# Identification of plan-in part.
**AGENCY:**
Environmental Protection Agency (EPA).
**ACTION:**
Final rule.
**SUMMARY:**
The Environmental Protection Agency (EPA) is taking final action to approve a revision to the Mojave Desert Air Quality Management District (MDAQMD) portion of the California State Implementation Plan (SIP). The revision concerns definitions that are necessary to implement and enforce local rules that regulate air pollution under the Clean Air Act (CAA or the “Act”). We are also approving the rescission of earlier versions of this rule from the California SIP as they are no longer needed under the CAA.
**DATES:**
This rule is effective February 9, 2026.
**ADDRESSES:**
The EPA has established a docket for this action under Docket ID No. EPA-R09-OAR-2022-0858. All documents in the docket are listed on the *https://www.regulations.gov* website. Although listed in the index, some information is not publicly available, *e.g.,* Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials are available through *https://www.regulations.gov,* or please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section for additional availability information. If you need assistance in a language other than English or if you are a person with a disability who needs a reasonable accommodation at no cost to you, please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section.
**FOR FURTHER INFORMATION CONTACT:**
Allison Kawasaki, EPA Region IX, 75 Hawthorne St., San Francisco, CA 94105; telephone number: (415) 972-3922; email address: *[email protected].*
**SUPPLEMENTARY INFORMATION:**
Throughout this document, “we,” “us,” and “our” refer to the EPA.
**Table of Contents**
I. Proposed Action
II. Public Comments and EPA Responses
III. EPA Action
IV. Incorporation by Reference
V. Statutory and Executive Order Reviews
**I. Proposed Action**
As listed in table 1, on July 10, 2025 (90 FR 30611), the EPA proposed to approve MDAQMD Rule 102, “Definition of Terms,” amended on September 28, 2020 (“Rule 102”), into the Mojave Desert portion of the California SIP. Additionally, as listed in table 2, we proposed to approve the rescission of other outdated definition rules from the Mojave Desert portion of the California SIP.
| Local agency | Rule No. | Rule title | Amended | Submitted |
| --- | --- | --- | --- | --- |
| MDAQMD | 102 | Definition of Terms | 9/28/2020 | 3/12/2021 |
| Local agency | Rule No. | Rule title | Adopted | SIP approval date and FR citation |
| --- | --- | --- | --- | --- |
| San Bernadino County Air Pollution Control District | 102 | Definition of Terms | July 5, 1977 | 43 FR 59489; December 21, 1978. |
| Riverside County Air Pollution Control District | 102 | Definition of Terms | Not Available | 43 FR 59489; December 21, 1978. |
We proposed to approve these SIP revisions because we determined that they comply with the relevant CAA requirements. Our proposed action contains more information on the rules and our evaluation.
**II. Public Comments and EPA Responses**
The EPA's proposed action provided a 30-day public comment period. During this period, we received one comment. The commenter suggests recognizing emerging pollutants and climate-related terminology and aligning definitions across all SIPs. The comment specifically suggests that “carbon dioxide equivalent,” “greenhouse gases,” and “net-zero emissions” be defined in the rule. We thank the commenter for their comment, but the comment submitted did not change our assessment of the rule as described in our proposed action. Under title I of the CAA, the EPA establishes the national ambient air quality standards (NAAQS) for six air pollutants, or criteria pollutants, known to be harmful to human health and the environment. [^1] Section 110(a) of the CAA requires states to submit SIPs that provide for implementation, maintenance, and enforcement of each NAAQS. Since SIP actions must pertain to the NAAQS, and the EPA has not established a NAAQS for carbon dioxide or other greenhouse gases, the suggested revisions are not required under the CAA; thus, this comment is outside the scope of the EPA's authority in this action. Therefore, because this submittal complies with the requirements of the CAA, the EPA is finalizing approval, as proposed, under CAA section 110(k).
[^1] The EPA maintains a table of the current NAAQS here: *https://www.epa.gov/criteria-air-pollutants/naaqs-table.*
**III. EPA Action**
No comments were submitted that change our assessment of the rule as described in our proposed action. Therefore, as authorized in section 110(k)(3) of the Act, the EPA is approving Rule 102 into the Mojave Desert portion of the California SIP and rescinding the definition rules listed in table 2 for the San Bernadino County Air Pollution Control District and Riverside County Air Pollution Control District. The September 28, 2020, version of Rule 102 will replace the previously approved version of this rule in the SIP. Our final action includes regulatory text in 40 CFR 52.220 that incorporates by reference Rule 102 and rescinds the previously approved rules listed in table 2.
**IV. Incorporation by Reference**
In this document, the EPA is finalizing regulatory text that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is finalizing the incorporation by reference of MDAQMD, Rule 102, “Definition of Terms,” amended on September 28, 2020, which states the definition of terms used in MDAQMD rules. The EPA has made, and will continue to make, these documents available through *https://www.regulations.gov* and at the EPA Region IX Office (please contact the person identified in the *FOR FURTHER INFORMATION CONTACT* section of this preamble for more information).
**V. Statutory and Executive Order Reviews**
Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action merely approves state law as meeting federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this action:
• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
• Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 *et seq.* );
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 *et seq.* );
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it approves a state program;
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and
• Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA.
In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where the EPA or an Indian Tribe has demonstrated that a Tribe has jurisdiction. In those areas of Indian country, the rule does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
This action is subject to the Congressional Review Act (CRA), and the EPA will submit a rule report to each House of the Congress and to the Comptroller General of the United States. This action is not a “major rule” as defined by 5 U.S.C. 804(2).
Under section 307(b)(1) of the CAA, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by March 9, 2026. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this action for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements (see CAA section 307(b)(2)).
**List of Subjects in 40 CFR Part 52**
Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Ozone, Particulate matter, Reporting and recordkeeping requirements, Volatile organic compounds.
Dated: December 22, 2025.
Michael Martucci,
Acting Regional Administrator, Region IX.
For the reasons stated in the preamble, the Environmental Protection Agency amends part 52, chapter I, title 40 of the Code of Federal Regulations as follows:
**PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS**
**40 CFR Part 52**
1. The authority citation for part 52 continues to read as follows:
**Authority:**
42 U.S.C. 7401 *et seq.*
**Subpart F—California**
**40 CFR Part 52**
2. Section 52.220 is amended by adding paragraphs (c)(42)(xiii)(G), (c)(42)(xiv)(E), (c)(542)(i)(A)( *2* ), and (c)(587)(i)(B) to read as follows:
§ 52.220
(c) * * *
(42) * * *
(xiii) * * *
(G) Previously approved on December 21, 1978, in paragraph (c)(42)(xiii)(A) of this section and now deleted with replacement in paragraph (c)(179)(i)(B)( *1* ) of this section: Rule 102.
(xiv) * * *
(E) Previously approved on December 21, 1978, in paragraph (c)(42)(xiv)(A) of this section and now deleted with replacement in paragraph (c)(44)(v)(A) of this section: Rule 102.
(542) * * *
(i) * * *
(A) * * *
( *2* ) Previously approved on November 12, 2020 in paragraph (c)(542)(i)(A)( *1* ) of this section and now deleted with replacement in (c)(587)(i)(B)( *1* ) of this section: Rule 102, “Definition of Terms,” amended on January 28, 2019.
(587) * * *
(i) * * *
(B) Mojave Desert Air Quality Management District.
( *1* ) Rule 102, “Definition of Terms,” amended on September 28, 2020.
( *2* ) [Reserved]