Arizona PM2.5 State Implementation Plan Approval

Content

ACTION:

Final rule.

SUMMARY:

The Clean Air Act (CAA) requires each state implementation plan (SIP) to contain adequate provisions prohibiting emissions
that will significantly contribute to nonattainment or interfere with maintenance of air quality in other states. The State
of Arizona submitted SIP revisions to the Environmental Protection Agency (EPA) to address these requirements for the 2012
fine particulate matter (PM 2.5) national ambient air quality standards (NAAQS). The EPA is finalizing approval of Arizona's SIP submission as meeting the
requirement that the Arizona SIP contains adequate provisions to prohibit emissions activity, within the State, from emitting
air pollutants in amounts that will significantly contribute to nonattainment or interfere with maintenance of the 2012 PM 2.5 NAAQS in any other state.

DATES:

This rule is effective May 18, 2026.

ADDRESSES:

The EPA has established a docket for this action under Docket ID No. EPA-R09-OAR-2025-0191. All documents in the docket are
listed on the https://www.regulations.gov website. Although potentially listed in the index, some information is not publicly available, e.g., Confidential Business Information 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:

Michael Dorantes, Geographic Strategies and Modeling Section (AIR 2-2), EPA Region IX, 75 Hawthorne Street, San Francisco,
CA, telephone number: (415) 972-3934, email address: dorantes.michael@epa.gov.

SUPPLEMENTARY INFORMATION:

Throughout this document, “we,” “us,” and “our” refer to the EPA.

Table of Contents

I. Summary of Proposed Action

II. Public Comments and EPA Responses

III. Final Action

IV. Statutory and Executive Order Reviews

I. Summary of Proposed Action

On October 23, 2025, the EPA proposed to approve the SIP revisions submitted by the State of Arizona on December 11, 2015,
and on February 10, 2022, (collectively referred to herein as “Arizona's 2012 PM 2.5 I-SIP submittals”) with respect to the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2012 PM 2.5 NAAQS. (1) Based on our evaluation summarized in our proposed rulemaking and fully detailed in the accompanying technical support document,
we proposed to find that Arizona's 2012 PM 2.5 I-SIP submittals contained adequate provisions to prohibit any source or other type of emissions activity within the state
from emitting air pollutants in amounts that will significantly contribute to nonattainment of the 2012 PM 2.5 NAAQS in another state (prong 1) or interfere with maintenance of the 2012 PM 2.5 NAAQS in another state (prong 2). Additionally, we proposed that Arizona's 2012 PM 2.5 I-SIP submittals met the procedural requirements for

  public participation under CAA section 110(a)(2) and 40 CFR 51.102.

II. Public Comments and EPA Responses

The EPA's proposed action provided a 30-day public comment period that ended on November 24, 2025. During this period, the
EPA received two comments, one from a private citizen and the other from a private organization. (2) The comment submission from the private citizen was supportive of our proposed approval of the Arizona's 2012 PM 2.5 I-SIP submittals with respect to the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I). This supportive
comment does not require a response. The comment submittal from the private organization raised several issues in opposition
to our proposed action, so we address each one individually in this section.

Comment 1A: First, the commenter references the Regulatory Flexibility Act (RFA) and Small Business Regulatory Flexibility Act (SBREFA)
and states that the EPA has done a conclusory certification under 5 U.S.C. 605(b) that the action will not have a significant
economic impact on a substantial number of small entities. They state that by approving Arizona's 2012 PM 2.5 I-SIP submittals, state control measures relied upon by the EPA and the State in its submittal become enforceable under Federal
law, materially changing the legal risk for small entities. The commenter states that the EPA should either prepare an initial
Federal regulatory flexibility analysis under 5 U.S.C. 603 or supplement the certification with a broader analysis than what
was provided in the proposal.

Response 1A: The EPA disagrees with this comment. The regulatory analysis provisions of the RFA are only triggered by a threshold determination
by the Agency that this rule will have a significant economic impact on a substantial number of small entities. This action
approving Arizona's 2012 PM 2.5 I-SIP submittals for the interstate transport provisions of CAA section 110(a)(2)(D)(i)(I) will not have a significant economic
impact on a substantial number of small entities under the RFA or SBREFA. This action merely approves Arizona's weight of
evidence analysis that emissions from sources in Arizona will not significantly contribute to nonattainment or interfere with
maintenance of the 2012 PM 2.5 NAAQS in any other state, as required by the CAA, and does not impose any additional requirements beyond those already approved
into the SIP or otherwise required by State law. Because the Agency has certified this rule will not have a significant economic
impact, section 603 of the RFA does not apply to this rulemaking. (3)

Comment 1B: Citing the Paperwork Reduction Act (PRA) and its implementing regulations at 5 CFR 1320, the commentor asserts that Federal
agencies must obtain OMB approval for “ collection of information' that an agencyconducts or sponsors,' including third-party
or state submissions when a Federal agency requires persons to obtain, maintain, or disclose information to third parties.”
The commentor states that many SIP provisions relied upon by Arizona in its submittal require recordkeeping, plan preparation,
and third-party disclosure, such as maintaining dust control logs onsite for inspectors and maintaining vendor records. The
commentor states that once these provisions are “federally approved” as part of the EPA's action on Arizona's 2012 PM 2.5 I-SIP submittals for interstate transport, EPA inspectors can require production of these records. The commentor states that
the EPA must clarify whether any SIP recordkeeping or reporting obligations relied upon in Arizona's submittal are subject
to the requirements of the PRA and if not, provide a reasoned explanation as to why the recordkeeping and reporting requirements
are not collections of information “conducted or sponsored” by the EPA.

Response 1B: The PRA does not apply to this action. The PRA generally provides that every Federal agency must obtain Office of Management
and Budget approval before using identical questions to collect information from 10 or more persons. (4) The EPA is not conducting nor sponsoring the collection of information from 10 or more persons. The EPA is merely approving
Arizona's weight of evidence analysis that emissions from sources in Arizona do not significantly contribute to nonattainment
or interfere with maintenance of the 2012 PM 2.5 NAAQS in any other state, as required by the CAA, and does not impose any additional requirements beyond those already approved
into the SIP or otherwise required by State law.

Comment 1C: Citing 2 U.S.C. 1532, the commentor states that “the [Unfunded Mandates Reform Act (UMRA)] requires a written statement for
any rule that includes a `Federal mandate' that may result in expenditures by State, local, and Tribal governments, in the
aggregate, or by the private sector, of $100 million or more in any one year.” The commentor asserts that the EPA should either
provide an UMRA analysis that shows expenditures from the EPA's approval of Arizona's interstate transport plan will not approach
the $100 million threshold or explain why the proposed approval falls outside the UMRA's definition of a “Federal mandate.”

Response 1C: The EPA disagrees that this action triggers any obligations under the UMRA. The EPA has complied by making its own determination
that this rule will not result in expenditures of $100 million or more in any one year, and therefore the Agency does not
need to complete a statement under 2 U.S.C. 1532. As previously stated, this action merely approves Arizona's weight of evidence
analysis that emissions from sources in Arizona do not significantly contribute to nonattainment or interfere with maintenance
of the 2012 PM 2.5 NAAQS in any other state, as required by the CAA. This action therefore does not impose any Federal mandate on Arizona as
that term is defined in the Act. 2 U.S.C. 1555 (“Notwithstanding section 3 of this Act [2 U.S.C. 1502], for purposes of this
title [2 U.S.C. 1551 et seq. ] the term “Federal mandate” means any provision in statute or regulation or any Federal court ruling that imposes an enforceable
duty upon State, local, or Tribal governments including a condition of Federal assistance or a duty arising from participation
in a voluntary Federal program.”).

Comment 1D: The commentor claims that the proposed action “raises novel policy and legal issues in the current administrative law landscape
(including post-Loper Bright interpretive standards) and has broad intergovernmental and economic implications by federalizing
source-level obligations across a large number of small entities in Arizona.” The commentor states that the “novel policy
issues” and “intergovernmental implications” of the action warrant review by the Office of Information and Regulatory Affairs
(OIRA), pursuant to Executive Order (E.O.) 12866. The commentor states that the EPA should either submit the rulemaking for
review by OIRA or explain why “federalizing SIP obligations” does not present novel legal or policy issues and explain why
the “intergovernmental implications” are not significant for purposes of E.O. 12866.

Response 1D: The EPA disagrees that a non-significance analysis is required under E.O. 12866. The Agency has complied with E.O. 12866 by
determining that this rulemaking is not a significant regulatory action as defined in E.O. 12866. This action is not “federalizing
SIP obligations.” As stated above, the EPA is merely approving Arizona's weight of evidence analysis that emissions from sources
in Arizona do not significantly contribute to nonattainment or interfere with maintenance of the 2012 PM 2.5 NAAQS in any other state, as required by the CAA. This action is consistent with the EPA's actions on other states' plans
across the country. Accordingly, this action does not raise any novel legal or policy issues but merely concludes that Arizona's
2012 PM 2.5 I-SIP submittals meet the requirements of prongs 1 and 2 of CAA section 110(a)(2)(D)(i)(I).

Comment 1E: The commentor notes that Arizona contains numerous Tribal lands that can be affected by the downwind transport of air emissions.
Because Tribal governments' air quality interests are at stake, the commentor asserts that the EPA should clarify whether
any consultation was undertaken or provide a reasoned basis for concluding that there are no Tribal implications. The commentor
states that the EPA should also revisit E.O. 13132 statement on federalism “in light of the practical enforcement and programmatic
effects on counties that administer key SIP measures relied upon in the transport demonstration.”

Response 1E: The EPA has complied with E.O. 13175 relating to consultation with Indian tribes by certifying that the action does not fall
under “policies that have Tribal implications” as that term is defined in E.O. 13175. As stated elsewhere, our action merely
approves Arizona's weight of evidence analysis that it does not cause or contribute to nonattainment or interfere with maintenance
in any other state, including on downwind Tribal lands. The action also does not incorporate any new rules or control measures
into the Arizona SIP for which there might be federalism implications as defined by E.O. 13132.

III. Final Action

For the reasons set forth in our proposed rulemaking and summarized herein, the EPA is taking final action to approve Arizona's
2012 PM 2.5 I-SIP submittals for compliance with the 2012 PM 2.5 NAAQS infrastructure SIP requirements of CAA section 110(a)(2)(D)(i)(I). Specifically, the EPA is finalizing our determination
that the Arizona SIP, through the 2012 PM 2.5 I-SIP submittals, contains adequate provisions to ensure that emissions from sources in Arizona will not significantly contribute
to nonattainment or interfere with the maintenance of the 2012 PM 2.5 NAAQS in any other state.

IV. 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 final 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, 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 Clean Air Act, petitions for judicial review of this action must be filed in the United States
Court of Appeals for the appropriate circuit by June 15, 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 section 307(b)(2).)

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Nitrogen dioxide,
Ozone, Particulate matter, Reporting and recordkeeping requirements, Volatile organic compounds.

Authority:

42 U.S.C. 7401 et seq.

Dated: April 6, 2026. Michael Martucci, Acting Regional Administrator, Region IX. For the reasons stated in the preamble, EPA amends 40 CFR part 52 as follows:

PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

Regulatory Text 1. The authority citation for part 52 continues to read as follows:

Authority:

42 U.S.C. 7401 et seq.

Subpart D—Arizona

Regulatory Text 2. In § 52.120, amend table 1 in paragraph (e) by, under the heading “Clean Air Act Section 110(a)(2) State Implementation
Plan Elements (Excluding Part D Elements and Plans)”, adding the entry “State Implementation Plan Revision: Clean Air Act
Section 110(a)(2) for the 2012 Fine Particulate & 2015 Ozone NAAQS (dated February 2022)” immediately before the entry for
“Ordinance No. 1993-128, Section 1, 17.040.190 “Composition” Section 6, 17.24.040 “Reporting for compliance evaluation” ”
to read as follows:

§ 52.120 Identification of plan

---

(e) * * *

| Name of SIP provision | Applicable
geographic ornonattainmentarea ortitle/subject | State
submittal date | EPA approval date | Explanation |
| --- | --- | --- | --- | --- |
| | | | | |
|                                                       * | | | | |
| The State of Arizona Air Pollution Control Implementation Plan | | | | |
| Clean Air Act Section 110(a)(2) State Implementation Plan Elements (Excluding Part D Elements and Plans) | | | | |
| | | | | |
|                                                       * | | | | |
| State Implementation Plan Revision: Clean Air Act Section 110(a)(2) for the 2012 Fine Particulate & 2015 Ozone NAAQS (dated
February 2022) | State-wide | February 10, 2022 | 4/16/2026, 91 FR [INSERT
FEDERAL REGISTER
PAGE WHERE THE DOCUMENT BEGINS] | Adopted by the Arizona Department of Environmental Quality on February 10, 2022.

           As of 4/16/2026 EPA has approved all elements of the submittal addressing requirements for the 2012 PM
           2.5
           NAAQS. |

| | | | | |
|                                                       * | | | | |
| 1 Table 1 is divided into three parts: Clean Air Act Section 110(a)(2) State Implementation Plan Elements (excluding Part D
Elements and Plans), Part D Elements and Plans (other than for the Metropolitan Phoenix or Tucson Areas), and Part D Elements
and Plans for the Metropolitan Phoenix and Tucson Areas. | | | | |

---

[FR Doc. 2026-07400 Filed 4-15-26; 8:45 am] BILLING CODE 6560-50-P

Footnotes

(1) 90 FR 48502 (October 23, 2025).

(2) Both comments are available in the docket associated with this rulemaking action at https://www.regulations.gov, docket ID No. EPA-R09-OAR-2025-0191.

(3) See 5 U.S.C. 605(b).

(4) See 44 U.S.C. 3502(3); 3507.

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