Proposed Rule2026-19495
Air Plan Approval; North Carolina; Charlotte-Rock Hill Area Maintenance Plan for the 2008 8-Hour Ozone NAAQS
Primary source
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Published
September 23, 2026
Issuing agencies
Environmental Protection Agency
Abstract
On February 28, 2025, the State of North Carolina, through the North Carolina Department of Environmental Quality, Division of Air Quality (NCDAQ), submitted a request for the U.S. Environmental Protection Agency (EPA) to approve a State Implementation Plan (SIP) revision containing the State's plan for maintaining the 2008 ozone National Ambient Air Quality Standard (NAAQS) through 2035 for the North Carolina portion of the bi-state Charlotte-Rock Hill, North Carolina-South Carolina 2008 8-hour ozone nonattainment area (the entire area is hereinafter referred to as the "bi-state Charlotte Area" and the North Carolina portion is hereinafter referred to as the "Charlotte Area"). The EPA is proposing to approve and incorporate North Carolina's second 10-year maintenance plan to maintain attainment of the 2008 8-hour ozone NAAQS in the bi-state Charlotte Area, including the 2018 and 2035 motor vehicle emission budgets (budgets) for nitrogen oxides (NO<INF>X</INF>) and volatile organic compounds (VOC) for the Charlotte Area, into the SIP. The EPA is also notifying the public of the status of the EPA's adequacy determination for the sub-area budgets for the Charlotte Area.
Full Text
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<title>Federal Register, Volume 91 Issue 183 (Wednesday, September 23, 2026)</title>
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[Federal Register Volume 91, Number 183 (Wednesday, September 23, 2026)]
[Proposed Rules]
[Pages 60349-60358]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-19495]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R04-OAR-2025-0223; FRL-13259-01-R4]
Air Plan Approval; North Carolina; Charlotte-Rock Hill Area
Maintenance Plan for the 2008 8-Hour Ozone NAAQS
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: On February 28, 2025, the State of North Carolina, through the
North Carolina Department of Environmental Quality, Division of Air
Quality (NCDAQ), submitted a request for the U.S. Environmental
Protection Agency (EPA) to approve a State Implementation Plan (SIP)
revision containing the State's plan for maintaining the 2008 ozone
National Ambient Air Quality Standard (NAAQS) through 2035 for the
North Carolina portion of the bi-state Charlotte-Rock Hill, North
Carolina-South Carolina 2008 8-hour ozone nonattainment area (the
entire area is hereinafter referred to as the ``bi-state Charlotte
Area'' and the North Carolina portion is hereinafter referred to as the
``Charlotte Area''). The EPA is proposing to approve and incorporate
North Carolina's second 10-year maintenance plan to maintain attainment
of the 2008 8-hour ozone NAAQS in the bi-state Charlotte Area,
including the 2018 and 2035 motor vehicle emission budgets (budgets)
for nitrogen oxides (NO<INF>X</INF>) and volatile organic compounds
(VOC) for the Charlotte Area, into the SIP. The EPA is also notifying
the public of the status of the EPA's adequacy determination for the
sub-area budgets for the Charlotte Area.
DATES: Comments must be received on or before October 23, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R04-
OAR-2025-0223 at <a href="http://regulations.gov">regulations.gov</a>. Follow the online instructions for
submitting comments. Once submitted, comments cannot be edited or
removed from 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 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>.
FOR FURTHER INFORMATION CONTACT: Nelsha Athauda, Multi Air Pollutant
Coordination Section, Air Planning and Implementation Branch, Air and
Radiation Division, U.S. Environmental Protection Agency, Region 4, 61
Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is
(404)-562-9360. Ms. Athauda can also be reached via electronic mail at
<a href="/cdn-cgi/l/email-protection#84e5f0ece5f1e0e5aaeae1e8f7ece5c4e1f4e5aae3ebf2"><span class="__cf_email__" data-cfemail="e485908c85918085ca8a8188978c85a4819485ca838b92">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Summary of the EPA's Proposed Action
II. Background
III. North Carolina's SIP Submittal
IV. The EPA's Evaluation of North Carolina's SIP Submittal
A. Attainment Emissions Inventory
B. Maintenance Demonstration
C. Monitoring Network
D. Verification of Continued Attainment
E. Contingency Plan
V. The EPA's Analysis of North Carolina's Proposed NO<INF>X</INF>
and VOC Sub-Area Budgets for the Charlotte Area
VI. The EPA's Adequacy Determination for the Proposed NO<INF>X</INF>
and VOC Sub-Area Budgets
VII. Effect of EPA's Proposed Action
VIII. Proposed Action
IX. Statutory and Executive Order Reviews
I. Summary of the EPA's Proposed Action
In accordance with the Clean Air Act (CAA or Act), the EPA is
proposing to approve the second 10-year Charlotte Area maintenance plan
for the 2008 8-hour ozone NAAQS, submitted by NCDAQ as a revision to
the North Carolina SIP on February 28, 2025.\1\ The
[[Page 60350]]
Charlotte Area includes all of Mecklenburg County and portions of
Cabarrus, Gaston, Iredell, Lincoln, Rowan, and Union Counties.\2\
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\1\ NCDAQ submitted a version of the submittal correcting a
minor subsection numbering issue via email, on February 28, 2025.
Both versions of the State's submittal can be found in the docket
for this action, including a copy of the email correspondence
providing the corrected submittal.
\2\ In the February 28, 2025, submittal NCDAQ refers to the
``Charlotte-Rock Hill, North Carolina-South Carolina Area'' as the
``Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina
Area.''
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The February 28, 2025, submittal is designed to maintain the 2008
8-hour ozone NAAQS within the Charlotte Area through the end of the
second 10-year portion of the maintenance period beyond redesignation.
The EPA is proposing to approve the plan because it meets all
applicable requirements under CAA sections 110 and 175A. The EPA is
also proposing to approve the 2018 and 2035 NO<INF>X</INF> and VOC sub-
area budgets in the Charlotte Area Maintenance Plan because the sub-
area budgets meet the applicable transportation conformity requirements
under 40 CFR 93.118(e).
II. Background
On March 12, 2008, the EPA promulgated a revised 8-hour ozone NAAQS
of 0.075 parts per million (ppm) to provide increased protection of
public health and the environment.\3\ Under the EPA's regulations at 40
CFR part 50, the 2008 8-hour ozone NAAQS is attained when the 3-year
average of the annual fourth-highest daily maximum 8-hour average
ambient air quality ozone concentrations is less than or equal to 0.075
ppm.\4\ Ambient air quality monitoring data for the 3-year period must
meet a data completeness requirement. The ambient air quality
monitoring data completeness requirement is met when the average
percent of days with valid ambient monitoring data is greater than 90
percent, and no single year has less than 75 percent data completeness
as determined in Appendix I of part 50.
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\3\ See 73 FR 16436 (March 27, 2008).
\4\ See 40 CFR 50.15(b). For a detailed explanation of the
calculation of the 3-year 8-hour average, see 40 CFR part 50,
appendix P.
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Upon promulgation of a new or revised NAAQS, section 107(d)(1) of
the CAA requires the EPA to designate as nonattainment any area that is
violating the NAAQS, based on the three most recent years of complete,
quality-assured, and certified ambient air quality data at the
conclusion of the designation process. The bi-state Charlotte Area was
designated nonattainment for the 2008 8-hour ozone NAAQS on May 21,
2012, effective July 20, 2012, using 2009-2011 ambient air quality
data.\5\ At the time of designation, the bi-state Charlotte Area was
classified as a marginal nonattainment area for the 2008 8-hour ozone
NAAQS. In the final implementation rule for the 2008 8-hour ozone
NAAQS,\6\ the EPA established ozone nonattainment area attainment dates
based on Table 1 of CAA section 181(a). This rule established an
attainment date three years after the July 20, 2012, effective date for
areas classified as marginal areas for the 2008 8-hour ozone
nonattainment designations. Therefore, the bi-state Charlotte Area's
attainment date was July 20, 2015. In 2015, the Charlotte Area was
redesignated to attainment for the 2008 8-hour ozone NAAQS, the first
10-year maintenance plan was approved, and the public was notified that
the EPA found the 2014 and 2026 sub-area budgets for NO<INF>X</INF> and
VOC adequate.\7\
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\5\ See 77 FR 30088 (May 21, 2012).
\6\ This rule, titled ``Implementation of the 2008 National
Ambient Air Quality Standards for Ozone: State Implementation Plan
Requirements'' and published at 80 FR 12264 (March 6, 2015),
addresses a range of nonattainment area SIP requirements for the
2008 ozone NAAQS, including requirements pertaining to attainment
demonstrations, reasonable further progress (RFP), reasonably
available control technology (RACT), reasonably available control
measures (RACM), major new source review (NSR), emission
inventories, and the timing of SIP submissions and of compliance
with emission control measures in the SIP. This rule also addresses
the revocation of the 1997 ozone NAAQS and the anti-backsliding
requirements that apply when the 1997 ozone NAAQS are revoked.
\7\ The EPA redesignated the South Carolina portion of the bi-
state Charlotte Area to attainment and approved South Carolina's
associated maintenance plan on December 11, 2015. See 80 FR 76865.
See also 80 FR 44873 (July 28, 2015).
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The primary guidance on maintenance plans and redesignation
requests is the September 4, 1992, memorandum from John Calcagni,
titled ``Procedures for Processing Requests to Redesignate Areas to
Attainment'' (Calcagni Memo).\8\ The Calcagni Memo outlines the key
elements of a maintenance plan, which include the following: attainment
emissions inventory, maintenance demonstration, monitoring network
requirements, verification of continued attainment, and contingency
plan elements.
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\8\ ``Procedures for Processing Requests to Redesignate Areas to
Attainment,'' Memorandum from John Calcagni, Director, Air Quality
Management Division, September 4, 1992. Available at <a href="https://www.epa.gov/ground-level-ozone-pollution/procedures-processing-requests-redesignate-areas-attainment">https://www.epa.gov/ground-level-ozone-pollution/procedures-processing-requests-redesignate-areas-attainment</a>.
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Since 2015, three SIP revisions to the first 10-year maintenance
plan have been approved. Two supplements updated the 2026 budgets for
NO<INF>X</INF> and VOC,\9\ and one supplement revised the motor vehicle
model year coverage of the emissions inspection and maintenance program
(I/M).\10\
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\9\ See 86 FR 47387 (August 25, 2021) and 89 FR 50227 (June 13,
2024).
\10\ See 84 FR 47889 (September 11, 2019).
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The EPA has revised the ozone NAAQS once since the 2008 standards
were finalized. On October 1, 2015, the Agency revised both the primary
and secondary NAAQS for ozone to a level of 0.070 ppm (annual fourth-
highest daily maximum 8-hour average concentration, averaged over 3
years).\11\ On November 16, 2017, the EPA published a final rule
establishing initial area designations for the 2015 8-hour ozone
NAAQS.\12\ The bi-state Charlotte Area was designated attainment for
that standard with an effective date of August 3, 2018.\13\
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\11\ See 80 FR 65296 (October 26, 2015).
\12\ See 82 FR 54232.
\13\ See 83 FR 25776 (June 4, 2018).
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III. North Carolina's SIP Submittal
On February 28, 2025, NCDAQ submitted a second 10-year maintenance
plan to the EPA as a revision to the North Carolina SIP. The submittal
includes the maintenance plan, air monitor data, emissions inventory
information, and appendices. \14\ Appendices include emissions
inventory documentation for onroad, nonroad, point, and nonpoint (area)
source emissions, as well as documentation of public notice, comments
received, and comment responses.
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\14\ Due to size and compatibility limitations of the Federal
Docket Management System, the supporting modeling files are instead
available at the EPA Region 4 office. To request these files, please
contact the person listed in this NPRM under the section titled FOR
FURTHER INFORMATION CONTACT.
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IV. The EPA's Evaluation of North Carolina's SIP Submittal
The EPA has reviewed the second 10-year maintenance plan for the
Charlotte Area, which is designed to maintain the 2008 8-hour ozone
NAAQS within the bi-state Charlotte Area through the end of the 20-year
period beyond redesignation, as required under CAA section 175A(b). The
following is a summary of the EPA's interpretation of the section 175A
requirements \15\ and the Agency's evaluation of how each requirement
is met.
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\15\ See Calcagni memo.
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A. Attainment Emissions Inventory
As discussed above, the EPA determined in 2015 that the bi-state
Charlotte Area had attained the 2008 8-hour ozone NAAQS at the time
that it redesignated the Charlotte Area to attainment.\16\ The bi-state
Charlotte Area continues to attain the 2008 8-hour ozone NAAQS. For the
second 10-year
[[Page 60351]]
maintenance plan, NCDAQ selected 2018 as the base year (i.e.,
attainment emissions inventory year) for developing a comprehensive
emissions inventory for NO<INF>X</INF> and VOC, for which projected
emissions could be developed for 2026 and 2035. The attainment
inventory identifies a level of emissions in the bi-state Charlotte
Area that is sufficient to attain the 2008 8-hour ozone NAAQS. North
Carolina began development of the attainment inventory by first
generating a baseline emissions inventory for the State's portion of
the bi-state Charlotte Area. The projected summer day emission
inventories have been estimated using projected rates of growth in
population, traffic, economic activity, and other parameters. In
addition to comparing the final year of the plan (2035) to the base
year (2018), North Carolina compared an interim year (2026) to the
baseline to demonstrate that the years in between are also expected to
show continued maintenance of the 2008 8-hour ozone standard.
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\16\ See 80 FR 44873 (July 28, 2015).
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The emissions inventory is composed of four major types of sources:
point, nonpoint (area), onroad mobile, and nonroad mobile. The complete
descriptions of how the inventories were developed are discussed in
Appendices A, B, C, and D of the February 28, 2025, submittal, which
can be found in the docket for this proposed action.
i. Point Sources
Point sources are those large, stationary (non-mobile),
identifiable sources of emissions that release pollutants into the
atmosphere. Point source emissions are tabulated from data collected by
direct on-site measurements of emissions or from mass balance
calculations utilizing emission factors from the EPA's AP-42 or stack
test results. Emission data are collected for each point source at a
facility and reported to NCDAQ through its online system.
For Electricity Generating Units (EGUs) with a Continuous Emissions
Monitoring System (CEMS), 2018 base year NO<INF>X</INF> emissions for
July were obtained from the EPA's Clean Air Markets Division (CAMD)
database for the G.G. Allen Steam Station in Gaston County, Lincoln
County Combustion Turbine Station in Lincoln County, and Buck Steam
Station and Plant Rowan in Rowan County. Base year 2018 summer day VOC
emissions were calculated for each unit using annual emissions that
Duke Energy Carolinas reported to NCDAQ. Duke Energy Carolinas provided
NCDAQ with 2026 and 2035 July day NO<INF>X</INF> and VOC emissions
forecasts for Lincoln Combustion Turbine Station and Buck Steam
Station.\17\ For Plant Rowan, NCDAQ used the Eastern Regional Technical
Advisory Committee (ERTAC) model v22.0 AEO2023 reference case's July
2026 and July 2035 NO<INF>X</INF> emissions forecast to develop summer
day NO<INF>X</INF> emissions. NCDAQ calculated 2018 to 2026 and 2018 to
2035 summer day NO<INF>X</INF> emission growth rates and applied the
growth rates to 2018 VOC summer day emissions to estimate VOC emissions
for 2026 and 2035.
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\17\ Emissions forecasts were not generated for the Duke Energy
Carolinas G.G. Allen Steam Station (Facility ID: 3600039) as the
remaining two coal units have both retired. Retirement notices for
Unit 1 and Unit 5, were received by the EPA Region 4 on January 13,
2025, and October 18, 2024, respectively. These notices are
available in the docket for this proposed action.
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NCDAQ compiled annual NO<INF>X</INF> and VOC emissions from the
2022 North Carolina point source inventory for the list of relevant
non-CEMS EGUs, and these emissions were used to estimate emissions in
2026. For 2018 and 2035, NCDAQ compiled annual 2018 and 2032 VOC and
NO<INF>X</INF> emissions from the 2018v2 Emissions Modeling Platform
(EMP) \18\ for the non-CEMS EGUs included in this plan. Given the
proximity of 2032 to 2035 and the lack of emission projections for
2035,\19\ the 2032 projections were used to represent 2035 emissions.
For non-EGU point sources, aircraft, and wild/prescribed/agricultural
fires, the 2018 inventory reflects county emissions from the EPA's
2018v2 EMP.\20\ Emissions for 2026 were estimated by interpolating
between the 2018 and 2032 emission estimates provided in the 2018v2
EMP.
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\18\ See ``Technical Support Document (TSD): Preparation of
Emissions Inventories for the 2018v2 North American Emissions
Modeling Platform,'' from the EPA's Office of State Air Partnerships
(formerly the `Office of Air Quality Planning and Standards'),
September 2023, for more details on the 2018v2 EMP. The TSD is
available at <a href="https://www.epa.gov/system/files/documents/2024-02/2018v2_emismod_tsd_sep2023_508_0.pdf">https://www.epa.gov/system/files/documents/2024-02/2018v2_emismod_tsd_sep2023_508_0.pdf</a>.
\19\ The EPA's 2018v2 EMP only contains base year emissions
inventories for 2018 and projected emissions for the year 2032. See
<a href="https://www.epa.gov/air-emissions-modeling/2018v2-emissions-modeling-platform">https://www.epa.gov/air-emissions-modeling/2018v2-emissions-modeling-platform</a>
\20\ North Carolina included aircraft, wildfire, prescribed
fire, and agricultural fire emissions in its non-EGU point source
inventory. See the February 28, 2025, submittal for additional
information.
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ii. Nonpoint Sources
Nonpoint sources collectively represent individual sources that
have not been inventoried as specific point or mobile sources. These
individual sources treated collectively as nonpoint sources are
typically too small, numerous, or difficult to inventory using the
methods for the other classes of sources. In general, emissions for
nonpoint sources are estimated by multiplying an emission factor by
some known indicator of collective activity such as production, number
of employees, or population. These types of emissions are estimated at
the county level. North Carolina's nonpoint source emissions inventory
is based on the EPA's 2018v2 EMP. Given the proximity of 2032 to 2035
and the lack of emission projections for 2035, the 2018v2 EMP
projections for 2032 are used to represent 2035 emissions. Emissions
for 2026 were estimated by interpolating between the 2018 and 2032
emission estimates provided in the 2018v2 EMP.
iii. Onroad Sources
Onroad mobile sources are vehicles licensed to operate on public
roadways, including a wide range of vehicle types, from motorcycles and
passenger cars to the largest buses and trucks. For these sources,
historical input data were used for modeling 2018 emissions, whereas
2026 and 2035 emissions were modeled using the EPA's MOtor Vehicle
Emissions Simulator (MOVES) 4.0.1 mobile model. Modeling inputs were
developed by projecting the latest available data to the needed future
years. NCDAQ used local county-level, partial county-level, and State
model input data in lieu of the MOVES4.0.1 default data, wherever
possible, to represent local vehicle fleet and emissions
characteristics more accurately.
On February 12, 2026, the EPA finalized the rescission of the GHG
Endangerment Finding and repealed all greenhouse gas (GHG) emission
standards for light-duty, medium-duty, and heavy-duty vehicles and
engines (``Endangerment Finding Rescission Rule'').\21\ Due to this
action, aspects of the State's planning assumptions from the EPA's
MOVES model versions 4 MOVES4.0.1 are no longer entirely consistent
with the latest information. The EPA recognizes that States have relied
on MOVES4 and MOVES5, including the national default electric vehicle
(EV) projections tied in part to the implementation of these now-
repealed standards, in developing some SIP actions that have been
submitted to the EPA.
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\21\ Rescission of the Greenhouse Gas Endangerment Finding and
Motor Vehicle Greenhouse Gas Emission Standards Under the Clean Air
Act, 91 FR 7686.
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This action was developed using MOVES4 and the latest EPA guidance
on the use of MOVES in SIP development that was available at the time.
Per the EPA's MOVES Policy Guidance, States ``should use the latest
[[Page 60352]]
version of MOVES that is available at the time that a SIP is
developed.'' \22\ In this guidance, the EPA also stated that an earlier
version of MOVES can be used in SIP development if significant work has
already been completed on a SIP using that earlier version.\23\
Therefore, the State developed this SIP based on an emissions model
that the EPA expected States to use. In addition, the EPA indicated
that for fuel type distributions for onroad vehicles that include
estimates of EVs, States should use local data if available and could
rely on the default information within the model as planning
assumptions.\24\ Therefore, based on the EPA's statements in the
Agency's MOVES Policy and Technical Guidance, the State reasonably
relied on the assumptions in MOVES4.
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\22\ See Section 6 ``Use of MOVES4 in SIPs'' on page 8 of
``Policy Guidance on the Use of MOVES4 for State Implementation Plan
Development, Transportation Conformity, General Conformity, and
Other Purposes'' (EPA-420-B-23-009, August 2023).
\23\ Id.
\24\ See Section of 4.8.3 (page 54) of ``MOVES4 Technical
Guidance: Using MOVES to Prepare Emission Inventories for State
Implementation Plans and Transportation Conformity'' (EPA-420-B-23-
011, August 2023).
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As a general principle, the SIP is an iterative document, subject
to various revisions over time. This is because the SIP revision
process is cyclical by nature per the different obligations under the
CAA. The EPA acknowledges the significant amount of time and resources
required by States to develop a SIP revision. In the evaluation of this
SIP submittal, the EPA is considering the modeling and information
provided by North Carolina and affirming that North Carolina relied on
the latest EPA model and guidance information available at the time it
developed the SIP. To acknowledge and accommodate reliance interests
States may have had in MOVES4 based on the EPA's statements in Agency's
MOVES Policy and Technical Guidance, and to treat all States
consistently that submitted SIPs prior to or shortly after the
Endangerment Finding Rescission Rule where significant work had been
completed, the EPA is proposing to find that North Carolina
appropriately estimated onroad mobile source emissions for this SIP
based on MOVES4.
iv. Nonroad Sources
The nonroad mobile source inventory contains emissions from mobile
vehicles and equipment not licensed for use on public roadways.
Emissions of NO<INF>X</INF> and VOC were estimated by running the
nonroad mobile source module of MOVES4.0.1. Model runs were performed
for each county and year of interest. The default data were used for
the input files used in the MOVES4.01 Nonroad model. The MOVES RunSpec
file (wherein all modeling variables are set) was tailored to reflect
North Carolina-specific information. NCDAQ estimated 2026 emissions
values by interpolating between the 2018 and 2032 emissions estimates.
The 2018 NO<INF>X</INF> and VOC emissions for the Charlotte Area,
as well as the emissions for other years, were developed with methods
consistent with the EPA guidance and are summarized in Tables 1 through
3 of the following subsection.
B. Maintenance Demonstration
The maintenance plan includes a maintenance demonstration that:
(i) Shows compliance with and maintenance of the 2008 8-hour ozone
NAAQS by providing information to support the demonstration that
current and future emissions of NO<INF>X</INF> and VOC remain at or
below 2018 emissions levels through 2035, the end of the second 10-year
portion of the maintenance period.
(ii) Uses 2018 as the attainment year and includes future emissions
inventory projections for 2026 and 2035.
(iii) Per 40 CFR part 93, NO<INF>X</INF> and VOC sub-area budgets
were established for the last year (2035) of the maintenance plan (see
section V below). Additionally, NCDAQ opted to establish sub-area
budgets for an interim year (2018).
(iv) Provides actual (2018) and projected emissions inventories, in
tons per ozone season day (tons/summer day), for the Charlotte Area, as
shown in Tables 1 through 3, below.
Table 1--Actual and Projected Annual NOX Emissions (Tons/Summer Day) for the Charlotte Area
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Sector 2018 2026 2035
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Point........................................................... 19.45 16.43 16.54
Nonpoint........................................................ 2.50 2.80 3.01
Onroad.......................................................... 57.07 29.46 13.45
Nonroad......................................................... 13.74 9.81 9.71
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Total....................................................... 92.76 58.50 42.71
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Table 2--Actual and Projected Annual VOC Emissions (Tons/Summer Day) for the Charlotte Area
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Sector 2018 2026 2035
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Point........................................................... 10.33 10.81 11.26
Nonpoint........................................................ 48.81 53.16 56.27
Onroad.......................................................... 29.64 20.44 15.88
Nonroad......................................................... 16.18 16.26 17.51
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Total....................................................... 104.96 100.67 100.92
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Table 3--Emission Estimates (Tons/Summer Day) for the Charlotte Area
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Year NOX VOC
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2018.................................... 92.76 104.96
2026.................................... 58.50 100.67
[[Page 60353]]
2035.................................... 42.71 100.92
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Difference from 2018 to 2035........ 50.05 4.04
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Tables 1 through 3 summarize the 2018 and future projected
emissions of NO<INF>X</INF> and VOC from the Charlotte Area. In
situations where local emissions are the primary contributor to
nonattainment, the NAAQS should not be violated in the future as long
as emissions from within the area remain at or below the baseline with
which attainment was achieved. North Carolina has projected emissions
as described previously and determined that emissions in the Charlotte
Area will remain below those in 2018--the attainment year inventory for
the duration of the maintenance plan.
A safety margin is the difference between the attainment level of
emissions from all source categories (i.e., point, nonpoint, onroad,
and nonroad) and the projected level of emissions in the maintenance
plan from all source categories.\25\ The attainment level of emissions
is the level of emissions during one of the years in which the area met
the NAAQS. NCDAQ selected 2018 as the attainment emissions inventory
year for the Charlotte Area and calculated safety margins for the years
2018, 2026, and 2035. Table 4 displays the established safety margins
for the Charlotte Area in tons per ozone season day (tons/summer day).
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\25\ See 40 CFR 93.101.
Table 4--Safety Margins for the Charlotte Area
[Tons/summer Day]
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Year NOX VOC
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2018.................................... N/A N/A
2026.................................... 34.26 4.29
2035.................................... 50.05 4.04
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The State has decided to allocate a portion of the available safety
margin to the 2035 budgets to allow for unanticipated growth in Vehicle
Miles Traveled, changes, and uncertainty in vehicle mix assumptions,
and uncertainty associated with mobile modeling. NCDAQ developed and
implemented a five-step approach for determining a factor to use to
calculate the amount of safety margin to allocate to the budgets for
2035. Based on this approach, NCDAQ allocated 50 percent of the total
NO<INF>X</INF> safety margin emissions and 100 percent of the total VOC
safety margin emissions to the 2035 budgets. After allocation of the
available safety margin, the remaining safety margin was calculated as
25.03 tons/summer day for NO<INF>X</INF> and 0.0 tons/summer day for
VOC. This allocation and the resulting available safety margin for the
Charlotte Area are discussed further in section V of this notice of
proposed rulemaking, along with the sub-area budgets to be used for
transportation conformity purposes.
C. Monitoring Network
There are currently five ozone monitors in the bi-State Charlotte
Area: one in Lincoln County, North Carolina; two in Mecklenburg County,
North Carolina; one in Rowan County, North Carolina; and one in Union
County, North Carolina.\26\ No monitors are located within the South
Carolina portion of the bi-state Charlotte Area. Table 5 presents the
design values (DV) \27\ (in ppm) for the currently active monitors in
the bi-state Charlotte Area over the 2012-2025 period.
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\26\ The bi-state Charlotte Area's attainment status was
assessed using data from these monitors, along with two additional
monitors that were shut down before the maintenance period began, in
2015. One monitor in Rowan County, NC (ID 37-159-0022) was shut down
in 2013, and the other monitor in Mecklenburg County, NC (ID 37-119-
1005) was shut down in 2014. Historical design values for these two
monitors are available in 80 FR 29250 (May 21, 2015).
\27\ Design values are calculated as the 3-year average of the
annual fourth-highest daily maximum 8-hour average ozone
concentration.
Table 5--8-Hour Ozone NAAQS Design Values (ppm) for Monitors in the Bi-State Charlotte Area for the 2012-2025 Time Period
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2010-2012 2011-2013 2012-2014 2013-2015 2014-2016 2015-2017 2016-2018 2017-2019 2018-2020 2019-2021 2020-2022 2021-2023 2022-2024 2023-2025
Monitor name County AQS Site ID DV DV DV DV DV DV DV DV DV DV DV DV DV DV
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Crouse................................ Lincoln, NC............. 37-109-0004 0.075 0.072 0.068 0.065 0.067 0.067 0.065 0.064 0.060 0.061 0.061 0.065 0.064 0.063
Garinger.............................. Mecklenburg, NC......... 37-119-0041 0.083 0.078 0.070 0.068 0.069 0.069 0.068 0.070 0.067 0.066 0.064 0.069 0.069 0.068
University Meadows.................... Mecklenburg, NC......... 37-119-0046 0.083 0.078 0.073 0.067 \a\ 0.070 \a\ 0.070 0.070 0.069 0.067 0.066 0.064 0.068 0.069 0.068
Rockwell.............................. Rowan, NC............... 37-159-0021 0.078 0.073 0.068 0.064 0.065 0.064 0.062 0.062 0.061 0.062 0.061 0.065 0.065 0.063
Monroe................................ Union, NC............... 37-179-0003 0.073 0.070 0.068 0.065 0.068 0.067 \b\ 0.068 \b\ 0.068 0.063 0.062 0.061 0.067 0.066 0.064
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Monitor started in 2016 to replace County Line (ID# 37-119-1009). The EPA approved the combination of data from both sites into a single site data record for the purpose of calculating design values. The design values shown
include data from both monitoring sites before and after the relocation.
\b\ The February 28, 2025, submittal incorrectly marked these design values as invalid. However, these design values are valid per the criteria in 40 CFR part 50, Appendix U.
As shown in Table 5, the design values derived from the monitors in
the bi-State Charlotte Area have been below the level of the 2008 8-
hour ozone NAAQS since redesignation. Furthermore, the overall ozone
concentrations for the Area decreased by 15 ppb between the 2010-2012
and 2023-2025 design values at three of the five monitors (AQS ID 37-
119-0041, 37-119-0046, and 37-159-0021). As the ozone levels have
dropped and remain
[[Page 60354]]
relatively stable, it is reasonable to conclude that the bi-State
Charlotte Area will not exceed the 2008 8-hour ozone NAAQS during the
second 10-year maintenance period.
The EPA periodically reviews the ozone monitoring networks operated
and maintained by the states in accordance with 40 CFR part 58. The
network plans are submitted annually to the EPA, and network
assessments are submitted every five years. NCDAQ operates a network
plan with monitors within the boundary of the Charlotte Area. The
annual network plan developed by NCDAQ follows a public notification
and review process. The local network plan from the Mecklenburg County
Air Quality (MCAQ) local air agency was also provided to the public for
inspection and comment, as required by 40 CFR 58.10(d). Known potential
monitor shutdowns or relocations are noted in these documents and will
only be made with the approval of the EPA. No plans are underway that
will affect the integrity of the ambient monitoring network in place.
The current monitors are operated consistent with 40 CFR part 58, and
no changes will be made that are inconsistent with 40 CFR part 58. The
EPA has reviewed and approved \28\ the North Carolina 2025-2026 Ambient
Air Monitoring Network Plan.
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\28\ See October 29, 2025, letter of approval from Denisse Diaz,
Director, Air and Radiation Division, the EPA Region 4 to Mike
Abraczinskas, Director, Division of Air Quality, North Carolina
Department of Environmental Quality, available in the docket for
this proposed action.
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Through state and local agencies, North Carolina has committed to
continue operation of the current ozone monitors in the Charlotte Area
in compliance with 40 CFR part 58, provided that sufficient funding is
available for continued operation. For further details on monitoring,
see the 2025-2026 Annual Monitoring Network Plan which can be found in
the docket for this proposed action.
D. Verification of Continued Attainment
The State of North Carolina, through NCDAQ, has the legal authority
to enforce and implement the maintenance plan for the North Carolina
portion of the Area. This includes the authority to adopt, implement,
and enforce any subsequent emissions control contingency measures
determined to be necessary to correct future ozone attainment problems.
In addition, North Carolina has adopted State rules to implement
and enforce Federal and State air pollution control requirements to
ensure that ozone precursor emissions reductions are permanent and
enforceable in the Charlotte Area. The State rules are codified at 15A
NCAC Subchapter 2D (Air Pollution Control Requirements) and Subchapter
2Q (Air Quality Permit Procedures). The MCAQ has also adopted rules
reflecting the State and Federal rules which are codified as
Mecklenburg County Air Pollution Control Ordinance (MCAPCO) Article
1.0000 (Sections 1.5100-1.5700, Permitting Provisions for Air Pollution
Sources; Rules and Operating Regulations) and MCAPCO Article 2.0000
(Sections 2.0100-2.2600, Air Pollution Control Regulations and
Procedures).
E. Contingency Plan
CAA section 175A requires that a maintenance plan include such
contingency measures as the EPA deems necessary to assure that the
state will promptly correct a violation of the NAAQS that occurs after
redesignation. The maintenance plan should identify the contingency
measures to be adopted, a schedule and procedure for adoption and
implementation, and a time limit for action by the State. A State
should also identify specific indicators to be used to determine when
the contingency measures need to be implemented. The maintenance plan
must include a requirement that a State will implement all measures
with respect to control of the pollutant that were contained in the SIP
before redesignation of the area to attainment in accordance with
section 175A(d).
In the February 28, 2025, submittal, North Carolina affirms that
all programs instituted by the State will remain enforceable and that
sources are prohibited from reducing emissions controls following the
redesignation of the Charlotte Area. The contingency plan included in
the submittal includes a triggering mechanism to determine when
contingency measures are needed and a process of developing and
implementing appropriate control measures. The State includes a
tertiary, a secondary, and a primary trigger to evaluate and implement
contingency measures. The tertiary trigger will not be an actual
violation of the 2008 8-hour ozone standard. This trigger will be a
first alert as to a potential air quality problem on the horizon. The
trigger will be activated when a monitor in the bi-state Charlotte Area
has a 4th highest value of 0.076 ppm or greater, starting the first
year after the maintenance plan has been approved. The trigger date
will be 60 days from the date on which an ozone monitor in the bi-state
Charlotte Area records a 4th highest value of 0.076 ppm or greater.
Once the tertiary trigger is activated, the Planning Section of NCDAQ,
in consultation with the South Carolina Department of Environmental
Services (SCDES) \29\ and MCAQ, shall commence analyses including
meteorological evaluation, trajectory analyses of high ozone days, and
emissions inventory assessment to understand why a 4th highest
exceedance of the standard has occurred. Once the analyses are
completed, NCDAQ will work with SCDES, MCAQ and the local air awareness
program to develop an outreach plan identifying any additional
voluntary measures that can be implemented. If the 4th highest
exceedance occurs early in the ozone season,\30\ the NCDAQ will work
with entities identified in the outreach plan to determine if the
measures can be implemented during the current season; otherwise, NCDAQ
will work with SCDES, MCAQ, and the local air awareness coordinator to
implement the plan for the following ozone season.
---------------------------------------------------------------------------
\29\ On July 1, 2024, SC DHEC was restructured into a health
agency, the Department of Public Health, and an environmental
agency, the Department of Environmental Services (DES). In a letter
dated June 20, 2024, South Carolina represented to the EPA that all
the functions, powers, and duties of the environmental divisions,
offices, and programs of DHEC, including the authority to administer
and enforce state implementation plans, are retained and continued
in full force and effect under DES.
\30\ The EPA mandates seasonal monitoring of ambient ozone
concentrations in North Carolina from March 1 through October 31 as
specified in 40 CFR Appendix-D-to-part-58(i) Table D-3.
---------------------------------------------------------------------------
The secondary trigger will then apply where no actual violation of
the 2008 8-hour ozone NAAQS has occurred, but where the State finds
monitored ozone levels indicating that an actual ozone NAAQS violation
may be imminent. North Carolina explains that a pattern will be deemed
to exist when there are two consecutive ozone seasons in which the 4th
highest values are 0.076 ppm or greater at a single monitor within the
Area. The trigger date will be 60 days from the date on which an ozone
monitor in the bi-state Charlotte Area records a 4th highest value of
0.076 ppm or greater for which the previous season had a 4th highest
value of 0.076 ppm or greater.
Finally, the primary trigger of the contingency plan will be a
violation of the 2008 8-hour ozone NAAQS or when the 3-year average of
the 4th highest values is equal to or greater than 0.076 ppm at a
monitor in the bi-state Charlotte Area. The trigger date will be 60
days from the date on which an ozone monitor in the bi-state Charlotte
Area records a 4th highest value that,
[[Page 60355]]
when averaged with the two previous ozone seasons' fourth highest
values, results in a 3-year average equal to or greater than 0.076 ppm.
Once the primary or secondary trigger is activated, which would
occur after the tertiary trigger, the Planning Section of NCDAQ, in
consultation with the SCDES and MCAQ, shall commence analyses including
trajectory analyses of high ozone days, and an emissions inventory
assessment to determine emission control measures that will be required
for maintaining the 2008 8-hour ozone standard. The analysis will
include an evaluation of any future Federal, State, and local measures
that will be implemented after the trigger is activated to determine
their effectiveness for bringing the area into attainment and assure
maintenance going forward. If deemed applicable, NCDAQ will submit to
the EPA an analysis supporting the conclusion that control measures
will be adequate to reduce ozone concentrations to attain and maintain
the 2008 8-hour ozone NAAQS. If additional State and local control
measures are determined to be necessary, NCDAQ will perform an analysis
to determine the most effective measure(s) to bring the area back into
attainment of and/or maintain compliance with the NAAQS. The analysis
of State and local control measures will focus on NO<INF>X</INF>
controls because North Carolina is NO<INF>X</INF> limited for ozone
formation.\31\
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\31\ See Section 1.1 of the February 28, 2025, submittal.
---------------------------------------------------------------------------
The measures that will be considered for adoption upon a primary or
secondary trigger of the contingency plan include:
<bullet> NO<INF>X</INF> Reasonably Available Control Technology
(RACT) on stationary sources with a potential to emit less than 100
tons per year in the Charlotte Area;
<bullet> Implementation of diesel retrofit programs, including
incentives for performing retrofits;
<bullet> Reinstatement of the emissions I/M program \32\ for on-
road light-duty gasoline vehicles in the counties subject to the
maintenance plan; and
---------------------------------------------------------------------------
\32\ On October 1, 2024, NCDAQ submitted a SIP revision to
remove its SIP-approved I/M program, covering 19 counties (including
all counties comprising the Charlotte Area). The revision also
removes I/M from three maintenance plans, including the Charlotte
Area Maintenance Plan for the 2008 8-Hour Ozone Maintenance Area.
This SIP revision has been submitted to the EPA for review and
approval. The EPA intends to finalize action on the second Charlotte
Area Maintenance Plan for the 2008 8-Hour Ozone Maintenance Area
when it finalizes action on the I/M SIP revision. The I/M program
did not apply to emissions estimates generated for the February 28,
2025, maintenance plan (see Table A-2 of the submittal).
---------------------------------------------------------------------------
<bullet> Additional controls in upwind areas.
By May 1 of the year following the ozone season in which the
primary or secondary trigger has been activated, North Carolina will
complete sufficient analyses to begin adoption of necessary rules for
ensuring attainment and maintenance of the 2008 8-hour ozone NAAQS.
These rules would become effective by the following March 1 (the
beginning of the ozone season) unless legislative review is required.
North Carolina commits to begin implementing as expeditiously as
practicable, but no later than 24 months after the primary or secondary
trigger, at least one control measure that is determined to be most
appropriate for reducing NO<INF>X</INF> emissions in order to attain
and maintain the NAAQS based on the analyses performed.
The EPA proposes to find that the contingency provisions in North
Carolina's second 10-year maintenance plan for the Charlotte Area for
the 2008 8-hour Ozone NAAQS meet the requirements of CAA section
175A(d).
V. The EPA's Analysis of North Carolina's Proposed NOX and VOC Sub-Area
Budgets for the Charlotte Area
Under CAA section 176(c), new transportation plans, programs, and
projects, such as the construction of new highways, must ``conform'' to
(i.e., be consistent with) the part of the state's air quality plan
that addresses pollution from cars and trucks. Conformity to the SIP
means that transportation activities will not cause or contribute to
new air quality violations, worsen existing violations, or delay timely
attainment of the NAAQS or any required interim milestones. If a
transportation plan does not conform, most new projects that would
expand the capacity of roadways cannot go forward because they would
not meet the requirements of CAA section 176(c). Regulations at 40 CFR
part 93 set forth the EPA policy, criteria, and procedures for
demonstrating and assuring conformity of such transportation activities
to a SIP. The regional emissions analysis is one, but not the only,
requirement for implementing transportation conformity. Transportation
conformity is a requirement for nonattainment and maintenance areas.
Under Title I of the CAA, states are required to submit, at various
times, control strategy SIPs and maintenance plans for nonattainment
areas and redesignated attainment areas. These control strategy SIPs
(including reasonable further progress (RFP) and attainment
demonstration requirements) and maintenance plans create budgets \33\
(or in this case, sub-area budgets) for criteria pollutants and/or
their precursors to address pollution from cars and trucks. The budgets
serve as a ceiling on emissions from an area's planned transportation
system. The budget concept is further explained in the preamble to the
November 24, 1993, Transportation Conformity Rule.\34\ The preamble
also describes how to establish the budgets in the SIP and how to
revise the budgets.
---------------------------------------------------------------------------
\33\ As defined in 40 CFR 93.101, a ``motor vehicle emissions
budget'' is that portion of the total allowable emissions allocated
to highway and transit vehicle use and emissions as defined in the
submitted or approved control strategy implementation plan revision
or maintenance plan for a certain date for the purpose of meeting
reasonable further progress milestones or demonstrating attainment
or maintenance of the NAAQS.
\34\ See 58 FR 62188.
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As part of the interagency consultation process on setting sub-area
budgets,\35\ NCDAQ held three conference calls with the Charlotte
Regional Transportation Planning Organization (CRTPO)-Rocky River Rural
Planning Organization (RRRPO), Gaston-Cleveland-Lincoln Metropolitan
Planning Organization (GCLMPO), and Cabarrus Rowan Metropolitan
Planning Organization (CRMPO) to determine what years to set sub-area
budgets for the second Charlotte Area maintenance plan. According to
the transportation conformity rule, a maintenance plan must establish
budgets for the last year of the maintenance plan (in this case, 2035).
The state may set a budget for an interim year (in this case, 2026),
but it is not a requirement.\36\ In the February 28, 2025, submittal,
North Carolina requests that the EPA replace the 2014 and 2026
NO<INF>X</INF> and VOC sub-area budgets associated with the first 10-
year maintenance plan with the 2018 and 2035 sub-area budgets. After
the EPA finds the 2018 and 2035 sub-area budgets adequate or approves
them, whichever is completed first, they must be used for future
conformity determinations. The previous 2014 and 2026 sub-area budgets
will no longer apply for transportation conformity purposes. Tables 6
through 8 below provide the NO<INF>X</INF> and VOC sub-area
[[Page 60356]]
budgets \37\ in kilograms per day (kg/day),\38\ for 2018 and 2035.
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\35\ See 40 CFR 93.105.
\36\ See 40 CFR 93.118(d)(2).
\37\ The values presented in Tables 6, 7, and 8 are accurate as
presented. However, the rounding of the variables used in the final
calculations may lead to minor discrepancies when reproducing these
results. These rounding differences do not compromise the integrity
of the data presented.
\38\ The conversion factor used is 907.1847 kg = 1 US Ton.
Table 6--CRMPO Sub-Area Budgets
[Kg/day]
----------------------------------------------------------------------------------------------------------------
2018 2035
---------------------------------------------------------------
NOX VOC NOX VOC
----------------------------------------------------------------------------------------------------------------
Base Emissions.................................. 9,608 5,456 1,919 2,576
Safety Margin Allocated to Budget............... N/A N/A 3,693 815
Conformity Budget............................... 9,608 5,456 5,612 3,391
----------------------------------------------------------------------------------------------------------------
Table 7--GCLMPO Sub-Area Budgets
[Kg/day]
----------------------------------------------------------------------------------------------------------------
2018 2035
---------------------------------------------------------------
NOX VOC NOX VOC
----------------------------------------------------------------------------------------------------------------
Base Emissions.................................. 8,391 4,667 1,375 1,824
Safety Margin Allocated to Budget............... N/A N/A 2,593 483
Conformity Budget............................... 8,391 4,667 3,968 2,307
----------------------------------------------------------------------------------------------------------------
Table 8--CRTPO-RRRPO Sub-Area Budgets
[Kg/day]
----------------------------------------------------------------------------------------------------------------
2018 2035
---------------------------------------------------------------
NOX VOC NOX VOC
----------------------------------------------------------------------------------------------------------------
Base Emissions.................................. 33,767 16,762 8,905 10,003
Safety Margin Allocated to Budget............... N/A N/A 16,416 2,367
Conformity Budget............................... 33,767 16,762 25,321 12,370
----------------------------------------------------------------------------------------------------------------
Because the initial budget year of 2018 is also the base year for
the maintenance plan inventory, there is no safety margin, therefore,
no adjustments were made to the budgets for 2018. As shown in Tables 6
through 8, above, North Carolina has chosen to allocate a portion of
the available safety margin to the NO<INF>X</INF> and VOC sub-area
budgets for 2035.
Through this rulemaking, the EPA is proposing to approve the 2018
and 2035 sub-area NO<INF>X</INF> and VOC budgets for the Charlotte Area
because the Agency believes that the Charlotte Area will maintain the
2008 8-hour ozone NAAQS with the emissions at the levels of the sub-
area budgets. The EPA is also proposing to replace the previous 2014
and 2026 NO<INF>X</INF> and VOC sub-area budgets from the first 10-year
maintenance plan. If the EPA finalizes that replacement, the 2014 and
2026 budgets will no longer apply for transportation conformity
purposes. The EPA intends to make its determination on the adequacy of
the 2018 and 2035 sub-area budgets for the Charlotte Area for
transportation conformity purposes in the near future by completing the
adequacy process that was started on February 28, 2025. If the EPA
finds the 2018 and 2035 sub-area budgets adequate or approves them,
whichever is completed first, they must be used for future conformity
determinations. The EPA is proposing to approve the budgets because
they are consistent with maintenance of the 2008 8-hour ozone NAAQS
through 2035.
VI. The EPA's Adequacy Determination for the Proposed NOX and VOC Sub-
Area Budgets
When reviewing submitted ``control strategy'' SIPs or maintenance
plans containing sub-area budgets, the EPA may affirmatively find the
budgets contained therein adequate for use in determining
transportation conformity. Once the EPA affirmatively finds the
submitted budgets adequate for transportation conformity purposes,
those budgets must be used by state and Federal agencies in determining
whether proposed transportation projects conform to the SIP as required
by CAA section 176(c).
The EPA's substantive criteria for determining adequacy of budgets
are set out in 40 CFR 93.118(e)(4). The process for determining
adequacy consists of three basic steps: Public notification of a SIP
submission, a public comment period, and the EPA's adequacy
determination. This process for determining the adequacy of submitted
budgets for transportation conformity purposes was initially outlined
in the EPA's May 14, 1999, guidance, ``Conformity Guidance on
Implementation of March 2, 1999, Conformity Court Decision.'' \39\ The
EPA adopted regulations to codify the adequacy process in the
Transportation Conformity Rule Amendments for the ``New 8-Hour Ozone
and PM<INF>2.5</INF> National Ambient Air Quality Standards and
Miscellaneous Revisions for Existing Areas; Transportation Conformity
Rule Amendments--Response to Court Decision and Additional Rule
Change.'' \40\ Additional information on the adequacy process for
transportation
[[Page 60357]]
conformity purposes is available in the proposed rule entitled,
``Transportation Conformity Rule Amendments: Response to Court Decision
and Additional Rule Changes.'' \41\
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\39\ The May 14, 1999, guidance is available via <a href="https://nepis.epa.gov/Exe/ZyPDF.cgi/P100B3HG.PDF?Dockey=P100B3HG.PDF">https://nepis.epa.gov/Exe/ZyPDF.cgi/P100B3HG.PDF?Dockey=P100B3HG.PDF</a>.
\40\ See 69 FR 40004 (July 1, 2004).
\41\ See 68 FR 38974, 38984 (June 30, 2003).
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As discussed earlier, North Carolina's second 10-year maintenance
plan includes NO<INF>X</INF> and VOC sub-area budgets for the Charlotte
Area for 2018, an interim year of the maintenance plan (2026), and the
last year of the maintenance plan (2035). The EPA is reviewing the
NO<INF>X</INF> and VOC sub-area budgets through the adequacy process.
The Charlotte Area NO<INF>X</INF> and VOC sub-area budgets were opened
for public comment on the EPA's adequacy website on May 2, 2025, found
at: <a href="https://www.epa.gov/state-and-local-transportation/adequacy-review-state-implementation-plan-sip-submissions-conformity">https://www.epa.gov/state-and-local-transportation/adequacy-review-state-implementation-plan-sip-submissions-conformity</a>. The EPA public
comment period on adequacy for the sub-area budgets for 2018 and 2035
for the Charlotte Area closed on June 2, 2025. No comments, adverse or
otherwise, were received during that public comment period.
The EPA intends to make its determination on the adequacy of the
2018 and 2035 sub-area budgets for the Charlotte Area for
transportation conformity purposes in the near future by completing the
adequacy process that was started on May 2, 2025. If the EPA finds the
2018 and 2035 sub-area budgets adequate or approves them, the new sub-
area budgets for NO<INF>X</INF> and VOC must be used for future
transportation conformity determinations. For required regional
emissions analysis that involves years 2018 through 2034, the
applicable 2018 sub-area budgets will be used. For regional emissions
analysis years 2035 and beyond, the 2035 sub-area budgets will be used,
as defined in section V of this notice of proposed rulemaking.
VII. Effect of the EPA's Proposed Action
The EPA's proposed action establishes the basis upon which the EPA
may take final action on the issues being proposed for approval.
Approval of North Carolina's SIP revisions would incorporate a plan for
maintaining the 2008 8-hour ozone NAAQS in the Charlotte Area through
2035 into the SIP. This second 10-year maintenance plan includes
contingency measures to remedy any future violations of the 2008 8-hour
ozone NAAQS and procedures for evaluation of potential violations. The
second 10-year maintenance plan also removes the budgets for 2014 and
2026, associated with the first 10-year maintenance plan, and
establishes new NO<INF>X</INF> and VOC budgets for 2018 and 2035 for
the Charlotte Area. The budgets are listed in Tables 6 through 8 in
section V of this notice. Additionally, the EPA is notifying the public
of the status of Agency's adequacy determination for the newly
established Charlotte Area NO<INF>X</INF> and VOC sub-area budgets for
2018 and 2035.
VIII. Proposed Action
The EPA is proposing to approve the second 10-year maintenance plan
for the 2008 8-hour ozone NAAQS for the Charlotte Area, including the
NO<INF>X</INF> and VOC sub-area budgets for 2018 and 2035 (to replace
the previous NO<INF>X</INF> and VOC sub-area budgets for 2014 and 2026
from the first 10-year maintenance plan), into the North Carolina SIP
under CAA section 175A. The second 10-year maintenance plan meets all
applicable requirements for maintenance plans and related contingency
provisions in CAA section 175A, including a demonstration that the
Charlotte Area will continue to maintain the 2008 8-hour ozone NAAQS
until August 27, 2035, the end of the 20-year maintenance period.
Further, as part of this proposed action, the EPA is describing the
status of its adequacy determination for the NO<INF>X</INF> and VOC
sub-area budgets for 2018 and 2035 in accordance with 40 CFR
93.118(f)(1). Within 24 months from the publication date of the EPA's
final rule for this action (if the EPA approves this maintenance plan
and the underlying budgets), or the effective date of the EPA's
adequacy determination for the budgets, whichever is earlier, the
transportation partners \42\ will need to demonstrate conformity to the
new NO<INF>X</INF> and VOC sub-area budgets pursuant to 40 CFR
93.104(e)(3).
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\42\ The transportation partners for the Charlotte area include
U.S. Department of Transportation (Federal Highway Administration--
North Carolina and the Federal Transit Administration Region 4's
office), the North Carolina Department of Transportation, CRTPO,
RRRPO, GCLMPO, and CRMPO.
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IX. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the CAA and applicable
Federal regulations.\43\ Thus, in reviewing SIP submissions, the EPA's
role is to approve state choices, provided that they meet the criteria
of the CAA. Accordingly, this proposed action merely proposes to
approve state law as meeting Federal requirements and does not impose
additional requirements beyond those imposed by state law. For that
reason, this proposed action:
---------------------------------------------------------------------------
\43\ See 42 U.S.C. 7410(k); 40 CFR 52.02(a).
---------------------------------------------------------------------------
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Order 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not an Executive Order 14192 (90 FR 9065, February 6,
2025) regulatory action because this action is not significant under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a state program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the CAA.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where EPA or an Indian Tribe has
demonstrated that a Tribe has jurisdiction. In those areas of Indian
country, the rule does not have Tribal implications and will not impose
substantial direct costs on Tribal governments or preempt Tribal law as
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Carbon monoxide,
Incorporation by reference, Intergovernmental relations, Lead, Nitrogen
dioxide, Ozone, Particulate matter, Reporting and recordkeeping
requirements, Sulfur oxides, Volatile organic compounds.
(Authority: 42 U.S.C. 7401 et seq.)
[[Page 60358]]
Dated: September 17, 2026.
Kevin McOmber,
Regional Administrator, Region 4.
[FR Doc. 2026-19495 Filed 9-22-26; 8:45 am]
BILLING CODE 6560-50-P
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This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.