Rule2026-06396
Air Plan Approval; Michigan; Detroit 2010 Sulfur Dioxide Redesignation and Maintenance Plan
Primary source
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Published
April 2, 2026
Effective
April 2, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is finding that the Detroit, Michigan area is attaining the 2010 sulfur dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS) and is acting in accordance with a request from the Michigan Department of Environment, Great Lakes, and Energy (EGLE) to redesignate the area to attainment for the 2010 SO<INF>2</INF> NAAQS, because the request meets the statutory requirements for redesignation under the Clean Air Act (CAA). The EPA is also approving Michigan's maintenance plan for the Detroit area. Michigan submitted the request for approval of the Detroit nonattainment area's redesignation and maintenance plan on May 5, 2025. The EPA approved Michigan's attainment plan for the Detroit area on May 19, 2025.
Full Text
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<title>Federal Register, Volume 91 Issue 63 (Thursday, April 2, 2026)</title>
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[Federal Register Volume 91, Number 63 (Thursday, April 2, 2026)]
[Rules and Regulations]
[Pages 16562-16566]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-06396]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 52 and 81
[EPA-R05-OAR-2025-0238; FRL-12841-02-R5]
Air Plan Approval; Michigan; Detroit 2010 Sulfur Dioxide
Redesignation and Maintenance Plan
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is finding that the
Detroit, Michigan area is attaining the 2010 sulfur dioxide
(SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS) and is
acting in accordance with a request from the Michigan Department of
Environment, Great Lakes, and Energy (EGLE) to redesignate the area to
attainment for the 2010 SO<INF>2</INF> NAAQS, because the request meets
the statutory requirements for redesignation under the Clean Air Act
(CAA). The EPA is also approving Michigan's maintenance plan for the
Detroit area. Michigan submitted the request for approval of the
Detroit nonattainment area's redesignation and maintenance plan on May
5, 2025. The EPA approved Michigan's attainment plan for the Detroit
area on May 19, 2025.
DATES: This final rule is effective on April 2, 2026.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-R05-OAR-2025-0238. All documents in the docket are
listed on the <a href="https://www.regulations.gov">https://www.regulations.gov</a> website. Although listed in
the index, some information is not publicly available, i.e.,
Confidential Business Information (CBI), Proprietary Business
Information (PBI), or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the internet and will be publicly available only in hard
copy form. Publicly available docket materials are available either
through <a href="https://www.regulations.gov">https://www.regulations.gov</a> or please contact the person
identified in the FOR FURTHER INFORMATION CONTACT section for
additional information.
FOR FURTHER INFORMATION CONTACT: Alexis Bender, Air and Radiation
Division (AR-18J), Environmental Protection Agency, Region 5, 77 West
Jackson Boulevard, Chicago, Illinois 60604, telephone number: (312)
886-9497, email address: <a href="/cdn-cgi/l/email-protection#7a181f141e1f08541b161f0213093a1f0a1b541d150c"><span class="__cf_email__" data-cfemail="4022252e2425326e212c25382933002530216e272f36">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean the EPA.
I. Background Information
On August 5, 2013 (78 FR 47191), the EPA designated the Detroit
area, a portion of Wayne County, Michigan, as nonattainment for the
2010 SO<INF>2</INF> NAAQS. On May 19, 2025 (90 FR 21228), the EPA
approved Michigan's plan for attaining the 2010 SO<INF>2</INF> NAAQS
for the Detroit area and for meeting other nonattainment area planning
requirements of CAA sections 110, 172, 179 and 192. On August 14, 2025
(90 FR 39148), the EPA proposed to approve Michigan's redesignation
request and maintenance plan for the Detroit nonattainment area for the
2010 SO<INF>2</INF> NAAQS.
II. Response to Comments
Upon publication of the August 14, 2025 (90 FR 39148), proposed
rulemaking, the EPA opened a 30-day comment period, ending September
15, 2025. The EPA received one adverse comment, which is summarized
below along with the EPA's response. The comment is included in the
docket for this action.
Comment: The commenter suggests that there is insufficient evidence
to demonstrate attainment in the Detroit area. Wayne County, in
partnership with JustAir, has placed 100 air sensors in the county that
have shown an average SO<INF>2</INF> level of 14.5 parts per billion
(ppb) from May 1, 2024, when they began operation, to June 30, 2025.
The commenter argues that the JustAir monitoring network demonstrates a
[[Page 16563]]
more granular measure of air quality than the five regulatory
SO<INF>2</INF> monitors that Michigan EGLE operates in the Detroit
area. While the commenter concedes that preliminary data from the
JustAir sensors shows SO<INF>2</INF> levels below the primary
SO<INF>2</INF> standard, the commenter suggests that the JustAir
sensors have captured values that could indicate an exceedance of the
recently revised secondary SO<INF>2</INF> standard. Additionally, the
commenter states that the attainment demonstration relies on modeling
using maximum allowable emissions but does not provide robust evidence
that the applicable facilities are complying with the emission limits
and associated requirements included in the plan.
Response: The reference to the secondary SO<INF>2</INF> standard is
outside of the scope of this action, as this action is only addressing
the primary standard for SO<INF>2.</INF> For monitoring compliance with
the NAAQS, the EPA utilizes an appendix of the CAA to address the
requirements for monitoring quality assurance. The appendix, 40 CFR
part 58 appendix A, specifies the minimum quality system requirements
applicable to State and Local Monitoring Stations and other monitor
types used to determine compliance with the NAAQS. The appendix
addresses quality system requirements, measurement quality check
requirements, calculations for data quality assessments, and reporting
requirements. Therefore, the JustAir monitoring program, which does not
follow this appendix, is not a reliable source of data for comparison
to the NAAQS.
With regard to modeling using maximum allowable emissions, the
EPA's April 23, 2014, ``Guidance for 1-Hour SO<INF>2</INF>
Nonattainment Area SIP Submissions'' states that the EPA may make
determinations of attainment based on the modeling, using allowable
emissions, from the attainment demonstrations for the applicable SIP
for the affected area. For a short-term (i.e., 1-hour) standard, the
EPA believes that dispersion modeling, using allowable emissions and
addressing stationary sources in the affected area (and in some cases
those sources located outside the nonattainment area which may affect
attainment in the area) is technically appropriate, efficient and
effective in demonstrating attainment in nonattainment areas because it
takes into consideration combinations of meteorological and emission
source operating conditions that may contribute to peak ground-level
concentrations of SO<INF>2.</INF> In reality, it is extremely unlikely
that all sources would be operating at maximum emission rates
simultaneously. The Detroit area met all compliance dates in Michigan's
plan, and Michigan included compliance documentation as appendix D of
its May 5, 2025, redesignation request, which is included in the docket
for this action. Additionally, Michigan has shown that it maintains an
active enforcement program to ensure ongoing compliance with the
requirements included in the Detroit attainment plan.
Comment: The commenter raises concern that the primary 1-hour
SO<INF>2</INF> NAAQS was set to protect against short-term
SO<INF>2</INF> exposure and does not reflect long-term exposure risks.
The commenter states that Wayne County residents have experienced
health impacts from long-term, low-level exposure to SO<INF>2,</INF>
which the primary 1-hour standard does not address.
Response: Under section 109 of the CAA, the EPA sets primary, or
health-based, NAAQS for all criteria pollutants to provide requisite
protection of public health, including the health of at-risk
populations, with an adequate margin of safety. In the EPA's June 22,
2010 (75 FR 35520), rulemaking strengthening the SO<INF>2</INF> NAAQS
to the level of 75 ppb, the EPA provided a detailed rationale for the
Administrator's determination that the 2010 SO<INF>2</INF> NAAQS would
be protective of public health. This rationale included explicit
consideration of protection for people, including children, with
asthma. Specifically, the standard was based on direct evidence of
SO<INF>2</INF>-related effects in controlled human exposure studies of
exercising individuals with asthma, as well as epidemiologic evidence
of associations between SO<INF>2</INF> concentrations in ambient air
and respiratory-related emergency department visits and
hospitalizations. This action does not address the primary
SO<INF>2</INF> NAAQS itself but rather recognizes that the Detroit area
has achieved the primary SO<INF>2</INF> NAAQS.
Comment: The commenter raises concerns over the potential for
increased pollution from facilities within the Detroit area, citing
that redesignating the area to attainment risks signaling that efforts
to reduce emissions are no longer a priority. The commenter states that
the decreased SO<INF>2</INF> levels in the Detroit area suggest that
the current nonattainment status of the area has successfully led to
lower pollution in the area and removing the enhanced scrutiny and
enforcement measures that come with nonattainment status may lead to
increased emissions. Additionally, the commenter contends that the
measures put forth by Michigan within the maintenance plan for the area
are reactive rather than preventative, as contingency measures would be
triggered only after exceedances occur. Therefore, the commenter
suggests that the maintenance plan should contain proactive measures
that would be triggered at the first signs of SO<INF>2</INF> increases.
Response: A redesignation to attainment does not remove any
emission control measures for existing sources that are already adopted
into the EPA approved SIP for Michigan. As discussed in the proposal
for this action, Michigan's redesignation request includes a
demonstration that attainment of the SO<INF>2</INF> NAAQS was
attributable to permanent and enforceable emissions reductions.
Further, Michigan's redesignation request includes a plan to maintain
the SO<INF>2</INF> NAAQS, which includes an attainment emission
inventory, a maintenance demonstration, a commitment for continued air
quality monitoring, a process for verification of continued attainment,
and a contingency plan, which all will support measures to ensure the
Detroit area remains in attainment and does not violate the
SO<INF>2</INF> NAAQS in the future.
In the ``General Preamble for the Implementation of Title I of the
Clean Air Act Amendments of 1990,'' published on April 16, 1992 (57 FR
13498), the EPA provides discussion of contingency measures
specifically for SO<INF>2</INF>. This guidance states that in many
cases, attainment revolves around compliance of a single source or a
small set of sources with emission limits shown to provide for
attainment. Although this guidance applies to contingency measures
under section 172(c)(9), the EPA applies a similar policy with respect
to contingency measures for SO<INF>2</INF> required in maintenance
plans under section 175A(d). The requirement to submit contingency
measures in accordance with section 175A of the CAA can be adequately
addressed for SO<INF>2</INF> by the operation of a comprehensive
enforcement program, which can quickly identify and address sources
that might be causing exceedances of the NAAQS.
As discussed in the proposal, Michigan has demonstrated that it
maintains a comprehensive and active enforcement program capable of
prompt action to remedy compliance issues. Beyond this, as part of its
contingency plan, Michigan commits to adopt and expeditiously implement
necessary corrective actions in the event of a violation of the
standard, or if an annual 99th percentile daily maximum 1-hour
SO<INF>2</INF> concentration of 79 ppb or above
[[Page 16564]]
occurs in a single calendar year in the Detroit area.
Comment: The commenter states that the attainment framework does
not adequately capture the cumulative impacts of long-term exposure to
pollution. The commenter states that residents living in the Detroit
area are disproportionately exposed to environmental hazards, including
SO<INF>2</INF> and other pollutants. The commenter also notes that
SO<INF>2</INF> can react in the atmosphere to form particulate matter
and argues that elevated levels of SO<INF>2</INF> could lead to health
effects from both exposure to SO<INF>2</INF> and particulate matter.
Response: The EPA is committed to protecting human health. For all
criteria pollutants, the EPA ensures that the NAAQS are set to provide
an adequate margin of safety for both the general population and
susceptible populations that are potentially at increased risk for
health effects in response to exposure to ambient air pollution.
When considering the primary SO<INF>2</INF> NAAQS, the EPA took
into account the Integrated Science Assessment (ISA) of scientific
information on known and potential human health effects associated with
exposure to SO<INF>2</INF> in the air via the (1) Assessments in the
Risk and Exposure Assessment (REA) of the most policy-relevant
information in the ISA as well as quantitative exposure and risk
analyses based on that information; (2) Clean Air Scientific Advisory
Committee (CASAC) Panel advice and recommendations, as reflected in its
letters to the Administrator and its public discussions of the ISA and
REA; (3) public comments received during the development of the ISA and
REA; and (4) public comments received on the EPA's notice of proposed
rulemaking. Additionally, the EPA referred to the ISA regarding health
effects and long-term exposures to SO<INF>2</INF> which addressed and
concluded the long-term health evidence to be of insufficient quantity,
quality, consistency, or statistical power to make a determination as
to whether SO<INF>2</INF> was truly associated with these health
outcomes. Therefore, when strengthening the SO<INF>2</INF> standard,
the EPA drew upon an entire body of evidence on human health effects
associated with the presence of SO<INF>2</INF> in the ambient air, and
upon the results of the quantitative exposure and risk assessments
reflecting this evidence.
In this action, the EPA is recognizing that the Detroit area has
achieved the primary SO<INF>2</INF> NAAQS and is approving Michigan's
maintenance plan for the area. While the EPA appreciates the
commenter's concerns regarding other pollutants in the Detroit area,
the EPA is not evaluating the air quality in the Detroit area with
respect to other NAAQS in this action.
III. What action is the EPA taking?
The EPA is redesignating the Detroit area from nonattainment to
attainment for the 2010 SO<INF>2</INF> NAAQS in accordance with
Michigan's May 5, 2025, request. The EPA has determined that the area
is attaining the 2010 SO<INF>2</INF> NAAQS and that the improvement in
air quality is due to permanent and enforceable SO<INF>2</INF> emission
reductions in the area. The EPA is also approving Michigan's
maintenance plan, which is designed to ensure that the area will
continue to maintain the 2010 SO<INF>2</INF> NAAQS.
In accordance with 5 U.S.C. 553(d) of the Administrative Procedure
Act (APA), this action shall become effective immediately upon
publication. The immediate effective date for this action is authorized
under 5 U.S.C. 553(d)(1).
Section 553(d)(1) of the APA provides that final rules shall not
become effective until 30 days after publication in the Federal
Register ``except . . . a substantive rule which grants or recognizes
an exemption or relieves a restriction.'' The purpose of this provision
is to ``give affected parties a reasonable time to adjust their
behavior before the final rule takes effect.'' Omnipoint Corp. v. Fed.
Commc'n Comm'n, 78 F.3d 620, 630 (D.C. Cir. 1996); see also United
States v. Gavrilovic, 551 F.2d 1099, 1104 (8th Cir. 1977) (quoting
legislative history). However, when the agency grants or recognizes an
exemption or relieves a restriction, affected parties do not need a
reasonable time to adjust because the effect is not adverse. The EPA
has determined that this rule relieves a restriction because this rule
relieves sources in the area of Nonattainment New Source Review
permitting requirements; instead, upon the effective date of this
action, sources will be subject to less restrictive Prevention of
Significant Deterioration permitting requirements. For this reason, the
EPA finds that under 5 U.S.C. 553(d)(1) it is appropriate for this
action to become effective on the date of publication of this action.
IV. Statutory and Executive Order Reviews
Under the CAA, redesignation of an area to attainment and the
accompanying approval of a maintenance plan under section 107(d)(3)(E)
are actions that affect the status of a geographical area and do not
impose any additional regulatory requirements on sources beyond those
imposed by state law. A redesignation to attainment does not in and of
itself create any new requirements, but rather results in the
applicability of requirements contained in the CAA for areas that have
been redesignated to attainment. Moreover, the Administrator is
required to approve a SIP submission that complies with the provisions
of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40
CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to
approve State choices, provided that they meet the criteria of the CAA.
Accordingly, this action merely approves State law as meeting Federal
requirements and does not impose additional requirements beyond those
imposed by State law. For that reason, this action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Order 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it 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 the EPA or an Indian Tribe
has demonstrated that a Tribe has jurisdiction. In those areas of
Indian country, the rule does not have Tribal implications and will not
impose substantial direct costs on Tribal governments or preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
[[Page 16565]]
This action is subject to the Congressional Review Act, and the EPA
will submit a rule report to each House of the Congress and to the
Comptroller General of the United States. This action is not a ``major
rule'' as defined by 5 U.S.C. 804(2).
Under section 307(b)(1) of the CAA, petitions for judicial review
of this action must be filed in the United States Court of Appeals for
the appropriate circuit by June 1, 2026. Filing a petition for
reconsideration by the Administrator of this final rule does not affect
the finality of this action for the purposes of judicial review nor
does it extend the time within which a petition for judicial review may
be filed, and shall not postpone the effectiveness of such rule or
action. This action may not be challenged later in proceedings to
enforce its requirements. (See section 307(b)(2).)
List of Subjects
40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Reporting and recordkeeping
requirements, Sulfur oxides.
40 CFR Part 81
Environmental protection, Air pollution control, National parks,
Wilderness areas.
Dated: March 26, 2026.
Anne Vogel,
Regional Administrator, Region 5.
For the reasons stated in the preamble, title 40 CFR parts 52 and
81 are amended as follows:
PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS
0
1. The authority citation for part 52 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
0
2. In Sec. 52.1170, the table in paragraph (e) is amended under
``Maintenance Plans'' by adding an entry for ``2010 SO<INF>2</INF>''
after the entry for ``2008 lead (Pb)'' to read as follows:
Sec. 52.1170 Identification of plan.
* * * * *
(e) * * *
EPA-Approved Michigan Nonregulatory and Quasi-Regulatory Provisions
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Name of nonregulatory SIP Applicable geographic or State
provision nonattainment area submittal date EPA approval date Comments
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* * * * * * *
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Maintenance Plans
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* * * * * * *
2010 SO2...................... Detroit area (Wayne 5/5/2025 4/2/2026, 91 FR [INSERT
County, part). FEDERAL REGISTER PAGE
WHERE THE DOCUMENT
BEGINS].
* * * * * * *
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PART 81--DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES
0
3. The authority citation for part 81 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
0
4. In Sec. 81.323, the table entitled ``Michigan-2010 Sulfur Dioxide
NAAQS [Primary]'' is amended by revising the entry for ``Detroit, MI''
to read as follows:
Sec. 81.323 Michigan.
* * * * *
Michigan--2010 Sulfur Dioxide NAAQS
[Primary]
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Designation
Designated area \1\ ---------------------------------------------------
Date \2\ Type
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Detroit, MI................................................. 4/2/2026 Attainment.
Wayne County (part)
The area bounded on the east by the Michigan-Ontario
border, on the south by the Wayne County-Monroe
County border, on the west by Interstate 75 north
to Southfield Road, Southfield Road to Interstate
94, and Interstate 94 north to Michigan Avenue, and
on the north by Michigan Avenue to Woodward Avenue
and a line on Woodward Avenue extended to the
Michigan-Ontario border.
* * * * * * *
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\1\ Includes any Indian country in each county or area, unless otherwise specified. EPA is not determining the
boundaries of any area of Indian country in this table, including any area of Indian country located in the
larger designation area. The inclusion of any Indian country in the designation area is not a determination
that the state has regulatory authority under the Clean Air Act for such Indian country.
\2\ This date is April 9, 2018, unless otherwise noted.
[[Page 16566]]
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[FR Doc. 2026-06396 Filed 4-1-26; 8:45 am]
BILLING CODE 6560-50-P
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