[Federal Register Volume 87, Number 121 (Friday, June 24, 2022)]
[Proposed Rules]
[Pages 37776-37783]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-13377]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2022-0291; EPA-HQ-OAR-2021-0663; FRL-9651-01-R9]


Approval of Air Quality State Implementation Plans; Arizona; 2015 
Ozone Interstate Transport Requirements

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 a SIP revision to the Environmental Protection Agency (EPA) 
to address these requirements for the 2015 ozone national ambient air 
quality standards (NAAQS). The EPA is proposing to approve Arizona's 
SIP submission as meeting the requirement that the Arizona SIP contain 
adequate provisions to prohibit emissions that will significantly 
contribute to nonattainment or interfere with maintenance of the 2015 
ozone NAAQS in any other state.

DATES: Any comments must arrive by July 25, 2022.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2022-0291 at https://www.regulations.gov. For comments submitted at 
Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. 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

[[Page 37777]]

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).
    There are two dockets supporting this action, EPA-R09-OAR-2022-0291 
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R09-OAR-2022-0291 contains 
information specific to Arizona, including this notice of proposed 
rulemaking. Docket No. EPA-HQ-OAR-2021-0663 contains additional 
modeling files, emissions inventory files, technical support documents, 
and other relevant supporting documentation regarding interstate 
transport of emissions for the 2015 ozone NAAQS that are being used to 
support this action. All comments regarding information in either of 
these dockets are to be made in Docket No. EPA-R09-OAR-2022-0291. 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 https://www.epa.gov/dockets/commenting-epa-dockets. If you need assistance in a 
language other than English or if you are a person with disabilities 
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: Ben Leers, Air Planning Office (AIR-
2), EPA Region IX, (415) 947-4279, [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,'' 
and ``our'' refer to the EPA.

Table of Contents

I. Background
    A. Statutory Background
    B. The EPA's 4-Step Interstate Transport Regulatory Framework
    C. The EPA's Ozone Transport Modeling Information
    D. The EPA's Approach To Evaluating Interstate Transport SIPs 
for the 2015 Ozone NAAQS
II. Arizona's Submission
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 October 1, 2015, the EPA promulgated a revision to the ozone 
NAAQS (2015 ozone NAAQS), lowering the level of both the primary and 
secondary standards to 0.070 parts per million (ppm).\1\ Section 
110(a)(1) of the CAA requires states to submit, within 3 years after 
promulgation of a new or revised standard, SIP submissions meeting the 
applicable requirements of section 110(a)(2).\2\ The requirements in 
CAA section 110(a)(2)(D)(i)(I), otherwise known as the ``interstate 
transport'' or ``good neighbor'' provision, generally require 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 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\ National Ambient Air Quality Standards for Ozone, Final 
Rule, 80 FR 65292 (October 26, 2015). Although the level of the 
standard is specified in the units of ppm, ozone concentrations are 
also described in parts per billion (ppb). For example, 0.070 ppm is 
equivalent to 70 ppb.
    \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. The EPA's 4-Step Interstate Transport Regulatory Framework

    The EPA is using the 4-step interstate transport framework (or ``4-
step framework'') to evaluate the states' SIP submittals addressing the 
interstate transport provision for the 2015 ozone NAAQS. The EPA has 
addressed the interstate transport requirements of CAA section 
110(a)(2)(D)(i)(I) with respect to prior ozone NAAQS in several 
regional regulatory actions, including the Cross-State Air Pollution 
Rule (CSAPR), which addressed interstate transport with respect to the 
1997 ozone NAAQS as well as the 1997 and 2006 fine particulate matter 
standards,\4\ and the CSAPR Update \5\ and the Revised CSAPR Update, 
both of which addressed the 2008 ozone NAAQS.\6\
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    \4\ See Federal Implementation Plans: Interstate Transport of 
Fine Particulate Matter and Ozone and Correction of SIP Approvals, 
76 FR 48208 (August 8, 2011).
    \5\ Cross-State Air Pollution Rule Update for the 2008 Ozone 
NAAQS, 81 FR 74504 (October 26, 2016).
    \6\ In 2019, the D.C. Circuit Court of Appeals remanded the 
CSAPR Update to the extent that it failed to require upwind states 
to eliminate their significant contribution by the next applicable 
attainment date by which downwind states must come into compliance 
with the NAAQS, as established under CAA section 181(a). Wisconsin 
v. EPA, 938 F.3d 303, 313 (D.C. Cir. 2019). The Revised CSAPR Update 
for the 2008 Ozone NAAQS at 86 FR 23054 (April 30, 2021) responded 
to the remand of the CSAPR Update in Wisconsin and the vacatur of a 
separate rule, the ``CSAPR Close-Out'' at 83 FR 65878 (December 21, 
2018), in New York v. EPA, 781 F. App. 4 (D.C. Cir. 2019).
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    Through the development and implementation of the CSAPR rulemakings 
and other prior regional rulemakings pursuant to the interstate 
transport provision,\7\ the EPA, working in partnership with states, 
developed the following 4-step framework to evaluate a state's 
obligations to eliminate interstate transport emissions under the 
interstate transport provision for the ozone NAAQS: (1) identify 
monitoring sites that are projected to have problems attaining and/or 
maintaining the NAAQS (i.e., nonattainment and/or maintenance 
receptors); (2) identify states that impact those air quality problems 
in other (i.e., downwind) states sufficiently such that the states are 
considered ``linked'' and therefore warrant further review and 
analysis; (3) identify the emissions reductions necessary (if any), 
applying a multifactor analysis, to eliminate each linked upwind 
state's significant contribution to nonattainment or interference with 
maintenance of the NAAQS at the locations identified in Step 1; and (4) 
adopt permanent and enforceable measures needed to achieve those 
emissions reductions.
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    \7\ In addition to the CSAPR rulemakings, other regional 
rulemakings addressing ozone transport include the NOX 
SIP Call, 63 FR 57356 (October 27, 1998), and the Clean Air 
Interstate Rule (CAIR), 70 FR 25162 (May 12, 2005).
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C. The EPA's Ozone Transport Modeling Information

    In general, the EPA has performed nationwide air quality modeling 
to project ozone design values that are used in combination with 
measured data to identify nonattainment and maintenance receptors. To 
quantify the contribution of emissions from specific upwind states to 
2023 ozone design values at the identified downwind nonattainment and 
maintenance

[[Page 37778]]

receptors, the EPA performed nationwide, state-level ozone source 
apportionment modeling for 2023. The source apportionment modeling 
estimated contributions to ozone concentrations at receptors from 
precursor emissions of anthropogenic nitrogen oxides (NOX) 
and volatile organic compounds in individual upwind states.
    The EPA has released several documents containing projected ozone 
design values, contributions, and information relevant to evaluating 
interstate transport with respect to the 2015 ozone NAAQS. First, on 
January 6, 2017, the EPA published a notice of data availability (NODA) 
in which we requested comment on preliminary interstate ozone transport 
data including projected ozone design values and interstate 
contributions for 2023 using a 2011 base year platform.\8\ In the NODA, 
the EPA used the year 2023 as the analytic year for this preliminary 
modeling because 2023 aligns with the expected attainment year for 
``Moderate'' ozone nonattainment areas for the 2015 ozone NAAQS.\9\ On 
October 27, 2017, the EPA released a memorandum (``October 2017 
memorandum'') containing updated modeling data for 2023. The October 
2017 memorandum incorporated changes made in response to comments on 
the NODA and noted that the modeling may be useful for states 
developing SIPs to address interstate transport obligations for the 
2008 ozone NAAQS.\10\ On March 27, 2018, the EPA issued a memorandum 
(``March 2018 memorandum'') noting that the same 2023 modeling data 
released in the October 2017 memorandum could also be useful for 
identifying potential downwind air quality problems with respect to the 
2015 ozone NAAQS at Step 1 of the 4-step interstate transport 
framework.\11\ The March 2018 memorandum also included the then newly 
available contribution modeling data to assist states in evaluating 
their impact on potential downwind air quality problems for the 2015 
ozone NAAQS under Step 2 of the 4-step interstate transport 
framework.\12\ The EPA subsequently issued two more memoranda in August 
and October 2018, providing additional information to states developing 
interstate transport SIP submissions for the 2015 ozone NAAQS 
concerning, respectively, potential contribution thresholds that may be 
appropriate to apply in Step 2 of the 4-step interstate transport 
framework, and considerations for identifying downwind areas that may 
have problems maintaining the standard at Step 1 of the 4-step 
interstate transport framework.\13\
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    \8\ See Notice of Availability of the Environmental Protection 
Agency's Preliminary Interstate Ozone Transport Modeling Data for 
the 2015 8-hour Ozone National Ambient Air Quality Standard (NAAQS), 
82 FR 1733 (January 6, 2017).
    \9\ Id. at 1735.
    \10\ EPA, Information on the Interstate Transport State 
Implementation Plan Submissions for the 2008 Ozone National Ambient 
Air Quality Standards under Clean Air Act Section 110(a)(2)(D)(i)(I) 
(October 27, 2017). The October 2017 memorandum is available at 
https://www.regulations.gov under docket ID no. EPA-HQ-OAR-2021-0663 
or at https://www.epa.gov/node/194139/.
    \11\ EPA, Information on the Interstate Transport State 
Implementation Plan Submissions for the 2015 Ozone National Ambient 
Air Quality Standards under Clean Air Act Section 110(a)(2)(D)(i)(I) 
(March 27, 2018). The March 2018 memorandum is available at https://www.regulations.gov under docket ID no. EPA-HQ-OAR-2021-0663 or at 
https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
    \12\ The March 2018 memorandum, however, provided, ``While the 
information in this memorandum and the associated air quality 
analysis data could be used to inform the development of these SIPs, 
the information is not a final determination regarding states' 
obligations under the good neighbor provision. Any such 
determination would be made through notice-and-comment rulemaking.''
    \13\ EPA, Analysis of Contribution Thresholds for Use in Clean 
Air Act Section 110(a)(2)(D)(i)(I) Interstate Transport State 
Implementation Plan Submissions for the 2015 Ozone National Ambient 
Air Quality Standards (August 31, 2018), and Considerations for 
Identifying Maintenance Receptors for Use in Clean Air Act Section 
110(a)(2)(D)(i)(I) Interstate Transport State Implementation Plan 
Submissions for the 2015 Ozone National Ambient Air Quality 
Standards (October 19, 2018). The August 2018 and October 2018 
memoranda are available at https://www.regulations.gov under docket 
ID no. EPA-HQ-OAR-2021-0663 or at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
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    Since the release of the modeling data shared in the March 2018 
memorandum, the EPA performed updated modeling using a 2016-based 
emissions modeling platform (the ``2016v1'' platform). This emissions 
platform was developed under the EPA/Multi-Jurisdictional Organization 
(MJO)/state collaborative project.\14\ This collaborative project was a 
multi-year joint effort by the EPA, MJOs, and states to develop a new, 
more recent emissions platform for use by the EPA and states in 
regulatory modeling as an improvement from the dated 2011-based 
platform that the EPA had used to project ozone design values and 
contribution data provided in the 2017 and 2018 memoranda. The EPA used 
the 2016v1 emissions to project ozone design values and contributions 
for 2023. On October 30, 2020, in the notice of proposed rulemaking for 
the Revised CSAPR Update, the EPA released and accepted public comment 
on 2023 modeling that used the 2016v1 emissions platform.\15\ Although 
the Revised CSAPR Update addressed transport for the 2008 ozone NAAQS, 
the projected design values and contributions from the 2016v1 platform 
are also useful for identifying downwind ozone problems and linkages 
with respect to the 2015 ozone NAAQS.\16\
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    \14\ The results of this modeling, as well as the underlying 
modeling files, are available at https://www.regulations.gov under 
docket ID no. EPA-HQ-OAR-2021-0663.
    \15\ 85 FR 68964, 68981 (October 30, 2020).
    \16\ EPA, Air Quality Modeling Technical Support Document for 
the Final Revised Cross-State Air Pollution Rule Update (March 
2021). This technical support document is available at https://www.regulations.gov under docket ID no. EPA-HQ-OAR-2021-0663.
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    Following the final Revised CSAPR Update, the EPA made further 
updates to the 2016 emissions platform to include mobile emissions from 
the EPA's Motor Vehicle Emission Simulator MOVES3 model \17\ and 
updated emissions projections for electric generating units that 
reflect the emissions reductions from the Revised CSAPR Update, recent 
information on plant closures, and other sector trends. Details about 
the updated emissions platform (the ``2016v2'' platform) are described 
in the emissions modeling technical support document (TSD) for this 
proposed rule.\18\ The EPA performed air quality modeling of the 2016v2 
emissions using the most recent public release version of the 
Comprehensive Air-quality Model with extensions (CAMx) photochemical 
modeling, version 7.10.\19\ The EPA now proposes to primarily rely on 
the updated modeling for the 2023 analytic year based on the newly 
available 2016v2 emissions platform (generally referred to herein as 
the 2016v2 modeling for 2023) in evaluating these submissions with 
respect to Steps 1 and 2 of the 4-step interstate transport framework. 
By using the updated modeling results, the EPA is using the most 
current and technically appropriate information for this proposed 
rulemaking. Section III of this document and the Air Quality Modeling 
TSD for 2015 Ozone NAAQS Transport

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SIP Proposed Actions, included in Docket ID No. EPA-HQ-OAR-2021-0663 
for this proposal, contain additional detail on the EPA's 2016v2 
modeling. In this document, the EPA is accepting public comment on this 
updated 2023 modeling, which uses a 2016v2 emissions platform. Comments 
on the EPA's air quality modeling should be submitted in the Regional 
docket for this action at docket ID no. EPA-R09-OAR-2022-0291. Comments 
are not being accepted to docket ID no. EPA-HQ-OAR-2021-0663.
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    \17\ Additional details and documentation related to the MOVES3 
model can be found at https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves.
    \18\ EPA, Technical Support Document (TSD) Preparation of 
Emissions Inventories for the 2016v2 North American Emissions 
Modeling Platform (February 2022). This technical support document 
is available at https://www.regulations.gov under docket ID no. EPA-
HQ-OAR-2021-0663.
    \19\ Ramboll Environment and Health, January 2021, www.camx.com.
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D. The EPA's Approach To Evaluating Interstate Transport SIPs for the 
2015 Ozone NAAQS

    The EPA proposes to apply a consistent set of policy judgments 
across all states for purposes of evaluating interstate transport 
obligations and the approvability of interstate transport SIP 
submittals for the 2015 ozone NAAQS. These policy judgments reflect 
consistency with relevant case law and past agency practice as 
reflected in the CSAPR and related rulemakings. Nationwide consistency 
in approach is particularly important in the context of interstate 
ozone transport, which is a regional-scale pollution problem involving 
many smaller contributors. Effective policy solutions to the problem of 
interstate ozone transport dating back to the NOX SIP Call 
\20\ have necessitated the application of a uniform framework of policy 
judgments in order to ensure an ``efficient and equitable'' 
approach.\21\
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    \20\ 63 FR 57356 (October 27, 1998).
    \21\ See EME Homer City Generation, LP v. EPA, 572 U.S. 489, 519 
(2014).
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    In the March, August, and October 2018 memoranda, the EPA 
recognized that states may be able to establish alternative approaches 
to addressing their interstate transport obligations for the 2015 ozone 
NAAQS that vary from a nationally uniform framework. The EPA emphasized 
in these memoranda, however, that such alternative approaches must be 
technically justified and appropriate in light of the facts and 
circumstances of each particular state's submittal. In general, the EPA 
continues to believe that deviation from a nationally consistent 
approach to ozone transport must be substantially justified and have a 
well-documented technical basis that is consistent with relevant case 
law. Where states submit SIPs that rely on any such potential 
flexibilities that have been identified or suggested in the past, the 
EPA will evaluate whether the state adequately justified the technical 
and legal basis for doing so.
    The EPA notes that certain concepts included in an attachment to 
the March 2018 memorandum require unique consideration, and these ideas 
do not constitute agency guidance with respect to transport obligations 
for the 2015 ozone NAAQS. Attachment A to the March 2018 memorandum 
identified a preliminary list of potential flexibilities that could 
potentially inform SIP development.\22\ However, the EPA made clear in 
that attachment that the list of ideas were not suggestions endorsed by 
the Agency, but rather ``comments provided in various forums'' on which 
the EPA sought ``feedback from interested stakeholders.'' \23\ Further, 
the attachment stated that the ``EPA is not at this time making any 
determination that the ideas discussed below are consistent with the 
requirements of the CAA, nor are we specifically recommending that 
states use these approaches.'' \24\ Attachment A to the March 2018 
memorandum, therefore, does not constitute agency guidance, but was 
intended to generate further discussion around potential approaches to 
addressing ozone transport among interested stakeholders. To the extent 
that states seek to develop or rely on these ideas in support of their 
SIP submittals, the EPA will thoroughly review the technical and legal 
justifications for doing so.
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    \22\ March 2018 memorandum, Attachment A.
    \23\ Id. at A-1.
    \24\ Id.
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    The remainder of this section describes the EPA's proposed 
framework with respect to analytic year, definition of nonattainment 
and maintenance receptors, selection of contribution threshold, and 
multifactor control strategy assessment.
1. Selection of Analytic Year
    In general, the states and the EPA must implement the interstate 
transport provision in a manner consistent with the provisions of title 
I of the CAA.\25\ This requires, among other things, that these 
obligations are addressed consistently with the timeframes for downwind 
areas to meet their CAA obligations. With respect to ozone NAAQS, under 
CAA section 181(a), this means obligations must be addressed ``as 
expeditiously as practicable'' and no later than the schedule of 
attainment dates provided in CAA section 181(a)(1).\26\ Several D.C. 
Circuit court decisions address the issue of the relevant analytic year 
for the purposes of evaluating ozone transport air-quality problems. On 
September 13, 2019, the D.C. Circuit issued a decision in Wisconsin v. 
EPA, remanding the CSAPR Update to the extent that it failed to require 
upwind states to eliminate their significant contribution by the next 
applicable attainment date by which downwind states must come into 
compliance with the NAAQS, as established under CAA section 181(a).\27\
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    \25\ CAA section 110(a)(2)(D)(i).
    \26\ For attainment dates for the 2015 ozone NAAQS, refer to CAA 
section 181(a), 40 CFR 51.1303, and Additional Air Quality 
Designations for the 2015 Ozone National Ambient Air Quality 
Standards, 83 FR 25776 (June 4, 2018, effective August 3, 2018).
    \27\ Wisconsin v. EPA, 938 F.3d 303, 313 (D.C. Cir. 2019).
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    On May 19, 2020, the D.C. Circuit issued a decision in Maryland v. 
EPA that cited the Wisconsin decision in holding that the EPA must 
assess the impact of interstate transport on air quality at the next 
downwind attainment date, including ``Marginal'' area attainment dates, 
in evaluating the basis for the EPA's denial of a petition under CAA 
section 126(b).\28\ The court noted that ``section 126(b) incorporates 
the Good Neighbor Provision,'' and, therefore, the ``EPA must find a 
violation [of section 126] if an upwind source will significantly 
contribute to downwind nonattainment at the next downwind attainment 
deadline. Therefore, the agency must evaluate downwind air quality at 
that deadline, not at some later date.'' \29\ The EPA interprets the 
court's holding in Maryland as requiring the states and the EPA, under 
the interstate transport provision, to assess downwind air quality as 
expeditiously as practicable and no later than the next applicable 
attainment date,\30\ which is now the Moderate area attainment date 
under CAA section 181 for ozone nonattainment. The Moderate area 
attainment date for the 2015 ozone NAAQS is August 3, 2024.\31\ The EPA 
believes that 2023 is now the appropriate year for analysis of 
interstate transport obligations for the 2015 ozone NAAQS because the 
2023 ozone season is the last relevant ozone

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season during which emissions reductions achieved in linked upwind 
states could assist downwind states in meeting the August 3, 2024 
Moderate area attainment date for the 2015 ozone NAAQS.
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    \28\ Maryland v. EPA, 958 F.3d 1185, 1203-1204 (D.C. Cir. 2020).
    \29\ Id. at 1204 (emphasis added).
    \30\ We note that the court in Maryland did not have occasion to 
evaluate circumstances in which the EPA may determine that an upwind 
linkage to a downwind air quality problem exists at Steps 1 and 2 of 
the interstate transport framework by a particular attainment date, 
but for reasons of impossibility or profound uncertainty, the Agency 
is unable to mandate upwind pollution controls by that date. See 
Wisconsin, 938 F.3d at 320. The D.C. Circuit noted in Wisconsin 
that, upon a sufficient showing, these circumstances may warrant 
flexibility in effectuating the purpose of the interstate transport 
provision.
    \31\ CAA section 181(a); 40 CFR 51.1303; Additional Air Quality 
Designations for the 2015 Ozone National Ambient Air Quality 
Standards, 83 FR 25776 (June 4, 2018, effective August 3, 2018).
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    The EPA recognizes that the attainment date for nonattainment areas 
classified as Marginal for the 2015 ozone NAAQS is August 3, 2021. 
Under the Maryland holding, any emissions reductions necessary to 
satisfy interstate transport obligations should have been implemented 
by no later than this date. At the time of the statutory deadline for 
states to submit interstate transport SIPs (i.e., October 1, 2018), 
many states relied upon the EPA's modeling of the year 2023, and no 
state provided an alternative analysis using a 2021 analytic year (or 
the prior 2020 ozone season). However, the EPA must act on SIP 
submittals using the information available at the time it takes such 
action. In this circumstance, the EPA does not believe it would be 
appropriate to evaluate states' obligations under CAA section 
110(a)(2)(D)(i)(I) as of an attainment date that is wholly in the past, 
because the EPA interprets the interstate transport provision as 
forward looking.\32\ Consequently, in this proposal, the EPA will use 
the analytical year of 2023 to evaluate Arizona's CAA section 
110(a)(2)(D)(i)(I) SIP submission with respect to the 2015 ozone NAAQS.
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    \32\ See 86 FR 23054, 23074; see also Wisconsin, 938 F.3d at 
322.
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2. Step 1 of the 4-Step Interstate Transport Framework
    In Step 1 of the 4-step interstate transport framework, the EPA 
identifies monitoring sites that are projected to have problems 
attaining and/or maintaining the NAAQS in the 2023 analytic year. Where 
the EPA's analysis shows that a site does not fall under the definition 
of a nonattainment or maintenance receptor, that site is excluded from 
further analysis under the EPA's 4-step interstate transport framework. 
Where the EPA's analysis shows that a site does meet the definition of 
a nonattainment or maintenance receptor in 2023, we proceed to the next 
step of our 4-step interstate transport framework by identifying the 
upwind state's contribution to those receptors.
    The EPA's approach to identifying ozone nonattainment and 
maintenance receptors in this action is consistent with the approach 
used in previous transport rulemakings. The EPA's approach gives 
independent consideration to both the ``contribute significantly to 
nonattainment'' and ``interfere with maintenance'' prongs of CAA 
section 110(a)(2)(D)(i)(I), consistent with the D.C. Circuit's 
direction in North Carolina v. EPA.\33\
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    \33\ See North Carolina v. EPA, 531 F.3d at 910-911 (holding 
that the EPA must give ``independent significance'' to each prong of 
CAA section 110(a)(2)(D)(i)(I)).
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    For the purpose of this proposal, the EPA identifies nonattainment 
receptors as those monitoring sites that are projected to have average 
design values that exceed the NAAQS and that are also measuring 
nonattainment based on the most recent monitored design values. This 
approach is consistent with prior transport rulemakings, such as the 
CSAPR Update, where the EPA defined nonattainment receptors as those 
areas that both currently measure nonattainment and that the EPA 
projects will be in nonattainment in the future analytic year (i.e., 
2023).\34\
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    \34\ See 81 FR 74504 (October 26, 2016). This same concept, 
relying on both current monitoring data and modeling to define 
nonattainment receptor, was also applied in CAIR. See 70 FR 25241, 
25249 (January 14, 2005); see also North Carolina, 531 F.3d at 913-
914 (affirming as reasonable the EPA's approach to defining 
nonattainment in CAIR).
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    In addition, in this proposal, the EPA identifies a receptor to be 
a ``maintenance'' receptor for the purpose of defining interference 
with maintenance consistent with the method used in the CSAPR and 
upheld by the D.C. Circuit in EME Homer City Generation, L.P. v. 
EPA.\35\ Specifically, the EPA identified maintenance receptors as 
those receptors that would have difficulty maintaining the relevant 
NAAQS in a scenario that takes into account historical variability in 
air quality at that receptor. The variability in air quality was 
determined by evaluating the ``maximum'' future design value at each 
receptor based on a projection of the maximum measured design value 
over the relevant period. The EPA interprets the projected maximum 
future design value to be a potential future air quality outcome 
consistent with the meteorology that yielded maximum measured 
concentrations in the ambient data set analyzed for that receptor 
(i.e., meteorology conducive to ozone formation). The EPA also 
recognizes that previously experienced meteorological conditions (e.g., 
dominant wind direction, temperatures, air mass patterns) promoting 
ozone formation that led to maximum concentrations in the measured data 
may reoccur in the future. The maximum design value gives a reasonable 
projection of future air quality at the receptor under a scenario in 
which such conditions do, in fact, reoccur. The projected maximum 
design value is used to identify upwind emissions that, under those 
circumstances, could interfere with the downwind area's ability to 
maintain the NAAQS.
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    \35\ EME Homer City Generation, L.P. v. EPA, 795 F.3d 118, 136 
(D.C. Cir. 2015). See also 76 FR 48208 (August 8, 2011). The CSAPR 
Update and Revised CSAPR Update also used this approach. See also 81 
FR 74504 and 86 FR 23054.
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    Recognizing that nonattainment receptors are also, by definition, 
maintenance receptors, the EPA often uses the term ``maintenance-only'' 
to refer to those receptors that are not nonattainment receptors. 
Consistent with the concepts for maintenance receptors, as described 
previously in this section, the EPA identifies ``maintenance-only'' 
receptors as those monitoring sites that have projected average design 
values above the level of the applicable NAAQS, but that are not 
currently measuring nonattainment based on the most recent official 
design values. In addition, those monitoring sites with projected 
average design values below the NAAQS, but with projected maximum 
design values above the NAAQS are also identified as ``maintenance-
only'' receptors, even if they are currently measuring nonattainment 
based on the most recent official design values.
3. Step 2 of the 4-Step Interstate Transport Framework
    In Step 2 of the 4-step interstate transport framework, the EPA 
quantifies the contribution of each upwind state to each nonattainment 
and maintenance receptor (as determined in Step 1) in the 2023 analytic 
year. The contribution metric used in Step 2 is defined as the average 
impact from each state to each receptor on the days with the highest 
ozone concentrations at the receptor based on the 2023 modeling. If a 
state's contribution value does not equal or exceed the threshold of 1 
percent of the NAAQS (i.e., 0.70 parts per billion [ppb] for the 2015 
ozone NAAQS), the upwind state is not ``linked'' to a downwind air 
quality problem, and the EPA therefore concludes that the state does 
not significantly contribute to nonattainment or interfere with 
maintenance of the NAAQS in the downwind states. However, if a state's 
contribution equals or exceeds the 1 percent threshold, the state's 
emissions are further evaluated in Step 3 considering both air quality 
and cost as part of a multi-factor analysis to determine what, if any, 
emissions might be deemed ``significant'' and must therefore be 
eliminated under CAA section 110(a)(2)(D)(i)(I). The EPA is proposing 
to rely on the 1 percent

[[Page 37781]]

threshold for the purpose of evaluating a state's contribution to 
nonattainment or maintenance of the 2015 ozone NAAQS (i.e., 0.70 ppb) 
at downwind receptors. This is consistent with the Step 2 approach that 
the EPA applied in CSAPR for the 1997 ozone NAAQS, which has 
subsequently been applied in the CSAPR Update when evaluating 
interstate transport obligations for the 2008 ozone NAAQS. The EPA 
continues to find 1 percent to be an appropriate threshold. For ozone, 
as the EPA found in the Clean Air Interstate Rule, CSAPR, and CSAPR 
Update, a portion of the nonattainment problems from anthropogenic 
sources in the United States results from the combined impact of 
relatively small contributions from many upwind states along with 
contributions from in-state sources and, in some cases, substantially 
larger contributions from a subset of particular upwind states. The 
EPA's analysis shows that much of the ozone transport problem being 
analyzed in this proposed rule is still the result of the collective 
impacts of contributions from many upwind states. Therefore, 
application of a consistent contribution threshold is necessary to 
identify those upwind states that should have responsibility for 
addressing their contribution to the downwind nonattainment and 
maintenance problems to which they collectively contribute. Continuing 
to use 1 percent of the NAAQS as the screening metric to evaluate 
collective contribution from many upwind states also allows the EPA 
(and states) to apply a consistent framework to evaluate interstate 
emissions transport under the interstate transport provision from one 
NAAQS to the next.\36\
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    \36\ See 81 FR 74504, 74518. See also 86 FR 23054, 23085 
(reviewing and explaining rationale from CSAPR) and 76 FR 48208, 
48237-48238 (for selection of 1 percent threshold).
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    The EPA's August 2018 memorandum recognized that in certain 
circumstances a state may be able to establish that an alternative 
contribution threshold of 1 ppb is justifiable. Where a state relies on 
this alternative threshold, and where that state determined it was not 
linked at Step 2 using the alternative threshold, the EPA will evaluate 
whether the state provided a technically sound assessment of the 
appropriateness of using this alternative threshold based on the facts 
and circumstances underlying its application in the particular SIP 
submission.
4. Step 3 of the 4-Step Interstate Transport Framework
    Consistent with the EPA's longstanding approach to eliminating 
significant contribution to nonattainment or interference with 
maintenance, at Step 3 of the 4-step interstate transport framework, 
states linked at Steps 1 and 2 are generally expected to prepare a 
multifactor assessment of potential emissions controls. The EPA's 
analysis at Step 3 in prior federal actions addressing interstate 
transport requirements has primarily focused on an evaluation of cost-
effectiveness of potential emissions controls (on a marginal cost-per-
ton basis), the total emissions reductions that may be achieved by 
requiring such controls (if applied across all linked upwind states), 
and an evaluation of the air quality impacts such emissions reductions 
would have on the downwind receptors to which a state is linked; other 
factors may potentially be relevant if adequately supported. In 
general, where the EPA's or alternative air quality and contribution 
modeling establishes that a state is linked at Steps 1 and 2, it will 
be insufficient at Step 3 for a state to merely point to its existing 
rules requiring control measures as a basis for approval. In general, 
the emissions-reducing effects of all existing emissions control 
requirements are already reflected in the air quality results of the 
modeling for Steps 1 and 2. If the state is shown to still be linked to 
one or more downwind receptor(s), states must provide a well-documented 
evaluation determining whether their emissions constitute significant 
contribution or interference with maintenance by evaluating additional 
available control opportunities by preparing a multifactor assessment. 
While the EPA has not prescribed a particular method for this 
assessment, the EPA expects states at a minimum to present a sufficient 
technical evaluation. This would typically include information on 
emissions sources, applicable control technologies, emissions 
reductions, costs, cost effectiveness, and downwind air quality impacts 
of the estimated reductions, before concluding that no additional 
emissions controls should be required.\37\
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    \37\ As examples of general approaches for how such an analysis 
could be conducted for their sources, states could look to the CSAPR 
Update (81 FR 74504, 74539-74551), CSAPR (76 FR 48208, 48246-48263), 
CAIR (70 FR 25162, 25195-25229), or the NOX SIP Call (63 
FR 57356, 57399-57405). See also the Revised CSAPR Update (86 FR 
23054, 23086-23116). Consistently across these rulemakings, the EPA 
has developed emissions inventories, analyzed different levels of 
control stringency at different cost thresholds, and assessed 
resulting downwind air quality improvements.
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5. Step 4 of the 4-Step Interstate Transport Framework
    At Step 4 of the 4-step interstate transport framework, states (or 
the EPA) develop permanent and federally enforceable control strategies 
to achieve the emissions reductions determined to be necessary at Step 
3 to eliminate significant contribution to nonattainment or 
interference with maintenance of the NAAQS. For a state linked at Steps 
1 and 2 to rely on an emissions control measure at Step 3 to address 
its interstate transport obligations, that measure must be included in 
the state's SIP so that it is permanent and federally enforceable.\38\
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    \38\ See CAA section 110(a)(2)(D) (``Each such [SIP] shall . . . 
contain adequate provisions . . .''). See also CAA section 
110(a)(2)(A); Committee for a Better Arvin v. EPA, 786 F.3d 1169, 
1175-1176 (9th Cir. 2015) (holding that measures relied on by state 
to meet CAA requirements must be included in the SIP).
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II. Arizona's Submission

    On September 24, 2018, the Arizona Department of Environmental 
Quality (ADEQ) submitted to the EPA the ``Arizona State Implementation 
Plan Revision under Clean Air Act Sections 110(a)(1) and 110(a)(2) for 
the 2015 Ozone National Ambient Air Quality Standards'' (``the 2018 
Ozone I-SIP submittal'') addressing the infrastructure requirements of 
CAA section 110(a)(2) for the 2015 ozone NAAQS.\39\ In this proposed 
rulemaking, the EPA is evaluating the section of the 2018 Ozone I-SIP 
submittal addressing CAA section 110(a)(2)(D)(i)(I).
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    \39\ Letter dated September 24, 2018, from Timothy S. Franquist, 
Director, Air Quality Division, ADEQ, to Michael Stoker, Regional 
Administrator, EPA Region IX, Subject: ``Submittal of the Arizona 
State Implementation Plan Revision under Clean Air Act Sections 
110(a)(1) and 110(a)(2) for the 2015 Ozone NAAQS.''
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    The 2018 Ozone I-SIP submittal describes the 4-step framework 
established by the EPA to address the good neighbor provision.\40\ 
Arizona references the results of the ozone modeling completed by the 
EPA using CAMx version 6.40, made available in the March 2018 
memorandum. Arizona noted that the modeling demonstrates that Arizona 
is not shown to contribute greater than 1 percent of the NAAQS (i.e., 
0.70 ppb) to any of the modeled nonattainment or maintenance receptors 
in other states.\41\ Despite asserting that ``Arizona still maintains 
that the 1 percent threshold is poorly suited for determining 
contribution obligations in the Southwestern US,'' Arizona relies

[[Page 37782]]

on the 1 percent of the NAAQS contribution threshold at Step 2.\42\ 
Based on the model results, Arizona finds that it does not contribute 
significantly to nonattainment or maintenance receptors in other states 
and that it is not necessary to identify emissions reductions or adopt 
any permanent or enforceable controls under the interstate transport 
provision for the 2015 ozone NAAQS.\43\ Arizona also asserts that the 
Arizona SIP contains adequate provisions to ensure that air emissions 
in Arizona will not significantly contribute to nonattainment or 
interfere with maintenance of the 2015 ozone NAAQS in any other state 
in the future.\44\
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    \40\ 2018 Ozone I-SIP submittal, 12.
    \41\ Id. at 13.
    \42\ Id.
    \43\ Id.
    \44\ Id. at 14.
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    The EPA notes that CAA sections 110(a)(1) and 110(l) and 40 CFR 
51.102 require states to provide reasonable notice and an opportunity 
for a public hearing prior to adoption of SIP revisions. Section 
110(k)(1)(B) requires the EPA to determine whether a SIP submittal is 
complete within 60 days of receipt. Any plan that the EPA does not 
affirmatively determine to be complete or incomplete will become 
complete by operation of law six months after the day of submittal. A 
finding of completeness does not approve the submittal as part of the 
SIP, nor does it indicate that the submittal is approvable. It does 
start a 12-month clock for the EPA to act on the SIP submittal.\45\
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    \45\ See CAA section 110(k)(2).
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    The 2018 Ozone I-SIP submittal documents the public review process 
followed by Arizona prior to its submittal to the EPA as a revision to 
the SIP. Appendix A of the 2018 Ozone I-SIP submittal includes 
documentation of a notice of public hearing and opportunity for comment 
on the SIP submittal. The notice of public hearing and opportunity for 
comment on the SIP submittal was provided on August 6 and 7, 2018. The 
public hearing for the SIP submittal was held on September 6, 2018. The 
public process documentation in Appendix A of the 2018 Ozone I-SIP 
submittal includes a meeting agenda, sign-in sheet, presiding officer 
certification, and hearing transcript for the September 6, 2018 public 
hearing and a responsiveness summary indicating that no oral or written 
comments were received by ADEQ during the 30-day public review period.

III. The EPA's Evaluation

    The 2018 Ozone I-SIP submittal relies on the 4-step framework and 
the analytic year 2023 contribution modeling results provided in the 
March 2018 memorandum to conclude that Arizona does not significantly 
contribute to nonattainment or interfere with maintenance of the 2015 
ozone NAAQS in any other state.
    As described in section I of this proposal, the EPA performed air 
quality modeling to project design values and contributions for 2023 
using the 2016v2 emissions platform. The EPA proposes to rely primarily 
on this updated modeling to evaluate Arizona's transport SIP submittal. 
The design values and contributions from the updated modeling were 
examined to determine if Arizona contributes at or above the threshold 
of 1 percent of the 2015 ozone NAAQS (0.70 ppb) to any downwind 
nonattainment or maintenance receptor.\46\ The data \47\ indicate that 
the highest contributions in 2023 from Arizona to downwind 
nonattainment and maintenance-only receptors are 0.40 ppb and 0.21 ppb, 
respectively.\48\ The EPA's evaluation of measured and monitored data 
and contribution values in 2023 indicates that the contribution to 
ozone concentrations in other states from emissions in Arizona will not 
exceed the contribution threshold of 0.70 ppb. The results of the EPA's 
evaluation are consistent with the conclusion drawn by Arizona in the 
2018 Ozone I-SIP submittal that emissions from sources in Arizona will 
not contribute to nonattainment or interfere with maintenance of the 
2015 ozone NAAQS in any other state.
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    \46\ While the EPA does not, in this action, approve of the 
state's suggestion or rationale to rely on an alternative threshold, 
based on the state's contributions of less than 1 percent to 
projected downwind nonattainment or maintenance receptors, and the 
state's reliance on a 1 percent threshold in its submittal, the 
consideration of an alternative threshold is inconsequential to our 
action on this SIP submittal. The EPA is proposing to approve 
Arizona's SIP submission on the basis of the use of a 1 percent 
contribution threshold at Step 2.
    \47\ Design values and contributions at individual monitoring 
sites nationwide are provide in the file 
2016v2_DVs_state_contributions.xlsx which is included in docket ID 
No. EPA-HQ-OAR-2021-0663.
    \48\ The EPA's analysis indicates that Arizona will have a 0.40 
ppb impact at the projected nonattainment receptor in Jefferson 
County, Colorado (site ID 80590011), which has a monitored 2020 
design value of 80 ppb, a 2023 projected average design value of 
73.8 ppb, and a 2023 projected maximum design value of 74.4 ppb. 
Furthermore, the EPA's analysis indicates that Arizona will have a 
0.21 ppb impact at the projected maintenance-only receptor in Clark 
County, Nevada (site ID 320030075), which has a monitored 2020 
design value of 74 ppb, a 2023 projected average design value of 
70.0 ppb, and a 2023 projected maximum design value of 71.0 ppb.
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IV. Proposed Action and Request for Public Comment

    Based on the EPA's evaluation of the impact of air emissions from 
Arizona to downwind states using 2023 analytic year modeling as 
described in this notice, the EPA is proposing to approve chapter 2.4.1 
of Arizona's 2018 Ozone I-SIP submittal as meeting the interstate 
transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2015 
ozone NAAQS. The EPA is seeking public comment on the issues discussed 
in this proposed rule. We will accept comments from the public on this 
proposal for the next 30 days.

V. Statutory and Executive Order Reviews

    Under the Clean Air Act, 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 Clean Air Act. 
Accordingly, this proposed action merely proposes to approve state 
plans as meeting federal requirements and does not impose additional 
requirements beyond those imposed by state law. For that reason, this 
proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);

[[Page 37783]]

     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 Clean Air Act; and
     Does not provide the EPA with the discretionary authority 
to address disproportionate human health or environmental effects with 
practical, appropriate, and legally permissible methods under Executive 
Order 12898 (59 FR 7629, February 16, 1994).
    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 proposed 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, 
Reporting and recordkeeping requirements, Volatile organic compounds.

    Authority: 42 U.S.C. 7401 et seq.

    Dated: June 14, 2022.
Martha Guzman Aceves,
Regional Administrator, Region IX.
[FR Doc. 2022-13377 Filed 6-23-22; 8:45 am]
BILLING CODE 6560-50-P