[Federal Register Volume 91, Number 51 (Tuesday, March 17, 2026)]
[Proposed Rules]
[Pages 12700-12736]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-05167]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 63
[EPA-HQ-OAR-2019-0178; FRL-7055.1-01-OAR]
RIN 2060-AW79
National Emission Standards for Hazardous Air Pollutants:
Ethylene Oxide Emissions Standards for Sterilization Facilities
Residual Risk and Technology Review Reconsideration
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule; reconsideration of final rule.
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SUMMARY: On April 5, 2024, the U.S. Environmental Protection Agency
(EPA) published the National Emission Standards for Hazardous Air
Pollutants (NESHAP): Ethylene Oxide Emissions Standards for
Sterilization Facilities Residual Risk and Technology Review (2024
Final Rule). The 2024 Final Rule revised the Commercial Sterilization
Facilities NESHAP based on a residual risk and technology review (RTR)
pursuant to the Clean Air Act (CAA) sections. On March 12, 2025, the
EPA announced that it was reconsidering the 2024 Final Rule. Based on
its reconsideration of the RTR in the 2024 Final Rule, the EPA is
proposing to amend the Commercial Sterilization Facilities NESHAP. The
amendments would rescind the risk based standards, revise the standard
for new aeration room vents that resulted from the technology review,
revise the compliance demonstration requirements, and rescind a
requirement related to permanent total enclosure (PTE). This proposal
also includes technical corrections and clarifications to the
Commercial Sterilization Facilities NESHAP and Performance
Specification 19 to address erroneous cross-references, omissions of
text, and typographical errors in the regulatory text that the EPA has
identified after publication of the 2024 Final Rule.
DATES: Comments must be received on or before May 1, 2026. Under the
Paperwork Reduction Act (PRA), comments on the information collection
provisions are best assured of consideration if the Office of
Management and Budget (OMB) receives a copy of your comments on or
before April 16, 2026.
Public hearing: The EPA will hold a virtual public hearing on April
1, 2026. Please refer to the SUPPLEMENTARY INFORMATION section for
information on registering for the public hearing.
[[Page 12701]]
ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0178, by any of the following methods:
Federal eRulemaking Portal: https://www.regulations.gov/
(our preferred method). Follow the online instructions for submitting
comments.
Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2019-0178 in the subject line of the message.
Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-
2019-0178.
Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID No. EPA-HQ-OAR-2019-0178, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
Hand/Courier Delivery: EPA Docket Center, WJC West
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004.
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except federal holidays).
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov/, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the SUPPLEMENTARY
INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact U.S. EPA, Attn: Brian Langloss, Mail Drop: D243-04, 109
T.W. Alexander Drive, P.O. Box 12055, Research Triangle Park, North
Carolina 27711; telephone number: (919) 541-0675; and email address:
[email protected].
SUPPLEMENTARY INFORMATION:
Participation in virtual public hearing. The hearing will be held
via virtual platform on April 1, 2026. The EPA may close a session 15
minutes after the last pre-registered speaker has testified if there
are no additional speakers. The EPA will announce further details at
https://www.epa.gov/stationary-sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities.
The EPA will begin pre-registering speakers for the hearing no
later than 1 business day after a request has been received. To
register to speak at the virtual hearing, please use the online
registration form available at https://www.epa.gov/stationary-sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities or contact the public hearing team at (888) 372-8699 or by
email at [email protected]. The last day to pre-register to
speak at the hearing will be March 30, 2026. Prior to the hearing, the
EPA will post a general agenda that will list pre-registered speakers
at: https://www.epa.gov/stationary-sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities.
The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule.
Each commenter will have 4 minutes to provide oral testimony. The
EPA encourages commenters to submit a copy of their oral testimony as
written comments electronically to the rulemaking docket.
The EPA may ask clarifying questions during the oral presentations
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral testimony and
supporting information presented at the public hearing.
Please note that any updates made to any aspect of the hearing will
be posted online at https://www.epa.gov/stationary-sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities.
While the EPA expects the hearing to go forward as set forth above,
please monitor our website or contact the public hearing team at (888)
372-8699 or by email at [email protected] to determine if there
are any updates. The EPA does not intend to publish a document in the
Federal Register announcing updates.
If you require the services of a translator or special
accommodation such as audio description, please pre-register for the
hearing with the public hearing team and describe your needs by March
24, 2026. The EPA may not be able to arrange accommodations without
advanced notice.
Docket. The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2019-0178. All documents in the docket are
listed in https://www.regulations.gov/. Although listed, some
information is not publicly available, e.g., Confidential Business
Information (CBI) 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 as pdf
versions that can only be accessed on the EPA computers in the docket
office reading room. Certain databases and physical items cannot be
downloaded from the docket but may be requested by contacting the
docket office at 202-566-1744. The docket office has up to 10 business
days to respond to these requests. Except for such material, publicly
available docket materials are available electronically at https://www.regulations.gov.
Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2019-0178. The EPA's policy is that all comments received will be
included in the public docket without change and may be made available
online at https://www.regulations.gov/, including any personal
information provided, unless the comment includes information claimed
to be CBI or other information whose disclosure is restricted by
statute. Do not submit electronically to https://www.regulations.gov/
any information that you consider to be CBI or other information whose
disclosure is restricted by statute. This type of information should be
submitted as discussed below.
The EPA may publish any comment received to its public docket.
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 https://www.epa.gov/dockets/commenting-epa-dockets.
The https://www.regulations.gov/ website allows you to submit your
comment anonymously, which means the EPA will not know your identity or
contact information unless you provide it in the body of your comment.
If you send an email comment directly to the EPA without going through
https://www.regulations.gov/, your email address will be automatically
captured and included as part of the comment that is placed in the
public docket and made available on the internet. If you submit an
electronic comment, the EPA recommends that you include your name and
other contact information in the body of your comment and with any
digital storage media you submit. If the EPA cannot read your comment
due to technical difficulties and cannot contact you for clarification,
the EPA may not
[[Page 12702]]
be able to consider your comment. Electronic files should not include
special characters or any form of encryption and should be free of any
defects or viruses. For additional information about the EPA's public
docket, visit the EPA Docket Center homepage at https://www.epa.gov/dockets.
Throughout this proposal, the EPA is soliciting comment on numerous
aspects of the proposed rule. The EPA has indexed each comment
solicitation with an identifier (e.g., ``Question 1, Question 2, . . .)
to provide a consistent framework for effective and efficient provision
of comments. Accordingly, we ask that commenters include the
corresponding identifier when providing comments relevant to that
comment solicitation. We ask that commenters include the identifier in
either a heading, or within the text of each comment (e.g., ``In
response to Question 1, . . .'') to make clear which comment
solicitation is being addressed.
Submitting CBI. Do not submit information containing CBI to the EPA
through https://www.regulations.gov/. Clearly mark the part or all the
information that you claim to be CBI. For CBI information on any
digital storage media that you mail to the EPA, note the docket ID,
mark the outside of the digital storage media as CBI, and identify
electronically within the digital storage media the specific
information that is claimed as CBI. In addition to one complete version
of the comments that includes information claimed as CBI, you must
submit a copy of the comments that does not contain the information
claimed as CBI directly to the public docket through the procedures
outlined in Instructions above. If you submit any digital storage media
that does not contain CBI, mark the outside of the digital storage
media clearly that it does not contain CBI and note the docket ID.
Information not marked as CBI will be included in the public docket and
the EPA's electronic public docket without prior notice. Information
marked as CBI will not be disclosed except in accordance with
procedures set forth in 40 Code of Federal Regulations (CFR) part 2.
Our preferred method to receive CBI is for it to be transmitted
electronically using email attachments, File Transfer Protocol (FTP),
or other online file sharing services (e.g., Dropbox, OneDrive, Google
Drive). Electronic submissions must be transmitted directly to the
Office of Clean Air Programs (OCAP) CBI Office at the email address
[email protected] and, as described above, should include clear CBI
markings and note the docket ID. If assistance is needed with
submitting large electronic files that exceed the file size limit for
email attachments, and if you do not have your own file sharing
service, please email [email protected] to request a file transfer
link. If sending CBI information through the postal service, please
send it to the following address: OCAP Document Control Officer (C404-
02), OCAP, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina 27711, Attention Docket ID No. EPA-HQ-OAR-2019-
0178. The mailed CBI material should be double wrapped and clearly
marked. Any CBI markings should not show through the outer envelope.
Preamble acronyms and abbreviations. Throughout this preamble the
use of ``we,'' ``us,'' or ``our'' is intended to refer to the EPA. We
use multiple acronyms and terms in this preamble. While this list may
not be exhaustive, to ease the reading of this preamble and for
reference purposes, the EPA defines the following terms and acronyms
here:
APCD air pollution control device
ARV aeration room vent
ASTM American Society for Testing and Materials
CAA Clean Air Act
CBI Confidential Business Information
CEMS continuous emission monitoring system
CEV chamber exhaust vent
CFR Code of Federal Regulations
CMS continuous monitoring system
EAV equivalent annualized values
EPA Environmental Protection Agency
EtO ethylene oxide
FTP File Transfer Protocol
FR Federal Register
HAP hazardous air pollutant
ICR information collection request
IRIS Integrated Risk Information System
NAICS North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
OCAP Office of Clean Air Programs
OMB Office of Management and Budget
ppm parts per million
PRA Paperwork Reduction Act
PTE permanent total enclosure
PS performance specification
PV present values
RFA Regulatory Flexibility Act
RGM Research Gas Mixture
RIA regulatory impact analysis
RTR risk and technology review
SCV sterilization chamber vent
SSM startup, shutdown, and malfunction
SWEL site wide emission limitation
TCEQ Texas Commission on Environmental Quality
tpy tons per year
VCS voluntary consensus standards
Table of Contents. The information in this preamble is organized as
follows:
I. General Information
A. Executive Summary
B. Does this action apply to me?
C. Where can I get a copy of this document and other related
information?
II. Background
A. What is the statutory authority for this proposed action?
B. What is the scope of this reconsideration proposal?
C. What is this source category and how does the current NESHAP
regulate its EtO emissions?
D. What data collection activities were conducted to support
this action?
E. What other relevant background information is available?
III. Reconsideration and Other Issues, Proposed Changes and
Rationale
A. What changes are we proposing for the CAA section 112(f)(2)
standards, and what is the rationale for those decisions?
B. What changes are we proposing for the CAA section 112(d)(6)
standards, and what is the rationale for those decisions?
C. What changes are we proposing for initial and continual
compliance with the emission reduction standards, and what is the
rationale for those decisions?
D. What changes are we proposing to PTE requirements, and what
is the rationale for those actions?
E. What technical corrections and amendments to the Commercial
Sterilization Facilities NESHAP are we proposing, and what is the
rationale for those actions?
F. What technical corrections and amendments to Performance
Specification 19 are we proposing, and what is the rationale for
those actions?
G. What compliance dates are we proposing, and what is the
rationale for the proposed compliance dates?
IV. Severability
V. Summary of Cost, Environmental, and Economic Impacts
A. What are the affected sources?
B. What are the air quality impacts?
C. What are the cost impacts?
D. What are the economic impacts?
E. What are the benefits?
F. What analysis of children's environmental health did we
conduct?
VI. Request for Comments
VII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
[[Page 12703]]
J. National Technology Transfer and Advancement Act (NTTAA)
I. General Information
A. Executive Summary
In this reconsideration action, the EPA is proposing, after
consultation with U.S. Department of Health and Human Services, to
rescind or revise certain amendments made to the Commercial
Sterilization Facilities NESHAP in the 2024 Final Rule to adhere to the
best reading of the statute. The Agency first promulgated standards for
this source category in 1994. Under CAA section 112(f)(2), the EPA was
required to review the standards within eight years to identify and
address residual risk to human health and the environment. Under CAA
section 112(d)(6), the EPA is also required to review and revise the
standards ``as necessary'' at least every eight years to address
developments in practices, processes, and control technologies. In
2006, the Agency discharged these obligations by completing the RTR for
the Commercial Sterilization Facilities source category, finding that
the existing standards adequately protected public health with an ample
margin of safety and, separately, concluding that no further revisions
were ``necessary'' at that time given the minimal emission reductions
and high costs associated with available control strategies.
In 2024, however, the EPA for the first time implemented an
interpretation of CAA section 112(f)(2) that authorizes the Agency to
conduct additional discretionary residual risk reviews (after
completing the mandatory residual risk review within eight years of
promulgating MACT standards) and impose risk-based standards pursuant
to a second risk review. We reasoned in the 2024 Final Rule and related
actions that the Agency possesses this authority because nothing in the
statute expressly precludes discretionary residual risk reviews. Upon
reconsideration, the EPA proposes that the interpretation as finalized
in the 2024 Final Rule is inconsistent with the best reading of the
statute. We ``possess only the authority that Congress has provided,''
\1\ and statutes have a ``single, best meaning'' that is `` `fixed at
the time of enactment.' '' \2\ We propose that, read in context, CAA
section 112(f)(2) explicitly authorizes a single residual risk review
of the MACT standards within eight years, coupled with an express
authority to review and revise the standards ``as necessary'' through a
technology review at least every eight years under CAA section
112(d)(6). This interpretation better reflects the structure of CAA
section 112, which Congress deliberately designed with detailed
implementation timelines and requirements that cannot be squared with
the assertion of authority to revisit residual risk reviews on an ad
hoc, category-by-category basis. We propose to rescind the section
112(f)(2) standards imposed by the 2024 Final Rule on this basis,
thereby returning the Commercial Sterilization Facilities source
category to the generally applicable regulatory framework arising under
section 112(d).
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\1\ NFIB v. DOL, 595 U.S. 109, 117 (2022).
\2\ Loper Bright Enters. v. Raimondo, 603 U.S. 369, 400, 411
(2024) (quoting Wis. Cent. Ltd. v. United States, 585 U.S. 274, 284
(2018)).
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The EPA is also proposing relatively minor adjustments to the
revised standards finalized in the 2024 Final Rule under CAA section
112(d)(6). We propose to reduce the emission standard for new ARVs at
facilities with EtO use of at least 10 tpy, which would result in a
single standard for both new and existing ARVs. This has the benefit of
allowing facilities to share infrastructure, streamline facility
operations, and reflect common practices at facilities. Finally, we are
proposing several technical corrections and clarifications to the
regulatory text identified after publication of the 2024 Final Rule,
including erroneous cross-references, omissions, and typographical
errors.
B. Does this action apply to me?
Table 1 of this preamble lists industrial categories potentially
affected by this action. Table 1 is not intended to be exhaustive but
rather provides a guide for readers regarding the entities that this
proposed action is likely to affect. The proposed standards, once
promulgated, will directly apply to the affected sources. Federal,
state, local, and Tribal government entities would not be affected by
this proposed action. As defined in the Initial List of Categories of
Sources Under Section 112(c)(1) of the Clean Air Act Amendments of 1990
and Documentation for Developing the Initial Source Category List,
Final Report,\3\ the Commercial Sterilization Facilities source
category includes any facility engaged in the use of EtO as a sterilant
and fumigant following the production of various products (e.g.,
medical equipment and supplies) and in miscellaneous sterilization and
fumigation operations at both major and area sources. These commercial
sterilization facilities use EtO as a sterilant for heat- or moisture-
sensitive materials and as a fumigant to control microorganisms.
Facilities may sterilize materials produced on site, or contract
sterilizers may sterilize products manufactured by other companies.
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\3\ 57 FR 31576 (July 16, 1992) and EPA-450/3-91-030, July 1992,
respectively.
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[[Page 12704]]
[GRAPHIC] [TIFF OMITTED] TP17MR26.011
C. Where can I get a copy of this document and other related
information?
In addition to being available in the docket, an electronic copy of
this action is available on the EPA website. Following signature by the
EPA Administrator, the EPA will post a copy of this proposed action at
https://www.epa.gov/stationary-sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities. Following publication in
the Federal Register, the EPA will post the Federal Register version of
the proposal and key technical documents on the same web page.
A memorandum showing the rule edits that would be necessary to
incorporate the changes to 40 CFR part 63, subpart O proposed in this
action is available in the docket (Docket ID No. EPA-HQ-OAR-2019-0178).
Following signature by the EPA Administrator, the EPA also will post a
copy of this document to https://www.epa.gov/stationary-sources-air-pollution/ethylene-oxide-emissions-standards-sterilization-facilities.
II. Background
A. What is the statutory authority for this proposed action?
The statutory authority for this action is provided by CAA section
112, as amended.\4\ CAA section 112 establishes a multi-stage
regulatory process to develop standards for emissions of HAP from
stationary sources. Generally, the first stage involves establishing
technology-based standards that reflect the maximum achievable control
technology (MACT) or an appropriate alternative.\5\ The second stage
involves evaluating those standards within eight years under CAA
section 112(f)(2) to determine whether additional standards are needed
to address any remaining risk associated with HAP emissions.\6\ This
second stage is commonly referred to as the ``residual risk review.''
In addition to the residual risk review, CAA section 112(d)(6) also
requires the EPA to review the standards every eight years and ``revise
as necessary,'' taking into account ``developments in practices,
processes, and control technologies.'' \7\ This review is commonly
referred to as the ``technology review.''
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\4\ 42 U.S.C. 7412.
\5\ 42 U.S.C. 7412(d)(1)-(3).
\6\ 42 U.S.C. 7412(f)(2).
\7\ 42 U.S.C. 7412(d)(6).
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In the first stage of the CAA section 112 standard-setting process,
the EPA promulgates technology-based standards under CAA section 112(d)
for categories of sources identified as emitting one or more of the HAP
listed in CAA section 112(b). Sources of HAP emissions are either major
sources or area sources, and CAA section 112 establishes different
requirements for major source standards and area source standards. The
requirements for major sources are the relevant requirements for the
present rulemaking. ``Major sources'' are those that emit or have the
potential to emit 10 tons per year (tpy) or more of a single HAP or 25
tpy or more of any combination of HAP.\8\ For major sources, CAA
section 112(d)(2) provides that the technology-based NESHAP must
reflect the maximum degree of reduction in emissions of HAP achievable
(after considering cost, energy requirements, and non-air quality
health and environmental impacts). These standards are commonly
referred to as MACT standards. CAA section 112(d)(3) also establishes a
minimum control level for MACT standards, known as the MACT ``floor,''
which is based on emission controls achieved in practice by a certain
percentage of the best performing sources. The EPA also considers
control options that are more stringent than the floor. Standards more
stringent than the floor are commonly referred to as ``beyond-the-
floor'' standards. The next stage in standard-setting focuses on
identifying and addressing any remaining (i.e., ``residual'') risk
within eight years pursuant to CAA section 112(f)(2) and concurrently
conducting a technology review pursuant to CAA section 112(d)(6). This
latter provision requires the EPA to review standards promulgated under
CAA section 112 and revise them ``as necessary (taking into account
developments in practices, processes, and control technologies)'' no
less often than every eight years. In conducting this review, which we
call the ``technology review,'' the EPA is not required to recalculate
the MACT floors that were established in earlier rulemakings.\9\ The
EPA considers cost in deciding whether to revise the standards pursuant
to CAA section 112(d)(6).
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\8\ 42 U.S.C. 7412(a)(1).
\9\ Ass'n of Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C.
Cir. 2013); Natural Resources Def. Council (NRDC) v. EPA, 529 F.3d
1077, 1084 (D.C. Cir. 2008).
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The proposed amendments in this action result from the EPA's
reconsideration of certain aspects of the 2024 Final Rule, including
the interpretation of CAA section 112(f)(2)
[[Page 12705]]
adopted in the 2024 Final Rule to justify imposing additional risk-
based standards rather than solely considering whether such standards
were ``necessary'' under CAA section 112(d)(6). Specifically, the EPA
took the position in the 2024 Final Rule (and again in two additional
rules finalized the following month) that the Agency may, on a
discretionary basis, utilize the risk-review process in CAA section
112(f)(2) to promulgate additional risk-based standards for a source
category that has already undergone a residual risk review after
promulgation of MACT standards.\10\ As explained further below, the EPA
now proposes to interpret CAA section 112(f)(2) as setting out a one-
time authority and obligation to assess the residual risk remaining for
the source category at issue within eight years of promulgating MACT
standards.
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\10\ See New Source Performance Standards for the Synthetic
Organic Chemical Manufacturing Industry and National Emission
Standards for Hazardous Air Pollutants for the Synthetic Organic
Chemical Manufacturing Industry and Group I & II Polymers and Resins
Industry, 89 FR 42932 (May 16, 2024) (finalizing NESHAP amendments
for two source categories in same Federal Register notice). The
Agency proposed to apply this interpretation to a third source
category in a December 2024 proposed rule on which we have not yet
taken final action. See Review of National Emission Standards for
Hazardous Air Pollutants for Polyether Polyols Production Industry,
89 FR 105986 (Dec. 27, 2024).
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Agencies have authority to reconsider prior policy and to revise,
replace, or repeal prior actions to the extent permitted by the
governing statute and supported by a reasoned explanation.\11\ This is
true when, as is the case here, an agency reconsiders a prior action
after a change in administration.\12\ As explained below, the EPA is
proposing to repeal certain standards imposed in the 2024 Final Rule on
the ground that the Agency erred in interpreting CAA section 112(f)(2)
as authorizing the imposition of further rounds of risk-based standards
in lieu of the ongoing authority and obligation at least every eight
years to revise the standards ``as necessary'' under CAA section
112(d)(6). We are also proposing revisions to certain additional
standards promulgated in the 2024 Final Rule under CAA section
112(d)(6). We propose that nothing in the relevant statutory language
precludes or conditions the EPA's authority to repeal the CAA section
112(f)(2) standards based on new conclusions about the best reading of
the statute or the EPA's authority to further revise prior standards
adopted under CAA section 112(d)(6).
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\11\ FDA v. Wages & White Lion Invs., L.L.C., 604 U.S. 542, 567
(2025); FCC v. Fox Television Stations, Inc., 556 U.S. 502, 515
(2009); Motor Vehicle Mfrs. Ass'n, Inc. v. State Farm Mutual Auto.
Ins. Co., 463 U.S. 29, 42 (1983).
\12\ See Nat'l Ass'n of Home Builders v. EPA, 682 F.3d 1032,
1038, 1043 (D.C. Cir. 2012) (explaining that an agency's
``reevaluation of which policy would be better in light of the
facts'' is ``well within'' its discretion and that a change in
administration is a ``perfectly reasonable basis for an executive
agency's reappraisal of the costs and benefits of its programs and
regulations'' (internal quotation marks omitted)).
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In doing so, the EPA acknowledges that this proposed action would,
if finalized, change the position taken in the 2024 Final Rule with
respect to CAA section 112(f)(2) and, at a more granular level, change
several of the Agency's conclusions with respect to standards adopted
in the 2024 Final Rule under CAA section 112(d)(6). The rationale for
each of these changes is described in the relevant section of this
document. We do not believe that the standards or supporting
interpretations adopted in the 2024 Final Rule have generated
significant and cognizable reliance interests, including because the
standards have not yet gone fully into effect. With respect to
questions of statutory interpretation, we do not believe any such
reliance interests could support retaining an action that is
inconsistent with the best reading of the statute. Nevertheless, we
seek comment on whether the 2024 Final Rule and underlying
interpretations have generated such reliance interests and, if so, how
the EPA should consider them in any final action (Question 1).
B. What is the scope of the reconsideration proposal?
On March 12, 2025, the EPA announced that it is reconsidering the
2024 Final Rule.\13\ Subsequently, in a letter dated March 21, 2025,
the EPA provided further details on the reconsideration, indicating
that we would reexamine our authority and decision to undertake a
second residual risk review pursuant to CAA section 112(f)(2), the
standards promulgated pursuant to CAA section 112(d)(6), and the
requirement to demonstrate compliance using a continuous emission
monitoring system (CEMS).\14\ This action is consistent with Executive
Order 14192 which promotes prudent financial management and alleviates
unnecessary regulatory burdens.
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\13\ U.S. EPA, Trump EPA Announces Reconsideration of Air Rules
Regulating American Energy, Manufacturing, Chemical Sectors
(NESHAPs), (March 12, 2025) [Press Release].
\14\ Letter from U.S. EPA to Ethylene Oxide Sterilization
Association, (March 21, 2025), https://www.epa.gov/system/files/documents/2025-03/revised-epa-response-to-meibao-zhuang-eto-sterilizers-reconsideration.pdf.
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In this action, based on the EPA's reconsideration of the 2024
Final Rule, we are proposing amendments to the Commercial Sterilization
Facilities NESHAP. Specifically, the EPA is proposing to rescind the
standards that were established under CAA section 112(f)(2), to amend
the standard promulgated under section 112(d)(6) for new aeration room
vents (ARVs) where EtO use is at least 10 tons per year (tpy), to amend
the compliance demonstration requirements to allow facilities to choose
between annual performance testing and parametric monitoring or
operation of a CEMS, and to rescind the requirement that PTE be used to
ensure complete capture of EtO. This proposal also includes technical
corrections and clarifications to the Commercial Sterilization
Facilities NESHAP and Performance Specification 19 (PS 19). Any other
issues or any other provisions of the 2024 Final Rule not specifically
addressed in this proposed rulemaking are not within the scope of this
proposal, and the EPA reserves the right to respond to such comments as
out of scope.
C. What is this source category and how does the current NESHAP
regulate its EtO emissions?
1. Regulatory Background
The Commercial Sterilization Facilities source category consists of
major and area sources that use EtO to sterilize or fumigate materials,
including medical equipment and supplies, certain spices, and other
miscellaneous products and items. Generally speaking, these facilities
use chambers or sealed pouches to disinfect materials through exposure
to EtO gas at predetermined concentrations (including materials not
amenable to other sterilization techniques, such as high temperatures),
which is then evacuated from the chamber or pouch prior to retrieving
the sterilized materials.\15\ Sources in this category provide
essential sterilization services at scale for hospitals, clinics, and
other medical locations that lack capacity to sterilize equipment at
the volume and regularity required to maintain safe and efficient
operations.
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\15\ For more information, see 88 FR 22796-97 (Apr. 13, 2023).
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The EPA promulgated the initial Commercial Sterilization Facilities
NESHAP on December 6, 1994.\16\ The standards are codified at 40 CFR
part 63, subpart O. The original 1994 rulemaking for this source
category set standards for EtO emissions originating from three
emission points: sterilization chamber vents (SCVs), ARVs, and chamber
exhaust vents (CEVs). The SCV evacuates EtO from the sterilization
[[Page 12706]]
chamber following sterilization, fumigation, and any subsequent gas
washes before the chamber door is opened. The ARV evacuates EtO-laden
air from the aeration room or chamber that is used to facilitate off-
gassing of the sterile product and packaging. The CEV evacuates EtO-
laden air from the sterilization chamber after the chamber door is
opened for product unloading following the completion of sterilization
and associated gas washes.
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\16\ 59 FR 62585 (Dec. 6, 1994).
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In 2006, the EPA finalized the RTR for the Commercial Sterilization
Facilities NESHAP under CAA section 112(f)(2) and CAA section
112(d)(6), respectively.\17\ With respect to the residual risk review,
we concluded that the MACT standards protected public health and the
environment with an ample margin of safety by reducing maximum
individual cancer risk, as well as chronic noncancer and acute risks,
below the levels generally considered acceptable for purposes of CAA
section 112(f)(2).\18\ With respect to the technology review, we
concluded that additional standards ``would achieve, at best, minimal
emission and risk reductions at a very high cost.'' \19\ No changes
were made in the RTR to MACT standards given these findings. In
responding to comments on the residual risk review, we explained that
the Agency considered a California EPA cancer risk estimate as the best
available estimate, for reasons including because it built upon our own
1985 EtO health assessment. We noted that the Agency was working on an
updated cancer assessment for EtO that was not yet complete.\20\
Finally, we disagreed with comments arguing that the residual risk
review should ``account for reasonably foreseeable changes that could
result in increased risk, such as new residences being built closer to
the facility, or increases in actual emissions within the current
permit limitations.'' Specifically, we stated that risk assessments
need not consider such foreseeable changes because we ``have the
authority to revisit (and revise, if necessary) any rulemaking if there
is sufficient evidence'' for doing so, citing to CAA section 301.\21\
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\17\ 71 FR 17712 (Apr. 7, 2006).
\18\ Id. at 17713.
\19\ Id. at 17714.
\20\ Id. at 17715-16.
\21\ Id. (citing 42 U.S.C. 7601).
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In 2022, several environmental groups filed a mandatory duty suit
against the EPA under CAA section 304(a)(2).\22\ The groups alleged
that the EPA failed to perform its non-discretionary duty under CAA
section 112(d)(6) to review, and as necessary revise, the Commercial
Sterilization Facilities NESHAP every eight years. The parties resolved
the lawsuit through a consent decree, which required the EPA to sign a
final rule completing the CAA section 112(d)(6) review by March 1,
2024. The consent decree did not speak to or reference CAA section
112(f)(2).
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\22\ Cal. Communities Against Toxics v. Regan, No. 1:22-cv-03724
(D.D.C).
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2. 2024 Final Rule
In April 2023, the EPA proposed ``decisions concerning'' the
completed RTR, including certain amendments resulting from a second
residual risk review for EtO and additional amendments resulting from a
technology review.\23\ With respect to the second residual risk review,
the Agency proposed to rely on the Integrated Risk Information System
(IRIS) value for EtO issued by the EPA in December 2016 \24\ and, in
``deciding whether to conduct a second residual risk review,''
considered ``the advantages of EtO reductions and the distribution of
those reductions consistent with the clear goal of CAA section
112(f)(2) to protect the most exposed and susceptible populations,
which in this case include communities with EJ [environmental justice]
concerns.'' \25\ We acknowledged at the time that ``CAA section
112(f)(2) requires only a one-time risk review, which is to be
conducted within eight years of the date the initial standards are
promulgated.'' However, we asserted that the provision ``does not limit
the EPA's discretion or authority to conduct another risk review'' and
identified a ``discretionary authority to conduct another CAA section
112(f)(2) analysis'' at will separate and apart from the review and
revision authority provided in CAA section 112(d)(6).\26\
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\23\ 88 FR 22790 (Apr. 13, 2023).
\24\ Evaluation of the Inhalation Carcinogenicity of Ethylene
Oxide, December 2016, EPA/635/R-16/350Fc.
\25\ Id. at 22793.
\26\ Id. at 22794.
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The 2024 Final Rule amended 40 CFR part 63, subpart O pursuant to
CAA sections 112(d)(2) and (3), 112(d)(5), 112(d)(6), and
112(f)(2).\27\ That action established standards for unregulated
sources of emissions (CEV,\28\ Group 1 \29\ and Group 2 \30\ room air
emissions) under the authority of CAA section 112(d)(2) and (3) for
major sources and CAA section 112(d)(5) for area sources. The EPA also
revised the existing standards in response to a technology review under
CAA section 112(d)(6). The EPA for the first time implemented an
interpretation that CAA section 112(f)(2) authorizes the imposition of
new standards based on additional discretionary residual risk reviews
and finalized new risk-based standards after conducting a second risk
review based largely on the 2016 EtO IRIS value. The 2024 Final Rule
also finalized other changes to the NESHAP, including adding
requirements and clarifications for periods of startup, shutdown, and
malfunction (SSM); requiring the use of CEMS to demonstrate compliance
for facilities where EtO use is at least 100 pounds per year (lb/yr);
adding provisions for electronic reporting of performance test results
and reports, performance evaluation reports, and compliance reports;
and other minor editorial and technical changes.
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\27\ 89 FR 24090 (Apr. 5, 2024).
\28\ The standards for CEVs were originally promulgated on
December 6, 1994. Following promulgation of the rule, the EPA
suspended certain compliance deadlines and ultimately removed the
standards for CEVs due to safety concerns. In the late 1990s, there
were multiple explosions at EtO commercial sterilization facilities
using oxidizers to control emissions from CEVs. It was determined
that the primary contributing issue leading to the explosions was
that EtO concentrations were above a safe level (i.e., above the
lower explosive limit (LEL)) within the CEV gas streams. The EPA
could not conclude at the time that the CEVs could be safely
controlled, so the standards for CEVs were removed on November 2,
2001 (66 FR 55583).
\29\ Group 1 room air emissions mean emissions from indoor EtO
storage, EtO dispensing, vacuum pump operations, and pre-aeration
handling of sterilized material.
\30\ Group 2 room air emissions mean emissions from post-
aeration handling of sterilized material.
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Table 2 shows a summary of the 2024 emission standards for
commercial sterilizers facilities in 40 CFR part 63, subpart O.
Footnote 1 of Table 2 shows the standards subject to reconsideration.
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For more information on the commercial sterilization industry and
the 2024 standards under 40 CFR part 63, subpart O see the 2024 Final
Rule preamble.\31\
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\31\ 89 FR 24090 (Apr. 5, 2024).
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D. What data collection activities were conducted to support this
action?
The EPA used data collected during the rulemaking for the 2024
Final Rule for this reconsideration. The EPA began with the facility
list used during the 2024 Final Rule. For details on the data collected
for the 2024 Final Rule, see section II.C of the 2023 proposal
preamble.\32\ Since the promulgation of the 2024 Final Rule, the EPA
identified two facilities that have opened and one facility that has
decommissioned its use of EtO, resulting in a final facility list of 89
commercial sterilization facilities. A complete list of known
commercial sterilization facilities is available in the document titled
2024 Facility List, which is available in the docket for this
rulemaking.
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\32\ 88 FR 22790 (Apr. 13, 2023).
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In addition to the information obtained during the investigation
for the 2024 Final Rule, the EPA held meetings with industry and trade
association representatives to discuss the 2024 Final Rule and the
implementation issues, unintended impacts, and challenges that have
resulted from the rule. Summaries of these meetings can be found in the
docket for this action (Docket ID No. EPA-HQ-OAR-2019-0178).
E. What other relevant background information is available?
On June 5, 2024, the Ethylene Oxide Sterilization Association
(EOSA) and various environmental and community groups, including
California Communities Against Toxics, Clean Power Lake County,
Comit[eacute] Di[aacute]logo Ambiental, Rio Grande International Study
Center, Sierra Club, and the Union of Concerned Scientists, brought
separate judicial challenges to the 2024 Final Rule. The cases were
consolidated and are currently being held in abeyance pending the EPA's
reconsideration of the rule.
On July 17, 2025, President Trump signed the Proclamation,
``Regulatory Relief for Certain Stationary Sources to Promote American
Security With Respect to Sterile Medical Equipment''
[[Page 12709]]
(90 FR 34747, July 23, 2025).\33\ This Proclamation exempted certain
facilities, identified in Annex 1 of the Proclamation, from compliance
with the 2024 Final Rule. The Presidential exemption is for a period of
2 years beyond the 2024 Final Rule's compliance dates. During the
exemption period, facilities identified in Annex 1 that were subject to
the Commercial Sterilization Facilities NESHAP, 40 CFR part 63, subpart
O, in effect prior to the issuance of the 2024 Final Rule must continue
to comply with those standards.
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\33\ A copy of the Presidential Proclamation and Annex 1 are
available in the rulemaking docket (Docket ID No. EPA-HQ-OAR-2019-
0178).
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III. Reconsideration and Other Issues, Proposed Changes and Rationale
The EPA is proposing amendments to the Commercial Sterilization
Facilities NESHAP. Specifically, the EPA is proposing to rescind
standards promulgated under CAA section 112(f)(2), to revise the
standard promulgated under CAA section 112(d)(6) for new ARVs at
facilities using at least 10 tpy of EtO, to amend the compliance
demonstration requirements to allow facilities to choose between
parametric monitoring or CEMS, and to rescind the requirement that PTE
be used to ensure complete capture of EtO. The EPA is also proposing
technical corrections and clarifications to the Commercial
Sterilization Facilities NESHAP and PS 19. The subsequent sections of
this preamble describe these changes in detail as well as provide the
EPA's reasoning for the proposed changes. Table 3 summarizes the
proposed changes to emission limits that would result from this
reconsideration. Specifically, the table shows the proposed rescission
of CAA section 112(f)(2) standards and the resulting changes in
applicable standards affected by this rescission. It also shows the
proposed revised standard for new ARVs at facilities using at least 10
tpy of EtO (i.e., 99.6 percent reduction).
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A. What changes are we proposing for the CAA section 112(f)(2)
standards, and what is the rationale for those decisions?
The EPA is proposing to rescind the risk-based standards
promulgated in 2024 pursuant to CAA section 112(f)(2) for the reasons
explained below.
In 2006, the EPA finalized the RTR for the Commercial Sterilization
Facilities source category pursuant to CAA sections 112(f)(2) and
112(d)(6), consisting of both the eight-year residual risk review under
section 112(f)(2) and the first technology review of the NESHAP for
this source category pursuant to section 112(d)(6).\34\ The EPA
determined that the MACT standards protected public health and welfare
with an ample margin of safety and that any revisions would achieve
minimal emissions reductions at high cost, such that no revisions were
necessary under CAA section 112(f)(2) or CAA section 112(d)(6). For
purposes of the risk review, the EPA relied on evidence and assessments
available at that time, including a cancer risk evaluation developed by
California EPA that was informed by a prior evaluation developed by the
EPA. Since the 2006 RTR, the EPA was subject to a mandatory duty suit
in connection with the ongoing obligation to review the standards under
CAA section 112(d)(6) but did not seek to revisit the residual risk
review until the rulemaking that resulted in the 2024 Final Rule.
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\34\ 71 FR 17712 (Apr. 7, 2006).
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In the 2024 Final Rule, the EPA for the first time implemented an
interpretation of CAA section 112(f)(2) that allowed the Agency to
conduct another residual risk review for this source category and
promulgate additional risk-based standards. In doing so, we
acknowledged that ``CAA section 112(f)(2) requires only a one-time risk
review, which is to be conducted within eight years of the date the
initial standards are promulgated.'' \35\ However, we also concluded
that ``[CAA section 112(f)(2)] does not limit our discretion or
authority to conduct another risk review should we consider that such
review is warranted.'' \36\ The EPA has since revisited the explanation
for this interpretation and proposes that it is incorrect for the
following reasons.\37\
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\35\ 89 FR 24090 (Apr. 5, 2024).
\36\ Id.
\37\ See Summary of Public Comments and Responses for Risk and
Technology Review for Ethylene Oxide Sterilization Facilities
(February 2024) (2024 Rule RTC) (Document ID No. EPA-HQ-OAR-2019-
0178-1595), 229-33.
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First, in 2024, the EPA concluded that the CAA authorizes
additional, discretionary risk reviews because the statute ``does not
prohibit the EPA from revisiting standards promulgated under . . . CAA
section 112(f)(2).'' \38\ However, the EPA did not consider at the time
that a limitation on authority must sometimes be inferred from the
structure of the provision and surrounding statutory language.
``[W]here Congress includes particular language in one section of a
statute but omits it in another section of the same Act, it is
generally presumed that Congress acts intentionally and purposely in
the disparate inclusion or exclusion.'' \39\ Here, Congress enacted a
detailed process and timeline for developing and revising HAP emission
standards under CAA section 112(d), including the general authority and
obligation to promulgate regulations for each listed source category
under section 112(d)(1), the development of MACT standards under
section 112(d)(2)-(3), the health-threshold and area-source regulatory
alternatives under section 112(d)(4) and (5), respectively, and the
ongoing obligation to review and revise standards ``as necessary''
every eight years under section 112(d)(6). In contrast, CAA section
112(f) sets out a one-time obligation and authority to conduct a risk
review for each source category within eight years of promulgating MACT
standards, including a requirement to promulgate additional standards
if the MACT standards-setting process did not adequately address
residual risk and provide an ample margin of safety. One can infer from
the explicit requirement to conduct subsequent technology reviews in
CAA section 112(d)(6), and the absence of such a requirement in section
112(f)(2),
[[Page 12713]]
that Congress did not authorize multiple risk reviews under section
112(f)(2).
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\38\ Id. at 229.
\39\ Nken v. Holder, 556 U.S. 418, 430 (2009) (quoting INS v.
Cardoza-Fonseca, 480 U.S. 421, 432 (1987)); see also Russello v.
United States, 464 U.S. 16, 23 (1983).
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Second, the EPA's prior interpretation did not fully consider the
overall statutory framework of CAA section 112. ``It is a fundamental
canon of statutory construction that the words of a statute must be
read in their context and with a view to their place in the overall
statutory scheme.'' \40\ Here, Congress explicitly set forth a system
of recurring technology reviews every eight years under CAA section
112(d)(6) and a one-time risk review under section 112(f). In addition,
Congress stated twice in section 112(f)(2) that any required standard
must be promulgated within 8 years of promulgating section 112(d)
standards.\41\ Reading section 112(f)(2) to allow more than one
residual risk review that could result in additional risk standards
long after the eight-year statutory deadline, in this case twenty years
after section 112(d) standards were promulgated in 1994, ``would
effectively gut Congress's carefully articulated existing system.''
\42\ Moreover, Congress enacted the detailed regulatory scheme in CAA
section 112 with the express goal of achieving rapid regulation of the
HAP identified in CAA section 112(b) across all relevant source
categories.\43\ An implied authority to conduct discretionary risk
reviews on an ad hoc basis disrupts the statutory scheme by eliminating
the finality of residual risk reviews, undermining certainty for
regulated industry and the public, and placing certain source
categories on a different trajectory from the rest, all without
providing a standard for the use of such implied discretion. This
approach is also inconsistent with CAA section 112(f) itself, which
envisions potential further action from Congress to address residual
risk. CAA section 112(f)(1) required the Agency to develop a report on
the calculation of residual risk, the impacts of such risk, including
the costs of control, and recommendations for further legislation. CAA
section 112(f)(2) required the one-time residual risk within eight
years only if ``Congress does not act on any recommendation submitted
under paragraph (1).'' In this way, CAA section 112 contemplates a one-
time residual risk review, followed by ongoing reductions achieved,
when ``necessary,'' through the promulgation of additional standards
under CAA section 112(d)(6).
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\40\ West Virginia v. EPA, 597 U.S. 697, 721 (2022) (internal
quotations omitted).
\41\ See CAA sections 112(f)(2)(A) and (C).
\42\ Loving v. I.R.S., 742 F.3d 1013, 1020 (D.C. Cir. 2014)
(finding IRS's regulations of tax preparers to be invalid because,
among other factors, the overall statutory framework did not support
IRS's interpretation of the statute to encompass authority to
regulate those entities); see also Natural Resources Def. Council v.
Regan, 67 F.4th 397, 404 (D.C. Cir. 2023) (``Regardless of how
serious the purported problem an administrative agency seeks to
address, it may not exercise its authority in a manner that is
inconsistent with the administrative structure that Congress enacted
into law.'' (citation modified)).
\43\ Per CAA section 112(e), Congress required the Agency to
promulgate MACT standards for all listed source categories by 2000,
with intervening milestones in 1992, 1994, and 1997. Initial source
categories and subcategories were to be listed by 1990 under CAA
section 112(c). The RTRs for those source categories were to be
completed within eight years of the initial standards, meaning that
by approximately 2008, all source categories would be regulated
under standards that provide an ample margin of safety. The
periodic, eight-year technology review under CAA section 112(d)(6)
is the only ongoing review-and-revise obligation for a provision
consciously designed to achieve protections for the HAPs Congress
listed for regulation in the 1990 CAA Amendments.
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Third, the EPA did not appropriately grapple with relevant
regulatory history. The 2024 Final Rule, together with a handful of
actions issued several months later, marked the first time that the
Agency had completed a second, ``discretionary'' residual risk review
and imposed corresponding standards under CAA section 112(f)(2). The
novelty of this approach presents an additional reason to proceed with
caution. In prior actions, including the Benzene NESHAP incorporated by
reference into the statute in CAA section 112(f)(2)(B), the EPA had
acknowledged that residual risk reviews entail significant uncertainty
accounted for, in part, by providing an ample margin of safety, and had
not taken the position that follow-on risk reviews under CAA section
112(f)(2) were the appropriate mechanism to address new information.
Rather, the EPA has reviewed and revised ``as necessary'' under CAA
section 112(d)(6), including by evaluating the cost-effectiveness of
potential developments by reference to the nature of the risk posed by
the particular HAP at issue (i.e., by accepting higher values for cost-
per-ton of emission reduction for extremely dangerous HAP).\44\ We
propose that contrary statements made in the 2024 Final Rule, including
the statement that ``the EPA's discretion to revise prior standards
where the statute does not contain limiting language . . . has been
implemented without controversy,'' misapprehended the nature of the
cited actions and did not account for the mine run of consistent
regulatory practice.\45\ We further propose that the 2024 Final Rule
overread the statement in the 2006 RTR that, in response to a comment
suggesting residual risk reviews should account for future
uncertainties, the Agency may ``revisit (and revise, if necessary) any
rulemaking if there is sufficient evidence'' for doing so, citing to
CAA section 301.\46\ Read in context, this statement is better
understood as a general reference to the EPA's authority to reconsider
and revise under CAA section 112(d)(6), which is where the operative
term ``necessary'' appears in the statute. In any event, that statement
does not stand for the proposition that the Agency anticipated
finalizing an entirely new residual risk review and associated
standards nearly 20 years later based on a new record and new
considerations, nor did it grapple with the text and structure of the
statute as we propose to do in this action.
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\44\ See National Emission Standards for Hazardous Air
Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating
Units: Final Repeal, 91 FR 9088, 9099 (Feb. 24, 2026) (``2026 MATS
Repeal'') (explaining that ``the statutory benchmarks for risk
provide relevant guidance on whether additional regulation is
`necessary' under CAA section 112(d)(6)'').
\45\ 2024 Rule RTC at 229-33. For example, the EPA cited at that
time a prior action to revise new locomotive and engine standards
under CAA section 213(a)(5) without acknowledging the substantially
different text and structure of that provision. Id. Similarly, the
EPA cited prior actions to remove standards or revise a MACT floor
that did not involve the imposition of new standards under CAA
section 112(f)(2). Id.
\46\ 71 FR 17715-16 (citing 42 U.S.C. 7601).
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Lastly, the EPA cited CAA section 307(d)(1)(C) as supporting the
EPA's authority to conduct a discretionary risk review. The EPA
concluded that this provision ``assumes the EPA might review standards
set under 112(f)(2) and imposes CAA section 307(d) rulemaking processes
on such revisions, when conducted.'' \47\ Section 307(d)(1)(C), which
references ``the promulgation or revision of . . . any standard under
section [112(f)(2)],'' acknowledges that there are situations where
section 112(f)(2) standards might be revised, not that the EPA has the
discretion to revise such standards when it chooses. For example, the
EPA might have to revise a section 112(f)(2) standard as the result of
an adverse judicial decision or mandatory administrative
reconsideration under CAA section 307(d)(7)(B). Under those scenarios,
the EPA would be required to reconsider a prior risk review. However,
because the EPA may be required to reconsider and revise section
112(f)(2) standards in certain limited circumstances does not speak to
whether the EPA may conduct a discretionary second risk review.
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\47\ See id.
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For these reasons, the EPA proposes to find that the CAA does not
authorize the discretionary second risk review that the Agency
conducted for this source category in 2024. The EPA is therefore
proposing to rescind the risk
[[Page 12714]]
standards promulgated in the 2024 rule. These standards can be seen in
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table 3 and are as follows:
99.99 percent reduction for new and existing SCVs where EtO
use is at least 30 tpy
99.9 percent reduction for new and existing SCVs where EtO use
is at least 10 but less than 30 tpy
99.9 percent reduction for new and existing ARVs where EtO use
is at least 30 tpy
99.6 percent reduction for existing ARVs where EtO use is at
least 10 but less than 30 tpy
99.9 percent reduction for area source CEVs where EtO use is
at least 60 tpy
98 percent reduction for new and existing Group 1 room air
emissions where EtO use is at least 40 tpy
98 percent reduction for new and existing Group 2 room air
emissions where EtO use is at least 20 tpy
80 percent reduction for new and existing Group 2 room air
emissions where EtO use is at least 4 but less than 20 tpy
After the proposed removal of these risk-based standards, affected
sources would be required to comply with their section 112(d)(2) and
(3) or 112(d)(5) standards; if such standards have been revised
pursuant to section 112(d)(6), affected sources would comply with their
section 112(d)(6) standards. Additionally, the EPA proposes that for
existing source Group 2 room air emissions, facilities may choose to
comply with either the existing source standard (lower EtO
concentration to 1 ppm before opening the aeration chamber) or the new
source standard (80 percent reduction of EtO). The EPA is proposing
this change to address concerns that the existing source standard may
impact the supply chain of medical equipment. Table 3 above identifies
the applicable standards for these affected sources with the removal of
the section 112(f)(2) standards.
The proposed amendments would remove the EtO-usage based
subcategories that resulted from the section 112(f)(2) standards, and
facilities that would have been subject to those standards would
instead be subject to the appropriate subcategories as promulgated by
the 2024 Final Rule under section 112(d)(2), (3), (5), or (6). For
instance, for both new and existing SCVs, EtO use categories for
facilities where EtO use is at least 30 tpy, and for facilities where
EtO use is at least 10 tpy but less than 30 tpy under CAA section
112(f)(2), would also be removed in conjunction with the proposed
rescission of section 112(f)(2) standards. As a result, these
facilities will all be in the subcategory of facilities where EtO use
is at least 10 tpy. Similarly, for new and existing ARVs, with the
removal of subcategories established under section 112(f)(2) for
facilities where EtO use is at least 30 tpy and facilities where EtO
use is at least 10 tpy but less than 30 tpy, these facilities would all
comprise a single subcategory of facilities where EtO use is at least
10 tpy.
Additionally, area sources of CEVs, Group 1 room air emissions,
existing Group 2 room air emissions, and new Group 2 room air emissions
would each have a single standard rather than different risk-based
standards due to subcategorization based on a facility's EtO use under
section 112(f)(2). The EPA is proposing amendments to the applicable
standards in tables 1 to 5 to subpart O of part 63 to address these
changes. The EPA is soliciting comment on the proposed removal of the
CAA section 112(f)(2) emission standards and all related questions of
statutory interpretation, including any additional regulatory history
or case law bearing on the best reading of CAA section 112 and the
Agency's rationale for changing the position taken in the 2024 Final
Rule and related actions (Question 2).
Separate from the EPA's position on the Agency's authority to
conduct a second CAA section 112(f)(2) risk review described above, we
are proposing that significant uncertainties regarding the magnitude of
EtO's carcinogenic potency, particularly at low concentrations, would
be an additional reason for rescinding the EtO standards in the 2024
Rule and seeking detailed comment on this issue from interested
stakeholders. Specifically, we propose that it would not be appropriate
to rely on the 2016 EtO IRIS value in setting standards. If this
position is finalized, the EPA would evaluate as necessary and
appropriate in future regulatory actions other EtO risk values, ranges,
or additional means to assess risk when relevant to the statutory
scheme.
Because such comment submissions will be essential to informing
whether this proposed rationale is an appropriate basis for taking
final action, we request that interested stakeholders provide relevant
data, studies, and analyses to support any claims made about the
adequacy or inadequacy of the 2016 EtO IRIS value and any alternative
values the commenter believes would be more appropriate and consistent
with the statutory framework. If commenters believe a range or multiple
potential values would be appropriate or wish to opine on the breadth
of the Agency's discretion to select among values, we ask that the
commenter support such assertions with appropriate citations. Although
the EPA will respond to all significant comments received, we view such
information as critical to ensuring that the record reflects all
perspectives and relevant information given the highly technical nature
of issue and the breadth of potentially relevant scientific and other
literature.
The EPA previously acknowledged that uncertainties regarding the
magnitude of EtO's carcinogenic potency could materially affect risk
estimates, thereby substantially informing the risk evaluation as a
whole and any resulting standards. As discussed in a 2019 technical
memorandum,\48\ the EPA identified two key sources of uncertainty in
the 2016 EtO IRIS value: dose-response model selection and the use of
the statistical upper confidence limit. Regarding the former, during
the development of the 2016 EtO IRIS value, the EPA considered many
different dose-response models to describe the available lymphoid
cancer data. Several of these models, including the one the EPA
ultimately selected, fit the exposure data well. However, the EPA
estimated that choosing one of the alternative viable models could have
resulted in an EtO IRIS value up to two times lower than the final 2016
EtO IRIS value. Regarding the latter, while the EPA chose to focus on
the statistical upper confidence limit of the cancer value, the Agency
later estimated that using the statistical central estimate instead
could have resulted in an EtO IRIS value up to three times lower than
the final value. The technical memo concluded that, if combined, these
two factors could have resulted in an EtO IRIS value that was up to
five times lower (i.e., EtO is five times safer than the 2016 EtO IRIS
value provided). The analysis in the technical memorandum demonstrates
that both model selection and the underlying cancer data (in this case
epidemiological studies of cancer in humans exposed to EtO) can greatly
influence the resulting risk estimate. It is important to note that the
analysis in the technical memorandum relies entirely on results and
equations presented in the final EtO IRIS assessment, which was peer
reviewed by EPA's Science Advisory Board.
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\48\ Sensitivity of Ethylene Oxide Risk Estimates to Dose-
Response Model Selection. Memorandum drafted by EPA's Office of
Research and Development, docketed in the Miscellaneous Organic
Chemical Manufacturing NESHAP Proposed Rule, 84 FR 69182 (Dec. 17,
2019).
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The EPA recognizes that the Agency defended its use of the 2016 EtO
IRIS value in Huntsman Petrochemical LLC
[[Page 12715]]
v. EPA.\49\ In that case, industry groups challenged the EPA's 2020
Miscellaneous Organic Chemical Manufacturing NESHAP (MON) rule \50\ and
the EPA's 2022 reconsideration of that rule.\51\ The main issues raised
in industry's reconsideration petition and the resulting consolidated
litigation were whether the EPA acted reasonably in using the 2016 EtO
IRIS value and rejecting the Texas Commission on Environmental
Quality's (TCEQ) alternative value. Industry challenged numerous
technical decisions made by the EPA in the course of developing the
2016 EtO IRIS value, including but not limited to, model selection and
choice of underlying epidemiological studies and exposure
estimates.\52\ Ultimately, the U.S. Court of Appeals for the D.C.
Circuit denied the petitions for review of the 2020 MON Rule and the
2022 reconsideration, finding that Petitioners failed to show that EPA
had acted arbitrarily and capriciously in using the 2016 EtO IRIS
value.\53\
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\49\ 114 F.4th 727 (D.C. Cir. 2024).
\50\ 85 FR 49,084 (Aug. 12, 2020).
\51\ 87 FR 77,985 (Dec. 21, 2022).
\52\ See Huntsman, 114 F.4th at 737-40.
\53\ Id. at 742.
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While the EPA defended its use of the 2016 EtO IRIS value in the
2020 MON rule and subsequent reconsideration action, the Agency
acknowledged at the time it issued the rule that significant
uncertainties remained regarding the magnitude of EtO's carcinogenic
potency, as discussed above. It is known that EtO can be produced
within the body (endogenously) via normal metabolic processes and that
tobacco smoke is a source of EtO exposure. However, the EPA recognized
that uncertainties remained regarding the quantity and relative
contribution of endogenous, tobacco smoke, and background EtO levels
from non-industrial sources. Furthermore, the EPA recognizes that new
empirical data may trigger a need to reevaluate toxicity values. For
example, prior to 2016, the EPA used a toxicity value derived in 1985
to estimate the cancer risk from EtO and, in rulemakings including the
2006 RTR for the Commercial Sterilization Facilities NESHAP, used
assessments that were informed by and built upon that value (including
an analysis issued by the California EPA). Such values reflected the
best evidence available at that time, but newer epidemiological studies
later prompted both the EPA and TCEQ to produce updated
assessments.\54\ Since the EPA defended the use of the 2016 EtO IRIS
value in Huntsman, new scientific evidence has continued to
emerge.55 56 While it is not entirely clear how many new
studies or methodological advancements have developed in recent years,
given the sensitivity of EtO risk estimates at low concentrations to
both model selection and the underlying cancer data, it is plausible
that any new information could change the EPA's understanding of EtO's
carcinogenic potency. Therefore, the EPA is proposing that the
significant uncertainties in the 2016 EtO IRIS value are an additional
reason to support reconsideration and repeal of the 2024 Final Rule,
separate and apart from the limits on our authority to conduct a
residual risk review under CAA section 112(f)(2), and seeking detailed
comment on that issue as indicated throughout this section.
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\54\ Both the 2016 EtO IRIS and the 2020 EtO TCEQ assessments
have undergone expert peer review by authoritative bodies. See
Science Advisory Board (SAB). 2015. Science Advisory Board Review of
the EPA's Evaluation of the Inhalation Carcinogenicity of Ethylene
Oxide (Revised External Review Draft--August 2014). EPA-SAB-15-012.;
and National Academies of Sciences, Engineering, and Medicine. 2025.
Review of Texas Commission on Environmental Quality's Ethylene Oxide
Development Support Document. Washington, DC: The National Academies
Press.
\55\ Kelly-Reif K., Bertke S.J., Stayner L., Steenland K.
Exposure to Ethylene Oxide and Relative Rates of Female Breast
Cancer Mortality: 62 Years of Follow-Up in a Large US Occupational
Cohort. Environ Health Perspect. 2025 May;133(5):57013. doi:
10.1289/EHP15566. Epub 2025 May 22. PMID: 40168621; PMCID:
PMC12097532.
\56\ Valdez-Flores C, Li A.A., Bender T.J., Teta M.J. Use of
updated mortality study of ethylene oxide manufacturing workers to
inform cancer risk assessment. Risk Anal. 2025 Sep;45(9):2822-2837.
doi: 10.1111/risa.70057. Epub 2025 Jun 3. PMID: 40458005; PMCID:
PMC12474530.
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Specifically, the EPA is soliciting comment on any new information
related to the underlying cancer data, such as epidemiological studies
of cancer in humans exposed to EtO or advancements relevant to
analyzing the relationship between occupational human exposure to EtO
and the development of cancer not yet considered by the Agency
(Question 3). Given the acknowledged impact of model selection, the EPA
is also soliciting comment on any new or updated information relevant
to dose-response model selection such as consideration of statistical
analyses, visual model fit, or biological plausibility (Question 4).
Further, the EPA is soliciting comment on any new or updated studies on
human exposure to EtO, including information on occupational, smoking,
background, or endogenous exposures not yet considered by the Agency
(Question 5). The EPA anticipates that such information would be useful
for updating the Agency's understanding of EtO exposure and toxicity
and determining whether the 2016 EtO IRIS value remains suitable for
estimating risk to inform regulatory decision-making. Finally,
acknowledging that the EPA has received additional comments on the 2016
EtO IRIS value in the context of other rulemaking proposals issued
after the 2024 Commercial Sterilizers final rule, the EPA is soliciting
comment on the information provided in those comments; this includes
information provided by commenters in the context of the more recent
proposed Chemical Manufacturing Area Sources NESHAP (January 22, 2025)
(see Docket ID EPA-HQ-OAR-2024-0303, comment numbers 0060, 0061, 0068,
0076, and 0079) (Question 6). As noted previously, we ask that
commenters support claims with respect to the 2016 EtO IRIS value, any
alternative value, or any alternative range or approach to determining
risk with relevant data, studies, analyses, and other citations that
the commenter believes should be considered in tandem with, or instead
of, the previously recognized uncertainties in the IRIS methodology.
B. What changes are we proposing for the CAA section 112(d)(6)
standards, and what is the rationale for those decisions?
The 2024 Final Rule also included a technology review pursuant to
CAA section 112(d)(6) for the Commercial Sterilization Facilities
source category that resulted in revisions to certain standards. Among
these revisions were emission standards for both new and existing ARVs
at facilities where EtO use is at least 10 tpy. The standard for new
ARVs at facilities using at least 10 tpy of EtO was 99.9 percent
reduction, and the standard for existing ARVs at facilities using at
least 10 tpy of EtO was 99.6 percent reduction. The EPA established the
new source standard based on the conclusion that it achieved greater
reduction and was more cost-effective than the two options considered
(the other option being 99.6 percent reduction). The EPA set the
existing source standard at a level that the Agency determined to be
achievable by all sources.\57\
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\57\ 89 FR 24090 (Apr. 5, 2024).
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The EPA continues to believe that the standard for existing ARVs at
facilities using at least 10 tpy of EtO is reasonable. The data
provided by industry when developing the 2024 Final Rule demonstrates
that 75 percent of facilities already achieve 99.6 percent reduction,
and 50 percent already achieve 99.9 percent reduction of EtO from ARVs,
demonstrating for purposes
[[Page 12716]]
of relevant considerations under CAA section 112(d)(6) that the
enhanced standard is reasonable and properly considered ``necessary''
as a revision.\58\ However, for the reasons explained below, the EPA is
proposing to amend the standard for new ARVs at facilities using at
least 10 tpy of EtO to 99.6 percent reduction.
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\58\ Although rates of achievement by individual sources are
often an indicator that revisions to a standard are ``necessary,''
that is not always the case, particularly when the costs of controls
are very high and the remaining risks are very low. See, e.g., 2026
MATS Repeal, 91 FR 9088 (Feb. 7, 2026).
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During the development of the 2024 Final Rule, for new ARVs at
facilities where EtO use is at least 10 tpy, the EPA evaluated the
cost-effectiveness of two options: 99.6 percent EtO reduction and 99.9
percent reduction.\59\ When preparing cost-effectiveness calculations
for new sources, the EPA based the calculations on a model plant for
new ARVs reflecting the average number of ARVs, EtO use, and operating
hours as an existing facility.\60\ This resulted in the following cost-
effectiveness values for the two options: $2.2 million per ton at a
99.9 percent EtO reduction and $2.6 million at a 99.6 percent EtO
reduction. As a result, the EPA promulgated the 99.9 percent EtO
reduction standard for new ARVs at facilities where EtO use is at least
10 tpy because it would achieve greater emission reductions and be more
cost-effective than a 99.6 percent reduction standard.\61\ However,
upon reconsideration, the EPA realizes that our cost-estimate approach
did not accurately reflect the costs of new ARVs installed at existing
facilities. Specifically, the EPA did not consider that, under the 99.6
percent reduction option, which would result in the same standards for
both new and existing ARVs, a new ARV could share and make use of
ductwork, control devices, and other existing infrastructure for the
ARVs already in place at the facility; therefore, the expected capital
and annual costs for the 99.6 percent reduction option would be much
lower than the estimate in the 2024 Final Rule. Sharing controls would
also reduce the amount of auxiliary fuel burned in combustion-type
control devices. Further, it is common practice for facilities to share
ductwork or control devices across multiple sources, and the 99.6
percent reduction option, which would result in a single standard for
both new and existing ARVs at facilities using at least 10 tpy of EtO,
has the benefit of allowing facilities to share infrastructure,
streamline facility operations, and reduce costs.
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\59\ For a detailed discussion of cost-effectiveness, see
section III.F.3 of the 2023 proposal preamble, 88 FR 22790 (Apr. 13,
2023).
\60\ 88 FR 22790 (Apr. 13, 2023).
\61\ 88 FR 22841 (Apr. 13, 2023).
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For the reasons explained above, the EPA is proposing to change
from 99.9 to 99.6 percent reduction for new ARVs at facilities with EtO
use of at least 10 tpy, resulting in a single uniform standard for both
new and existing ARVs at these facilities. This standard reflects the
level already achieved by 75 percent of ARVs for which the EPA has
data. The EPA is soliciting comment on this proposed emission standard,
the approach by which the EPA arrived at this decision, and data
regarding the costs of installing ARVs at existing facilities versus
new facilities (Question 7).
Additionally, some industry representatives have suggested that the
ARV standards be based on manufacturer guaranteed levels for emission
reductions. This issue was also raised during the rulemaking that led
up to the 2024 Final Rule.\62\ At that time, industry concerns
regarding this topic were focused on the requirement to use CEMS for
demonstrating compliance. However, as discussed in the following
section of this document, the EPA is proposing to revise the standards
so that the use of CEMS is no longer mandatory. In any case, while the
EPA is significantly concerned about setting standards more stringent
than manufacturer certifications, the Agency does not have data on the
manufacturer's guaranteed levels for reducing ARV emissions. As such,
the EPA is also soliciting comment on whether there is still a concern
that would necessitate considering setting ARV standards based on
manufacturer guaranteed levels and, if so, what the manufacturer
guaranteed level of EtO reduction is for ARVs (Question 8).
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\62\ 88 FR 24090 (Apr. 5, 2024).
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C. What changes are we proposing for initial and continual compliance
with the emission reduction standards, and what is the rationale for
those decisions?
The 2024 Final Rule requires compliance demonstration using EtO
CEMS for all facilities except those using less than 100 lb/year
``because risk remains at acceptable levels for these facilities even
when considering uncontrolled emissions.'' \63\ The 2024 Final Rule
allows these facilities with ``acceptable [risk] levels'' the option of
using either parametric monitoring and performance testing or CEMS to
demonstrate compliance with the promulgated emission standards. The EPA
acknowledged that ``in the majority of instances, parametric monitoring
is used to good effect as an ongoing means of ensuring that the control
devices continue to get necessary emission reductions.'' \64\ The EPA
is proposing to provide all facilities, including those using at least
100 lb/yr of EtO, the option of using either parametric monitoring and
performance testing or CEMS to demonstrate compliance for the following
reason.
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\63\ 89 FR 24132 (Apr. 5, 2024).
\64\ Id.
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Under the 2024 Final Rule, whether EtO CEMS is required is based on
facility risks, which were derived from a second residual risk
assessment the EPA conducted for this source category under CAA section
112(f)(2). However, for the reasons explained in section III.A of this
preamble, the EPA is proposing that CAA section 112(f)(2) does not
authorize the EPA to conduct a second residual risk review and
promulgate associated risk-based standards when the RTR has already
been completed and the ongoing review-and-revise obligation and
authority arises only under CAA section 112(d)(6). Because the EtO CEMS
requirement was based on the results of an unauthorized second residual
risk assessment and risk-based standards-setting for this source
category, the EPA is proposing to amend the 2024 Final Rule to remove
EtO CEMS as a requirement for facilities using at least 100 lb/yr of
EtO and instead allow all facilities, regardless of the amount of EtO
used, the option to choose between parametric monitoring or CEMS for
demonstrating compliance. As proposed, both demonstration options would
be available for all facilities. The EPA thus proposes revisions to 40
CFR 63.363(a), (b), (d), (e), and (f)(2) and to 63.365(a), (b), (c),
and (d) to allow initial and continuous compliance with annual
performance testing and parameter monitoring, and to allow EtO CEMS as
an alternative compliance option. The EPA is soliciting comment on
allowing all facilities the option to choose between parametric
monitoring or CEMS for demonstrating compliance (Question 9).
In addition, the EPA is proposing amendments to the parametric
monitoring provisions in the 2024 Final Rule. In reconsidering the
compliance demonstration requirements in the 2024 Final Rule, the EPA
noticed that the parametric monitoring provisions, which were
promulgated in the original Commercial Sterilization Facilities NESHAP
in 1994, with technical corrections in the 2001 amendments, do not
reflect the current understanding of air pollution control devices
(APCDs) or the sterilization process(es). The EPA is
[[Page 12717]]
thus proposing to update the monitoring parameters for APCDs in 40 CFR
63.361, 63.363(c), and 63.364(b), (c), and (d). In addition, the EPA is
proposing revisions to the procedures for establishing operating
parameter limits during the performance test in 40 CFR 63.365(e). The
EPA is also proposing clarifying language that describes where the
performance testing should be conducted in 40 CFR 63.365(b)(1),
providing for the myriad of APCD configurations expected from this
source category. The proposed amendments for parametric monitoring are
described in the following paragraphs.
For those facilities that use acid-water scrubbers, thermal
oxidizers, catalytic oxidizers, gas-solid reactors, or other control
devices, the EPA is proposing they demonstrate compliance with the
emission reduction standard through initial and annual performance
testing and establish parametric operating limits. The EPA is also
proposing to allow continuous compliance through parametric monitoring
using a continuous parametric monitoring system. The EPA is proposing
that facilities must determine compliance with the operating limits
continuously on a 1-hour block basis instead of the current 3-hour
block. Sterilization is an irregular process where the EtO emissions
may fluctuate greatly with different steps in the process, some of
which are less than three hours. Longer averaging times could mask how
the emission controls operate and achieve the required control
efficiency during operational periods immediately before or after
higher EtO loading to the control devices (e.g., during SCV exhaust
cycles).
For facilities that use an acid-water scrubber, the current
monitoring parameters are ethylene glycol concentration, scrubber
liquid tank level, and scrubber liquid pH. Based on EPA's current
understanding of acid-water scrubbers, the EPA believes that scrubber
liquid-to-gas ratio and scrubber liquid temperature are more accurate
indicators of compliance than ethylene glycol concentration and
scrubber liquor tank level. The EPA believes this because they are
direct indicators that EtO will be captured in the scrubbing columns
and the parameters can be monitored in real-time to ensure continuous
operation. The EPA is therefore proposing to require continuous
monitoring of scrubber liquid-to-gas ratio, scrubber liquid
temperature, and scrubber liquid pH. The Agency is proposing that
during each annual performance test, the owner or operator determines
the average scrubber liquid-to-gas ratio, average inlet scrubber
temperature, and average scrubber liquid pH. The EPA is proposing these
parameter test averages would be the operating limit for the minimum
scrubber liquid-to-gas ratio, maximum temperature of the scrubber
liquid, and the maximum scrubber liquid pH.
For facilities that use thermal oxidizers, the current monitoring
parameter in the rule is the temperature in or immediately downstream
of the firebox. The EPA is proposing to require continuous monitoring
of the combustion chamber temperature and flue gas flow rate. First,
the Agency is proposing to replace the term ``firebox'' with
``combustion chamber'' as the latter is a more commonly used term in
the industry. Second, the EPA is proposing monitoring the combustion
chamber temperature (instead of allowing the option of monitoring
immediately downstream) at a location designated by pollution control
manufacturers to ensure proper control and operation. Third, the Agency
is also proposing to monitor flue gas flow rate. The flue gas flow rate
provides an indication of the thermal oxidizer residence time, which is
a critical operating parameter because it will ensure proper flow rate
through the thermal oxidizer is being maintained to ensure the
continued removal efficiency of any EtO in the sample stream sent to
the oxidizer. The EPA is proposing that during each annual performance
test facilities determine the average combustion chamber temperature
and average flue gas flow rate. The EPA is proposing these parameter
test averages would be the operating limit for the minimum combustion
temperature and maximum flue gas flow rate.
For facilities that use a catalytic oxidizer, the current
parameters are the temperature at the inlet to the catalyst bed and the
temperature difference across the catalyst bed, which requires
monitoring the inlet temperature to the catalyst bed and the outlet
temperature to the catalyst bed. The EPA is proposing to also require
continuous monitoring of flue gas flow rate. The flue gas flow rate
parameter would provide an indication of the catalytic oxidizer
residence time, which is a critical operating parameter because it will
ensure that proper flow rate through the catalytic oxidizer is being
maintained to ensure the continued removal efficiency of any EtO in the
sample stream sent to the oxidizer. Thus, the Agency is proposing to
require continuous monitoring of the inlet and outlet temperatures and
flue gas flow rate. The EPA is proposing that during each annual
performance test, facilities determine the average inlet temperature to
the catalyst bed, the average temperature difference between the inlet
and the outlet of the catalyst bed, and average flue gas flow rate. The
EPA is proposing these parameter test averages would be the operating
limit for the minimum temperature at the inlet to the catalyst bed, the
minimum temperature difference across the catalyst bed, and the maximum
flue gas flow rate.
For facilities that use a gas-solid reactor, the current parameters
include bed media analysis (i.e., sample the bed media and analyze for
activity) and the pressure drop across the media beds. In its place,
the EPA is proposing that facilities must determine the average
pressure drop across the reactor during each annual performance test
and for this test average to be the operating limit for the maximum
gas-solid reactor pressure drop. The EPA is also proposing that when a
gas-solid reactor is used as the last air pollution control device
prior to exhausting to the atmosphere, facilities must determine the
EtO average mass emission sent to the pollution control and the outlet
flow rate during the annual performance test. Using this information
and the applicable emission reduction standard, facilities must
calculate the upper gas-solid reactor outlet EtO concentration
operating limit. The EPA is also proposing that compliance with the
outlet EtO concentration operating limit must be measured and recorded
weekly. Compared to the current media analysis, this proposed parameter
monitoring provides a direct assessment of ongoing performance and will
ensure that the control device is optimized, and that the applicable
emission reduction standard is being met by meeting the set operating
limit.
To maximize flexibility in conducting parametric monitoring, the
2024 Final Rule allows facilities to apply to the EPA Administrator for
approval of alternative monitoring requirements for the typical APCDs.
The EPA is proposing to provide the requirements to be included in the
application for alternative monitoring parameters in 40 CFR
63.365(e)(6).
For those facilities using performance testing and a control device
other than acid-water scrubbers, catalytic or thermal oxidizers, or
gas-solid reactors, the 2024 Final Rule requires that facilities must
establish operating limits and appropriate monitoring parameters that
are approved by the EPA Administrator for that specific control device.
In this action, the EPA is proposing that facilities must develop a
[[Page 12718]]
monitoring plan for their chosen continued compliance option
(parametric monitoring or CEMS); see proposed rule text in 40 CFR
63.364(a)(6) and (7).
The EPA is proposing to update the reporting and recordkeeping
requirements of the Commercial Sterilization Facilities NESHAP in 40
CFR 63.366 and 63.367 to reflect the revised parametric monitoring
discussed above. As required by the 2024 Final Rule, if there are
deviations from the established operating parameter limits, facilities
must report the deviation in the quarterly compliance report.
Facilities must take corrective actions to minimize emissions and
return the unit to normal operations. If the established operating
parameters cannot be met after the corrective action, the facility must
reset the operating parameters with a performance test.
The EPA is soliciting comment on these proposed changes to the
performance testing, parametric monitoring, and reporting requirements
(Question 10).
D. What changes are we proposing to PTE requirements, and what is the
rationale for those actions?
The EPA is proposing to rescind the requirement to use PTE to
ensure capture of EtO to comply with the emission reduction standards.
In the 2024 Final Rule, the EPA finalized requirements to operate PTE
in accordance with the requirements of Method 204 as a compliance
assurance measure. In the proposal to the 2024 Final Rule, the EPA
noted that these requirements were ``consistent with what has been
applied to many of the commercial sterilizers that have installed PTEs,
through permit conditions.'' \65\ In this reconsideration, we are
reevaluating this approach. Based on our review of state permits for
sterilization facilities, we note that some permits require PTE while
others do not. We further note that configuration and design of
sterilization facilities vary widely. The above observations suggest
that whether PTE would be necessary to assure compliance with an
emission standard could depend on a facility's design and
configuration. The EPA has historically left such case-by-case reviews
of facility design to the states to decide as part of their permitting
process.
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\65\ See 88 FR 22819 (Apr. 13, 2023).
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The EPA is proposing in the alternative to rescind the requirement
for PTE on the following bases. First, we propose that the EPA did not
account for the impacts of facilities shutting down due to this
variation. If the facility is unable to establish a PTE and meet the
other requirements, then the facility would be required to shut down
thus significantly raising the costs and making it not cost-effective
to establish PTE. The feasibility of PTE has been raised by
stakeholders over time with respect to this NESHAP, and we seek comment
on this potential alternative basis (Question 11).
Second, the EPA is proposing in the alternative that the PTE
requirement is not compelled by the D.C. Circuit's decision in
Louisiana Environmental Action Network v. Environmental Protection
Agency (LEAN),\66\ meaning that, at minimum, the Agency has discretion
whether to remove the PTE requirement as a compliance mechanism. In
previous rules, the EPA has stated or suggested that LEAN requires the
Agency, as part of the technology review process under CAA section
112(d)(6), not only to regulate previously unregulated pollutants, but
also to prescribe additional standards for already regulated pollutants
emitted in a manner (i.e., from points or fugitive) not expressly
contemplated under the existing standards. In LEAN, the D.C. Circuit
discussed its view of the Agency's obligation to regulate previously
unregulated (i.e., unaddressed) pollutants when conducting a technology
review and revising standards ``as necessary'' under CAA section
112(d)(6). In context, the court analyzed the statute with respect to,
and referred specifically to, different types of air toxics (i.e.,
previously regulated and previously unregulated pollutants).\67\ In
certain actions since that decision, however, the EPA has sometimes
suggested that this holding includes not only previously unregulated
pollutants, but also additional emission points within an already
regulated source (e.g., an additional point or fugitive) that emit
pollutants already captured by the NESHAP. We now propose to clarify
that when conducting a CAA section 112(d)(6) review, the EPA is not
obligated under the interpretation adopted in LEAN to prescribe
particular standards for emission points with respect to pollutants
already regulated under the NESHAP. If finalized, this proposed
position would mean that the EPA's rationale for adopting the PTE
requirement--i.e., that such a requirement was necessary to assure
compliance with additional standards mandated by LEAN--is no longer
operative, and we would decline to adopt such a requirement as a
discretionary matter for the reasons discussed previously. The EPA
requests comments on all aspects of these alternative proposals,
including with respect to the scope of the interpretation adopted by
the D.C. Circuit in LEAN and the scope of the Agency's obligation and
statutory authority to impose additional standards under the CAA
section 112(d)(6) process for particular emission points not previously
regulated (Question 12).
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\66\ 955 F.3d 1088 (D.C. Cir. 2020)
\67\ See id. at 1096.
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In light of the above, we propose to rescind the requirement to use
PTE as a compliance assurance measure. The proposed change would not
affect the permitting process for any state, which could continue to
decide on a case-by-case basis, deferring to States to make the
determination as States are in better positioned to determine whether
PTE is required for any given sterilization facility. We solicit
comment on this approach (Question 13).
E. What technical corrections and amendments to the Commercial
Sterilization Facilities NESHAP are we proposing, and what is the
rationale for those actions?
After the publication of the 2024 Final Rule, the EPA discovered,
through internal reassessment of the regulatory text and through
communications with stakeholders, erroneous cross-references and
typographical errors within the regulatory text. Through those same
processes, the EPA also identified erroneous language in the regulatory
text (or in some cases, erroneous omissions) requiring minor wording
changes to conform with the 2024 Final Rule preamble and other parts of
the regulatory text. The technical corrections and amendments
identified here in subsection III.E.1 of this preamble are separate
from the proposed substantive changes that resulted from
reconsideration; the proposed technical changes and amendments address
unintended errors in the 2024 Final Rule. The EPA is proposing these
corrections and clarifications to the regulatory text so that the
regulated community can rely on regulatory text that is accurate and
complete and avoid confusion about how to comply with the Commercial
Sterilization Facilities NESHAP. This action addresses the technical
errors in the 2024 Final Rule identified to date by stakeholders and
the EPA.
[[Page 12719]]
1. Technical Corrections to the Commercial Sterilization Facilities
NESHAP
a. Cross-Reference and Typographical Errors
Following promulgation of the 2024 Final Rule, both the EPA and
stakeholders identified inadvertent errors in the regulatory text of
the Commercial Sterilization Facilities NESHAP, including cross-
reference and typographical errors. Table 4 includes the section and
paragraph of each identified error, the corrections being proposed in
this action, and the reasoning for the corrections. The EPA is not
soliciting comment on these corrections.
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b. Clarifying Technical Corrections
This action proposes technical corrections to clarify language in
the regulatory text of the Commercial Sterilization Facilities NESHAP
that was erroneously included (or in some cases, erroneously omitted)
in the 2024 Final Rule. Table 5 includes the sections and paragraphs of
the identified errors, the corrections being proposed, and the
reasoning for the corrections.
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A redline strike-out version of the proposed corrected regulatory
language for the Commercial Sterilization Facilities NESHAP is
available in Docket ID No. EPA-HQ-OAR-2019-0178.
2. Proposed Amendments to the Commercial Sterilization Facilities
NESHAP
In addition to the technical corrections discussed above, the EPA
is proposing additional amendments to the Commercial Sterilization
Facilities NESHAP that are more substantive in nature.
a. Definition of Operating Day
Currently, 40 CFR 63.361 defines an ``Operating day'' as ``any day
that a facility is engaged in a sterilization operation.'' The EPA is
proposing to define an ``operating day'' as ``any day that an affected
source is engaged in a sterilization operation'' for the following
reason. ``Sterilization operation'' is defined in 40 CFR 63.361 as
``any time when EtO is removed from the sterilization chamber through
the SCV or the CEV, when EtO is removed from the aeration room through
the aeration room vent, when EtO is stored within the building, when
EtO is dispensed from a container to a chamber, when material is moved
from sterilization to aeration, or when materials are handled post-
aeration.'' The EPA's intent with this definition was to make sure no
EtO emissions from sterilization and related processes go unchecked;
however, one company has indicated that the operating day definition
may inadvertently include facility operation emission streams from a
non-operating vent in the compliance determination because the
definition implies that if any affected source at a facility is engaged
in a sterilization operation then all affected sources are engaged in a
sterilization operation, regardless of whether or not they are actually
in use. As an example, suppose a facility is engaged in a sterilization
operation, but the aeration room does not contain any sterilized
material. Because the operating day is currently defined by the
facility itself being engaged in operation (as opposed to the affected
source), the ARV (and its control device) would need to be included in
the compliance analysis even when no aeration is occurring. If this
example site was using CEMS for compliance, the site would be forced to
report EtO mass emissions for this ARV, which result from the minimal
background values from the CEMS, which do not reflect EtO use, and the
flowrate from the aeration room vent.
The EPA is proposing to modify the definition of operating day so
that it applies to when an affected source is engaged in a
sterilization operation, as opposed to the entire facility, and the EPA
solicits comment on this proposed modification to the definition
(Question 14).
b. Definitions of Single-Item Sterilization and Sterilization Operation
The EPA reviewed the use of the terms ``container,'' ``EtO non-
cartridge storage media,'' and ``pouch'' within five definitions in 40
CFR 63.361 and is proposing to modify two of the definitions for
consistency.
The definition of ``Sterilization operation'' uses the term
``container'' to refer to EtO storage vessels. However, in other
definitions, the different term ``non-cartridge storage media (e.g.,
drums, cylinders)'' is used to refer to EtO storage vessels. For
example, ``non-cartridge storage media (e.g., drums, cylinders)'' is
used in the definition of ``EtO dispensing''. In order to be consistent
in referring to EtO storage vessels, the EPA is proposing to change the
definition of ``Sterilization operation'' by replacing the term
``container'' with ``non-cartridge storage media'' to read as ``any
time when EtO is removed from the sterilization chamber through the SCV
or the CEV, when EtO is removed from the aeration room through the ARV,
when EtO is stored within the building, when EtO is dispensed from a
non-cartridge storage media (e.g., drums, cylinders) to a chamber, when
material is moved from sterilization to aeration, or when materials are
handled post-aeration.''
The definition for ``Single-item sterilization'' uses the term
``pouch'' to refer to the containers used to hold the single items to
be sterilized; however, other definitions use the different term
``container (e.g., bags, pouches)'' to refer to a container to hold
single items. For example, ``container (e.g., bags, pouches)'' is used
in the definitions of ``Injection room'' and ``Post-injection handling
of containers.'' For consistency, the EPA is proposing to change the
definition for ``Single-item sterilization'' by replacing the term
``pouch'' with ``container'' to read as ``a process in which one or
more items are placed in a container (e.g., bags, pouches), EtO is
injected into the container, and the sealed container is placed in a
vessel to allow sterilization to occur.'' The EPA solicits comment on
the proposed modifications to these definitions (Question 15).
c. Definition of Indoor EtO Storage
In the 2024 Final Rule, Group 1 room air emissions, which include
indoor EtO storage, are subject to either 112(f)(2) or section 112(d)
standards, both of which require operation in accordance with PTE
requirements to assure compliance.\34\ 40 CFR 63.361 states, ``Indoor
EtO storage means the storage of EtO within non-cartridge media (e.g.,
drums, cylinders) inside a sterilization building.'' However, this
definition does not distinguish between EtO calibration gas cylinders
that are only being used to evaluate the performance of EtO CEMS and
are not used for sterilization and the EtO used for sterilization.
Since promulgation of the 2024 Final Rule, the EPA has been asked to
clarify whether the definition of indoor EtO storage includes those EtO
calibration gas cylinders that are being used to evaluate the
performance of EtO CEMS. The EPA had not intended to include in the
definition of ``indoor EtO storage'' EtO gas calibrations cylinders,
which are used for verifying EtO CEMS performance, because properly
stored and handled cylinders should not leak, and even if the cylinders
were to leak, the EPA expects any EtO released would be negligible in
light of the very small amount kept in these cylinders for EtO CEMS
performance evaluation only. As such, the EPA is proposing to modify
the definition of ``indoor EtO storage'' to exclude the EtO calibration
gas cylinders stored or used only to verify the performance of EtO
CEMS. The EPA proposes to modify the definition of indoor EtO storage
to state ``Indoor EtO storage means the storage of EtO within non-
cartridge media (e.g., drums, cylinders) inside a sterilization
building to be used in the sterilization process (excluding EtO storage
media of calibration gas cylinders that is only used to verify the
performance of EtO CEMS).'' The EPA solicits comment on this proposed
modification to the definition (Question 16).
d. EtO CEMS Inlet Time-Sharing
40 CFR 63.363(e)(1) states that facilities may time-share their EtO
CEMS provided that, among other things, the measurement points are
equidistant. Some facilities have provided input that this requirement
is impractical for systems with many measurement points (particularly
inlet measurement systems). Similarly, facilities have noted that it
may be impractical to retrofit these systems to comply with the
equidistance requirement at 40 CFR 63.363(e)(1)(A). This requirement
ensured similar response times between sources sharing
[[Page 12727]]
the CEMS; however, the EPA has learned that CEMS manufacturers have
developed systems that are able to maintain similar response times
despite different distances in sampling lines, rendering the
equidistance requirement unnecessary when such systems are used.\68\
The EPA therefore proposes to revise the regulatory text in 40 CFR
63.363(b)(1)(i)(A) \69\ to read ``The measurement points are
approximately equidistant from the CEMS or the response times are
approximately the same under the system design'' to account for those
systems designed to ensure similar response times between shared
systems.\70\ The EPA solicits comment on this proposed change (Question
17).
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\68\ 89 FR 24090 (Apr. 5, 2024).
\69\ Redesignated to 40 CFR 63.353(e)(1)(i) in this
reconsideration. See the redline strikeout of the regulatory text in
the docket for this rule.
\70\ See PS-19 in Appendix B to 40 CFR part 60 for response time
testing requirements.
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e. Requirements for Flow Rate Monitors in EtO CEMS Applications
The 2024 Final Rule requires the use of a flow rate monitor to
demonstrate compliance with the use of EtO CEMS. Flow rate monitoring
is an essential component of EtO CEMS. However, in the 2024 Final Rule,
the EPA incorporated two different sets of requirements for flow rate
monitors as an oversight. At 40 CFR 63.364(g)(3), the EPA provided the
requirements for flow rate monitors that are used to verify the
performance of PTEs; these requirements are the correct requirements.
Appendix A to subpart O provides a different and incorrect set of flow
rate monitoring requirements. The requirements included in Appendix A
to subpart O were modelled after and referenced those found in Appendix
B to 40 CFR part 63, subpart UUUUU, which includes requirements
relating to the monitoring of hydrochloric acid. Sterilization
facilities do not use hydrochloric acid and as such, these requirements
are not applicable to the subpart O NESHAP. Because the EPA is
proposing to rescind the PTE requirements, we propose to update 40 CFR
63.364(g) to remove references to PTE while retaining the appropriate
flow rate monitoring requirements, which would be needed should a
facility choose to utilize CEMS. Additionally, the EPA is proposing
revisions to Appendix A to replace any reference to the incorrect flow
rate requirements with references to the updated 40 CFR 63.364(g)(2) to
ensure that the flow rate monitoring requirements in Appendix A to
subpart O are appropriate for sterilization facilities. The EPA is also
proposing to remove additional unnecessary references found in Appendix
A as a result of this oversight.
In conjunction with this proposed change, there are several
sections of the regulatory text within Appendix A to the Commercial
Sterilization Facilities NESHAP that would change because they would
become irrelevant. Table 6 includes the sections of each correction,
the correction that would need to be made should the change discussed
above be finalized, and the reasoning for the correction
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The EPA solicits comment on the proposal to remove all references
to 40 CFR part 75 for flow rate monitors within Appendix A to the
Commercial Sterilization Facilities NESHAP, with references to 40 CFR
63.364(g)(2), as well as the corrections described in table 6 that
would result from this change (Question 18).
f. Other Proposed Corrections
In addition to the proposed amendments described above, the EPA is
also proposing, and solicits comment on, the following correction to
add text regarding the timing requirements for RATA testing consistent
with other performance specifications that was inadvertently omitted
from the 2024 Final Rule:
In section 2.2.4.3 of Appendix A to subpart O, add ``RATA
test runs must be at least 21 minutes in length'' at the end (Question
19).
A redline strike-out version of the proposed regulatory language
for the Commercial Sterilization Facilities NESHAP is available in
Docket ID No. EPA-HQ-OAR-2019-0178.
F. What technical corrections and amendments to Performance
Specification 19 are we proposing, and what is the rationale for those
actions?
The 2024 Final Rule introduced a new performance specification for
EtO CEMS (PS 19) and an associated quality assurance procedure that are
applicable not just to Commercial Sterilization Facilities but for any
facility that chooses to continuously monitor its EtO
[[Page 12729]]
emissions. After the publication of the 2024 Final Rule, the EPA
discovered, through its own internal reassessment of the regulatory
text as well as through communications with stakeholders, erroneous
cross-references and typographical errors within PS 19. This action
addresses the technical errors in PS 19 identified to date by
stakeholders and the EPA.
1. Technical Corrections for PS 19
The EPA has identified inadvertent errors in the regulatory text of
PS 19, including cross-reference and typographical errors. Table 7
includes the sections of each identified error, the corrections being
made by this action, and the reasoning for the corrections.
[GRAPHIC] [TIFF OMITTED] TP17MR26.026
This action proposes technical corrections to clarify language in
the regulatory text that was erroneously included (or in some cases,
erroneously omitted). First, in section 3.1, the EPA is proposing to
revise the definition of ``Calibration drift'' to delete everything
from ``Calibration Span'' to the end of section 3.1. Then, the Agency
is proposing to add section 3.2 to define ``Calibration Span'', which
includes all the text that was deleted from section 3.1. Second, in
section 3.18, the EPA is proposing to revise the definition of
``Standard addition'' by adding ``to the actual measurement path or''
between ``dynamically)'' and ``measured'' to clarify that the term
applies to both the measurement path and the measured sample gas
stream. Also, through this correction, the definition of ``Standard
addition'' will be consistent with how that term is defined in PS 18,
which was the model for PS 19. A redline strike-out version of the
proposed corrected regulatory language for PS 19 is available in Docket
ID No. EPA-HQ-OAR-2019-0178.
2. Technical Corrections for PS 19 Appendix A
Following signature of the 2024 Final Rule, the EPA identified
inadvertent errors in the regulatory text of PS 19 Appendix A,
including cross-reference and table designation errors. In section
8.1.4, the Agency is proposing to replace ``section 8.2 or 8.3'' with
``section 8.2'' to correct an inadvertent cross-reference error. In
section 13.0, the Agency is proposing to redesignate ``Table A13--1''
to ``Table A1''. A redline strike-out version of the proposed corrected
regulatory language for PS 19 Appendix A is available in Docket ID No.
EPA-HQ-OAR-2019-0178.
3. Technical Corrections for PS 19 Appendix B
Following signature of the 2024 Final Rule, the EPA identified
inadvertent errors in the regulatory text of PS 19 Appendix B,
including cross-reference and typographical errors. Table 8 includes
the sections of each identified error, the proposed corrections being
made by this action, and the reasoning for the proposed corrections.
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A redline strike-out version of the proposed corrected regulatory
language for PS 19 Appendix B is available in Docket ID No. EPA-HQ-OAR-
2019-0178.
4. Technical Corrections for Procedure 7 of 40 CFR 60 Appendix F
Following signature of the 2024 Final Rule, the EPA identified
inadvertent errors in the regulatory text of Procedure 7 of 40 CFR 60
Appendix F, including cross-reference, section designation, and
typographical errors. Table 9 includes the section of each identified
error, the corrections being proposed in this action, and the reasoning
for the corrections.
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This action also proposes technical corrections to clarify language
in the regulatory text that was erroneously included. First, in section
5.1.3.2, the EPA is proposing to delete ``5.2.3.3 Calculate results as
described in section 6.3.'' and add a new section 5.1.3.3 which will
read ``Calculate results as described in section 6.3''. This language
was clearly meant to be its own section, but due to an inadvertent
typographical error, it was made part of section 5.1.3.2. Second, in
section 7.1.1, the EPA is proposing to delete '' 7.1.2 If the accuracy
audit results show the CEMS to be out-of-control, you must report both
the audit results showing the CEMS to be out-of-control and the results
of the audit following corrective action showing the CEMS to be
operating within specifications.'', as this language is already present
in section 7.1.2.
A redline strike-out version of the proposed corrected regulatory
language for Procedure 7 is available in Docket ID No. EPA-HQ-OAR-2019-
0178.
G. What compliance dates are we proposing, and what is the rationale
for the proposed compliance dates?
The 2024 Final Rule includes standards promulgated under CAA
section 112(d)(2) and (3), (d)(5), and (d)(6), and existing sources
must comply within three years, the maximum time allowed under CAA
section 112(i)(3)(A).\71\ In addition, the 2024 Final Rule includes
more stringent risk-based standards for some affected sources pursuant
to CAA section 112(f)(2), and existing sources must comply within two
years, as required by CAA section 112(f)(4).\72\ Accordingly, under the
2024 Final Rule, the compliance deadlines for existing sources are
April 6, 2026, for the section 112(f)(2) standards, and April 5, 2027,
for the section 112(d) standards. For all standards, new sources must
comply by the effective date of the 2024 Final Rule (i.e., April 5,
2024) or upon startup, whichever is later. See 40 CFR 63.360(j) and
tables 1 through 5 to subpart O of part 63; see also CAA sections
112(i)(3)(A) and 112(f)(4).
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\71\ 89 FR 24090 (Apr. 5, 2024).
\72\ Id.
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As discussed in section III.A of this document, the EPA is
proposing to remove the CAA section 112(f)(2) standards. As a result,
existing sources that currently are subject to both section 112(d)
standards and section 112(f)(2) standards promulgated in the 2024 Final
Rule would only be subject to the applicable section 112(d) standards.
As mentioned above, the compliance deadline for section 112(d)
standards for existing sources is April 5, 2027.\73\ For new sources
(as defined under the 2024 Final Rule) subject to section 112(f)(2)
standards that have already started up, because the section 112(f)(2)
standards in the 2024 Final Rule are more stringent than section 112(d)
standards (with several that are the same as section 112(d)(6)
standards), compliance with section 112(f)(2) standards would also mean
compliance with section 112(d) standards. For the reasons stated above,
the EPA believes that sources can still meet the current compliance
deadlines with the removal of the section 112(f)(2) standards.
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\73\ As discussed in section II.D of this preamble, this
compliance deadline is now extended to April 5, 2029, for facilities
granted a two-year waiver via Presidential Proclamation,
``Regulatory Relief for Certain Stationary Sources to Promote
American Security With Respect to Sterile Medical Equipment,'' 90 FR
34747 (July 23, 2025).
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In addition to proposing removal of the CAA section 112(f)(2)
standards, the EPA is proposing to amend the section 112(d)(6) standard
for new ARVs at facilities where EtO usage is at least 10 tpy. For the
reasons explained in section III.B, the EPA is proposing to change this
standard from 99.9 percent reduction to 99.6 percent reduction. Because
new ARVs (as defined in the 2024 Final Rule) that already started up
are currently operating under the more stringent 99.9 percent reduction
standard in the 2024 Final Rule, they are already meeting the less
stringent proposed standard of 99.6 percent reduction. The EPA does not
foresee problems with new ARVs (as defined by the 2024 Final Rule) at
facilities where EtO usage is at least 10 tpy complying with the
proposed revised standard by the current deadlines in the 2024 Final
Rule (i.e., upon startup or by April 5, 2024, whichever is later).\74\
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\74\ Supra n.10.
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The EPA considered whether the proposed changes to the methods for
demonstrating compliance could impact facilities' ability to
demonstrate compliance with existing source standards under the current
deadline. This reconsideration proposes to remove the requirement that
CEMS be used for demonstrating compliance; thus, industry will not need
time to comply with this requirement. However, this change represents a
return to the compliance demonstration practice currently used by
industry. While the EPA is proposing to amend the specific requirements
and details of the parametric monitoring and performance testing
approach, these changes do not represent a substantial change in
methods and should not present a substantial burden to industry. As
such, the EPA does not anticipate these changes to need more time than
provided by the compliance deadline already in place.
For these reasons, the EPA is proposing to retain the compliance
dates for existing and new sources in 40 CFR 63.360 and in tables 1 to
5 to subpart O of part 63. The EPA is soliciting comment on compliance
deadlines (Question 20).
IV. Severability
This proposed rule contains several discrete components, which the
EPA views as severable as a practical matter--i.e., they are
functionally independent and operate in practice independently of the
other components. These discrete components are generally delineated by
the section headings and subheadings of this preamble. For example, the
proposed rescission of the risk-based standards based on the best
reading of CAA section 112(f)(2) is severable from the proposed
revision to the new source standard for ARV at facilities using at
least 10 tpy based on EPA's reconsideration of this standard under
section 112(d)(6). The final rule also includes other revisions to the
Sterilization Facilities NESHAP that generally function independently
of one another (e.g., revisions to the compliance demonstration
requirements to allow facilities to choose between parametric
monitoring or using CEMS, rescission of the requirement to use PTE to
ensure complete capture of EtO).
V. Summary of Cost, Environmental, and Economic Impacts
A. What are the affected sources?
There are 89 facilities in the Commercial Sterilization Facilities
source category that are currently operating. A complete list of
facilities that are currently subject to the NESHAP is available in the
document ``2024 Facility List,'' which is available in the docket for
this rulemaking.
B. What are the air quality impacts?
For the standards that the EPA is proposing, there is an estimated
EtO emissions increase of 7.8 tpy for the total source category because
of the removal of CAA section 112(f)(2) standards and revision of the
section 112(d)(6) standards for new ARVs at facilities where EtO use is
at least 10 tpy. See the memorandum titled Regulatory Impact Analysis
for the Proposed Reconsideration of the 2024 National Emission
Standards for Hazardous Air Pollutants: Ethylene
[[Page 12733]]
Oxide Commercial Sterilization and Fumigation Operations, which is
available in the docket for this rulemaking.
C. What are the cost impacts?
The nationwide costs of the proposed amendments are presented in
table 10 of this preamble. As described in this preamble, the EPA is
removing the CAA section 112(f)(2) standards and revising the section
112(d)(6) standards for new ARVs at facilities where EtO use is at
least 10 tpy. As a result, industry will see overall cost savings in
comparison to the 2024 Final Rule. The total savings for capital
investment for the proposal is estimated to be about $280 million in
2024 dollars. The Agency estimates the total annual compliance cost
savings of the proposal, compared to the estimated costs associated
with the 2024 Final Rule, to be approximately $50 million.
[GRAPHIC] [TIFF OMITTED] TP17MR26.030
D. What are the economic impacts?
The present value (PV) of the estimated compliance cost savings
from 2026 to 2045 for the proposed reconsideration is $630 million in
2024 dollars, discounted at a 3 percent rate. The equivalent annualized
value (EAV) of the estimated cost savings is $43 million, using a 3
percent discount rate. Using a 7 percent discount rate, the PV and EAV
of the cost savings are estimated to be $510 million and $48 million,
respectively. This proposed reconsideration is estimated to result in
net compliance cost savings for the impacted source category.
The EPA conducted economic impact analyses for this proposal, as
detailed in the memorandum titled Regulatory Impact Analysis for the
Proposed Reconsideration of the 2024 National Emission Standards for
Hazardous Air Pollutants: Ethylene Oxide Commercial Sterilization and
Fumigation Operations, which is available in the docket for this
action. For the proposed reconsideration, the EPA performed a screening
analysis which compared facility-level annualized compliance costs to
annual revenues of the ultimate owner of the facility (or facilities),
known as the ultimate parent company. These cost-to-sales ratios (CSRs)
underpin the ``sales test'' methodology the EPA uses to assess small
business impacts for a rulemaking.
There are 89 facilities, owned by 49 ultimate parent companies,
affected by the proposed amendments. Of these 89 facilities, 23
facilities (26 percent), are owned by a total 19 ultimate parent
companies that are small entities. The Agency calculated the CSRs for
all affected parent companies to assess the magnitude of the costs of
the proposed amendments and determine whether there is potential for
significant impacts on small entities. As shown in table 10, this
proposed reconsideration does incur cost increases related to one-time
costs for cycle revalidations and recordkeeping and reporting costs.
However, these cost increases are less than the net cost savings for 16
of the affected 19 small entities. The 16 small entities estimated to
experience net cost savings under this proposed reconsideration are
expected to have lower CSRs relative to the 2024 Final Rule. Of the 3
small entities projected to incur additional requirement costs relative
to 2024 Final Rule, one has an estimated CSR above 3 percent. The
average annualized cost savings for small entities is about $0.68
million and about $0.35 million for the remaining entities. The average
annual sales for the 19 small entities is $38 million, while the
remaining 30 entities have average annual sales of $15 billion.
Relative to the 2024 Final Rule, the average CSR for all firms
decreased by 4.3 percent, down to approximately 3.8 percent. Similarly,
the CSRs for large and small firms decreased by 0.26 percent (down to
approximately 0.11 percent) and by 10.6 percent (down to approximately
10 percent), respectively. Large firms incur most of the total costs
estimated for the proposed rule and they incur higher total annual
costs per firm on average than small firms. However, when estimated
costs are examined relative to revenues, large firms are less affected
by the proposed rule than small firms.
EtO sterilization services are a critical input in the provision of
safe medical devices. According to the U.S. Food and Drug
Administration (FDA), more than 20 billion medical devices used in the
U.S. every year are sterilized with EtO, accounting for approximately
50 percent of medical devices that require sterilization. In the 2024
Final Rule regulatory impact analysis (RIA), the industry profile in
section 2 discusses the role of EtO in providing a significant number
of healthcare products to the
[[Page 12734]]
public and why it is often the only sterilization method that can be
used for a wide variety of common medical devices.\75\ The EPA was not
able to quantitatively assess potential market impacts for this
proposed rule. However, it is likely that this proposed reconsideration
would reduce the risk of capacity constraints in the sterilization
sector. In the 2024 Final Rule RIA, the EPA examined a scenario where
the 2024 Final Rule requirements lead to facilities needing to
temporarily reduce their capacity and thus lose revenue during that
time. The EPA requests comment on whether the proposed standards would
result in a similar risk of capacity constraints in the sterilization
sector (Question 21). To the extent that this proposed reconsideration
avoids the need for facilities to reduce capacity, the cost savings of
this action are estimated to be higher than the estimates of the
examined scenario in the 2024 Final Rule RIA.
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\75\ U.S. EPA. (2024). Regulatory Impact Analysis for the Final
National Emission Standards for Hazardous Air Pollutants: Ethylene
Oxide Commercial Sterilization and Fumigation Operations. Available
at: https://www.regulations.gov/document/EPA-HQ-OAR-2019-0178-1557.
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E. What are the benefits?
Being unable to adequately supply sterilized medical equipment to
our medical personnel to safely treat patients in hospitals, operating
rooms, and other medical facilities would undermine our national
security. This rule, if finalized, would help ensure a secure medical
supply chain as it would decrease the probability of commercial
sterilizers shuttering and the United States having to rely on other
countries to sterilize medical devices. While the EPA acknowledges
significant national security benefits if this rule is finalized, the
Agency is unable to monetize these national security benefits
Consistent with longstanding practice, the EPA did not monetize the
foregone benefits from the estimated emission changes in HAP associated
with this proposed reconsideration. The EPA currently does not have
sufficient methods to monetize benefits associated with HAP. This does
not imply that there are no impacts associated with the EtO emission
increases estimated for this proposed rule. Non-monetized health
disbenefits are expected under this proposed reconsideration from
estimated increases of 7.8 tons of EtO annually relative to the 2024
Final Rule. A qualitative discussion of the health effects associated
with EtO exposure is provided in the memorandum titled Regulatory
Impact Analysis for the Proposed Reconsideration of the 2024 National
Emission Standards for Hazardous Air Pollutants: Ethylene Oxide
Commercial Sterilization and Fumigation Operations, which is available
in the docket for this rulemaking.
VI. Request for Comments
We solicit comment on all aspects of this proposed action. In
addition to general comments on this proposed action, we are also
interested in additional data that may improve the analyses.
Throughout this proposal, the EPA is soliciting comment on numerous
aspects of the proposed rule. The EPA has indexed each comment
solicitation with an identifier (e.g., ``Question 1, Question 2, . . .)
to provide a consistent framework for effective and efficient provision
of comments. Accordingly, we ask that commenters include the
corresponding identifier when providing comments relevant to that
comment solicitation. We ask that commenters include the identifier in
either a heading, or within the text of each comment (e.g., ``In
response to Question 1, . . .'') to make clear which comment
solicitation is being addressed. Below, we list the questions for which
the EPA invites comment.
Question #1: Has the 2024 Final Rule and underlying interpretations
generated reliance interests and, if so, how should the EPA consider
them in any final action?
Question #2: Should the EPA rescind the standards set under CAA
section 112(f)(2) in the 2024 Final Rule, as proposed, based on the
proposed finding that the discretionary second risk review conducted as
part of the 2024 Final Rule was not authorized under the CAA?
Question #3: Is there new information that could be used in dose-
response modeling, such as epidemiological studies of cancer in humans
exposed to EtO?
Question #4: Is there any new information relevant to dose-response
model selection such as consideration of statistical analyses, visual
model fit, or biological plausibility?
Question #5: Is there new information related to human exposure to
EtO, including information on occupational, smoking, background or
endogenous exposures that may be relevant to estimating the dose-
response relationship of EtO carcinogenicity?
Question #6: Is there additional information on the comments of the
2016 IRIS value provided by commenters in the context of the more
recent proposed CMAS NESHAP (January 22, 2025) (see Docket ID EPA-HQ-
OAR-2024-0303, comment numbers 0060, 0061, 0068, 0076, and 0079)?
Question #7: Should the EPA modify the emission reductions levels
for new ARVs at facilities where EtO use is at least 10 tpy from 99.9
to 99.6 percent reduction, as proposed?
Question #8: Should the EPA consider manufacturer guarantee levels
of EtO reduction for ARVs, and if so, what are these levels?
Question #9: Should facilities have the option of using either
parametric monitoring and performance testing or CEMS to demonstrate
initial and continuous compliance with the Commercial Sterilization
Facilities NESHAP, as proposed?
Question #10: Should the EPA finalize the proposed changes to
performance testing, parametric monitoring, and reporting requirements
as proposed?
Question #11: Is PTE cost effective and feasible?
Question #12: Should the EPA not be allowed to treat unregulated
sources of regulated pollutants the same as unregulated pollutants?
Question #13: Should the EPA remove PTE requirements?
Question #14: Should the EPA modify the definition of ``Operating
day'' so that it applies to when an affected source is engaged in a
sterilization operation, as opposed to the entire facility, as
proposed?
Question #15: Should the EPA modify the definitions of
``Sterilization operation'' and ``Single-item sterilization'' be
modified as proposed?
Question #16: Should the EPA modify the definition of ``Indoor EtO
storage'' to clarify that EtO storage media of calibration gas
cylinders that is only used to verify the performance of EtO CEMS is
excluded, as proposed?
Question #17: Should the EPA modify 40 CFR 63.363(b)(1) to indicate
that CEMS measurement points do not need to be equidistant so long as
the response times are similar, as proposed?
Question #18: Should the EPA remove all references to 40 CFR part
75 for flow rate monitors within Appendix A to the Commercial
Sterilization Facilities NESHAP and should we make the corrections
described in table 6 be made, as proposed?
Question #19: Should the EPA add the phrase ``RATA test runs must
be at least 21 minutes in length'' to the end of section 2.2.4.3 of
Appendix A to subpart O, as proposed?
Question #20: Should the EPA retain the compliance deadlines
promulgated
[[Page 12735]]
in the 2024 Final Rule for the section 112(d) standards as proposed?
Question #21: Would the proposed standards result in a similar risk
of capacity constraints as the 2024 Final Rule in the sterilization
sector?
VII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is a significant regulatory action and therefore, the
EPA submitted this action to the Office of Management and Budget (OMB)
for Executive Order 12866 review. Any changes made in response to E.O
12866 review have been documented in the docket. The EPA has prepared
an analysis of the potential costs and benefits associated with this
action. This analysis, Regulatory Impact Analysis for the Proposed
Reconsideration of the 2024 National Emission Standards for Hazardous
Air Pollutants: Ethylene Oxide Commercial Sterilization and Fumigation
Operations, is available in the docket. A summary of the costs and
economic impacts is included in section IV of this preamble.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
This action is expected to be an Executive Order 14192 deregulatory
action. Details on the estimated cost savings of this proposed rule can
be found in the EPA's analysis of the potential costs and benefits
associated with this action.
C. Paperwork Reduction Act (PRA)
The information collection activities in this proposed rule have
been submitted for approval to OMB under the PRA. The information
collection request (ICR) document that the EPA prepared has been
assigned EPA ICR number 1666.12. You can find a copy of the ICR in the
docket for this rulemaking, and it is briefly summarized here.
The EPA is proposing amendments that change the reporting and
recordkeeping requirements for several emission sources at commercial
sterilization facilities (e.g., SCV, ARV, CEV and room air emissions).
This information would be collected to assure compliance with 40 CFR
part 63, subpart O.
Respondents/affected entities: Owners or operators of commercial
sterilization facilities.
Respondent's obligation to respond: Mandatory (40 CFR part 63,
subpart O).
Estimated number of respondents: 89 facilities.
Frequency of response: Quarterly, or annual. Responses include
monitoring plan, notification of compliance status reports, performance
test reports and quarterly compliance reports.
Total estimated burden: 24,077 hours (per year) for the responding
facilities and 2,541 hours (per year) for the Agency. Burden is defined
at 5 CFR 1320.3(b).
Total estimated cost: $6,883,047 (per year), which includes
$4,529,143 annualized capital and operation and maintenance costs for
the responding facilities.
An Agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for the
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
Submit your comments on the Agency's need for this information, the
accuracy of the provided burden estimates and any suggested methods for
minimizing respondent burden to the EPA using the docket identified at
the beginning of this rule. The EPA will respond to any ICR-related
comments in the final rule. You may also send your ICR-related comments
to OMB's Office of Information and Regulatory Affairs using the
interface at www.reginfo.gov/public/do/PRAMain. Find this information
collection by selecting ``Currently under Review--Open for Public
Comments'' or by using the search function. OMB must receive comments
no later than April 16, 2026.
D. Regulatory Flexibility Act (RFA)
The EPA certifies that this action will not have a significant
economic impact on a substantial number of small entities under the
RFA. In making this determination, the EPA concludes that the impact of
concern for this rule is any adverse economic impact on small entities
and that the Agency is certifying that this rule will not have a
significant economic impact on a substantial number of small entities
because the rule relieves regulatory burden on the small entities
subject to the rule. This proposed action would lead to reduction in
EAV of costs over the 2026 to 2046 timeframe of about $43 and $48
million per year at discount rates of 3 percent and 7 percent,
respectively. The average annualized cost savings for small entities is
about $0.68 million and about $0.35 million for the remaining entities.
For a more detailed analysis, please see the document Regulatory Impact
Analysis for the Proposed Reconsideration of the 2024 National Emission
Standards for Hazardous Air Pollutants: Ethylene Oxide Commercial
Sterilization and Fumigation Operations available in the docket for
this rule.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain an unfunded mandate of $100 million or
more as described in UMRA, 2 U.S.C. 1531-1538, and does not
significantly or uniquely affect small governments. The action imposes
no enforceable duty on any state, local or Tribal government.
F. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States or on the distribution of power
and responsibilities among the various levels of government.
G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have tribal implications as specified in
Executive Order 13175. None of the commercial sterilization facilities
that have been identified as being affected by this action are owned or
operated by Tribal governments or located within Tribal lands. Thus,
Executive Order 13175 does not apply to this action.
H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
Executive Order 13045 directs federal agencies to include an
evaluation of the health and safety effects of the planned regulation
on children in federal health and safety standards and explain why the
regulation is preferable to potentially effective and reasonably
feasible alternatives. This action is subject to Executive Order 13045
because it is a significant regulatory action under section 3(f)(1) of
Executive Order 12866, and the EPA believes that the environmental
health and safety risk addressed by this action may have a
disproportionate effect on children. The environmental health and
safety risks addressed by this action present a disproportionate risk
to children due to EtO being mutagenic (i.e., it can damage DNA).
The EPA did not conduct a new analysis of children's environmental
health for this action. For details on children's health and the impact
of the CAA section 112(d) standards, please see the Executive Order
13045 discussion and tables 17 and 18 in the 2024 Final Rule (89 FR
24090).
[[Page 12736]]
This action is preferred over other regulatory options analyzed
because, while it removes the CAA 112(f)(2) standards to better comply
with the text and structure of the applicable statutory language (see
section III.A), it retains the first-time standards promulgated in the
2024 Final Rule under CAA sections 112(d)(2), (3) and (5) for emission
sources that were unregulated prior to the 2024 Final Rule. These
standards will continue to apply and protect children's health.
Furthermore, the EPA's Policy on Children's Health applies to this
action. For details on children's health and the impact of the CAA
section 112(d) standards, please see the discussion in the 2024 Final
Rule (89 FR 24090).
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. The overall energy impact of this rule
should be minimal for commercial sterilization facilities and their
parent companies.
J. National Technology Transfer and Advancement Act (NTTAA)
The NTTAA requires the EPA to use voluntary consensus standards
(VCS) in addition to EPA methods in regulatory activities unless doing
so would be inconsistent with applicable law or otherwise
impracticable. VCS are technical documents, such as test methods, that
are developed or adopted by VCS bodies using procedures that ensure
that the standards development process is open to all interested
parties. VCS bodies are generally private sector, not-for-profit
entities such as the American Society for Testing and Materials (ASTM).
The EPA searched the Enhanced NSSN Database managed by the American
National Standards Institute (ANSI) for VCS that could be used in the
National Emission Standards for Hazardous Air Pollutants for Ethylene
Oxide Emissions Standards for Sterilization Facilities. The EPA also
contacted VCS organizations and accessed and searched their databases.
While the EPA has made a reasonable effort to identify and evaluate
potentially practical VCS, the findings do not necessarily represent
all potential alternative standards which may exist.
Searches were conducted for: EPA Methods 204 and 205 of 40 CFR part
51, Appendix M; EPA Methods 1, 1A, 2, 2A, 2B, 2C, 2D, 3A, 3B, and 4 of
40 CFR part 60, Appendix A; and, EPA Methods 301 and 320 of 40 CFR part
63, Appendix A. The EPA found no VCS are acceptable alternatives for
EPA Methods 1, 1A, 2, 2A, 2B, 2C, 2D, 3A, 4, 204, 205, and 301. The EPA
found no acceptable alternative VCS for EPA Methods 1, 1A, 2, 2A, 2B,
2C, 2D, 3A, 4, 204, 205, and 301.
The proposed rule continues to include one VCS as an alternative to
EPA Method 3B for the purposes of this rule. The manual methods in
ANSI/ASME PTC 19-10-1981 Part 10, ``Flue and Exhaust Gas Analyses''
(2010 version) are acceptable alternatives to EPA Method 3B to analyze
oxygen and carbon dioxide concentrations in the stack gas. The
instrumental methods in the voluntary consensus standard ANSI/ASME PTC
19-10-1981 Part 10, ``Flue and Exhaust Gas Analyses'' (2010 version)
are not acceptable alternatives to EPA Method 3B.
The proposed rule continues to include one VCS as an alternative to
EPA Method 320 for the purposes of this rule. The VCS ASTM D6348-12
(2020), ``Determination of Gaseous Compounds by Extractive Direct
Interface Fourier Transform (FTIR) Spectroscopy'' is an acceptable
alternative to EPA Method 320 with caveats requiring inclusion of
selected annexes to the standard as mandatory. When using ASTM D6348-
12(2020), the following conditions must be met:
(1) The test plan preparation and implementation in the Annexes to
ASTM D 6348-12 (R2020), sections A1 through A8 are mandatory; and
(2) In ASTM D6348-12 (R2020) Annex A5 (Analyte Spiking Technique),
the percent (%) R must be determined for each target analyte (equation
A5.5). For the test data to be acceptable for a compound, %R must be
70% <= R <= 130%. If the %R value does not meet this criterion for a
target compound, the test data is not acceptable for that compound and
the test must be repeated for that analyte (i.e., the sampling and/or
analytical procedure should be adjusted before a retest). The %R value
for each compound must be reported in the test report, and all field
measurements must be corrected with the calculated %R value for that
compound by using equation 1 to this paragraph:
(eq. 1) Reported Results = ((Measured Concentration in Stack))/(%R) x
100
According to 40 CFR 63.7(f) and 40 CFR 63.8(f) of subpart A of the
general provisions, a source may apply to the EPA to use alternative
test methods or alternative monitoring requirements in place of any
required testing methods, performance specifications or procedures in
the final rule or any amendments. The EPA welcomes comments on this
aspect of the proposed rulemaking and, specifically, invites the public
to identify potentially applicable VCS and to explain why such
standards should be used in this regulation.
List of Subjects in 40 CFR Part 63
Environmental protection, Air pollution control, Hazardous
substances, Reporting and recordkeeping requirements.
Lee Zeldin,
Administrator.
[FR Doc. 2026-05167 Filed 3-16-26; 8:45 am]
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