Rule2025-20150
Air Plan Approval; Michigan; Revisions to Part 1 and 2 Rules
Primary source
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Published
November 18, 2025
Effective
December 18, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is approving revisions to the Michigan State Implementation Plan (SIP) that Michigan's Department of Environment, Great Lakes, and Energy (EGLE) submitted on March 8, 2022. These revisions amend Michigan's SIP- approved rules for minor New Source Review (NSR) found in Michigan Air Pollution Control Rules Part 2, Air Use Approval. This action updates Michigan's minor NSR rules in the SIP to exempt certain processes and equipment from the requirement to obtain a preconstruction permit.
Full Text
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<title>Federal Register, Volume 90 Issue 220 (Tuesday, November 18, 2025)</title>
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[Federal Register Volume 90, Number 220 (Tuesday, November 18, 2025)]
[Rules and Regulations]
[Pages 51518-51525]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-20150]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R05-OAR-2022-0295; FRL-10162-05-R5]
Air Plan Approval; Michigan; Revisions to Part 1 and 2 Rules
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is approving
revisions to the Michigan State Implementation Plan (SIP) that
Michigan's Department of Environment, Great Lakes, and Energy (EGLE)
submitted on March 8, 2022. These revisions amend Michigan's SIP-
approved rules for minor New Source Review (NSR) found in Michigan Air
Pollution Control Rules Part 2, Air Use Approval. This action updates
Michigan's minor NSR rules in the SIP to exempt certain processes and
equipment from the requirement to obtain a preconstruction permit.
DATES: This final rule is effective on December 18, 2025.
ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-R05-OAR-2022-0295. 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 at the Environmental Protection Agency, Region
5, Air and Radiation Division, 77 West Jackson Boulevard, Chicago,
Illinois 60604. This facility is open from 8:30 a.m. to 4:30 p.m.,
Monday through Friday, excluding Federal holidays. We recommend that
you telephone David Ogulei, Environmental Engineer, at (312) 353-0987
before visiting the Region 5 office.
FOR FURTHER INFORMATION CONTACT: David Ogulei, Air and Radiation
Division (AR-18J), Environmental Protection Agency, Region 5, 77 West
Jackson Boulevard, Chicago, Illinois 60604, (312) 353-0987,
<a href="/cdn-cgi/l/email-protection#337c54465f565a1d5752455a57735643521d545c45"><span class="__cf_email__" data-cfemail="571830223b323e793336213e331732273679303821">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean EPA. This supplementary information
section is arranged as follows:
I. Background
II. Summary of EPA Analysis
III. EPA's Response to Comments
IV. What action is EPA taking?
V. Incorporation by Reference.
VI. Statutory and Executive Order Reviews
I. Background
Section 110(a)(2)(C) of the Clean Air Act (CAA or Act) requires
that the SIP include a program to provide for the regulation of the
modification and construction of any stationary source within the areas
covered by the plan as necessary to ensure that National Ambient Air
Quality Standards (NAAQS) are achieved. This includes a program for
permitting construction and modification of both major sources and
minor sources that the State deems necessary to protect air quality.
Specific elements for an approvable construction permitting plan are
found in the implementing regulations at 40 CFR 51 subpart I--Review of
New Sources and Modifications. Requirements relevant to minor
construction programs are 40 CFR 51.160-51.164. Generally, State minor
NSR programs must set forth legally enforceable procedures that allow
the State to determine if a planned construction activity would result
in a violation of the State's SIP or a national standard and prevent
any activity that would do so. In accordance with 40 CFR 51.162, the
State plan must identify the responsible agency for making permitting
decisions. Under 40 CFR 51.160, the plan must identify the types and
sizes of activities that are subject to the plan, including a
discussion of the basis for determining which facilities will be
subject to review, provide that sources undertaking an activity submit
adequate information regarding the location, design, and emissions
related information, and discuss the air quality data and dispersion or
other air quality modeling used to determine whether the activity would
comply with the CAA. Restrictions on allowable stack heights are found
in 40 CFR 51.164. Under 40 CFR 51.161, the plan must meet specific
criteria for public availability of information and opportunity for
public comment. Finally, 40 CFR 51.163 requires that the plan identify
the administrative procedures that will be followed in making
permitting decisions.
Michigan's minor source preconstruction permitting rules are
contained in Part 2 of the Michigan Administrative Code, which EPA last
approved into the Michigan SIP on April 27, 2023 (88 FR 25498). See 40
CFR 52.1170. Michigan's SIP generally requires a permit to install
(PTI) for any change resulting in an increase in the emissions of a
regulated pollutant unless the change falls into one or more of the
categories of exemptions contained in Michigan R 336.1280 through
Michigan R 336.1290.
On September 27, 2022 (87 FR 58471), EPA proposed to approve (via a
direct final rulemaking) revisions to the Michigan SIP that EGLE
submitted on March 8, 2022. During the public comment period, EPA
received adverse comments on the proposed approval of revisions to
Michigan R 336.1285 ``Permit to install exemptions; miscellaneous'' and
R 336.1291 ``Permit to install exemptions; emission units with ``de
minimis'' emissions.'' These rules exempt certain processes and
equipment from Michigan's minor NSR permitting program. On November 15,
2022 (87 FR 68364), EPA published an action withdrawing the direct
final rule. On April 27, 2023 (88 FR 25498), EPA approved the revisions
to Michigan's Air Pollution Control Rules Part 1, Definitions, and Part
2, Air Use Approval, for inclusion in the Michigan SIP but deferred
action on the Michigan Part 2 rule revisions to R 336.1285 and R
336.1291.
On November 14, 2023, in response to comments we received on the
2022 direct final rule, Michigan supplemented its March 8, 2022,
submittal with additional information regarding Michigan R
336.1285(2)(oo) and R 336.1291. On April 25, 2024 (89 FR 31677), EPA
proposed approval of the Michigan Part 2 rule revisions to Michigan R
336.1285 ``Permit to install exemptions; miscellaneous'' and R 336.1291
``Permit to install exemptions; emission units with ``de minimis''
emissions.''
II. Summary of EPA Analysis
When determining approvability of State permitting exemption rules,
EPA evaluates the possibility that an exemption might allow an activity
that should be subject to major or minor source permitting requirements
to escape appropriate review and permitting, that sources are required
to maintain information adequate for the State to ensure that
exemptions have been applied appropriately, and that the exemptions
would not interfere with any applicable requirement concerning
attainment of any NAAQS and reasonable further progress, or any other
applicable requirement of the CAA.
Consistent with 40 CFR 51.160-51.164 and section 110 of the Act,
EPA has previously approved into the Michigan SIP certain minor source
air
[[Page 51519]]
permit exemptions found in Michigan R 336.1280 through R 336.1290
(Rules 280-290), as well as Michigan R 336.1278 and R 336.1278a (Rules
278 and 278a), which explain the scope of those exemptions. See 40 CFR
52.1170. These rules provide the requirements for certain sources and
emission units that are seeking to avoid air permitting, subject to the
recordkeeping requirements of those provisions. The existing air permit
exemptions are specific to certain categories of equipment such as oil
and gas processing, plastic processing, and surface coating, among
others.
Michigan's air permit exemption rules have restrictions on the use
of the exemptions in Michigan R 336.1280-336.1290 and require sources
using the exemptions to maintain certain records to demonstrate that
the exemptions have been applied appropriately. Specific exemptions may
include additional monitoring and recordkeeping as necessary to ensure
that the equipment is operating as required under the exemption. As
further explained below, this action pertains to additional air permit
exemptions found in Michigan R 336.1285(oo) and R 336.1291. Sources
seeking to rely on the new exemptions in Michigan R 336.1285(oo) and R
336.1291 would generally be subject to the same recordkeeping
requirements as those that currently apply to those relying on Michigan
R 336.1280-336.1290.
Under Michigan R 336.1278, the exemptions in R 336.1280 to R
336.1291 do not apply to any ``activity'' that is subject to the
prevention of significant deterioration of air quality (PSD)
regulations or NSR regulations for major sources in nonattainment
areas. An ``activity'' is defined to include all ``concurrent and
related installation, construction, reconstruction, relocation, or
modification of any process or process equipment,'' which will ensure
that projects are aggregated properly before applying an exemption. The
exemptions in Michigan R 336.1280 to R 336.1291 also do not apply to
the construction, modification, or reconstruction of major sources of
hazardous pollutants as defined in 40 CFR parts 61 and 63. Further, the
exemptions apply to the requirement to obtain a PTI only and do not
exempt any source from complying with any other applicable requirement
or existing permit limitation.
In this final action, EPA finds that EGLE's proposed revisions to
Michigan's SIP-approved Part 2 rules meet the requirements of section
110(a)(2)(C) of the Act and the minimum program requirements of 40 CFR
51.160-51.164. EPA is approving into the Michigan SIP the following
revisions to Michigan's Part 2 rules:
A. Michigan R 336.1285(2)(oo) ``Permit to install exemptions;
miscellaneous''
Michigan R 336.1285(2)(oo) exempts vapor intrusion mitigation
systems from the requirement to obtain a PTI. Specifically, this
exemption applies to equipment or systems, or both, used exclusively to
mitigate vapor intrusion of an indoor space, that is not on the
property where the release of the hazardous substance occurred, and
which has an exhaust that is: (1) unobstructed vertically upward; (2)
at least 12 inches above the nearest eave of the roof or at least 12
inches above the surface of the roof at the point of penetration; (3)
more than 10 feet above the ground; and (4) more than 2 feet above or
more than 10 feet away from windows, doors, other buildings, and other
air intakes.
B. Michigan R 336.1291 ``Permit to install exemptions; emission units
with ``de minimis'' emissions''
Michigan R 336.1291 exempts emission units with ``de minimis''
emissions from the requirement to obtain a PTI. Specifically, Michigan
R 336.1291 exempts each emission unit in which potential emissions of
non-greenhouse gas (GHG) criteria pollutants do not exceed emission
rates ranging from 0.1 tons per year for lead to 10 tons per year for
carbon monoxide, nitrogen oxides (NO<INF>X</INF>), sulfur dioxide
(SO<INF>2</INF>) or total particulate matter. The ``de minimis''
emissions threshold for GHGs is 75,000 tons per year when reported as
carbon dioxide equivalents. As relevant to Michigan R 336.1291,
``potential emissions'' refers to the emission unit's potential to emit
(PTE) as defined at Michigan R 336.1116(n), R 336.2801(hh), and R
336.2901(z). Under those provisions, PTE means the maximum capacity of
a stationary source to emit an air contaminant under its physical and
operational design. Any physical or operational limit on the capacity
of the stationary source to emit an air contaminant, including air
pollution control equipment and restrictions on the hours of operation
or the type or amount of material combusted, stored, or processed, must
be treated as part of its design only if the limit, or the effect it
would have on emissions, is legally enforceable.
Rule 291 would provide for a general exemption from air permitting
for sources and projects with de minimis emissions and can be
considered a backstop for the overall air permitting exemptions across
all industry types. Any emission unit that has potential emissions
above those defined in Rule 291 would be required to obtain a
preconstruction permit from EGLE. Rule 291 requires the owner or
operator to maintain a description of the emission unit throughout the
life of the unit including documentation and calculations identifying
the quality, nature, and quantity of the air contaminant emissions.
This information is to be maintained in sufficient detail to
demonstrate that the potential emissions of the emission unit are less
than those listed in Rule 291.
III. EPA's Response to Comments
During the comment period, which closed on May 28, 2024, EPA
received one set of consolidated comments from Great Lakes
Environmental Law Center, Sierra Club Environmental Law Program, and
Air Law for All, Ltd. We respond to the comments in this section.
Comment: The commenters note that section 110(l) of the CAA
prohibits approval of any SIP revision that would interfere with any
applicable requirement of the Act, and that for minor NSR programs, the
section 110(l) analysis must consider the program as a whole to
determine whether the construction or modification of sources would
interfere with attainment and maintenance of the NAAAQs.
EPA Response: The CAA's NSR program requires EPA and States to
regulate the construction or modification of stationary sources of air
emissions under a program of cooperative federalism. The NSR program
governs both large sources of emissions, referred to as ``major''
sources, and small sources of emissions, referred to as ``minor''
sources. Because major sources have the potential to have a greater
impact on air quality, the CAA's requirements largely focus on
controlling those sources' emissions, and EPA and States have likewise
focused most of their regulatory efforts on addressing major sources'
emissions.
This final action does not change any elements of Michigan's NSR
program for major sources in attainment or nonattainment areas as
addressed by parts C and D of the CAA and its implementing regulations
at 40 CFR 51.165 and 40 CFR 51.166. Rather, this action is limited to
revisions to Michigan's minor NSR program to clarify the types of
construction or modification activities that must obtain a PTI under
that program.
The commenters correctly note that section 110(l) of the CAA
prohibits EPA from approving a SIP revision if the revision would
interfere with any applicable requirement concerning
[[Page 51520]]
attainment and reasonable further progress towards attainment of a
NAAQS or any other applicable requirement of the CAA. 42 U.S.C.
7410(l). However, EPA does not interpret section 110(l) to require a
full attainment or maintenance demonstration before any changes to a
SIP may be approved; rather, a SIP revision may be approved under
section 110(l) if EPA finds it will at least preserve status quo air
quality. See 83 FR 44493 (August 31, 2018) (citing Kentucky Resources
Council, Inc. v. EPA, 467 F.3d 986 (6th Cir. 2006); GHASP v. EPA, No.
06-61030 (5th Cir. Aug. 13, 2008)).
In its final rule approving the existing air permit exemptions in
Michigan R 336.1280 through Michigan R 336.1290, EPA explained that it
approved Michigan's permit exemptions after examining various
information EGLE provided in support of its proposed rules, including
emission projections, the structure of the existing SIP permitting
rules and the structure of each new exemption, and in some cases
conservative modeling or qualitative air quality analysis. For example,
where the exemption did not contain enforceable limitations on
production and operation, and projected emission increases were greater
than 10 tons per year of a criteria pollutant, EGLE provided an air
quality analysis that EPA found to be adequate. EPA determined that the
exemptions would not interfere with attainment of any NAAQS or any
other CAA requirement because the use of the exemption would provide
the same level of control measures as the control measures that would
be included in an individual preconstruction permit, the exemption
would result in little or no increase in emissions of a criteria
pollutant, or EGLE provided a suitable air quality analysis
demonstrating no interference with attainment, reasonable further
progress, or any other requirement of the Act. See 83 FR 44493-44494
(August 31, 2018).\1\
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\1\ On April 22, 2019, the Michigan Department of Environmental
Quality was reorganized as EGLE. At the time this Federal Register
notice was published, the former title was still in use.
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The Rule 291 exemptions address sources that are small, have low
emissions (including several pollutants with thresholds substantially
less than 10 tons per year), and which are few compared to those
already relying on existing exemptions. Indeed, Michigan provided
information indicating that emission units that would be exempted under
Rule 291 at major sources subject to title V of the Act represent less
than 1 percent of the subset of exemptions required to be included in
the title V permit renewal application. Thus, Rule 291 would only allow
a limited additional number of inconsequential emission units to forego
minor NSR. See 86 FR 31927 (June 16, 2021) (finding that the Arizona
Department of Environmental Quality (ADEQ) adequately demonstrated that
emissions from the sources and projects to be exempted from ADEQ's
minor NSR program were inconsequential to attainment or maintenance of
the NAAQS). Michigan's minor NSR program would continue to cover a
large majority of emissions from minor stationary sources and meet
applicable statutory and regulatory standards. Further, Rule 291, in
conjunction with the SIP-approved Rules 278 through 290, would subject
exempt emission units with potential emissions of non-GHG pollutants
less than 10 tons per year to the same level of other control measures
(including monitoring and recordkeeping requirements contained in any
applicable State and Federal rules) as would normally be required in an
individual preconstruction permit for units of that size.
Therefore, consistent with section 110(l) of the Act, Michigan has
demonstrated to EPA's satisfaction that the exemptions in this action
would not cause Michigan's minor NSR program to interfere with
attainment, reasonable further progress, or any other requirement of
the Act.
Comment: The commenters assert that the combination of existing
exemptions with the new exemptions may push the minor NSR program to
the point where it no longer protects the NAAQS, and that EPA cannot
rely on how Michigan's minor NSR program has performed historically. In
particular, the commenters note that the Detroit area is very close to
the nonattainment threshold for ozone.
EPA Response: Emissions from the Rule 291 emission units are
insignificant compared to those from emission units and activities that
are required to obtain a PTI or are relying on the existing approved
air permit exemptions. With rare exceptions, emission units of the
type, size, and emissions that would be exempted under R
336.1285(2)(oo) and R 336.1291 would be subjected to the same level of
other control measures (including recordkeeping requirements) as would
be required in an individual preconstruction permit for such units in
any area. Where additional control measures or a site-specific air
quality analysis might be needed, EPA and EGLE's review of the records
that are required to be kept under these rules would provide EGLE and
EPA with the information needed to support imposing such additional
control measures on the facility as necessary. In addition, exempt
emission units would still be required to comply with all applicable
non-PTI related SIP requirements or standards under the CAA and the
Michigan SIP.
Based on our review of information that Michigan submitted
regarding emissions from sources that are likely to use these
exemptions, we disagree that the additional exemptions would impact
Michigan's ability to address particulate matter with an aerodynamic
diameter less than 2.5 micrometers (PM<INF>2.5</INF>) or ozone NAAQS
attainment issues or that their approval into the Michigan SIP would
somehow push Michigan's minor NSR program over the point where it no
longer protects the NAAQS. As we explained at proposal, EGLE
demonstrated through single- and multiple-emission unit air quality
modeling that the proposed exemptions will not affect Michigan's
attainment status for any NAAQS or cause any backsliding on achieved
improvements.
With respect to EPA's redesignation of the Detroit area from
moderate nonattainment to attainment of the 2015 ozone standard,\2\
there is no evidence suggesting that if EGLE were to require PTIs for
the exempted units in an area, and the area were to subsequently fall
into nonattainment, the permitting of these exempted units would have
somehow precluded that from happening. Historically, where Michigan has
not achieved attainment, there have been no indications that exemptions
have been the cause. Similarly, when an area has come into attainment--
such as the Detroit area--Michigan did not find it necessary to modify
any exemptions to accomplish the attainment redesignation by permitting
the affected facilities. For the Detroit area redesignation to
attainment, EGLE did not need to change any air permitting exemptions
as part of its plan to attain the standards to demonstrate it had met
the criteria for the redesignation. Regarding those standards for which
Michigan was not able to demonstrate attainment, there is no evidence
the permitting of these exempted facilities would address the issue.
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\2\ 88 FR 32594 (May 19, 2023).
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It is worth noting that sources and projects of the size that would
be exempted by Rules 280 to 291 are not required to be modeled as part
of the standard air permitting process, so a project-specific NAAQS
compliance
[[Page 51521]]
demonstration is not done for such projects. Also, additional controls
are normally not prescribed when permitting such small projects
regardless of the attainment status of the project's location beyond
those control measures required by any applicable Federal or State
regulations. In nonattainment areas, emissions offsets would be
required for sources and projects that would emit at levels that are
higher than the thresholds we are approving today.
Furthermore, under section 110(k)(5) of the Act, if EPA
subsequently concludes that the Michigan SIP is substantially
inadequate to attain or maintain a specific NAAQS, or to otherwise
comply with any requirement of the Act, EPA may order the State to
revise and correct its SIP as necessary. 42 U.S.C. 7410(k)(5).
Comment: The commenters state that Michigan's section 110(l)
modeling demonstration indicates that the new exemptions could cause
the Detroit area to violate the ozone standard again.
EPA Response: The commenters point to Michigan's comparison of
theoretical maximum emission rates and ambient impacts to significant
impact levels (SILs). SILs are modeling screening thresholds used in
PSD air quality analyses to determine whether additional,
comprehensive, air quality analyses are needed to demonstrate that
major projects do not cause or contribute to NAAQS violations. A
modeled exceedance of the SIL does not mean that the NAAQS would be
violated; it is simply one step in a multi-step process of proving that
the project would not cause or contribute to a NAAQS violation.
Michigan used EPA's Modeled Emission Rates for Precursors (MERPs)
as a Tier 1 demonstration tool to address ozone and PM<INF>2.5</INF>
impacts from single sources. Michigan evaluated worst case scenarios
against Rule 291 exemption thresholds. As explained in Michigan's
supplemental submittal, there is no evidence sources are using the Rule
291 exemptions at the levels in the modeled scenarios. Actual air
quality impacts from sources relying on the Rule 291 exemptions would
be much lower than those estimated in Michigan's analysis. This is
confirmed by Michigan's analysis of the State's universe of permitted
sources which showed that the use of Rule 291 air permit exemptions is
extremely limited in practice.
Comment: The commenters object to EPA using data from Michigan's
implementation of Rule 291 before it has been approved into the
Michigan SIP to show that the SIP, with the new exemptions, would
continue to protect the NAAQS.
EPA Response: In previous comments on our 2022 direct final rule,
the commenters noted that Michigan had not provided an estimate of the
air emissions from Rule 291 implementation as part of the SIP
submittal. In response to this comment, Michigan supplemented its
submittal with emissions data from the Michigan Air Emissions Reporting
System (MAERS). Michigan's supplemental submittal provided estimates of
emissions that have resulted from the application of each rule
exemption including the exemptions that Rule 291 covers. The submittal
contained actual emissions data submitted to EGLE according to various
recordkeeping and reporting requirements of its rules and air
permitting program. The submittal demonstrated that many of the
exemptions would result in very low levels of emissions that are
inconsequential to the overall air permitting program's ability to
comply with the CAA and its implementing regulations for minor sources
at 40 CFR 51.160-51.164.
The commenters have taken issue with the use of MAERS data to
support the conclusion that these emissions are inconsequential but
have not disputed the accuracy of the supplied data. EPA believes EGLE
has supplied information that adequately illustrates the emissions that
would result from implementation of the Rule 291 exemptions in
conjunction with the already approved air permit exemptions. Because
Michigan provided actual emissions information, not hypothetical
projections, EPA has confidence that approval of the Rule 291
exemptions would not result in a consequential increase in unpermitted
emissions that would otherwise interfere with Michigan's ability to
protect the NAAQS.
Comment: The commenters are concerned that the new exemptions could
lead to new nonattainment areas for PM<INF>2.5</INF>. The commenters
speculate that EPA will likely designate at least three new
nonattainment areas in Michigan for the new annual PM<INF>2.5</INF>
standards and that creating new exemptions in the minor NSR program for
PM<INF>2.5</INF> precursors will only exacerbate the problem.
EPA Response: Under section 110(a) of the Act, each State is
mandated to adopt and submit to EPA a plan which provides for
implementation, maintenance, and enforcement of NAAQS within such
State. EGLE has developed attainment strategies to address its
nonattainment areas, which include a combination of source-specific air
pollutant reduction plans and maintenance of existing attainment areas.
As EPA demonstrated in its approval of the 2015 ozone standard
redesignation to attainment for the Detroit area, the improvement in
air quality with respect to ozone was due to Michigan and EPA programs
that reduced NO<INF>X</INF> and volatile organic compounds (VOC)
emissions. 88 FR 32594 (May 19, 2023). These control measures include
more protective vehicle emissions standards, nonroad engine emissions
standards, and programs to reduce emissions from power plants. For the
Detroit area, the past 20-plus years have seen a substantial decrease
in ozone concentrations, with additional emission reductions expected
to occur in the future. 87 FR 14210 (March 14, 2022).
It is worth noting that minor sources are not required to conduct
an air quality analysis or install Best Available Control Technology
(BACT) or Lowest Achievable Emissions Rate (LAER) control measures for
each proposed change under the PSD and nonattainment NSR regulations
found at 40 CFR 51.166 and 51.165, respectively. Neither EPA's
regulations at 40 CFR 51.160-51.164 nor the CAA require that State
minor NSR programs include requirements for BACT, LAER, or an air
quality analysis as a prerequisite for obtaining a preconstruction
permit for minor sources. This is in recognition of the ubiquitous
nature of such sources and to ensure the State's resources are
preserved for larger sources with the greatest potential impact on air
quality. While States are not prohibited from including such provisions
in their SIPs, EGLE has not proposed, and EPA has not approved, such
provisions in the Michigan SIP. Accordingly, under the SIP, without the
new exemptions, sources of PM<INF>2.5</INF> emissions that would
otherwise qualify for the new exemptions would generally not be
required to conduct a complex air quality analysis to demonstrate that
their emissions do not significantly impact nearby PM<INF>2.5</INF>
monitors, nor be required to implement additional measures beyond those
required by Rule 285 and 291.
Except under rare circumstances, EPA believes the low emissions
from those projects are so inconsequential to compliance with NAAQS and
the ability for EGLE to maintain reasonable further progress that
project-specific ambient air quality demonstrations are not necessary.
EGLE, as the State permitting authority, has the discretion to require
an air quality analysis or impose other
[[Page 51522]]
control measures as necessary in the rare situations where it
determines that a specific source may be causing or contributing to a
violation of the NAAQS, regardless of whether the source relied on an
air permit exemption to avoid permitting. In addition, EPA has
enforcement authority under sections 113 and 114 of the Act to require
such a demonstration as necessary. As already discussed, the air permit
exemptions require the facility to adequately keep records of its
emissions to ensure that they do not exceed the air permit exemption
thresholds.
Comment: The commenters assert that Michigan should not rely on the
minor NSR program applicable in Indian country (Tribal Minor NSR Rule)
as the basis for establishing de minimis emissions thresholds for its
air permit exemptions.\3\
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\3\ The commenters also object to EPA's redesignation of the
Detroit area to attainment for the 2015 ozone NAAQS. See 88 FR 32594
(May 19, 2023). EPA is not addressing this comment as it is outside
the scope of this action.
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EPA Response: While Michigan relied on a similar approach to that
EPA used to develop the Tribal Minor NSR Rule's thresholds when
developing the de minimis thresholds in Rule 291, the State did not
exclusively rely on the Tribal Minor NSR Rule's approach. As explained
in Michigan's supplemental submittal, the Tribal Minor NSR Rule is
simply one of many sources of thresholds ultimately used to draft the
thresholds in Rule 291. Michigan also relied on EPA modeling guidance,
regulatory significance emissions rates, Michigan's existing permitting
policies and guidance, and decades of experience using, creating, and
evaluating exemptions in Michigan's NSR program. Moreover, EPA has
previously determined that the approach EPA took in developing the
thresholds in the Tribal Minor NSR Rule is appropriate for establishing
such thresholds in SIPs. See, e.g., 86 FR 31932 (June 16, 2021)
(approving certain NSR permitting exemptions for the ADEQ's portion of
the Arizona SIP).
Similar to the approach EPA followed for the Tribal Minor NSR Rule
and Arizona SIP, EGLE conducted a source distribution analysis using
data from MAERS and the State's database of staff reports for title V
permits. Through this analysis, EPA estimates that the percentage of
emissions that would be exempt from minor NSR under Rule 291's
thresholds would be less than 0.1 percent for each regulated NSR
pollutant except for VOC, which would be about 0.8 percent. This
analysis demonstrates that sources with emissions below the proposed
minor NSR thresholds in Rule 291 will be inconsequential to attainment
and maintenance of the NAAQS.
While the proposed thresholds apply to individual units and not
groups of units, Michigan's rules implementing the PSD and
nonattainment NSR significance rates, as well as Michigan R
336.1278(1)(b), would serve as a backstop for projects with multiple
emissions units. Under those provisions, projects involving multiple
units must sum up emissions from all affected units to determine
whether the thresholds for PSD or nonattainment NSR permitting are
exceeded. As already stated, the exemptions in R 336.1280 to R 336.1291
do not apply to projects that are subject to PSD or nonattainment NSR
permitting requirements.
Comment: The commenters would like EPA to consider the potential
cumulative impact of multiple projects relying on the air permit
exemptions.
EPA Response: As already discussed, EGLE has the discretion to
conduct an air quality analysis if it believes that there may be an
impact on the NAAQs or PSD increments from a planned or existing
activity. The commenters' main argument is that an unlimited number of
sources whose impacts are less than the SILs could cumulatively cause a
violation of the NAAQs or increments. However, Michigan's existing SIP
already requires that major sources and sources that may cause impacts
that would exceed the SILs or cause a violation of the NAAQs or
increments must conduct an air quality analysis before a
preconstruction permit may be issued. Further, as part of their
statutory obligations, EPA and EGLE review data from air quality
monitors to determine whether individual sources or groups of sources
are substantively impacting air quality in certain areas. Based on the
results of those reviews, EPA and EGLE have the discretion to require
targeted actions that may include, but are not limited to, a
comprehensive air quality modeling demonstration, source-specific
control measures, or a revision of the SIP, among others.
Comment: The commenters assert that the MERPs, modeling protocol,
model inputs, and model results were not provided with Michigan's
supplemental submittal and thus were not available for public comment.
According to the commenters, EPA is therefore required to re-propose
its action and make the MERPs, modeling protocol, model inputs, and
model results available for public comment before relying on them.
EPA Response: EGLE's supplemental submittal was made available for
public comment by EPA. In its supplemental submittal, EGLE provided
emissions data from MAERS in addition to its MERPs analysis. With
respect to the MERPs analysis, EGLE stated it completed the analysis
following formulas and procedures contained in an April 30, 2019, EPA
guidance document addressing the subject, and utilizing data from EPA's
MERPs website. The submittal noted that further details of the analysis
could be provided upon request.
Significantly, EGLE provided data on emission units and pollutant
levels for various exemptions demonstrating the negligible emissions
that would be expected from the Rule 291 exemptions. EGLE's
supplemental submittal included MAERS emissions data for all Michigan
air permit exemptions including Rule 291 exemptions. While the
information EGLE provided on its MERPs analysis provides additional
support for the exemptions, the additional information was not needed
to satisfy the Act's minimum requirements for minor NSR program
submittals. Most importantly, the information EPA relied upon for
today's final action was made available during the public comment
period.
Comment: EPA should not draw conclusions about the performance of
the new exemptions based on sources that have been ``violating the
SIP'' during the period where Michigan's State rules contained the new,
proposed exemptions but the approved SIP did not (known as the ``SIP
gap'').
EPA Response: The existence of a SIP gap in a particular SIP is not
uncommon due in large part to the often-lengthy procedural requirements
associated with approving new State rules into the SIP. The commenters
correctly point out that until the new exemptions are approved into the
Michigan SIP, State actions implementing those provisions are not
federally enforceable. However, the commenters appear to misunderstand
the intent of Michigan's inclusion in its submittal of emissions and
other data related to its implementation of the SIP gap exemptions.
Michigan provided emissions information from existing sources that
utilized those exemptions to satisfy State requirements to address
concerns that it had not sufficiently explained how implementation of
the new exemptions could impact future compliance with NAAQS. EPA
considers the information Michigan provided as an illustration of how
the exemptions would be implemented in practice and the potential
impacts from their implementation. As demonstrated in Michigan's
submittal, the projected
[[Page 51523]]
actual total emissions from the Rule 291 exemptions would be
inconsequential compared to the total tons per year emitted from all
the exempted units. There is no evidence that the data EGLE provided is
incorrect.
Comment: The commenters assert that annual PTE limitations may not
sufficiently protect short-term NAAQS. According to the commenters, an
annual PTE is not more restrictive than a short-term PTE with respect
to short term spikes in emissions, which is a concern for short term
NAAQS such as the 8-hour ozone standard.
EPA Response: We disagree with the notion that one must have short-
term PTE limits in a minor NSR SIP to protect short-term NAAQS such as
the 8-hour ozone standard. While sources may have variability in their
hourly or daily emissions, EPA has generally found that annual de
minimis thresholds in SIPs are sufficient to ensure that only those
sources with inconsequential emissions are exempted from rigorous
permitting requirements, including an air quality analysis. For this
reason, EPA does not require air quality analyses for pollutants whose
PTE in tons per year is not ``significant'' or modifications that would
not result in a ``significant'' net emissions increase in tons per
year. See 40 CFR 52.21(m).
EPA and Michigan define PTE similarly: the maximum capacity of a
stationary source to emit an air contaminant under its physical and
operational design. See 40 CFR 51.165(a)(1)(iii), 40 CFR 51.166(b)(4),
40 CFR 52.21(b)(4), and Michigan R 336.1116(n), R 336.2801(hh) and R
336.2901(z). In determining the PTE of an emission unit seeking to
utilize the Rule 291 exemptions, federally enforceable restrictions on
operations or the use of air pollution control equipment are not
considered since the emission unit does not have a permit. The
commenters' assertion that a short-term spike in emissions could impact
a short-term NAAQS does not take into account that the short-term spike
in emissions would have already been factored into the determination of
the emission unit's annual PTE and whether it could utilize the Rule
291 air permit exemptions. This is because there would be no other
practically enforceable limit such as would be contained in a permit to
restrict the emission unit's PTE.
A PTE or an emissions increase is ``significant'' if it equals or
exceeds any of the emission rates specified in 40 CFR 51.166(b)(23)(i)
and 40 CFR 51.165(a)(1)(x)(A) for attainment and nonattainment areas,
respectively. See also Michigan R 336.1119(e), R 336.2801(qq) and R
336.2901(hh). Because these values are expressed as a rate of emissions
in tons per year, EPA often refers to each value as a ``significant
emissions rate.'' Significant emissions rates are premised on the
foundational legal principles for de minimis levels as laid out by the
D.C. Circuit Court of Appeals in Alabama Power Co. v. Costle. 81 FR
68120 (October 3, 2016) (citing 636 F.2d 323, D.C. Cir. 1979).
It is worth noting that significant emissions rates for the NSR
program are not differentiated by the averaging times of the NAAQS
applicable to some of the listed pollutants. Although short-term NAAQS
for ozone, SO<INF>2</INF>, carbon monoxide, particulate matter, and
nitrogen dioxide have been promulgated for many years, EPA has not
promulgated alternate ``short-term'' significant emissions rates for
those standards. In so doing, EPA continues to find the significant
emissions rates expressed in tons per year to be adequate for screening
for sources or projects that could threaten the NAAQS, regardless of
the standard's averaging time. Notably, these significant emissions
rates are much greater than the de minimis thresholds listed in Rule
291 suggesting that the Rule 291 thresholds would be more protective of
short-term and annual NAAQS than the significant emissions rates.
In support of their comments, the commenters cite a non-binding EPA
memorandum that provided guidance to State, local, and tribal
governments for the development of SIPs and tribal implementation plans
for areas designated as nonattainment for the primary 2010 NAAQS for
SO<INF>2</INF>.\4\ In that guidance, EPA observed that it may be
possible in specific cases for States to develop control strategies for
their nonattainment areas that account for variability in l-hour
emissions rates through emission limits with averaging times that are
longer than 1 hour, using averaging times as long as 30 days, but still
provide for attainment of the 2010 SO<INF>2</INF> NAAQS. As explained
in the memorandum, the guidance discussed the CAA statutory
requirements that air agencies need to address when implementing the
2010 SO<INF>2</INF> NAAQS in areas designated as nonattainment for the
2010 SO<INF>2</INF> standard. Specifically, it provided recommendations
for air agencies to consider as they developed plans to satisfy the
requirements of sections 172, 175A, 191, and 192 of the CAA to show
future attainment and maintenance of the 2010 SO<INF>2</INF> NAAQS.
Importantly, this guidance did not pertain to and was not intended for
the development of permitting SIPs under section 110 of the Act and 40
CFR 51.160-164 as relevant for this action. We therefore disagree with
the commenters' suggestion that this guidance advocates for inclusion
of short-term PTE limits in SIPs that are submitted to satisfy the
minor NSR programs under 40 CFR 51.160-164.
---------------------------------------------------------------------------
\4\ Available in the docket and at <a href="https://www.epa.gov/sites/default/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf">https://www.epa.gov/sites/default/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf</a>.
---------------------------------------------------------------------------
Comment: The commenters request that Michigan develop more
stringent exemption thresholds in nonattainment areas.
EPA Response: EPA's longstanding interpretation of section 110(l)
of the Act is that we may approve a SIP revision so long as emissions
to the air are not increased, thereby preserving ``status quo air
quality.'' See, for example, 89 FR 82561 (October 11, 2024). In this
context, we interpret the word ``interfere'' as used in section 110(l)
to mean that the SIP revision does not hamper, frustrate, hinder, or
impede any applicable CAA requirements. As already stated, Michigan has
submitted a section 110(l) analysis which sufficiently demonstrates
that the proposed exemptions would not interfere with attainment of the
NAAQS or reasonable further progress in nonattainment and maintenance
areas.
The commenters take issue with Michigan's explanation that
implementing an exemption threshold that varies with attainment status
would be difficult, ``particularly with an installation-based
permitting program.'' Although a variable, location-based, exemption
threshold may be desirable, EPA believes such a variable threshold is
unnecessary and would pose significant implementation challenges in the
minor NSR program for sources with inconsequential emissions. As the
commenters acknowledge, areas routinely come in and out of
nonattainment as air quality worsens and improves, respectively, which
could lead to unnecessary business uncertainty and confusion for small
businesses as different exemption thresholds could apply at various
times from project conception to implementation. EPA believes the
existing permitting thresholds for nonattainment areas in conjunction
with the exemptions that EPA is approving today would adequately
protect air quality in nonattainment areas.
We also note that the exemptions Michigan has proposed, and EPA is
approving, would generally not change the status quo with respect to
emissions
[[Page 51524]]
and air quality control requirements for the emissions units that would
qualify for the exemptions. This action does not alter the permitting
thresholds or requirements that EPA has approved into the Michigan SIP
for sources and projects located in nonattainment areas. As already
discussed, this action would merely free up State resources so that
they can be used to focus on those emissions units and projects that
would have the greatest potential impact on attainment and maintenance
of the NAAQS.
This action also does not relieve Michigan of its statutory
obligation to ensure sources in its jurisdiction do not cause or
contribute to a violation of the NAAQS or interfere with reasonable
further progress in nonattainment and maintenance areas. Additionally,
under section 110(k)(5) of the Act, EPA retains authority to order a
SIP revision if it subsequently determines that exempt sources in
Michigan are interfering with attainment of the NAAQS in an area. 42
U.S.C. 7410(k)(5).
IV. What action is EPA taking?
EPA is approving revisions to the Michigan SIP that EGLE submitted
on March 8, 2022. EPA approves into the Michigan SIP at 40 CFR 52.1170
the following regulations: Michigan R 336.1285(2)(oo) ``Permit to
install exemptions; miscellaneous'' and R 336.1291 ``Permit to install
exemptions; emission units with ``de minimis'' emissions.''
V. Incorporation by Reference
In this rule, EPA is finalizing regulatory text that includes
incorporation by reference. In accordance with requirements of 1 CFR
51.5, EPA is finalizing the incorporation by reference of the Michigan
Regulations described in section II of this preamble and set forth in
the amendments to 40 CFR part 52 below. EPA has made, and will continue
to make, these documents generally available through <a href="https://www.regulations.gov">https://www.regulations.gov</a>, and at the EPA Region 5 Office (please contact the
person identified in the FOR FURTHER INFORMATION CONTACT section of
this preamble for more information). Therefore, these materials have
been approved by EPA for inclusion in the SIP, have been incorporated
by reference by EPA into that plan, are fully federally enforceable
under sections 110 and 113 of the CAA as of the effective date of the
final rulemaking of EPA's approval, and will be incorporated by
reference in the next update to the SIP compilation.\5\
---------------------------------------------------------------------------
\5\ 62 FR 27968 (May 22, 1997).
---------------------------------------------------------------------------
VI. 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. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, 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 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).
This action is subject to the Congressional Review Act, and 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 January 20, 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 in 40 CFR Part 52
Environmental protection, Air pollution control, Ammonia, Carbon
monoxide, Incorporation by reference, Intergovernmental relations,
Lead, Nitrogen oxides, Ozone, Particulate matter, Reporting and
recordkeeping requirements, Sulfur oxides, Volatile organic compounds.
Dated: October 28, 2025.
Anne Vogel,
Regional Administrator, Region 5.
For the reasons stated in the preamble, title 40 CFR part 52 is
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 (c) is amended under ``Part
2. Air Use Approval'' by revising the entry for ``R 336.1285'' and by
adding a new entry for ``R 336.1291'' after the entry for ``R
336.1290'' to read as follows:
Sec. 52.1170 Identification of plan.
* * * * *
(c) * * *
[[Page 51525]]
EPA Approved-Michigan Regulations
----------------------------------------------------------------------------------------------------------------
State
Michigan citation Title effective date EPA approval date Comments
----------------------------------------------------------------------------------------------------------------
* * * * * * *
----------------------------------------------------------------------------------------------------------------
Part 2. Air Use Approval
----------------------------------------------------------------------------------------------------------------
* * * * * * *
R 336.1285..................... Permit to install 1/2/2019 11/18/2025, 90 FR ..................
exemptions; [Insert Federal
miscellaneous. Register page where
the document begins].
* * * * * * *
R 336.1291..................... Permit to install 1/2/2019 11/18/2025, 90 FR ..................
exemptions; [Insert Federal
emission units Register page where
with ``de the document begins].
minimis''
emissions.
* * * * * * *
----------------------------------------------------------------------------------------------------------------
* * * * *
[FR Doc. 2025-20150 Filed 11-17-25; 8:45 am]
BILLING CODE 6560-50-P
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