Proposed Voluntary Ozone Precursor Prevention of Significant Deterioration (PSD) Offsets Program

An informal public comment period opened on September 8, 2026. On September 24, 2026, DEQ held a public meeting where staff provided information regarding the proposed rules. Oral comments were provided on the record during this meeting. The informal public comment period ended on October 8, 2026.

A Notice of Rulemaking Intent will be published in The Oklahoma Register on November 2, 2026, opening a formal rulemaking public comment period which will end on December 2, 2026. A copy of the notice and proposed rules will be published to the December 9, 2026 AQAC meeting page.

DEQ staff will give a presentation on the proposed rules to the AQAC at the meeting on December 9. Oral comments may be made by the public during the AQAC meeting. The AQAC will vote on whether to recommend adoption of the proposed rules to the EQB.

If the AQAC has recommended adoption, the Chair of the AQAC will present the proposed rules to the EQB at the meeting on January 20, 2027. Oral comments may be made by the public during this meeting. The EQB may vote to remand the proposal back to the AQAC for possible amendment or approve the rules for adoption. If the EQB votes to adopt the proposed rules during the January 20, 2027, meeting, the rules will be sent to the 2027 Oklahoma Legislature for review and approval or disapproval, followed by Gubernatorial review. If the rule receives approval, the rules are expected to go into effect on September 15, 2027.

The rules must be in effect before any facility may obtain a construction permit that authorizes the creation (generation) of ERCs. The use (and extinguishment) of ERCs would require the submission of an application for a PSD construction permit for a project that would use the created ERCs to offset project emission increases. The permit review process for both generating and extinguishing ERCs is time consuming.

Ozone (O₃) is a gas composed of three oxygen atoms, unlike the oxygen (O₂) we breathe. Ozone is not usually emitted directly into the air by sources but is, rather, created by chemical reactions between oxygen, nitrogen oxides (NO_X), and volatile organic compounds (VOCs) in the presence of sunlight. NO_X and VOCs come from motor vehicle exhaust, industrial emissions, gasoline vapors, chemical solvents, and even natural sources.

Ozone can be “good” or “bad” depending on its location in the atmosphere. The natural ozone layer in the upper atmosphere absorbs most of the sun’s damaging ultraviolet radiation. Ground-level ozone in the lower atmosphere is considered “bad.” Many urban areas tend to have high levels of “bad” ozone, but even rural areas can have high ozone because wind carries it and its precursor pollutants (NOx and VOCs) hundreds of miles away from their original sources. This is referred to as “transport,” and it is a common problem in Oklahoma, especially during the warm season months of May to August, when southerly winds prevail and ozone concentrations are highest.

The complicated nature of ozone as a pollutant and the complex interaction of sources at various distances makes it difficult to pinpoint any one problematic source or even a small number of problematic sources. As a result, DEQ is developing this rule proposal as one part of its plan to bring the concentrations currently exceeding the ozone NAAQS back into compliance. By ensuring that each project approved using this voluntary mechanism will result in a net reduction in airshed emissions, DEQ expects to move closer to our goal of all ozone monitors reporting data below the NAAQS.

To learn more about ozone, see DEQ’s ozone factsheet.

DEQ maintains a statewide network of ozone monitors to ensure that ambient concentrations of ozone across the state are remaining below the ozone NAAQS. Recent monitoring  data are showing ozone concentrations near or above the ozone NAAQS for the Oklahoma City, Tulsa, and Lawton metropolitan areas. These high ozone measurements are the result of both ozone formation within the cities and the transport of ozone from other areas into the cities. Because these areas are monitoring ozone concentrations near the ozone NAAQS, the concentrations of ozone precursors in these cities leave little room for large-scale industrial growth. For more information, visit the NAAQS page. 

DEQ welcomes all comments on the proposed rule language and on the program in general. To view the proposed rule and comment, visit the December 9, 2026 AQAC meeting page after November 2.

DEQ will develop a Response to Comments document prior to the presentation of the proposed rule language to the EQB. In addition, DEQ will summarize the comments received on the record and will provide responses to those comments during the presentation of the rules to the AQAC. DEQ may revise its rule proposal prior to the AQAC meeting based on comments received.

Because certain areas in Oklahoma are monitoring ozone concentrations that are higher than that allowed under the NAAQS, DEQ staff developed the proposed rules to allow continued economic growth. The voluntary ozone precursor PSD offsets program incorporates elements of both the traditional PSD program and the Nonattainment NSR program. For example, the proposal requires that applicants using this offsets mechanism must use the Lowest Achievable Emission Rate (LAER) rather than the Best Available Control Technology (BACT) for any new units constructed. Furthermore, the proposal requires that the project must offset 110% of NOx and VOC emissions increases.

Injecting Nonattainment NSR requirements into the PSD framework is intended to provide an air quality benefit to the airshed, as the stricter rules on emissions will support a net reduction in the emissions even as industry is allowed to grow. The proposal involves the generation and use of ERCs. These ERCs will be generated and used through NSR construction permit applications, and they will have a lifespan of five years. ERCs will expire after that five year window, unless they are included in a PSD permit application.

For questions, contact:
Melanie Foster
melanie.foster@deq.ok.gov
(405) 702-4100