Virginia VOC Definition Updated: What It Means for Air Quality Compliance

If your facility operates under a Virginia air permit — or if you're working toward one — the EPA just made a change you need to understand. On April 23, 2026, the EPA published a final rule approving Virginia's State Implementation Plan (SIP) Revision A23, which updates the regulatory definition of Volatile Organic Compound (VOC) in the Virginia Administrative Code (VAC) to align with the federal definition under 40 CFR Part 51.

This is not a dramatic overhaul. But it is the kind of quiet regulatory update that catches facilities off guard when their permits, procedures, or product formulations were written against the old language. Here's what changed, why it matters, and what you should do about it.

What Is a SIP Revision, and Why Does It Matter?

A State Implementation Plan is the mechanism through which states demonstrate to the EPA that they will meet National Ambient Air Quality Standards (NAAQS) — the federal thresholds for criteria pollutants including ground-level ozone. VOCs are among the primary precursors to ozone formation, so how Virginia defines a "VOC" has direct downstream consequences for which compounds require controls, which emissions must be reported, and which products are regulated as ozone-precursor sources.

When a state's definition of VOC diverges from the EPA's federal definition, you can end up in a situation where a compound is treated differently under state versus federal rules. That kind of gap creates compliance risk — not because a facility is doing anything wrong, but because the regulatory framework itself is internally inconsistent.

Virginia's Revision A23 closes that gap. The Commonwealth submitted the revision to bring 9 VAC 5-10-20 into conformance with 40 CFR 51.100(s), the EPA's longstanding regulatory definition of VOC. The EPA reviewed the submission, found it consistent with the Clean Air Act and applicable federal requirements, and approved it through a direct final rule published in the Federal Register on April 23, 2026.

What Specifically Changed in Virginia's VOC Definition?

The core change is alignment. Virginia's prior definition of VOC in the VAC had not kept pace with incremental updates the EPA has made to 40 CFR 51.100(s) over the years. The EPA periodically adds compounds to its list of VOC exemptions — substances that, despite fitting the chemical definition of a VOC, have been determined to have negligible photochemical reactivity and therefore do not meaningfully contribute to ozone formation.

These exempt compounds include substances like acetone, t-butyl acetate, and a growing list of others that the EPA has assessed through its reactivity-based framework. When Virginia's definition lagged behind, those newer exemptions were technically not recognized under Virginia's SIP, even though the EPA had already determined they posed negligible ozone risk at the federal level.

Revision A23 brings Virginia's list of exempt compounds current with the federal list. In practical terms, this means:

• Compounds the EPA has determined to be negligibly reactive are now also recognized as non-VOC under Virginia's air quality rules
• Facilities using those compounds have a clearer regulatory basis under state law for not counting them toward VOC emissions totals
• Permit calculations, emission inventories, and applicability determinations that reference the VAC definition now rest on language that matches federal intent

According to the EPA, there are currently more than 80 compounds listed as exempt from the federal VOC definition under 40 CFR 51.100(s). Virginia's SIP now reflects that full list.

Effective Date and Regulatory Coordinates

The EPA published this rule as a direct final rule in the Federal Register. Under the direct final rulemaking process, the rule becomes effective 30 days after publication absent significant adverse comment — placing the effective date in late May 2026.

Key regulatory coordinates for your compliance files:

If you have active permit applications, renewals, or ongoing compliance reporting cycles, the effective date is the threshold you should be tracking.

Why the EPA Uses a Reactivity-Based VOC Exemption Framework

It's worth understanding the underlying logic here, because it shapes how these exemptions are applied in practice.

Not all organic compounds contribute equally to ozone formation. The photochemical reactivity of a compound — its tendency to react with nitrogen oxides in sunlight to form ground-level ozone — varies enormously. Ethanol and acetone are both organic compounds, but their ozone-forming potential is vastly different. The EPA's Maximum Incremental Reactivity (MIR) scale provides the scientific basis for distinguishing between them.

When the EPA removes a compound from the VOC definition, it is not saying the compound is harmless or unregulated in all contexts. It is saying that, for the specific purpose of ozone precursor control, that compound does not need to be counted. The Clean Air Act's ozone provisions target compounds that actually form ozone — not all organic carbon emissions.

This distinction matters operationally. A facility that switches from a high-reactivity solvent to a low-reactivity alternative may be able to demonstrate meaningful emissions reductions for ozone purposes, even if the mass of organic compound emitted stays the same or increases. Revision A23 makes that kind of argument available under Virginia state law to the same extent it is available under federal rules.

Practical Compliance Guidance for Virginia Facilities

Here is what I'd recommend reviewing in the wake of this change.

1. Audit Your VOC Emission Calculations

If your facility's emission calculations, permit applications, or emission inventories were prepared using Virginia's prior VOC definition, check whether any of the newly aligned exempt compounds appear in your process. If a compound you've been counting as a VOC is now recognized as exempt under the updated 9 VAC 5-10-20, your reported emissions may be overstated — and that has permit applicability implications.

2. Review Product Formulations and Raw Material Inventories

Facilities in industries like surface coating, adhesives, printing, industrial cleaning, and chemical manufacturing should cross-reference their material safety data sheets against the updated exempt compound list in 40 CFR 51.100(s). If any materials you use contain compounds that are now exempt under Virginia's updated definition, document that finding.

3. Check Permit Conditions That Reference the VAC VOC Definition

Some Virginia air permits include conditions that reference specific regulatory definitions. If your permit language is tied to the prior version of 9 VAC 5-10-20, talk to your permit engineer about whether a clarification or administrative amendment is warranted. Virginia DEQ typically provides guidance on this when SIP revisions affect permit language.

4. Update Internal Compliance Procedures

If your Environmental Management System (EMS) or internal compliance procedures cite the old VOC definition, update them. This sounds administrative, but outdated internal procedures are a real liability in the event of an inspection. Inspectors compare what your procedures say against current regulatory requirements — and any gap, even a benign one, invites scrutiny.

5. Confirm Applicability Thresholds Under the New Definition

For facilities near major source or synthetic minor thresholds under Virginia's air program, a shift in VOC accounting can affect whether you're subject to Title V, New Source Review, or other major source requirements. If newly exempt compounds push you below a relevant threshold, that's worth formal documentation. If you were already well below threshold, document that too.

How This Fits Into the Broader Federal-State Air Quality Framework

Virginia is not unique in needing periodic SIP revisions to stay current with federal VOC exemption updates. Across the country, EPA Region III and other regional offices regularly work with states to process these kinds of alignment revisions. The process is largely technical and non-controversial — which is why the EPA used a direct final rule here rather than a notice-and-comment rulemaking.

What makes this worth tracking is the cumulative effect over time. Each new compound the EPA exempts from the federal VOC definition represents a potential change in how facilities calculate emissions, how products are regulated, and how permit applicability is determined. States that keep their SIPs current give regulated entities a cleaner regulatory framework to work under. States that fall behind create interpretive ambiguity that tends to resolve, in my experience, in the direction of more compliance burden rather than less.

Virginia's Revision A23 is a positive development from that standpoint. The Commonwealth submitted it, the EPA reviewed it, and the result is a more coherent, internally consistent set of state air quality rules.

According to a 2023 EPA analysis, VOC emissions from stationary sources in the United States have declined by approximately 43% since 1990, a reduction attributable in significant part to source-specific controls applied under state SIPs. Keeping state VOC definitions current is part of maintaining the integrity of that regulatory infrastructure.

A Note on What This Change Does Not Do

It's worth being direct about the limits of this revision, because I've seen facilities over-interpret alignment updates.

Revision A23 does not change any emission limits. It does not relax any permit conditions. It does not exempt any facility from its existing obligations under Virginia's air quality program. What it does is ensure that the definitional foundation of those obligations is consistent with the federal framework the EPA has established.

If you were subject to VOC controls before this revision, you remain subject to VOC controls after it. The question is whether the specific compounds driving your VOC calculations have changed in their regulatory status — and for most facilities, the answer will be that the change is minor or has no practical effect at all.

Where the change matters is in edge cases: facilities that use compounds the EPA has recently added to its exemption list, facilities preparing new permit applications, and facilities that have been operating under an interpretive ambiguity about how to classify certain materials. For those facilities, this revision provides clarity.

Comparison: Old vs. Updated Virginia VOC Definition Framework

What to Do Right Now

The timeline here is short. With an effective date in late May 2026, facilities with active compliance cycles — particularly those in the middle of permit renewals, Title V certifications, or annual emission inventory submissions — should move quickly.

In my view, the most practical first step is a brief internal audit: pull your current VOC accounting methodology, compare the compounds you're tracking against the updated exemption list in 40 CFR 51.100(s), and flag any discrepancies for follow-up. That review shouldn't take more than a few hours for most facilities, and it will tell you whether any further action is warranted.

If you're unsure how to interpret the exemption list or whether a specific compound qualifies, that's a question worth getting answered before your next compliance filing — not after.

At Certify Consulting, I've helped more than 200 clients navigate exactly this kind of regulatory alignment work, and the consistent lesson is that early review costs far less than reactive correction. You can learn more about our air quality compliance consulting services or explore related environmental permitting and regulatory guidance resources on our site.

Source: Federal Register, April 23, 2026 — Air Plan Approval; Virginia; Revision to the Regulatory Definition of Volatile Organic Compound, Docket No. EPA-R03-OAR-2025-0328.

Last updated: 2026-05-07