Proposed Rule2025-19638
Air Plan Approval; Arizona; Interstate Transport Requirements for the 2012 Fine Particulate Matter National Ambient Air Quality Standard
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Published
October 23, 2025
Issuing agencies
Environmental Protection Agency
Abstract
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 (PM<INF>2.5</INF>) national ambient air quality standards (NAAQS). The EPA is proposing to approve 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<INF>2.5</INF> NAAQS in any other state.
Full Text
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<title>Federal Register, Volume 90 Issue 203 (Thursday, October 23, 2025)</title>
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[Federal Register Volume 90, Number 203 (Thursday, October 23, 2025)]
[Proposed Rules]
[Pages 48502-48504]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-19638]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2025-0191; FRL-12978-01-R9]
Air Plan Approval; Arizona; Interstate Transport Requirements for
the 2012 Fine Particulate Matter National Ambient Air Quality Standard
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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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
(PM<INF>2.5</INF>) national ambient air quality standards (NAAQS). The
EPA is proposing to approve 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<INF>2.5</INF> NAAQS in any other state.
DATES: Comments must be received on or before November 24, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2025-0191 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. For comments submitted at
<a href="http://Regulations.gov">Regulations.gov</a>, follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
<a href="http://Regulations.gov">Regulations.gov</a>. The EPA may publish any comment received to its public
docket. Do not submit electronically any information you consider to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Multimedia submissions (audio,
video, etc.) must be accompanied by a written comment. The written
comment is considered the official comment and should include
discussion of all points you wish to make. The EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e., on the web, cloud, or other file sharing system). For
additional submission methods, please contact the person identified in
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public
comment policy, information about CBI or multimedia submissions, and
general guidance on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>. 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, telephone
number: (415) 972-3934, email address: <a href="/cdn-cgi/l/email-protection#0b6f64796a657f6e7825666268636a6e674b6e7b6a256c647d"><span class="__cf_email__" data-cfemail="55313a27343b2130267b383c363d343039153025347b323a23">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.
Table of Contents
I. Background
A. Statutory Background
B. EPA's Interstate Transport Considerations for the 2012
PM<INF>2.5</INF> NAAQS
II. Arizona's Submittal
III. The EPA's Evaluation
IV. Proposed Action and Request for Public Comment
V. Statutory and Executive Order Reviews
I. Background
A. Statutory Background
On January 15, 2013 the EPA promulgated a revision to the
PM<INF>2.5</INF> NAAQS (2012 PM<INF>2.5</INF> NAAQS), lowering the
level of the primary standard to 12.0 [micro]g/m\3\, while maintaining
the secondary standard.\1\ Section 110(a)(1) of the CAA requires states
to submit, within three years after promulgation of a new or revised
NAAQS, SIP submissions meeting the applicable requirements of section
110(a)(2).\2\ Within CAA section 110(a)(2), are the requirements in CAA
section 110(a)(2)(D)(i)(I), otherwise known as the ``interstate
transport'' or ``good neighbor'' provision, which generally requires
SIPs to contain adequate provisions to prohibit in-state emissions
activities from having certain adverse air quality effects on other
states due to interstate transport of air pollution. There are two so-
called ``prongs'' within CAA section 110(a)(2)(D)(i)(I), which require
that the SIP for a new or revised NAAQS contain adequate provisions
prohibiting 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 NAAQS in another state (prong 1) or
interfere with maintenance of the NAAQS in another state (prong 2). The
EPA and states must give independent significance to prong 1 and prong
2 when evaluating downwind air quality problems under CAA section
110(a)(2)(D)(i)(I).\3\
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\1\ 78 FR 3086 (January 15, 2013).
\2\ SIP revisions that are intended to meet the applicable
requirements of section 110(a)(1) and (2) of the CAA are often
referred to as infrastructure SIPs, and the applicable elements
under section 110(a)(2) are referred to as infrastructure
requirements.
\3\ See North Carolina v. EPA, 531 F.3d 896, 909-911 (D.C. Cir.
2008).
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B. EPA's Interstate Transport Considerations for the 2012 PM2.5 NAAQS
The EPA has addressed the interstate transport requirements of CAA
section 110(a)(2)(D)(i)(I) with respect to the PM<INF>2.5</INF> NAAQS
in several regulatory actions. In 2011, the EPA promulgated
[[Page 48503]]
the Cross-State Air Pollution Rule (CSAPR) to address the obligations
of states under prongs 1 and 2 to prohibit air pollution from
contributing significantly to nonattainment in, or interfering with the
maintenance of, any other state with regard to several NAAQS, including
the 1997 annual and 2006 24-hour PM<INF>2.5</INF> NAAQS.\4\ In that
rule, we used an air quality threshold of one percent of the applicable
PM<INF>2.5</INF> NAAQS to link contributing states to projected
nonattainment or maintenance air quality monitors (i.e., receptors). If
air quality modeling projected that an upwind state contributed more
than the one percent threshold to a downwind receptor, we determined
that the state was ``linked.'' On September 13, 2013, the EPA issued
the ``Guidance on Infrastructure State Implementation Plan (SIP)
Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2)'' (``2013
I-SIP Guidance'') for the development of infrastructure SIPs for
several NAAQS including the 2012 PM<INF>2.5</INF> standard.\5\ On March
12, 2016, the EPA issued the memorandum titled ``Information on the
Interstate Transport ``Good Neighbor'' Provision for the 2012 Fine
Particulate Matter National Ambient Air Quality Standards under Clean
Air Act Section 110(a)(2)(D)(i)(I)'' (``2016 PM<INF>2.5</INF> Transport
Memo''), specifically developed for the infrastructure SIP transport
requirements for the 2012 PM<INF>2.5</INF> NAAQS.\6\ Using CSAPR, the
2013 I-SIP guidance, and the 2016 PM<INF>2.5</INF> Transport Memo, we
have developed a consistent framework for evaluating the interstate
transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2012
PM<INF>2.5</INF> NAAQS, and outlined a four-step process to evaluate
the obligations under interstate transport provision under
110(a)(2)(D)(i)(I), which includes:
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\4\ 76 FR 48208 (August 8, 2011).
\5\ Memorandum dated September 13, 2013 from Stephen D. Page,
Director, Office of Air Quality and Planning Standards, U.S. EPA, to
Regional Air Division Directors, Regions 1-10, Subject: ``Guidance
on Infrastructure State Implementation Plan (SIP) Elements under
Clean Air Act Sections 110(a)(1) and 110(a)(2).''
\6\ Memorandum dated March 17, 2016, from Stephen D. Page,
Director, Office of Air Quality and Planning Standards, U.S. EPA, to
Regional Air Division Directors, Regions 1-10, Subject:
``Information on the Interstate Transport ``Good Neighbor''
Provision for the 2012 Fine Particulate Matter National Ambient Air
Quality Standards under Clean Air Act Section 110(a)(2)(D)(i)(I).''
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(1) Identifying downwind receptors that are expected to have
problems attaining or maintaining the NAAQS;
(2) Identifying which upwind states contribute to these identified
problems in amounts sufficient to warrant further review and analysis;
(3) For states identified as contributing to downwind air quality
problems, identifying upwind emissions reductions necessary to prevent
an upwind state from significantly contributing to nonattainment or
interfering with maintenance of the NAAQS downwind;
(4) For states that are found to have emissions that significantly
contribute to nonattainment or interfere with maintenance of the NAAQS
downwind, reducing the identified upwind emissions through adoption of
permanent and enforceable measures.
To satisfy Step 1 of the interstate framework, the 2016
PM<INF>2.5</INF> Transport Memo provides annual PM<INF>2.5</INF> design
values for monitors in the United States based on quality-assured and
certified ambient air quality monitoring data. For each ambient
monitoring site, the EPA calculated the projected average design value
and projected maximum design values for the then future projection
years of 2017 and 2025. In total, the 2016 PM<INF>2.5</INF> Transport
Memo identified 17 California monitoring sites located in the San
Joaquin Valley and the South Coast nonattainment areas, one site in
Shoshone County, Idaho, and one site in Allegheny County, Pennsylvania
as having projected 2017 and 2025 average and/or maximum future year
PM<INF>2.5</INF> design values above the 2012 PM<INF>2.5</INF> NAAQS.
The modeled annual PM<INF>2.5</INF> projections for the years 2017 and
2025 evaluated projected air quality relative to the 2012
PM<INF>2.5</INF> NAAQS and are therefore consistent with Step 1 of the
four-step interstate framework originally used in CSAPR. This
rulemaking considers these receptors, as well as additional analysis
conducted by the State and the EPA when evaluating step 2 of the
framework as to whether emissions from Arizona contribute to
nonattainment or interfere with maintenance of the PM<INF>2.5</INF>
NAAQS, and whether further evaluation under steps 3 and 4 are
necessary.
II. Arizona's Submittal
The Arizona Department of Environmental Quality (ADEQ) submitted
two SIP revisions to address the infrastructure SIP requirements in CAA
sections 110(a)(1) and 110(a)(2) for the 2012 PM<INF>2.5</INF> NAAQS.
On December 11, 2015, ADEQ submitted the ``Arizona State Implementation
Plan Revision for the 2012 Fine Particulate Matter (PM<INF>2.5</INF>)
National Ambient Air Quality Standard'' (``2015 PM<INF>2.5</INF> I-SIP
Submittal).\7\ On February 10, 2022, ADEQ submitted the ``State
Implementation Plan Revision: Clean Air Act Section 110(a)(2) for the
2012 Fine Particulate & 2015 Ozone NAAQS'' (``2022 I-SIP
Supplement'').\8\ The submittals collectively address the requirements
of 110(a)(2)(D)(i)(I) as described by this proposed rulemaking. We
refer to them collectively herein as ``Arizona's 2012 PM<INF>2.5</INF>
I-SIP submittals.'' We find that Arizona's 2012 PM<INF>2.5</INF> I-SIP
submittals meet the procedural requirements for public participation
under CAA section 110(a)(2) and 40 CFR 51.102.\9\ We have previously
proposed or finalized actions on these submittals except for those
portions of the 2012 PM<INF>2.5</INF> I-SIP submittals addressing
prongs 1 and 2 of the interstate transport requirements under
110(a)(2)(D)(i)(I).\10\ Herein, we are proposing action on these
submittals with respect to the 110(a)(2)(D)(i)(I) interstate transport
requirements for the 2012 PM<INF>2.5</INF> NAAQS.
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\7\ Letter dated December 11, 2015, from Eric Massey, Director,
Air Quality Division, ADEQ, to Jared Blumenfeld, Regional
Administrator, EPA Region IX, Subject ``Arizona Infrastructure State
Implementation Plan for the 2012 PM<INF>2.5</INF> National Ambient
Air Quality Standards.''
\8\ Letter dated February 10, 2022, from Daniel Czecholinski,
Director, Air Quality Division, ADEQ, to Martha Guzman, Regional
Administrator, EPA Region IX, Subject: ``Submittal of the Arizona
State Implementation Plan Revision under Clean Air Act Sections
110(a)(2) for the 2012 Fine Particulate and the 2015 Ozone NAAQS.''
\9\ For the 2015 PM<INF>2.5</INF> I-SIP submittal, ADEQ provided
a 30-day public comment period that started on November 9, 2015, and
concluded on December 9, 2015, with a public hearing occurring on
the same date. No comments were expressed during the 30-day comment
period no at the public hearing, The details of this public comment
period and hearing can be found in appendix B of the 2015
PM<INF>2.5</INF> I-SIP submittal. Similarly, for the 2022 I-SIP
supplement, ADEQ provided a 30-day public comment period between
December 13, 2021, and January 13, 2022, with a public hearing
occurring on January 13, 2022. ADEQ received no verbal nor written
comments on the 2022 I-SIP supplement. The details of this public
comment period and hearing can be found in appendix E to the 2022 I-
SIP supplement.
\10\ 89 FR 50245, June 13, 2024 and 89 FR 102744, December 18,
2024.
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III. The EPA's Evaluation
We have evaluated Arizona's 2012 PM<INF>2.5</INF> I-SIP submittals
for compliance with the infrastructure SIP requirements of CAA section
110(a)(2)(D)(i)(I) and the applicable regulations of 40 CFR part 51
(``Requirements for Preparation, Adoption, and Submittal of State
Implementation Plans''). The technical support document (TSD) for this
rulemaking is available in the docket and includes our detailed
evaluation of direct and precursor emissions of PM<INF>2.5</INF> within
Arizona and from other sources, geographical information,
climatological information, and topographical information such as
terrain and its potential effect on transport of
[[Page 48504]]
pollutants. Considering the weight of the evidence, the EPA agrees with
the conclusion drawn by Arizona in the 2012 PM<INF>2.5</INF> I-SIP
submittals that emissions from sources in Arizona will not
significantly contribute to nonattainment or interfere with the
maintenance of the 2012 PM<INF>2.5</INF> NAAQS in any other state. In
particular, the EPA finds that Arizona is not ``linked'' to any out-of-
state receptors, and as such, the State is not required to perform the
last two steps of the four-step framework outlined in the EPA's
interstate transport guidance and rulemakings.
IV. Proposed Action and Request for Public Comment
Based on the EPA's weight-of-evidence evaluation summarized in this
document and fully detailed in the accompanying TSD, the EPA proposes
to approve Arizona's 2012 PM<INF>2.5</INF> I-SIP submittals with
respect to the 2012 PM<INF>2.5</INF> NAAQS for the interstate transport
requirements of CAA section 110(a)(2)(D)(i)(I). The EPA is soliciting
public comments on this proposed rulemaking. We will accept comments
from the public for the next 30 days. We will consider any comments
received before taking final action.
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
proposed action merely proposes to approve state law as meeting federal
requirements and does not impose additional requirements beyond those
imposed by state law. For that reason, this proposed action:
<bullet> 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);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> 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.);
<bullet> 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);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it proposes to approve a state program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> 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).
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: October 14, 2025.
Cheree D. Peterson,
Acting Regional Administrator, Region IX.
[FR Doc. 2025-19638 Filed 10-22-25; 8:45 am]
BILLING CODE 6560-50-P
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