Proposed Rule2026-08372
Utah; Northern Wasatch Front; 2015 8-Hour Ozone National Ambient Air Quality Standards; Reconsideration and Repeal of Finding of Failure To Attain and Reclassification to a Serious Nonattainment Area; Determination of Attainment by the Moderate Attainment Date But for International Emissions
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
April 30, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The U.S. Environmental Protection Agency (EPA) is proposing to repeal the December 9, 2024, final rule in which the Agency determined that the Northern Wasatch Front (NWF) nonattainment area (NAA) in Utah failed to attain the Clean Air Act (CAA) 2015 ozone National Ambient Air Quality Standards (NAAQS) by the August 3, 2024, Moderate area attainment date, and reclassified the area by operation of law to Serious nonattainment (the "December 2024 Final Rule"). The EPA is also proposing to determine that the NWF ozone NAA would have attained the 2015 ozone NAAQS by the Moderate area attainment date but for emissions emanating from outside the United States (U.S.). If the EPA finalizes this proposed action, the NWF ozone NAA would no longer be subject to the CAA requirements pertaining to reclassification to Serious nonattainment upon failure to attain and would remain classified as Moderate for the 2015 ozone NAAQS.
Full Text
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<title>Federal Register, Volume 91 Issue 83 (Thursday, April 30, 2026)</title>
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[Federal Register Volume 91, Number 83 (Thursday, April 30, 2026)]
[Proposed Rules]
[Pages 23209-23221]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-08372]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 52 and 81
[EPA-R08-OAR-2024-0552; FRL-13198-01-R8]
Utah; Northern Wasatch Front; 2015 8-Hour Ozone National Ambient
Air Quality Standards; Reconsideration and Repeal of Finding of Failure
To Attain and Reclassification to a Serious Nonattainment Area;
Determination of Attainment by the Moderate Attainment Date But for
International Emissions
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule; reconsideration of final rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing to
repeal the December 9, 2024, final rule in which the Agency determined
that the Northern Wasatch Front (NWF) nonattainment area (NAA) in Utah
failed to attain the Clean Air Act (CAA) 2015 ozone National Ambient
Air Quality Standards (NAAQS) by the August 3, 2024, Moderate area
attainment date, and reclassified the area by operation of law to
Serious nonattainment (the ``December 2024 Final Rule''). The EPA is
also proposing to determine that the NWF ozone NAA would have attained
the 2015 ozone NAAQS by the Moderate area attainment date but for
emissions emanating from outside the United States (U.S.). If the EPA
finalizes this proposed action, the NWF ozone NAA would no longer be
subject to the CAA requirements pertaining to reclassification to
Serious nonattainment upon failure to attain and would remain
classified as Moderate for the 2015 ozone NAAQS.
DATES: Written comments must be received on or before June 1, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2024-0552, to the Federal Rulemaking Portal: <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
<a href="http://www.regulations.gov">www.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, 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>.
Docket: All documents in the docket are listed in the <a href="https://www.regulations.gov">https://www.regulations.gov</a> index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available electronically in
<a href="https://www.regulations.gov">https://www.regulations.gov</a>. Please email or call the person listed in
the FOR FURTHER INFORMATION CONTACT section if you need to make
alternative arrangements for access to the docket.
FOR FURTHER INFORMATION CONTACT: Abby Fulton, Air and Radiation
Division, EPA, Region 8, Mailcode 8ARD-AQ-R, 1595 Wynkoop Street,
Denver, Colorado 80202-1129; phone: (303) 312-6563; email:
<a href="/cdn-cgi/l/email-protection#a5c3d0c9d1cacb8bc4c7c7dce5c0d5c48bc2cad3"><span class="__cf_email__" data-cfemail="1177647d657e7f3f70737368517461703f767e67">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Preamble Acronyms and Abbreviations. Throughout this preamble the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:
AMNP Annual Monitoring Network Plan
AQS Air Quality System
CAA Clean Air Act
CFR Code of Federal Regulations
DV Design Value
EPA U.S. Environmental Protection Agency
FDV Future Design Value
FDV<INF>adj</INF> Adjusted Future Design Value
FDV<INF>adj-atyp</INF> Adjusted Future Design Value accounting for
exclusion of international anthropogenic contributions and atypical,
wildfire smoke-impacted days
LLC Limited Liability Company
MDA8 Maximum Daily 8-hour Average
NAA Nonattainment Area
NAAQS National Ambient Air Quality Standards
NASA National Aeronautics and Space Administration
NOAA National Oceanic and Atmospheric Administration
NO<INF>X</INF> Nitrogen Oxides
[[Page 23210]]
NTTAA National Technology Transfer and Advancement Act
NWF Northern Wasatch Front
OMB Office of Management and Budget
PM<INF>2.5</INF> Fine particulate matter with aerodynamic diameter
<=2.5 micrometers
ppb Parts per billion
ppm Parts per million
PRA Paperwork Reduction Act
RACM Reasonably Available Control Measures
RACT Reasonably Available Control Technology
RFA Regulatory Flexibility Act
RFP Reasonable Further Progress
RRF Relative Response Factor
SIP State Implementation Plan
TSD Technical Support Document
U.S. United States
UMRA Unfunded Mandates Reform Act
USGS United States Geological Survey
VOC Volatile Organic Compounds
Organization of this Document: The information in this preamble is
organized as follows:
I. Background
A. 2015 Ozone NAAQS and Area Designations
B. Clean Air Act Requirements for Moderate Ozone NAAs
C. Requirement for Determination of Attainment of the 2015 Ozone
NAAQS
D. International Transport and Clean Air Act Section 179B
E. Atypical Events: Exclusion of Unrepresentative Air Quality
Data
II. Legal Authority
III. Proposed Action
IV. Northern Wasatch Front Ozone NAA--Proposed Determination of
Attainment But for International Emissions
A. NWF Ozone NAA
B. Overview of NWF Proposed Determination of Attainment But for
International Emissions
C. Evidence Supporting NWF Ozone Attainment Status
D. Conclusions on NWF Attainment Status Based on the Available
Evidence
V. Statutory and Executive Order Reviews
I. Background
A. 2015 Ozone NAAQS and Area Designations
Ground-level ozone pollution is formed from the reaction of
volatile organic compounds (VOC) and nitrogen oxides (NO<INF>X</INF>)
in the presence of sunlight. These two pollutants, referred to as ozone
precursors, are emitted by many types of sources, including on-road and
non-road motor vehicles and engines, and industrial facilities, and
smaller area sources such as lawn and garden equipment and paints.
Scientific evidence indicates that adverse public health effects occur
following exposure to ground-level ozone pollution.\1\ Exposure to
ozone can harm the respiratory system (the upper airways and lungs),
can aggravate asthma and other lung diseases, and is linked to
premature death from respiratory causes. People most at risk from
breathing air containing ozone include people with asthma, children,
older adults, and people who are active outdoors, especially outdoor
workers.\2\
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\1\ 80 FR 65296 (October 26, 2015).
\2\ EPA Fact Sheet--Ozone and Health, available at <a href="https://www.epa.gov/sites/default/files/2016-04/documents/20151001healthfs.pdf">https://www.epa.gov/sites/default/files/2016-04/documents/20151001healthfs.pdf</a> and in the docket for this action.
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Under CAA section 109, the EPA promulgates NAAQS (or ``standards'')
for ``each air pollutant for which air quality criteria have been
issued. . . .'', such as ozone.\3\ The EPA promulgated NAAQS for ozone
in 1979 and revised them in 1997 and 2008.\4\ On October 26, 2015, the
EPA revised the NAAQS for ozone to establish new 8-hour standards (the
``2015 Ozone NAAQS Implementation Rule).\5\ In the 2015 Ozone NAAQS
Implementation Rule, the EPA promulgated identical revised primary and
secondary ozone standards designed to protect public health and
welfare, respectively, that specified an 8-hour ozone level of 0.070
parts per million (ppm).\6\ Specifically, the standards require that
the 3-year average of the annual fourth highest maximum daily 8-hour
average (MDA8) ozone concentration (i.e., the design value (DV)) may
not exceed 0.070 ppm.\7\ If the DV does not exceed 0.070 ppm at each
ambient air quality monitoring site within the area, the area is deemed
to be attaining the ozone NAAQS.\8\
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\3\ 42 U.S.C. 7409.
\4\ 44 FR 8202 (February 8, 1979); 62 FR 38856 (July 18, 1997);
73 FR 16436 (March 27, 2008).
\5\ See footnote 1 in this preamble.
\6\ Because the 2015 primary and secondary NAAQS for ozone are
identical, for convenience, the EPA refers to them in the singular
as ``the 2015 ozone NAAQS'' or as ``the standard.'' Further, while
the NAAQS is in units of ppm, ozone measurements are often discussed
in terms of parts per billion (ppb), with 0.070 ppm being equal to
70 ppb.
\7\ A DV is a statistic used to compare data collected at an
ambient air quality monitoring site to the applicable NAAQS to
determine compliance with the standard. The DV for the 2015 ozone
NAAQS is the 3-year average of the annual fourth highest MDA8 ozone
concentration. The DV is calculated for each air quality monitor in
an area and the area's DV is the highest DV among the individual
monitoring sites in the area.
\8\ The data handling convention in 40 Code of Federal
Regulations (CFR) part 50, appendix U dictates that concentrations
shall be reported in ``ppm'' to the third decimal place, with
additional digits to the right being truncated. Thus, a DV of 0.071
ppm is greater than 0.070 ppm and would exceed the standard, but a
DV of 0.0709 ppm is truncated to 0.070 ppm and attains the 2015
ozone NAAQS.
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CAA section 107(d) provides that when the EPA promulgates a new or
revised NAAQS, the Agency must designate areas of the country as
nonattainment, attainment, or unclassifiable. This is based on whether
an area is not meeting (or is contributing to air quality in a nearby
area that is not meeting) the NAAQS, meeting the NAAQS, or cannot be
classified as meeting or not meeting the NAAQS, respectively. Subpart 2
of part D of title I of the CAA governs the classification, State
planning, and emissions control requirements for any areas designated
as nonattainment for a revised primary ozone NAAQS.\9\ In particular,
CAA section 181(a)(1) also requires the EPA to classify each ozone NAA
at the time of designation, based on the area's DV.\10\ Classifications
for ozone NAAs range from Marginal to Extreme. CAA section 182 provides
the specific attainment planning and additional requirements that apply
to each ozone NAA based on its classification.\11\ CAA section 182, as
interpreted in the EPA's implementing regulations at 40 CFR 51.1308
through 51.1317, also establishes the timeframes by which air agencies
must submit and implement State Implementation Plan (SIP) revisions to
satisfy the applicable attainment planning elements, and the timeframes
by which NAAs must attain the 2015 ozone NAAQS.
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\9\ 42 U.S.C. 7407(d).
\10\ 42 U.S.C. 7511(a)(1).
\11\ 42 U.S.C. 7511a.
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Effective August 3, 2018, the EPA designated 51 areas throughout
the U.S., including the NWF area in Utah, as nonattainment for the 2015
ozone NAAQS.\12\ The NWF ozone NAA includes the Salt Lake City
metropolitan area. In a separate action, the EPA assigned
classification thresholds and attainment dates based on each NAAs ozone
DV.\13\ The EPA established the attainment date for Marginal, Moderate,
and Serious NAAs as 3 years, 6 years, and 9 years, respectively, from
the effective date of the final designations. Thus, the attainment date
for Marginal NAAs for the 2015 ozone NAAQS was August 3, 2021, the
attainment date for Moderate areas was August 3, 2024, and the
attainment date for Serious areas is August 3, 2027. The EPA initially
classified the NWF NAA as Marginal for the 2015 ozone NAAQS. On October
7, 2022, the EPA determined that 22 areas, including the NWF NAA, did
not attain the 2015 ozone NAAQS by the Marginal area attainment date,
and these areas were reclassified to Moderate by operation of law.\14\
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\12\ 83 FR 25776 (June 4, 2018), effective Aug. 3, 2018. The EPA
later designated the San Antonio area as a 2015 ozone NAAQS NAA
effective September 24, 2018. 83 FR 35136 (July 25, 2018).
\13\ 83 FR 10376 (March 9, 2018), effective May 8, 2018.
\14\ 87 FR 60897 (October 7, 2022).
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[[Page 23211]]
B. Clean Air Act Requirements for Moderate Ozone NAAs
The applicable requirements for ozone NAAs classified as Moderate
include a baseline emissions inventory, source emission statement
rules, nonattainment New Source Review program requirements, an
attainment demonstration, a Reasonably Available Control Measures
(RACM) demonstration, Reasonably Available Control Technology (RACT)
requirements, a Reasonable Further Progress (RFP) demonstration, and
contingency measures for failure to attain or achieve RFP.\15\
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\15\ See, e.g., 42 U.S.C. 7502(c), 7511a.
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Attainment contingency measures are triggered upon the EPA's
determination that an area failed to attain a given NAAQS by its
applicable attainment date. For ozone NAAs, such a finding would be
made pursuant to CAA section 181(b)(2), as described in section I.C of
this preamble. However, CAA section 179B(b) provides that if a State
demonstrates to the satisfaction of the Administrator that the area
would have attained the ozone NAAQS by the applicable attainment date
but for emissions emanating from outside the U.S., the area is not
subject to the reclassification provisions in CAA section 181(b)(2) and
will not be reclassified to a higher nonattainment level.\16\
Therefore, following the EPA's approval of a demonstration under CAA
section 179B(b), attainment contingency measures will not be triggered.
Given these considerations, the CAA does not require the State to have
EPA approved contingency measures for failure to attain the NAAQS in an
area with an approved CAA section 179B(b) demonstration.\17\
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\16\ 42 U.S.C. 7509a(b). Note that the statute cites 42 U.S.C.
7511(a)(2), but that provision establishes ozone attainment
deadlines for Severe areas under the 1-hour standard. The EPA has
long interpreted the citation in CAA section 179B(b) to be a
scrivener's error that was supposed to refer to 42 U.S.C.
7511(b)(2), which addresses consequences for failure to attain by
the attainment date. See ``State Implementation Plans; General
Preamble for the Implementation of Title I of the Clean Air Act
Amendments of 1990,'' 57 FR 13498, 13569 n.41 (April 16, 1992).
\17\ 84 FR 58641, 58660 (November 1, 2019) (proposing the same
interpretation with respect to Imperial County for the 2008 ozone
NAAQS); 85 FR 11817 (February 27, 2020) (finalizing the same).
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In the case of Moderate ozone NAAs, the EPA's longstanding
interpretation is that RFP contingency measures for the ozone NAAQS can
be triggered in Moderate areas only by an EPA finding that the area has
failed to attain the NAAQS by the attainment date under CAA section
181(b)(2).\18\ Under CAA section 182(g), ozone NAAs classified Serious
or higher are required to meet RFP emissions reduction ``milestones''
and to demonstrate compliance with those milestones.\19\ For Moderate
areas, there are no RFP milestone compliance demonstration
requirements.\20\ Thus, the statute does not impose a requirement on
either the State or the EPA to determine whether a Moderate ozone NAA
achieved RFP.
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\18\ 57 FR 13498, 13511 (April 16, 1992) (contrasting Moderate
areas, for which contingency measures would be triggered ``when the
area fails to attain the standard by the attainment date'' with
Serious and above areas, for which contingency measures would also
be triggered ``if the area fails to meet the rate-of-progress
requirements for any milestone other than one falling on an
attainment year''); See also Memorandum from G.T. Helms, Chief
Ozone/Carbon Monoxide Programs Branch, to Air Branch Chief, Regions
I through X (March 11, 1993) (``The test for moderate areas will be
whether they attained the standard because the attainment date for
moderate areas coincides with the milestone demonstration date.
Failure to attain will cause an area to be required to implement its
contingency measures . . .''), available in the docket for this
rulemaking. See also Sierra Club v. EPA, 99 F.3d 1551, 1557 (10th
Cir. 1996) (upholding the EPA's interpretation not to require RFP
contingency measures for moderate ozone NAA if the NAA attains the
NAAQS); NRDC v. EPA, 571 F.3d 1245, 1260 (2009) (agreeing with
Sierra Club v. EPA).
\19\ 42 U.S.C. 7511a(g)(2).
\20\ 42 U.S.C. 7511a(g)(1).
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C. Requirement for Determination of Attainment of the 2015 Ozone NAAQS
CAA section 181(b)(2)(A) requires that within 6 months following
the applicable attainment date, the EPA shall determine whether an
ozone NAA attained the ozone standard based on the area's DV as of that
date. If the EPA determines that an area failed to attain, CAA section
181(b)(2)(A) requires the area to be reclassified by operation of law
to the higher of: (1) the next higher classification for the area, or
(2) the classification applicable to the area's DV as of the
determination of failure to attain. CAA section 181(b)(2)(B) requires
the EPA to publish the determination of failure to attain in the
Federal Register no later than 6 months after the attainment date,
which was February 3, 2025, for the NWF ozone NAA. A finding by the EPA
that an area has not attained the standard by the attainment date
results in that area being reclassified by operation of law to the next
higher classification.
The level of the 2015 ozone NAAQS is 0.070 ppm.\21\ Under the EPA
regulations at 40 CFR part 50, appendix U, the 2015 ozone NAAQS is
attained at a site when the 3-year average of the annual fourth highest
MDA8 ambient ozone concentration (i.e., DV) does not exceed 0.070 ppm.
When the DV does not exceed 0.070 ppm at each ambient air quality
monitoring site within the area, the area is deemed to be attaining the
ozone NAAQS. Each area's DV is determined by the highest DV among
monitors with valid DVs.\22\
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\21\ 40 CFR 50.19.
\22\ See footnote 7 of this preamble. According to appendix U to
40 CFR part 50, ambient monitoring sites with a DV of 0.070 ppm or
less must meet minimum data completeness requirements in order to be
considered valid. These requirements are met for a 3-year period at
a site if daily maximum 8-hour average ozone concentrations are
available for at least 90 percent of the days within the ozone
monitoring season, on average, for the 3-year period, with a minimum
of at least 75 percent of the days within the ozone monitoring
season in any one year. Ozone monitoring seasons are defined for
each State in appendix D to 40 CFR part 58. DVs greater than 0.070
ppm are considered to be valid regardless of the data completeness.
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For the NWF ozone NAA, the Moderate attainment date was August 3,
2024. Because the DV is based on the three most recent, complete
calendar years of data, attainment must occur no later than December 31
of the year prior to the attainment date (i.e., December 31, 2023, in
the case of Moderate NAAs for the 2015 ozone NAAQS). Therefore, the
EPA's determination for this area was based on calendar years 2021,
2022, and 2023.
On December 9, 2024, the EPA determined that the NWF ozone NAA
failed to attain the 2015 ozone NAAQS by the Moderate attainment date
based on monitored ozone data from 2021 through 2023. The EPA further
determined that the area did not meet the requirements under CAA
section 181(a)(5)(B) or 40 CFR 51.1307 necessary to grant a 1-year
extension of the attainment date because at least one monitor had a
2023 fourth highest MDA8 that was greater than 0.070 ppm. As a result,
the NWF ozone NAA was reclassified to Serious by operation of law with
an effective date of January 8, 2025.\23\ As shown in table 1, all
regulatory monitors in the NWF ozone NAA had a 2021-2023 DV greater
than the standard of 0.070 ppm.
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\23\ 89 FR 97545 (December 9, 2024).
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[[Page 23212]]
[GRAPHIC] [TIFF OMITTED] TP30AP26.004
Following the EPA's publication of the December 2024, Final Rule
making the finding of failure to attain, the EPA received petitions to
reconsider the rule from the Utah Congressional delegation on January
14, 2025, the State of Utah on January 22, 2025, and the Utah Petroleum
Association on February 4, 2025. On March 5, 2025, the EPA granted the
petitions for reconsideration and stated the Agency's intention to
undertake a notice and comment rulemaking to reconsider the December
2024 Final Rule.\24\ Additionally, the State and the Utah Petroleum
Association filed petitions for review in the U.S. Court of Appeals for
the Tenth Circuit, and the court granted the petitioners' subsequent
motion to stay the December 2024 Final Rule on April 30, 2025.\25\
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\24\ Copies of the petitions and the EPA's responses granting
the petitions are provided in Docket ID No. EPA-R08-OAR-2024-0552.
The docket also includes a January 22, 2025, letter to the EPA from
Kennecott Utah Copper LLC in support of Utah's petition, and a
January 14, 2025, letter from the Utah Congressional delegation
asking the EPA to reconsider the December 9, 2024, final rule.
\25\ Utah v. EPA, No. 25-9519 (10th Cir. April 30, 2025); Utah
Petroleum Association v. EPA, No. 25-9520 (10th Cir. April 30,
2025). The practical implication of this judicial stay is that the
NWF ozone NAA is currently classified as Moderate as of the date of
this proposal.
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Further, on January 6, 2026, the EPA approved a request from the
State of Utah that expanded the NWF ozone NAA boundary to include 12
additional townships within Tooele County.\26\ As detailed in Utah's
February 2023 request and associated analysis, a magnesium processing
plant owned by US Magnesium, LLC located upwind of the NWF ozone NAA
was directly impacting high ozone levels within the NWF ozone NAA and
the State submitted a request to the EPA to expand the NAA boundary to
include this facility.\27\ This proposed rule impacts the NWF ozone NAA
in its entirety, which includes this newly added portion and the US
Magnesium facility.
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\26\ 91 FR 339 (January 6, 2026).
\27\ 90 FR 46128, 46130 nn.9-10 (September. 25, 2025).
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D. International Transport and Clean Air Act Section 179B
On December 12, 2024, the State of Utah submitted a demonstration
pursuant to CAA section 179B(b) concerning the impact of international
emissions on the NWF ozone NAA (``Utah 179B(b) Demonstration'').\28\
CAA section 179B(b) provides that if a State demonstrates to the
Administrator's satisfaction that an ozone NAA would have attained the
NAAQS by the applicable attainment date but for emissions emanating
from outside the U.S., that area shall not be subject to the provisions
of CAA section 181(b)(2).\29\ In the event an air agency does not
demonstrate to the Administrator's satisfaction that it would have
attained the NAAQS but for international emissions, the area will
remain subject to the provisions of CAA section 181(b)(2).
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\28\ See letter dated December 12, 2024 from Utah Governor
Spencer J. Cox to EPA Region 8 Administrator Kathleen Becker,
transmitting Utah's submittal of a CAA section 179B(b) International
Transport Demonstration for the NWF ozone NAA to the EPA for review,
and see accompanying demonstration from the Utah Department of
Environmental Quality Air Quality Division titled ``Northern Wasatch
Front Nonattainment Area 2015 Ozone NAAQS--Clean Air Act 179B(b)
Demonstration'' (``Utah 179B(b) Demonstration''), available in the
docket for this action.
\29\ See footnote 16 of this preamble.
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Emission sources outside of the U.S. can affect to varying degrees
the air quality of NAAs in the U.S. In a NAA affected by international
emissions, a State may elect under CAA section 179B to develop and
submit to the EPA a demonstration intended to show that a NAA would
attain, or would have attained, the relevant NAAQS by the applicable
statutory attainment date but for emissions emanating from outside the
U.S.\30\ Under CAA section 179B, the EPA evaluates such demonstrations
and, if the Agency agrees with the air agency's demonstration, the
Agency considers the impacts of international emissions in taking
specific regulatory actions.
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\30\ All references to CAA section 179B are to 42 U.S.C. 7509a,
titled ``International border areas,'' as added in Public Law 101-
549, title VIII, section 818, 104 Stat. 2697 (1990).
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CAA section 179B provides the EPA with authority to consider
impacts from international emissions in two contexts: (1) a
``prospective'' State demonstration submitted as part of an attainment
plan, which the Agency considers when determining whether the SIP
submission adequately demonstrates that a NAA will attain the NAAQS by
its future attainment date but for emissions emanating from outside the
U.S. (CAA section 179B(a)), or (2) a ``retrospective'' State
demonstration, which the EPA considers after the attainment date in
determining whether a NAA attained the NAAQS by the attainment date but
for emissions emanating from outside the U.S. (CAA section 179B(b)-
(d)).
[[Page 23213]]
First, CAA section 179B(a) provides that: ``Notwithstanding any
other provision of law, an implementation plan or plan revision
required under this chapter shall be approved by the Administrator if--
(1) such plan or revision meets all the requirements applicable to it .
. . other than a requirement that such plan or revision demonstrate
attainment and maintenance of the relevant national ambient air quality
standards by the attainment date specified under the applicable
provision of this chapter, or in a regulation promulgated under such
provision, and (2) the submitting State establishes to the satisfaction
of the Administrator that the implementation plan of such State would
be adequate to attain and maintain the relevant national ambient air
quality standards by the attainment date . . . but for emissions
emanating from outside of the United States.'' \31\ The EPA refers to
CAA section 179B(a) demonstrations as ``prospective'' demonstrations
because they are intended to assess future air quality, taking into
consideration the impact of international emissions.
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\31\ 42 U.S.C. 7509a(a) (emphasis added).
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Second, CAA section 179B(b) provides that, for ozone NAAs,
``[n]otwithstanding any other provision of law, any State that
establishes to the satisfaction of the Administrator that . . . such
State would have attained the national ambient air quality standard . .
. by the applicable attainment date but for emissions emanating from
outside of the United States,'' shall not be subject to the provisions
of CAA section 181(b)(2), including reclassification to a higher
classification category by operation of law.\32\ The EPA refers to
demonstrations developed under CAA section 179B(b) as ``retrospective''
demonstrations because they involve analyses of past air quality (e.g.,
air quality data from the years evaluated for determining whether an
area attained by the attainment date). Thus, an EPA-approved
retrospective demonstration provides relief from reclassification that
would have resulted from the EPA determining that the area failed to
attain the NAAQS by the relevant attainment date.
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\32\ 42 U.S.C. 7509a(b) (emphasis added).
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The 2015 Ozone NAAQS Implementation Rule did not include regulatory
requirements specific to CAA section 179B but did provide guidance on
certain points.\33\ In the preamble to the 2015 Ozone NAAQS
Implementation Rule, the EPA confirmed that: (1) only areas classified
Moderate and higher must show that they have implemented RACM/RACT; (2)
CAA section 179B demonstrations are not geographically limited to NAAs
adjoining an international border; and (3) a State demonstration
prepared under CAA section 179B can consider emissions emanating from
sources in any country, including outside North America.\34\ In the
preamble to the 2015 Ozone NAAQS Implementation Rule, the EPA
encouraged air agencies to consult with the appropriate EPA regional
office in developing CAA section 179B demonstrations.
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\33\ 83 FR 62998, 63010 (December 6, 2018).
\34\ Id.
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The EPA issued more detailed guidance regarding CAA section 179B on
December 18, 2020, which included recommendations to assist State,
local, and Tribal air agencies that intend to develop a CAA section
179B demonstration (``179B Guidance'').\35\ On April 7, 2025, the
Administrator rescinded the 179B Guidance and announced that the ``EPA
intends to work with State and local air agencies to develop the
evidence necessary to grant regulatory relief under CAA Section
[179B].'' \36\ Accordingly, in this rulemaking, the EPA is applying
interpretations and policies that differ in certain respects from those
set forth in the rescinded 179B Guidance and previous actions under CAA
section 179B(b), consistent with the discretion provided to the EPA
under the CAA and relevant case law concerning agencies' authority to
reconsider prior decisions.\37\
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\35\ ``Guidance on the Preparation of Clean Air Act Section 179B
Demonstrations for Nonattainment Areas Affected by International
Transport of Emissions'' (December 18, 2020). The EPA also issued a
notice of availability in the Federal Register on January 7, 2021
(86 FR 1105).
\36\ See EPA News Release: Administrator Zeldin Moves Forward
with Ensuring U.S. States Are Not Punished for Foreign Air, April 7,
2025, <a href="https://www.epa.gov/newsreleases/administrator-zeldin-moves-forward-ensuring-us-states-are-not-punished-foreign-air">https://www.epa.gov/newsreleases/administrator-zeldin-moves-forward-ensuring-us-states-are-not-punished-foreign-air</a>.
\37\ See, e.g., FDA v. Wages & White Lion Invs., L.L.C., 604
U.S. 542, 567-68 (2025); FCC v. Fox Television Stations, Inc., 556
U.S. 502, 515 (2009) (referencing Motor Vehicle Mfrs. Ass'n v. State
Farm Mut. Auto. Ins. Co., 463 U.S. 29 (1983)) (an agency is free to
change a prior policy and ``need not demonstrate . . . that the
reasons for the new policy are better than the reasons for the old
one; it suffices that the new policy is permissible under the
statute, that there are good reasons for it, and that the agency
believes it to be better'').
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E. Atypical Events: Exclusion of Unrepresentative Air Quality Data
The EPA allows for the exclusion of unrepresentative air quality
data from certain regulatory determinations that qualify either as
``exceptional events'' or ``atypical events.'' As described below in
sections IV.B and IV.C of this preamble, the Utah 179B(b) Demonstration
excludes atypical event air quality data impacted by wildfire smoke
from its air quality modeling.
Congress has recognized that it may not be appropriate for the EPA
to use certain monitoring data collected by the ambient air quality
monitoring network and maintained in the Air Quality System in certain
regulatory determinations.\38\ Thus, in 2005, Congress provided the
statutory authority for the exclusion of data influenced by
``exceptional events'' meeting specific criteria by adding section
319(b) to the CAA.\39\ To implement this 2005 CAA amendment, the EPA
promulgated administrative rules codified at 40 CFR parts 50 and 51
(sections 50.1, 50.14 and 51.930) (``Exceptional Events Rule'').\40\
The Exceptional Event Rule contains definitions, procedural
requirements, requirements for air agency demonstrations, criteria for
the EPA's approval of the exclusion of exceptional event-affected air
quality data from the data set used for regulatory decisions, and
requirements for air agencies to take appropriate and reasonable
actions to protect public health from exceedances or violations of the
NAAQS. In 2016, the EPA promulgated a comprehensive revision to the
Exceptional Events Rule.\41\ Under the 2016 revisions, if a State
demonstrates to the EPA's satisfaction that emissions from an
exceptional event as defined by 40 CFR 50.1 including a wildfire,
caused a specific air pollution concentration in excess of the NAAQS at
a particular air quality monitoring location and otherwise satisfies
the requirements of 40 CFR 50.14, the Agency must exclude that data
from use in determinations of exceedances and violations.\42\
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\38\ U.S. Environmental Protection Agency, Air Quality System
(AQS) Data Mart, available via <a href="https://www.epa.gov/outdoor-air-quality-data">https://www.epa.gov/outdoor-air-quality-data</a>.
\39\ 42 U.S.C. 7619(b).
\40\ 72 FR 13560 (March 22, 2007).
\41\ 81 FR 68216 (October 3, 2016).
\42\ 40 CFR 50.14(b)(4).
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In addition to exceptional events, the EPA and States may also
exclude unrepresentative air quality data from certain modeling
analyses. Among other things, past air quality monitoring data
reflecting elevated, unrepresentative pollutant levels due to wildfires
and other ``atypical events'' may be excluded from DV calculations used
in air quality modeling. The EPA allows for modeling to exclude
monitoring air quality data influenced by atypical events because these
events result in unrepresentative monitoring data that, if used in
modeling calculations, would not create representative modeled air
quality estimates.
[[Page 23214]]
In the preamble to the final 2016 Exceptional Events Rule, the EPA
explained that ``it may be appropriate to exclude data using mechanisms
other than the Exceptional Events Rule,'' based upon whether a
particular situation concerns `` `past' versus `predicted' exceedances
and/or violations.'' \43\ The preamble further explained:
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\43\ 81 FR 68216, 68228 (October 3, 2016).
``[P]redictions of future NAAQS violation(s) generally involve
reviewing the historical ambient concentration data that are the
evident focus of CAA section 319(b), estimating expected future
emissions, and then using both of these data sets as inputs to an
air quality modeling tool or other analytical approach that
extrapolates these data to predict a future outcome . . . . [T]he
fact that these predicted future values rely only in part on
historical monitoring data implies that a different standard for
data exclusion may be appropriate.'' \44\
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\44\ Id.
The EPA further stated that ``we . . . intend to develop a
supplementary guidance document . . . which will describe the
appropriate additional pathways for data exclusion for some `predicted
future' monitoring data applications.'' \45\
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\45\ Id. at 68229.
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The EPA published that supplementary guidance document in 2019, the
Clarification Memo on Data Modification.\46\ The Clarification Memo on
Data Modification clarified what types of air quality data exclusions
fall under the Exceptional Events Rule and identified ``other
determinations, actions, and analyses that are not covered by the scope
of the Exceptional Events Rule, but for which the exclusion, selection,
or adjustment of monitoring data may be appropriate and allowable''
under the CAA and applicable rules and guidance.\47\ For example, the
Clarification Memo on Data Modification cites an EPA administrative
rule titled ``Guideline on Air Quality Models,'' which allows for
modification of the ambient data record for purposes of certain
modeling analyses.\48\ In particular, the Guideline on Air Quality
Models allows for ``removal of data from specific days or hours when a
monitor is being impacted by activities that are not typical or not
expected to occur again in the future (e.g., construction, roadway
repairs, forest fires, or unusual agricultural activities).'' \49\ The
Clarification Memo on Data Modification also cites modeling guidance
issued by the EPA in 2018 discussing exclusion of data influenced by
atypical events in the context of (1) establishing a base DV, and (2)
developing relative response factors (RRF) as part of modeling
calculations (``2018 Modeling Guidance'').\50\
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\46\ Memorandum from Richard Wayland, Director Air Quality
Assessment Division, ``Additional Methods, Determinations, and
Analyses to Modify Air Quality Data Beyond Exceptional Events,''
dated April 4, 2019 (``Clarification Memo on Data Modification''),
available at <a href="https://www.epa.gov/sites/default/files/2019-04/documents/clarification_memo_on_data_modification_methods.pdf">https://www.epa.gov/sites/default/files/2019-04/documents/clarification_memo_on_data_modification_methods.pdf</a>.
\47\ Id.
\48\ 40 CFR part 51, appendix W.
\49\ 40 CFR part 51, appendix W, section 8.3.2.c.ii. See also
id. sections 8.3.2.d and 8.3.3.d.
\50\ Memorandum from Richard Wayland, Director Air Quality
Assessment Division, ``Modeling Guidance for Demonstrating
Attainment of Air Quality Goals for Ozone, PM<INF>2.5</INF> and
Regional Haze,'' dated November 29, 2018 (``2018 Modeling
Guidance''), available at <a href="https://www.epa.gov/sites/default/files/2020-10/documents/o3-pm-rh-modeling_guidance-2018.pdf">https://www.epa.gov/sites/default/files/2020-10/documents/o3-pm-rh-modeling_guidance-2018.pdf</a>, at 102-106.
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II. Legal Authority
The statutory authority for the actions proposed in this rulemaking
is provided by the CAA, as amended.\51\ Relevant portions of the CAA
include, but are not limited to, CAA sections 179B and 181(b)(2).
Additionally, the EPA has the authority to reconsider and revise,
rescind, and repeal final actions to the extent permitted by law so
long as it offers a reasonable basis for doing so and considers
applicable reliance interests.\52\
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\51\ 42 U.S.C. 7401 et seq.
\52\ See footnote 37 of this preamble.
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As explained in section I.C of this preamble, CAA section
181(b)(2)(A) requires that within 6 months following the applicable
attainment date, the EPA shall determine whether an ozone NAA attained
the ozone standard based on the area's DV as of that date. A finding by
the EPA that an area has not attained the standard by the attainment
date results in that area being reclassified by operation of law to the
next higher classification.
As explained in section I.D of this preamble, CAA section 179B
provides the EPA with the authority to consider, based on a State's
demonstration, whether a NAA will attain or would have attained the
NAAQS by the applicable attainment date but for impacts from
international emissions. If a State provides a demonstration under CAA
section 179B(b) that establishes to the satisfaction of the
Administrator that an area would have attained the ozone NAAQS by the
applicable attainment date but for emissions emanating from outside of
the U.S., the area shall not be subject to specified provisions,
including CAA section 181(b)(2), which includes determinations of
attainment by the relevant attainment date and reclassification for
failure to attain.\53\
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\53\ See footnote 16 of this preamble.
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III. Proposed Action
This notice and comment rulemaking arises out of the EPA's March 5,
2025, granting of the petitions for reconsideration of the December
2024 Final Rule submitted by the Utah Congressional delegation, the
State of Utah, and the Utah Petroleum Association. Upon reconsideration
and review of technical information submitted by the State of Utah,
including a 179B(b) demonstration for the NWF ozone NAA, the EPA is
proposing to repeal the December 2024 Final Rule, which determined that
the NWF ozone NAA area failed to attain by the Moderate attainment date
and reclassified it by operation of law to a Serious ozone NAA. The EPA
is proposing to repeal that prior action because the Agency is also
proposing to determine that the NWF ozone NAA would have attained the
2015 ozone NAAQS by the applicable Moderate area attainment date but
for emissions emanating from outside the U.S., thereby retaining the
area's Moderate nonattainment classification. In doing so, the EPA is
proposing that it is appropriate to exclude atypical events due to
wildfire smoke in the modeling supporting the determination that the
NWF ozone NAA would have attained the NAAQS by the attainment date but
for international emissions.
In this rulemaking, the EPA is applying interpretations and
policies that differ in certain respects from those set forth in the
rescinded 179B Guidance and previous actions under CAA section 179B(b),
consistent with the discretion provided to the EPA under the CAA and
relevant case law concerning agencies' authority to reconsider prior
decisions. The CAA does not specify what technical analyses would be
sufficient to demonstrate ``to the satisfaction of the Administrator''
that a ``State would have attained the [ozone NAAQS] by the applicable
attainment date, but for'' international emissions. The best reading of
the phrase ``to the satisfaction of the Administrator'' is that it
provides inherent flexibility to the EPA to determine what analyses are
sufficient.\54\ As described in previous EPA 179B(b) determinations:
``[t]he EPA considers and qualitatively weighs all
[[Page 23215]]
evidence based on its relevance to CAA section 179B and the nature of
international contributions as described in the demonstration's
conceptual model. Every demonstration should include fact-specific
analyses tailored to the [NAA] in question.'' \55\
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\54\ Loper Bright Enters. v. Raimondo, 603 U.S. 369, 395 (2024)
(``[Other statutes] empower an agency . . . to regulate subject to
the limits imposed by a term or phrase that `leaves the agencies
with flexibility,' . . . such as `appropriate' or `reasonable.' '').
\55\ 87 FR 50030, 50033 (August 15, 2022); see also 87 FR 21842,
21852 (April 13, 2022).
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The EPA is retaining this overall approach to evaluating 179B(b)
demonstrations, which the Agency finds to be consistent with the
discretion granted to the Agency under section 179B(b). However, the
EPA no longer considers specific characteristics related to a given NAA
as necessarily suggesting the need for a more detailed demonstration
with additional evidence.\56\ Similarly, the EPA is no longer applying
the previous policy that ``[w]hen a CAA section 179B demonstration
shows that international contributions are larger than domestic
contributions, the weight of evidence will be more compelling than if
the demonstration shows domestic contributions exceeding international
contributions.'' \57\
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\56\ In previous actions on CAA section 179B demonstrations, the
EPA has stated the following characteristics would suggest the need
for a more detailed demonstration with additional evidence: (1)
affected monitors are not located near an international border; (2)
specific international sources and/or their contributing emissions
are not identified or are difficult to identify; (3) exceedances on
internationally influenced days are in the range of typical
exceedances attributable to local sources; and (4) exceedances
occurred in association with other processes and sources of
pollutants, or on days in which meteorological conditions were
conducive to local pollutant formation (e.g., for ozone, clear
skies, and elevated temperatures). See 87 FR 21842, 21852 (April 13,
2022); 87 FR 60897, 60906 (October 7, 2022); 87 FR 50030, 50033
(August 15, 2022).
\57\ Guidance on the Preparation of Clean Air Act Section 179B
Demonstrations for Nonattainment Areas Affected by International
Transport of Emissions, EPA-457/P-20-001F, December 2020, at page 7
(rescinded); see also 87 FR 21842, 21852 (April 13, 2022); 87 FR
60897, 60906 (October 7, 2022).
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In evaluating previous CAA section 179B demonstrations, the EPA has
also considered what measures an air agency has implemented to control
local emissions. Specifically, the EPA has stated, ``[f]or the EPA to
concur with a state's CAA section 179B retrospective demonstration, the
weight of evidence should show the area could not attain with on-the-
books measures and potential reductions associated with controls
required for that particular NAAQS and classification that are to be
implemented by the attainment date.'' \58\ The EPA has also previously
noted that ``[b]ecause CAA section 179B does not relieve an air agency
of its planning or control obligations, the air agency should show that
it has implemented all required emissions controls at the local level
as part of its demonstration.'' \59\
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\58\ 87 FR 50030, 50034 (August 15, 2022); see also 87 FR 21842,
21852 (April 13, 2022).
\59\ 87 FR 21842, 21852; see also ``Technical Support Document
(TSD), Northern Wasatch Front (NWF), Utah: Failure to Attain 2015
Ozone National Ambient Air Quality Standard by Attainment Date;
Reclassification and Disapproval of International Emissions
Demonstration, January 2022,'' available in the docket for this
action. However, a State could choose to follow the recommended
procedures in the 179B Guidance, and the EPA would consider that as
part of the weight of evidence. See 83 FR 62998, 63010 (December 6,
2018) (``For purposes of CAA section 179B demonstrations for the
2015 ozone NAAQS, we are maintaining the approach used for prior
ozone standards that only areas classified Moderate and higher must
show that they have implemented RACM/RACT.'').
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The EPA now proposes that the Agency's prior interpretation of CAA
section 179B(b), with regard to planning and control obligations as
noted above, was not the best reading of the statute. CAA section
179B(b) does not expressly require that a State meet all CAA
requirements for an area's classification as a precondition before the
EPA can approve a retrospective demonstration. Accordingly, the EPA is
now proposing to change the Agency's policy with respect to analysis of
potential controls as part of a 179B(b) demonstration. Under the
proposed new interpretation, States will no longer be expected to show
that they could not attain with on-the-books measures and potential
reductions associated with controls required to be implemented by the
attainment date to qualify for approval of a CAA section 179B(b)
determination. For example, areas classified Moderate and higher would
no longer need to show that they could not attain by implementing RACM
and RACT. However, approval of a 179B(b) demonstration does not relieve
a State of its obligation to adopt and submit the required SIP elements
for its existing classification, with the exception of contingency
measures.\60\
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\60\ See footnote 11 of this preamble.
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As noted, the EPA proposes to find that, if the Agency finalizes
approval of the 179B(b) determination as proposed, the contingency
measure requirements of CAA section 172(c)(9) would no longer apply to
the NWF Moderate 2015 ozone NAA. Specifically, as explained in section
I.B of this preamble, attainment contingency measures and RFP
contingency measures can only be triggered for a Moderate ozone NAA by
a finding of failure to attain under CAA section 181(b)(2). As
previously noted, if the EPA finalizes the Agency's proposed
determination under 179B(b), the NWF ozone NAA will no longer be
subject to the provisions of CAA section 181(b)(2). Therefore, neither
contingency measures for failing to attain, nor RFP contingency
measures will be triggered for the NWF NAA. Accordingly, if the EPA
finalizes the 179B(b) determination for the NWF Moderate 2015 ozone
NAA, the requirement for Utah to submit contingency measures for
failure to attain and RFP will no longer apply to this area.
This proposed determination of attainment but for international
emissions under CAA section 179B(b) would not constitute formal
redesignation to attainment as provided for under CAA section
107(d)(3). Redesignations to attainment require, among other things,
that the States responsible for ensuring attainment and maintenance of
the NAAQS have met the applicable requirements under CAA section 110
and title I, Part D (sections 171-193) and require States to submit to
the EPA for approval a maintenance plan to ensure continued attainment
of the standard for 10 years following redesignation, as provided under
CAA section 175A. This action, if finalized, will result in the NWF
ozone NAA retaining its Moderate nonattainment classification and will
not be subject to being reclassified to any higher nonattainment
classifications under CAA section 181(b)(2).
If the EPA takes final action determining that the NWF ozone NAA
would have attained the 2015 ozone NAAQS by the Moderate attainment
date of August 3, 2024, but for emissions emanating outside of the U.S.
(as demonstrated by modeling of international emissions and the
exclusion of wildfire smoke atypical events from modeling calculations,
among other factors), the NWF will remain a Moderate NAA and still will
be required to submit all outstanding required Moderate SIP elements
aside from contingency measures.
Additional information supporting the EPA's proposed action is
included in the Technical Support Document (TSD) provided in the docket
for this rulemaking.
The EPA seeks comment on all aspects of the proposed actions
described in this preamble, including with respect to our statutory
authority to reconsider and repeal the December 2024 Final Rule and any
changes in interpretation and policy relevant thereto. Because this
action would, if finalized, relieve certain obligations for the State
of Utah and adopt interpretations and policies that clarify the ways in
which other States may satisfy statutory obligations under similar
circumstances, the EPA does not believe there are reasonable and
[[Page 23216]]
cognizable reliance interests that would be adversely impacted by
finalizing this action as proposed. Nevertheless, the EPA seeks comment
on whether such reliance interests exist and, if so, how the Agency
should consider them in taking any final action on this proposal.
IV. Northern Wasatch Front Ozone NAA--Proposed Determination of
Attainment But for International Emissions
A. NWF Ozone NAA
The NWF ozone NAA is an urbanized area with a population over 1.8
million.\61\ The meteorology of the urbanized Wasatch Front is strongly
influenced by the Wasatch Mountain Range to the east of the urban
corridor and the Great Salt Lake and Utah Lake to the west of the
urbanized area.\62\ Peak ozone season is typically from May through
September, with ozone exceedances often occurring when wind speed and
relative humidity are low, temperature is high, and cloud cover is
minimal. Further, ozone levels are commonly impacted by wildfire smoke
from summer wildfire events, as well as from ozone and ozone precursor
emissions that are transported into the NAA from upwind sources,
including the upper troposphere, portions of Utah not within the
designated NAA, other States, and other countries.\63\
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\61\ 2020 U.S. Census, <a href="https://www.census.gov/data/datasets/2020/dec/2020-census-redistricting-summary-file-dataset.html">https://www.census.gov/data/datasets/2020/dec/2020-census-redistricting-summary-file-dataset.html</a>.
\62\ Utah 179B(b) Demonstration, Appendix I, Section 2.3 and
Appendix II, page 123 of 478.
\63\ Pan and Faloona. (2022). The Impacts of Wildfires on Ozone
Production and Boundary Layer Dynamics in California's Central
Valley, Atmospheric Chemistry and Physics Discussions, 1-30. See
also Lindaas J. et al. (2017). Changes in ozone and precursors
during two aged wildfire smoke events in the Colorado Front Range in
summer 2015, Atmospheric Chemistry and Physics, 17(17), 10691-10707.
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Utah currently operates ozone monitors at 22 locations statewide,
including 11 active regulatory monitoring sites, as defined by 40 CFR
58.1, in the NWF ozone NAA (See table 1). Each year, the Air Monitoring
Section of Utah's Division of Air Quality produces an Annual Monitoring
Network Plan (AMNP) in accordance with 40 CFR 58.10.\64\ The most
recent AMNP was approved by the EPA in July 2025.\65\ Data from this
monitoring network are what the EPA previously relied upon in issuing a
finding of failure to attain in the December 2024 Final Rule.
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\64\ The purpose of the document is to apprise stakeholders
(public, private, government) and other entities of the current and
the upcoming changes to the State's air monitoring network.
\65\ See letter dated June 30, 2025, from Bryce Bird, Director,
Division of Air Quality, Utah Department of Environmental Quality to
Adrienne Sandoval, EPA Region 8 Director, Air and Radiation
Division, submitting Utah's 2025 Annual Monitoring Network Plan,
available in the docket for this action.
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B. Overview of NWF Proposed Determination of Attainment but for
International Emissions
On December 12, 2024, the State of Utah submitted a retrospective
179B(b) demonstration showing that the NWF ozone NAA would have met the
2015 ozone NAAQS by the Moderate attainment date of August 3, 2024, but
for emissions emanating from international sources (as demonstrated by
modeling of international emissions and the exclusion of wildfire smoke
atypical events from modeling calculations, among other factors).
The EPA has used a weight-of-evidence approach to evaluate whether
the data, technical analyses, and overall strength of the evidence
provided by Utah supports a proposed determination that emissions from
outside the U.S. prevented the NWF ozone NAA from attaining the ozone
standard by the attainment date. Additional details are included in the
TSD provided in the docket for this rulemaking.
The CAA does not specify what technical analyses would be
sufficient to demonstrate ``to the satisfaction of the Administrator''
that a ``State would have attained the [ozone NAAQS] by the applicable
attainment date, ``but for'' international emissions''. The CAA does
not define the term ``but for.'' The plain meaning of this term,
however, as evidenced by standard dictionary definitions, is that
something is the ``but for'' cause of an event if the event would not
have occurred absent that factor. This meaning is the best reading of
the term in CAA section 179B(b), for which the proper question is
whether a NAA would have attained the relevant NAAQS by the applicable
attainment date in the absence of impacts of international emissions.
When a State properly establishes the existence of, and quantity of,
such international impacts in the NAA, the EPA can evaluate whether
such impacts caused the failure to attain.
Moreover, the best reading of the phrase ``to the satisfaction of
the Administrator'' is that it provides inherent flexibility to the EPA
to determine what analyses are sufficient for this purpose.\66\ As
described in previous EPA 179B(b) determinations:
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\66\ See footnote 54 of this preamble.
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Given the extensive number of technical factors and meteorological
conditions that can affect international transport of air pollution,
and the lack of specific guidance in the Act, the EPA evaluates CAA
section 179B demonstrations based on the weight of evidence of all
information and analyses provided by the air agency.\67\
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\67\ See footnote 55 of this preamble.
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C. Evidence Supporting NWF Ozone Attainment Status
The primary lines of evidence provided in the Utah 179B(b)
Demonstration to support that the NWF ozone NAA would have attained the
2015 ozone NAAQS by the attainment date but for the impacts of
international emissions included an assessment of local and synoptic
weather patterns, air quality measurements, satellite imagery, remote
sensing data, and wildfire smoke information provided by the National
Oceanic and Atmospheric Administration (NOAA), the National Aeronautics
and Space Administration (NASA), and the United States Geological
Survey (USGS). Trajectory and air quality modeling were also completed
to understand the conditions associated with elevated ozone levels in
the NWF ozone NAA. In general, these analyses illustrated that the NWF
ozone NAA is located in an environment with complex meteorological
conditions and terrain that can transport air originating from areas
outside of Utah and trap pollution, contributing to degraded local air
quality and elevated ozone levels.
The transport trajectories also support the finding that pollution
originating from regions in Asia and Mexico impacted the ozone levels
in the NWF ozone NAA during days with ozone exceedances. Because
transport trajectories are used to determine the origin and dispersion
of air parcels,\68\ Utah also used an air quality model that included
source apportionment to account for the complex physical and chemical
processes that occur as air pollution disperses from international
sources and to quantify the contributions from international
anthropogenic sources. Here, the results from the air quality model
predicted that the average international anthropogenic emission
contributions over the 10 highest modeled ozone days across the State
of Utah ranged from an estimated 3 ppb to 6 ppb. Further, the back
trajectory and air quality model analyses and air quality observations
showed that wildfire smoke from outside of the State of Utah (e.g.,
from the Western and Northwestern U.S.) impacted the NWF ozone NAA
monitors on several days with ozone
[[Page 23217]]
exceedances, and support excluding the unrepresentative and atypical
air quality monitoring data on these days from modeled DV calculations
for the purpose of the 179B(b) demonstration as explained in section
IV.C.4 of this preamble.
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\68\ An air parcel is a body of air that retains its general
characteristics as it moves through the atmosphere.
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Additionally, as described further below in section IV.C.3 of this
preamble and in section 2.c of the TSD, the EPA's modeling supported
Utah's modeled estimates of international anthropogenic emissions
contributions. As described further below in section IV.C.4 of this
preamble and in section 2.d of the TSD, the EPA's analysis of wildfire
smoke impact on air quality monitors in the NWF ozone NAA supported the
exclusion of atypical air quality monitoring data from modeled DV
calculations for the purpose of the Utah 179B(b) Demonstration.
1. Conceptual Model of NWF Ozone Exceedances
The Utah 179B(b) Demonstration assessed various types of
information and data to describe the factors and conditions that may
cause the exceedances at the regulatory monitors within the NWF ozone
NAA. This information included an examination of the existing air
quality, meteorology, local and long-range transport, and the influence
of emissions from within and outside the NAA on days with ozone
exceedances. Based on monitoring data, the elevated ozone levels are an
area-wide problem because all 11 monitors within the NWF NAA exceeded
the 70-ppb standard in all three years between 2021 and 2023 (which
comprise the 2023 DV). In addition to local emissions contributing to
ozone formation in the NWF ozone NAA, the Utah 179B(b) Demonstration
showed that the area's complex terrain and meteorological conditions
can also make the area susceptible to air pollution originating from
outside of the State. Utah's analysis showed that these conditions can
create persistent high-pressure systems, low wind speeds, low relative
humidity, high temperatures, and suppressed mixing heights and cloud
formations. These conditions are commonly associated with elevated
ozone levels and were shown to exist in the NWF ozone NAA during the
period of 2021 through 2023.\69\ The relatively high baseline
elevation, coupled with its warm and dry climate, can also enhance the
vertical circulation of air that exposes the area to mid- and upper-
tropospheric air with foreign pollution during the summer ozone season.
Additionally, Utah's analysis showed that persistent global circulation
patterns, or large-scale movement of air, created a direct transport
route in the mid- to upper-troposphere that could bring pollution from
Mexico and Asia to the Western U.S. and into the NWF ozone NAA within
days to weeks.
---------------------------------------------------------------------------
\69\ See the EPA's TSD for this rulemaking, section 2.a. See
also Utah 179B(b) Demonstration, Appendix II (page 130).
---------------------------------------------------------------------------
Utah's 179B(b) demonstration shows that the total number of days
with ozone exceedances ranged from 1 to 28 days across all regulatory
monitors between 2021 and 2023. Extensive wildfire activity in the
Western U.S. during the summer of 2021 was associated with a high
number of ozone exceedances.\70\ Utah used a two-factor methodology
involving surface monitoring of particulate matter (PM<INF>2.5</INF>)
concentrations and satellite imagery to identify days that were
impacted by wildfire smoke.\71\ Days identified with the presence of
wildfire smoke were confirmed by the use of NOAA's Hazard Mapping
System. Based upon this analysis, the EPA has determined that the
number of exceedance days in 2021 was an average of 4 times higher than
when compared to 2022 and 2023 across the entire monitoring network (6
and 8 wildfire smoke influenced exceedance days in 2022 and 2023
respectively, compared to 27 wildfire smoke influenced exceedance days
in 2021), indicating a widespread wildfire smoke impact on ozone levels
in the NWF ozone NAA that is separate from any local source
influences.\72\
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\70\ Utah 179B(b) Demonstration, Appendix I, Section 2, Figure
3.
\71\ Id.
\72\ See Utah 179B(b) Demonstration, Appendix I, Section 2.3.
---------------------------------------------------------------------------
2. Back Trajectory Model Analyses of International Transport Patterns
on Ozone Exceedance Days
Utah completed back trajectory model analyses to explore the
origins of air parcels that arrived in the NWF ozone NAA from long-
range transport on days with ozone exceedances between 2021 and 2023.
These analyses focused on 33 ozone exceedance days without impacts from
wildfire smoke. After the wildfire smoke days between 2021 and 2023
were excluded, the results indicated that 29 of the 33 ozone exceedance
days (88 percent) had air parcels originating from Asia (40 percent) or
Mexico (48 percent), and the remaining four ozone exceedance days had
air parcels originating from other areas of the U.S. outside of Utah.
The results from this analysis support Utah's assertion that most of
the local ozone exceedances were impacted by international
anthropogenic emissions.
3. Quantification of International Contributions Using Photochemical
Air Quality Modeling
Utah used a photochemical air quality model that included source
apportionment to quantify the local, regional, and international
anthropogenic source contributions to ozone exceedances in the NWF
ozone NAA. For 8 of the 11 monitors in the NWF ozone NAA, modeling
demonstrated that the NAA would have attained but for international
emissions. For the remaining three monitors, modeling demonstrated that
the NAA would have attained but for international emissions after
excluding wildfire smoke atypical events from modeling calculations.
Utah used modeling to simulate ozone levels during the 2017 base year
and 2023 future year. The 2017 base year was selected to serve as the
baseline for modeling the air quality conditions because Utah
considered it representative of typical air quality events that have
occurred in more recent years. Utah also selected the 2023 future year
as the target year for projecting future ozone levels because it is the
last full year of data that the EPA evaluated for determining
attainment of Moderate NAAs for the 2015 ozone NAAQS. Utah used the
conditions from these years in the model to quantify the contribution
of the international anthropogenic sources on the modeled ozone values
across the NWF ozone NAA and to determine the projected 2023 future DV
(FDV). Utah's source apportionment analysis also focused on model
results between June and July 2023. The 2018 Modeling Guidance does not
require the model simulations to cover the entire base and future years
or the typical ozone season because of the resources needed to complete
the model simulations.\73\ Instead, the 2018 guidance recommends
selecting a time period to model that captures the meteorological
conditions conducive to elevated pollution concentrations or poor air
quality and corresponds with the observed MDA8 at the monitoring sites
with the NAA. The modeling episode was selected after careful
examination by Utah of several summertime episodes in 2014, 2016, 2017,
and 2018 that exhibited multiple ozone exceedances. Selection was based
on an analysis of meteorological
[[Page 23218]]
conditions, ozone exceedances, and pollutants trends to ensure that the
selected time period satisfied the EPA's recommended selection
criteria.\74\
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\73\ See 2018 Modeling Guidance. See also Software for the
Modeled Attainment Test--Community Edition (SMAT-CE), EPA
Photochemical Modeling Tools: <a href="https://www.epa.gov/scram/photochemical-modeling-tools">https://www.epa.gov/scram/photochemical-modeling-tools</a>.
\74\ Utah Divion of Air Quality, Ozone Non-Attainment
Demonstration Wasatch Front, Modeling Protocol, October 2021, pages
10-15, <a href="https://lf-public.deq.utah.gov/WebLink/ElectronicFile.aspx?docid=545062&eqdocs=DAQ-2023-001304">https://lf-public.deq.utah.gov/WebLink/ElectronicFile.aspx?docid=545062&eqdocs=DAQ-2023-001304</a>.
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To determine the international anthropogenic contributions to
monitored DVs, Utah completed modeling based upon the model attainment
test procedures from the 2018 Modeling Guidance and model attainment
test tool.\75\ As described in the 2018 Modeling Guidance, typical
attainment demonstrations calculate a model-derived RRF at each
selected monitoring site, which is based on the relative (or
fractional) change in the concentrations between base year and future
year model results. The RRF calculated at each monitoring site is then
multiplied by the monitored base year DV to provide an estimated FDV
for comparison to the NAAQS. For determining the international
contributions in the Moderate attainment year (i.e., 2023), instead of
using the modeled base year and future year to develop the RRFs, Utah
used model results from two 2023 future year simulations to develop
international anthropogenic RRFs at each monitoring site. These
simulations comprised of one simulation that included international
anthropogenic emissions and another that excluded the international
anthropogenic emissions. This approach attempts to represent the
fractional change in ozone levels when international sources are
excluded from the model and identifies the modeled ozone sensitivity to
international anthropogenic emissions. Utah then applied these RRFs to
adjust the monitored 2023 DVs and estimate the 2023 DVs that account
for the estimated impact of the international anthropogenic emissions
for purposes of comparison to the NAAQS. The methods and assumptions
used in the air quality model and the assessment of international
anthropogenic emissions are appropriate for the purpose of this
demonstration.
---------------------------------------------------------------------------
\75\ See 2018 Modeling Guidance.
---------------------------------------------------------------------------
The EPA previously estimated the impact of international
anthropogenic emissions on ozone in the NWF ozone NAA using a 2016
model platform and following the Agency's modeling guidance.\76\ This
analysis considered international contributions relative to 2018-2020
DVs for the Bountiful and Rose Park monitors. The EPA compared ozone
simulated from the 2016 model platform that included a full estimate of
emissions (i.e., included international anthropogenic emissions) to
ozone predicted from a model simulation without the international
anthropogenic emissions. Here, the international anthropogenic
contribution to ozone was determined based on the differences in ozone
predicted by these two model simulations. Because this previous
analysis completed by the EPA focused on ozone at the Bountiful and
Rose Park monitors located in the NWF ozone NAA, the EPA expanded this
analysis to include all monitors with exceedances for the 2021-2023 DVs
in the NWF ozone NAA. This additional analysis supported the evidence
presented in Utah's demonstration (See section 2.c of the TSD for more
details).
---------------------------------------------------------------------------
\76\ Memorandum from Barron Henderson and Heather Simon (EPA,
Office of Air Quality Planning and Standards), Modeled U.S. and
International Contributions for 2015 Ozone NAAQS Nonattainment Areas
(December 10, 2021). Available at <a href="https://www.regulations.gov/document/EPA-HQ-OAR-2021-0742-0038">https://www.regulations.gov/document/EPA-HQ-OAR-2021-0742-0038</a>. See also Policy Assessment for
the Review of the Ozone National Ambient Air Quality Standards. No.
EPA-452/R-20-001, dated May 2020. EPA, Research Triangle Park, NC.
Available at <a href="https://www.epa.gov/sites/production/files/2020-05/documents/o3-final_pa-05-29-20compressed.pdf">https://www.epa.gov/sites/production/files/2020-05/documents/o3-final_pa-05-29-20compressed.pdf</a>. See also 2018 Modeling
Guidance.
---------------------------------------------------------------------------
Table 2 presents observed ozone levels based on monitoring data and
estimated international anthropogenic contributions from the two air
quality model analyses (namely the ``EPA Assessment'' and the ``Utah
179B(b) Demonstration''). While the results from these analyses show
different estimated contributions from international anthropogenic
sources, the results still offer a range of plausible contributions.
Based on the model results included in the Utah 179B(b) Demonstration,
the site-specific international anthropogenic contributions to ozone
levels ranged from an estimated 4.3 ppb to 5.2 ppb across the
regulatory monitoring sites in the NWF ozone NAA, while the model
results from the EPA's Assessment showed the contributions ranging from
an estimated 8.2 ppb to 9.8 ppb across these sites. The modeled
international contributions included in the Utah 179B(b) Demonstration
are generally lower than estimates from the EPA Assessment, so that the
international contribution to ozone levels in Utah's demonstration may
be seen as relatively conservative. Ultimately, these results indicate
that all but three of the NWF ozone NAA monitors (Copperview, Inland
Port, and Near Road) would have attained the ozone NAAQS after
subtracting the site-specific international anthropogenic contributions
to ozone (See FDV<INF>adj</INF> in table 2 of this preamble).\77\ Based
upon these results, the remaining three monitors required further
evaluation to determine whether they too would have attained the ozone
NAAQS after subtracting international anthropogenic contributions and
wildfire smoke atypical events on specific exceedance days. As
discussed in section IV.C.4 of this preamble, when modeling also
excluded air quality data impacted by atypical events--unrepresentative
monitored ozone data impacted by wildfire smoke--the modeling
demonstrated that these three monitors also would have attained the
ozone NAAQS.
---------------------------------------------------------------------------
\77\ See footnote 8 of this preamble for explanation regarding
truncation of FDV<INF> adj</INF>.
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[[Page 23219]]
[GRAPHIC] [TIFF OMITTED] TP30AP26.005
4. Influence of Wildfire Smoke on Ozone Exceedances
Wildfires emit pollutants including carbon monoxide,
PM<INF>2.5</INF>, NO<INF>X</INF>, and VOCs.\78\ Because NO<INF>X</INF>
and VOCs are key ozone precursors, the presence of wildfire smoke and
the associated wildfire emissions is an important factor to ozone
production.\79\ As a part of the Utah 179B(b) demonstration, the State
also submitted an assessment of air quality information and model
results that connects wildfire smoke to elevated ozone levels to
support the exclusion of specific ozone exceedance days as atypical
events from the DV calculation. The information provided by Utah
focused on several dates in July and August 2021 at the Copperview
monitoring site because this site continued to show a DV that exceeded
the 2015 ozone standard after accounting for contributions from
international anthropogenic sources. The EPA also conducted analyses to
evaluate the relevance of Utah's evidence for the Inland Port and Near
Road monitors that also continued to exceed the ozone standard after
accounting for the international anthropogenic contributions. As
discussed below, the analyses completed by Utah and EPA demonstrate
that all of the NWF ozone NAA monitors would have attained the ozone
NAAQS after excluding days identified as atypical events and
subtracting the site-specific international anthropogenic contributions
to ozone from the DV calculations.
---------------------------------------------------------------------------
\78\ Ninneman, M. and Jaffe, D. (2021). The impact of wildfire
smoke on ozone production in an urban area: Insights from field
observations and photochemical box model. Atmospheric Environment,
267, 118764.
\79\ See the EPA's TSD for this rulemaking, section 2.d.
---------------------------------------------------------------------------
As described in section I.E of this preamble, past air quality
monitoring data reflecting elevated, unrepresentative pollutant levels
due to wildfire smoke and other atypical events may be excluded from DV
calculations used in air quality modeling that supports a 179B(b)
demonstration. In this case, the Utah 179B(b) Demonstration relied in
part on modeling to estimate ozone levels in the NWF ozone NAA due to
international anthropogenic emissions. Consistent with the 2018
Modeling Guidance, Utah's modeling utilized past monitoring air quality
data to calculate the future ozone levels for purposes of estimating
the ozone contribution from international anthropogenic emissions.\80\
The EPA allows for modeling to exclude this type of monitoring air
quality data influenced by atypical events, such as wildfire smoke,
because these events result in unrepresentative monitoring data that,
if used in modeling calculations, would not create representative
simulated air quality estimates. Because Utah identified
unrepresentative wildfire smoke influenced air quality data as part of
its modeling calculations to predict future ozone concentrations, for
the purposes of estimating ozone contributions to the NWF ozone NAA
from international anthropogenic emissions, it is appropriate to
exclude that data due to influence by atypical events for the reasons
outlined in the preamble to the final 2016 Exceptional Events Rule, the
Clarification Memo on Data Modification, the Guideline on Air Quality
Models, and the 2018 Modeling Guidance.
---------------------------------------------------------------------------
\80\ See 2018 Modeling Guidance.
---------------------------------------------------------------------------
The Utah 179B(b) Demonstration's atypical events assessment
included evidence relating upwind wildfire smoke in the NWF ozone NAA
area on five days in 2021 with ozone exceedances measured at the
Copperview monitor. These dates in 2021 included July 12, July 24,
August 7, August 8, and August 16. The EPA compiled additional evidence
of wildfire smoke influenced days with ozone exceedances at the Near
Road and Inland Port monitor sites. The EPA's assessment focused on
July 12, 2021, at the Inland Port monitor and July 11, July 12, and
July 24 in 2021 at the Near Road monitor. While the Utah 179B(b)
Demonstration focused on July 12, 2021,
[[Page 23220]]
for the Copperview monitor, the EPA expanded the assessment to July 11,
2021, at the Near Road monitor because July 11, 2021, was part of a
multi-day wildfire smoke event. On the days evaluated, record-high or
elevated levels of ozone, PM<INF>2.5</INF>, and brown carbon were
observed relative to days without impacts from wildfire smoke. The
meteorological conditions and synoptic weather patterns during these
events also indicated conditions that would cause wildfires and the
transport of wildfire smoke into the NWF ozone NAA, including
persistent ridging events, deep and well-mixed boundary layers, and
exceptionally dry and warm conditions. Satellite imagery and remote
sensing revealed expansive and dense plumes of wildfire smoke
transported from major wildfires in the Western and Northwestern
portion of the U.S. Trajectories also indicated that wildfire smoke was
transported between the wildfire events occurring outside of the State
of Utah and the NWF ozone NAA.
Overall, the analyses provided multiple lines of evidence
illustrating that episodic wildfire smoke across the Western U.S.
influenced the NWF ozone NAA on these six days. The evidence provided
in the analyses also indicated that the high ozone levels observed
during these wildfire smoke events are unrepresentative of the local
conditions, which, as described in section I.E of this preamble,
supports treating these days as atypical events for exclusion from DV
calculations for the purpose of the Utah 179B(b) Demonstration. Table 3
of this preamble presents the 2021-2023 DV at each of these three
monitors after excluding the atypical event days from the 179B(b) DV
calculations.
[GRAPHIC] [TIFF OMITTED] TP30AP26.006
After excluding these days as atypical events from the DV
calculations for this demonstration, all of the NWF ozone NAA monitors
would have attained the ozone NAAQS after subtracting the site-specific
international anthropogenic contributions to ozone (See
FDV<INF>adj-atyp</INF> in table 4 of this preamble).\81\
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\81\ See footnote 8 of this preamble for explanation regarding
truncation of FDV<INF>adj-atyp</INF>.
[GRAPHIC] [TIFF OMITTED] TP30AP26.007
[[Page 23221]]
D. Conclusions on NWF Attainment Status Based on the Available Evidence
As previously discussed, the EPA evaluates CAA section 179B
demonstrations by considering the available weight of evidence as it
relates to the specific relief being sought. Upon review of the
available lines of evidence, the EPA has concluded that the Utah
179B(b) Demonstration establishes that the NWF ozone NAA would have
attained the 2015 ozone NAAQS by the Moderate attainment date of August
3, 2024, but for emissions emanating from outside of the U.S. (as
demonstrated by modeling of international emissions and the exclusion
of wildfire smoke atypical events from modeling calculations, among
other factors). CAA section 179B(b) requires a State to demonstrate to
the satisfaction of the Administrator that an ozone area would have
attained but for the impacts of international emissions. The EPA is
proposing to find that the Utah 179B(b) Demonstration for the NWF ozone
NAA for purposes of the 2015 ozone NAAQS meets that requirement. Under
CAA section 179B(b), that proposed determination would exempt the NWF
ozone NAA from the provisions of CAA section 181(b)(2), including
determinations of attainment by the relevant attainment date and
reclassification for failure to attain. As a result, the EPA is also
proposing to repeal the December 2024 Final Rule in which the Agency
determined that the NWF ozone NAA failed to attain the 2015 ozone NAAQS
by the August 3, 2024, Moderate area attainment date and reclassified
the area by operation of law to Serious nonattainment.
V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
Executive Order 14192 does not apply because this action is not a
significant regulatory action and is therefore exempted from review
under Executive Order 12866.
C. Paperwork Reduction Act (PRA)
This rule does not impose an information collection burden under
the provisions of the PRA of 1995 (44 U.S.C. 3501 et seq.). This action
does not contain any information collection activities.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA (5
U.S.C. 601 et seq.). This action will not impose any requirements on
small entities. The proposed determination that the NWF NAA would have
attained the 2015 ozone NAAQS but for international emissions and
wildfire smoke does not in and of itself create any new requirements
beyond what is mandated by the CAA. This action would not itself
directly regulate any small entities.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any State,
local, or Tribal governments or the private sector.
F. Executive Order 13132 Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government. The
division of responsibility between the Federal government and the
States for purposes of implementing the NAAQS is established under the
CAA.
G. Executive Order 13175 Consultation and Coordination With Indian
Tribal Governments
Executive Order 13175 requires the EPA to develop an accountable
process to ensure ``meaningful and timely input by Tribal officials in
the development of regulatory policies that have Tribal implications.''
This action does not have Tribal implications.
H. Executive Order 13045 Protection of Children From Environmental
Health and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the Agency has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. This action is not subject to
Executive Order 13045 because it does not concern an environmental
health risk or safety risk.
I. Executive Order 13211 Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not subject to Executive Order 13211 because it is
not a significant regulatory action under Executive Order 12866.
J. National Technology Transfer and Advancement Act (NTTAA)
This rulemaking does not involve technical standards.
List of Subjects
40 CFR Part 52
Environmental protection, Air pollution control, Carbon oxides,
Incorporation by reference, Intergovernmental relations, Nitrogen
oxides, Ozone, Reporting and recordkeeping requirements, Sulfur oxides,
and Volatile organic compounds.
40 CFR Part 81
Environmental protection, Administrative practice and procedure,
Air pollution control, Intergovernmental relations, Nitrogen oxides,
Ozone, Reporting and recordkeeping requirements, Sulfur oxides, and
Volatile organic compounds.
Dated: April 20, 2026.
Cyrus M. Western,
Regional Administrator, Region 8.
[FR Doc. 2026-08372 Filed 4-29-26; 8:45 am]
BILLING CODE 6560-50-P
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