2020
“Major MACT to Area Source” framework (MM2A).

Translation: the regulatory zombie got a stake through the heartat least for the version Congress disapproved. In this article we’ll unpack
what died, what survived, why it matters, and what facilities should do next (besides refreshing their emissions spreadsheets and muttering,
“I just want to be an area source in peace.”).

First: What People Mean by “Once In, Always In”

“Once In, Always In” (often shortened to OIAI) is a nickname for EPA’s historical approach to a simple question under Clean Air Act
section 112: If you were once classified as a major source of hazardous air pollutants, can you ever become an area source?

Under the Clean Air Act, a major source generally means a stationary source that emits (or has the potential to emit)
10 tons per year of any single HAP, or 25 tons per year of combined HAPs. Anything below that is typically an
area source. That classification matters because major sources usually face tougher federal requirements (think MACT-level controls),
while area sources often face a different set of standards that can be less burdensome.

For decades, EPA’s OIAI posture essentially treated “major source” as a one-way door. Over time, EPA guidance and later rulemakings moved away
from that approachallowing a major source to reclassify as an area source if it takes enforceable steps to limit emissions.

Then came 2024: EPA did not fully resurrect the old, across-the-board OIAI policybut it did adopt a targeted version for
seven persistent and bioaccumulative HAPs listed in Clean Air Act section 112(c)(6). That’s the version Congress later disapproved.

Major vs. Area Source: Why the Label Changes Your Life

To a compliance team, “major source” isn’t just a labelit’s a lifestyle. Major-source status can drive:

• Which NESHAP standards apply (often MACT-based standards for major sources)
• Permitting posture (including how you manage potential-to-emit limits)
• Monitoring, recordkeeping, and reporting obligations
• Capital planning for controls, maintenance, and upgrades
• Operational flexibility (because “one more coating line” is never just “one more coating line”)

One reason the debate never dies is incentives. Industry argues that if reclassification is impossible, facilities have less motivation
to install controls that would get them below major-source thresholds. Environmental advocates often respond that MACT-level controls are a key
public-health safeguard, and relaxing major-source obligations can increase riskespecially for communities already burdened by industrial pollution.

Both perspectives can be true at the same time. That’s why the fine print matters: who can reclassify, when, and what follows.

The 2020 “MM2A” Rule: The Door Back to Area Source Status

In 2020, EPA finalized a rule commonly called Major MACT to Area Source (MM2A). In plain terms, it allowed major sources
of HAP to reclassify as area sources after taking steps to limit emissions, relying on the Clean Air Act’s definitions and the idea that
a source’s status should track its enforceable emissions potential.

Practically, this meant a facility could pursue reclassification by:

• Installing or optimizing controls to reduce actual emissions
• Taking enforceable limits that cap potential-to-emit (not just what you emitted last year)
• Updating permits and compliance systems to ensure those limits are real, measurable, and enforceable

The core concept: if you genuinely operate like an area sourceand your potential-to-emit is capped like an area sourceyou should be treated like one.

The 2024 Rule: A Targeted “Once In” Requirement for Seven PBT HAPs

On September 10, 2024, EPA finalized a rule titled “Review of Final Rule Reclassification of Major Sources as Area Sources Under
Section 112 of the Clean Air Act.” This 2024 rule amended the NESHAP General Provisions and effectively created a targeted “stay major” requirement:
certain sources of the seven persistent and bioaccumulative HAPs listed in CAA section 112(c)(6) would have to continue complying with
specified major-source emission standards even if they reclassified to area-source status.

Those seven pollutants (as listed in the statute and repeatedly referenced in agency materials) are:

• Alkylated lead compounds
• Polycyclic organic matter (POM)
• Mercury (and mercury compounds)
• Hexachlorobenzene
• Polychlorinated biphenyls (PCBs)
• 2,3,7,8-tetrachlorodibenzofurans (TCDF)
• 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

EPA’s stated rationale tied back to Clean Air Act section 112(c)(6), which directs EPA to list source categories and ensure that sources accounting
for not less than 90% of the aggregate emissions of each of those pollutants are subject to standards under section 112(d)(2) or 112(d)(4).
The 2024 rule aimed to prevent the MM2A pathway from undercutting that 90% coverage goal.

So if 2020 was “you can become an area source,” the 2024 rule was “you can become an area source, but for these seven PBT HAPs,
you may still have to keep major-source-level obligations.”

Enter the CRA: Congress Hits the Big Red Button

The Congressional Review Act is Congress’s fast-track method for overturning certain federal agency rules. If both chambers pass a joint
resolution of disapproval and the President signs it, the targeted rule generally has “no force or effect.”

In this case, Congress passed S.J. Res. 31, which disapproved the 2024 rule (published September 10, 2024). The resolution became
Public Law 119–20 on June 20, 2025.

Here’s the part that makes regulated entities sit up straight: under the CRA, once a rule is disapproved, the agency generally
cannot reissue the rule in “substantially the same form” unless Congress specifically authorizes it through a later law.
That phrase is famously squishybut it’s still a real constraint, and it’s why people describe the 2024 approach as “dead” under the CRA.

EPA’s 2026 Follow-Through: Back to the 2020 Language

After the CRA disapproval, EPA amended the Code of Federal Regulations effective January 2, 2026. In that final rule, EPA removed
the provisions added in 2024 and restored the language of the 2020 MM2A final rule. EPA also acknowledged that, by operation of the CRA,
the 2024 rule has no legal force or effect.

EPA’s 2026 action is, in many ways, the regulatory equivalent of putting a sticky note on the rulebook that says:
“Ignore the 2024 editsreturn to the 2020 version.”

So… What Does This Mean for Facilities Right Now?

The short version: facilities considering reclassification should evaluate their options under the restored 2020 MM2A framework,
while staying alert to lingering obligations, permitting realities, and enforcement risk.

1) Reclassification is back on the table (but it’s not a free pass)

The CRA disapproval removes the 2024 rule’s targeted “keep major-source standards for seven PBT HAPs” mechanism. That tends to broaden the value of
reclassification for facilities that were worried the 2024 requirements would follow them around like a bad office nickname.

But reclassification still hinges on potential-to-emit limits. Emissions calculations, enforceable permit conditions, operational caps,
and monitoring are the difference between “credible area source” and “please enjoy this enforcement letter.”

2) Your permit is the main character

Even when federal rules shift, state implementation and permitting do not instantly morph. Facilities pursuing area-source status often need:

• Permit modifications to embed enforceable HAP limits
• Clear monitoring approaches (e.g., parametric monitoring, material balance, throughput limits)
• Recordkeeping that stands up to an inspector with caffeine and curiosity
• Coordination with Title V implications (in some cases, reclassification affects Title V applicability)

If you take one lesson from this saga, let it be this: “We’re below the threshold” is not the same sentence as
“Our potential-to-emit is federally enforceable below the threshold.”

3) For the seven PBT HAPs, the conversation changesbut the scrutiny may not

The 2024 rule was laser-focused on seven persistent and bioaccumulative pollutants for a reason: they are dangerous at low levels and can accumulate
in ecosystems and bodies. Even without the 2024 provisions, regulators and communities may still scrutinize:

• Whether controls remain operated and maintained properly
• Whether emissions increases occur after reclassification
• Whether state air toxics programs or permit conditions impose parallel requirements
• Whether NESHAP requirements still apply based on subpart-specific definitions or applicability triggers

In other words, the legal “always in” may be gone, but the practical “always watched” can still be very realespecially for high-profile pollutants.

4) CRA “substantially the same” puts guardrails on future whiplash

The CRA doesn’t just erase; it also limits the ability to re-create the same approach without new legislation.
That does not mean the debate ends. It means future administrations may need to pursue different regulatory routes (or get Congress to bless a new one).

For planning purposes, this can cut both ways:

• For industry: potentially more predictability that the exact 2024 approach won’t reappear overnight in identical form.
• For advocates: a higher bar to reinstate the same reclassification restrictions via rulemaking alone.

What About Public Health and Environmental Protection?

The policy fight isn’t just proceduralit’s about risk. Major-source MACT standards are designed to represent the maximum achievable reductions
(considering statutory factors), and advocates argue they are critical to limiting toxic pollution exposure.
Supporters of reclassification emphasize that if a facility truly reduces emissions below major thresholdsand locks those reductions in with enforceable limits
the environmental outcome can still be positive.

The uncomfortable truth is that outcomes depend on implementation:

• If reclassification leads to sustained, enforceable emissions reductions, it can reward actual pollution control.
• If reclassification becomes a paperwork trick that relaxes oversight without meaningful reductions, communities lose protection.

That’s why the most credible compliance programs treat reclassification as a long-term operating commitmentnot a one-time regulatory escape room.

Practical Examples: How This Plays Out

Example A: The “We Installed ControlsNow What?” Facility

A metal fabrication plant installs upgraded capture and control equipment and switches to lower-HAP materials. Actual emissions drop below major thresholds.
Under MM2A, the plant may be able to pursue area-source status if it also secures enforceable limits on potential-to-emit.
The win is not just “we emitted less last year.” The win is “we can’t exceed these limitsby permitand we can prove it.”

Example B: The “Seven-Pollutant” Anxiety Case

A facility in a source category associated with one of the seven persistent and bioaccumulative HAPs feared that even after reclassification it would be stuck
with major-source standards under the 2024 rule. After the CRA disapproval and EPA’s 2026 restoration of the 2020 language,
the facility’s strategic calculus may changepotentially making reclassification more attractive, while still requiring robust permit limits and compliance proof.

Example C: The “State Programs Still Exist” Reality Check

A facility reclassifies under federal definitions but operates in a state with stringent air toxics requirements, local risk review,
or permit conditions that effectively keep certain controls and reporting in place. The facility gets relief from some federal obligations,
but not a total reset. This is commonbecause federal status is just one layer of the compliance cake.
(And yes, compliance cake has layers. Unfortunately, it is not frosted.)

What Facilities Should Do Next

If you’re responsible for HAP compliance, consider this a checklist-friendly moment:

• Reconfirm your HAP inventory (including speciation where needed, and fugitive sources that love to hide in the margins)
• Recalculate potential-to-emit using defensible assumptions and current operations
• Evaluate enforceable limits you can actually live with (throughput caps that ruin production plans are… not living)
• Map subpart applicability and how standards shift under major vs. area status
• Stress-test monitoring and recordkeeping before you file anythingassume your future self will be tired and audited
• Coordinate early with regulators to avoid “surprise, your permit doesn’t say that” moments

Also: keep an eye on litigation and policy developments. EPA’s 2026 final rule includes standard judicial review language and deadlines,
and the broader regulatory environment can evolve quickly.

Bottom Line

The headline “Once In, Always In is dead” is true in the specific sense that matters here: the 2024 rule that imposed a targeted “keep major-source
standards” requirement for seven persistent and bioaccumulative HAPs has been disapproved under the CRA, and EPA has restored the 2020 MM2A language.
Reclassification pathways are back in their 2020 form, and the CRA makes it harder to simply resurrect the same 2024 approach without new legislation.

But the deeper lesson is timeless: major vs. area status is not a vibe; it’s a defensible, enforceable emissions reality.
The facilities that succeed are the ones that treat reclassification as a compliance system redesignsupported by permits, monitoring, training,
and operational disciplinenot as a legal shortcut.

Experiences From the Real World (Composite Stories, 500+ Words)

The following experiences are composite, anonymized scenarios that mirror what environmental managers, consultants, and counsel commonly run into when
navigating major-source reclassification and “once in, always in”-style debates. They are not legal advicejust the kind of “been there” texture you don’t get
from a sterile rule summary.

1) The Spreadsheet That Ate a Weekend

One plant’s environmental lead described reclassification planning as “the week I learned my calculator had feelings.” The facility was confident it had
driven HAP emissions downnew controls, better capture, tighter operating practices. But when they moved from “actual emissions” to “potential-to-emit,”
everything got messy. That’s because potential-to-emit isn’t a diary of what happened; it’s a forecast of what could happen under worst-case operations
unless enforceable limits prevent it.

They ended up rebuilding the emissions model from scratch: raw material usage rates, operating hours, control device uptime assumptions, emission factors,
andmost painfulwhat happens during startups, shutdowns, and maintenance events. The breakthrough wasn’t fancy math. It was translating operations into
enforceable permit conditions: throughput limits that production could accept, monitoring that maintenance could reliably perform, and recordkeeping that
wouldn’t collapse the first time someone went on vacation.

The “experience” takeaway: reclassification is as much change management as it is air modeling. If your plan can’t survive staffing turnover, it won’t survive
an inspection.

2) The Permit Negotiation That Turned Into a Trust Exercise

Another team tried to reclassify quicklybecause leadership wanted cost savings yesterday. The regulator’s reaction was polite but firm:
“Show me how you’ll ensure you stay below the threshold, and how we’ll know.” That shifted the entire strategy from “tell” to “demonstrate.”

They proposed federally enforceable limits and a monitoring plan. The first draft was ambitious: multiple caps, multiple calculation methods, and an
impressive number of “we will” statements. The regulator pushed back, not because the idea was wrong, but because the plan was too complicated to enforce.
The final permit approach was simpler: fewer limits, clearer monitoring triggers, a recordkeeping format that was actually usable, and a defined corrective-action
process if parameters drifted.

The “experience” takeaway: the best permit is not the one that looks smartest on paper. It’s the one that your facility can run every day and that a third
party can verify without reading your mind.

3) The “Once In” Fear That Became a Culture Problem

In some facilities, the phrase “once in, always in” becomes a kind of fatalism. People stop proposing improvements because they believe the regulatory
benefit is unattainable. In one composite scenario, an EHS manager had to actively reframe the internal narrative: “We’re not chasing a label. We’re chasing
real reductions and a compliance structure that matches our actual emissions.”

When the 2024 rule came out, the mood worsenedespecially at facilities near the seven persistent and bioaccumulative HAP discussion. Staff worried that
even if they spent money and reduced emissions, they’d still be treated as major sources for key obligations. That uncertainty bled into capital planning:
should they invest in controls if the payoff is unclear?

After the CRA disapproval and the 2026 restoration of the 2020 MM2A language, that same manager treated the moment like a reset button for culture.
They ran internal workshops on what reclassification actually requires, what it doesn’t, and how permit limits would work in practice. The goal wasn’t to
“game” the system. It was to align the organization around enforceable emissions disciplineand to restore incentives to reduce.

The “experience” takeaway: policy shifts don’t just change rules; they change morale. Smart programs address both.

4) The Unexpected Twist: Community Attention Doesn’t Reclassify

Even when a facility successfully reclassifies, public attention often remains. One composite facility found that local stakeholders didn’t care about the
label change; they cared about whether emissions stayed down and whether monitoring was transparent. The facility responded by improving its public-facing
reporting, enhancing odor and complaint response procedures, and building a stronger relationship with local officials.

The “experience” takeaway: reclassification can reduce regulatory burden, but it doesn’t automatically reduce reputational risk. If anything, it can increase
scrutinybecause people worry it’s a loophole. The antidote is consistency and proof.