Protection of Stratospheric Ozone: Listing of Substitutes Under the Significant New Alternatives Policy Program in Refrigeration and Air Conditioning and Fire Suppression

Federal RegisterNov 10, 2025

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[EPA-HQ-OAR-2024-0503; FRL-12207-01-OAR]

RIN 2060-AW45

Protection of Stratospheric Ozone: Listing of Substitutes Under the Significant New Alternatives Policy Program in Refrigeration and Air Conditioning and Fire Suppression

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

Pursuant to the U.S. Environmental Protection Agency's Significant New Alternatives Policy program, this action proposes to list several substitutes as acceptable, subject to use conditions, for residential and light commercial air conditioning and heat pumps, chillers, household refrigerators and freezers, motor vehicle air conditioning, and fire suppression and explosion protection. This action also proposes to update use conditions for substitutes previously listed for certain air conditioning end-uses and for water coolers.

DATES:

Comments must be received on or before December 26, 2025 unless a public hearing is held. If a public hearing is held, comments on this notice of proposed rulemaking must be received on or before date 30 days after date of public hearing.

Public hearing:

Any party requesting a public hearing must notify the contact listed in the

FOR FURTHER INFORMATION CONTACT

section, which is Emily Maruyama at email address:

maruyama.emily@epa.gov

by 5 p.m. Eastern Daylight Time on or before November 17, 2025. If a public hearing is held, it will take place on or around November 25, 2025. Please refer to the

SUPPLEMENTARY INFORMATION

section for additional information on the public hearing.

ADDRESSES:

You may send comments, identified by Docket ID No. EPA-HQ-OAR-2024-0503 by any of the following methods:

•

Federal Rulemaking Portal: https://www.regulations.gov

(our preferred method). Follow the online instructions for submitting comments.

•

Email: a-and-r-Docket@epa.gov.

Include Docket ID No. EPA HQ-OAR-2024-0503 in the subject line of the message.

•

Mail:

U.S. Environmental Protection Agency, EPA Docket Center, Air and Radiation Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460.

•

Hand Delivery or Courier:

EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. The Docket Center's hours of operations are 8:30 a.m. to 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 personal information provided. For detailed instructions on sending comments and additional information on the rulemaking process, see the “Public Participation” heading of the

SUPPLEMENTARY INFORMATION

section of this document. For information on EPA Docket Center services, please visit us online at

https://www.epa.gov/dockets.

If a public hearing is requested on or before November 17, 2025, the EPA will post an update at

https://www.epa.gov/snap.

The EPA does not intend to publish a document in the

Federal Register

announcing updates. The public hearing will be held on or around November 25, 2025. Information on the hearing including the time and URL will be posted at EPA's Stratospheric Ozone website at

https://www.epa.gov/snap.

Refer to the section titled, Public Participation for additional information.

FOR FURTHER INFORMATION CONTACT:

For information about this proposed rule, contact Emily Maruyama, Stratospheric Protection Division, Office of Atmospheric Protection (Mail Code 6205A), Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460; telephone number: (202) 564-2809; email address:

maruyama.emily@epa.gov.

Notices and rulemakings under the EPA's Significant New Alternatives Policy (SNAP) program are available on the EPA's SNAP website at

https://www.epa.gov/snap/snap-regulations.

SUPPLEMENTARY INFORMATION:

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:

2-BTP—2-bromo-3,3,3-trifluoropropene

AC—Air Conditioning

AIHA—American Industrial Hygiene Association

AIM—American Innovation and Manufacturing

ANSI—American National Standards Institute

APU—Auxiliary Power Unit

ASHRAE—American Society of Heating, Refrigerating and Air-Conditioning Engineers

ASTM—American Society for Testing and Materials

BTMS—Battery Thermal Management Systems

CAA—Clean Air Act

CAS Reg. No.—Chemical Abstracts Service Registry Identification Number

CBI—Confidential Business Information

CFC—Chlorofluorocarbon

CFR—Code of Federal Regulations

CMAQ—Community Multiscale Air Quality

—Carbon Dioxide

CRP—Cooperative Research Program

DIY—Do it yourself

DOT—United States Department of Transportation

EEAP—Environmental Effects Assessment Panel

EPA—United States Environmental Protection Agency

ER&R—Emissions Reduction and Reclamation

EV—Exchange Value

FMEA—Failure Mode and Effects Analysis

FR—Federal Register

GHG—Greenhouse Gas

GSHP—Ground-Source Heat Pump

HC—Hydrocarbon

HCFC—Hydrochlorofluorocarbon

HCFO—Hydrochlorofluoroolefin

HCR—Hydrocarbon Refrigerant

HD—Heavy-Duty

HDOH—Heavy-Duty On-Highway

HFC—Hydrofluorocarbon

HFO—Hydrofluoroolefin

ICF—ICF International, Inc.

IEC—International Electrotechnical Commission

IPCC—Intergovernmental Panel on Climate Change

IPR—Industrial Process Refrigeration

IRC—International Residential Code

LD—Light-Duty

LFL—Lower Flammability Limit

LMDV—Light- and Medium-Duty Vehicle

MIR—Maximum Incremental Reactivity

MVAC—Motor Vehicle Air Conditioning or Motor Vehicle Air Conditioner

MY—Model Year

NAAQS—National Ambient Air Quality Standard

NAICS—North American Industrial Classification System

NCEL—New Chemical Exposure Limit

NFPA—National Fire Protection Association

NRTL—Nationally Recognized Testing Laboratory

ODP—Ozone Depletion Potential

ODS—Ozone-Depleting Substances

OECD—Organisation for Economic Co-operation and Development

OEL—Occupational Exposure Limit

OEM—Original Equipment Manufacturer

OMB—United States Office of Management and Budget

OSHA—United States Occupational Safety and Health Administration

PBI—Proprietary Business Information

PEL—Permissible Exposure Limit

PFAS—Per- and Polyfluoroalkyl Substances

PFC—Perfluorocarbon

PMN—Pre-Manufacture Notice

PMS—Pantone® Matching System

PPE—Personal Protective Equipment

ppm—Parts Per Million

PRA—Paperwork Reduction Act

PTAC—Packaged Terminal Air Conditioner

PTHP—Packaged Terminal Heat Pump

RAL—“Reichs-Ausschuß für Lieferbedingungen und Gütesicherung,” Germany's National Commission for Delivery Terms and Quality Assurance

RCRA—Resource Conservation and Recovery Act

RFA—Regulatory Flexibility Act

RfC—Reference Concentration

SAE—SAE International, previously known as the Society of Automotive Engineers

SDS—Safety Data Sheet

SIP—State Implementation Plan

SNAP—Significant New Alternatives Policy

SNUR—Significant New Use Rule

TEAP—Technology and Economic Assessment Panel

TFA—Trifluoroacetic Acid

TLV—Threshold Limit Value

TWA—Time Weighted Average

UL—UL, formerly known as Underwriters Laboratories, Inc.

UMRA—Unfunded Mandates Reform Act

VOC—Volatile Organic Compounds

VRF—Variable Refrigerant Flow

WEEL—Workplace Environmental Exposure Limit

WMO—World Meteorological Organization

WSHP—Water-Source Heat Pump

Table of Contents

I. Executive Summary

A. Purpose of the Regulatory Action

B. Summary of the Major Provisions of the Regulatory Action

II. Public Participation

A. Written Comments

B. Participation in Virtual Public Hearing

C. Public Access to Voluntary Consensus Safety Standards

III. General Information

A. Does this action apply to me?

B. What action is the Agency proposing to take?

C. What is the Agency's authority for taking this action?

D. What are the guiding principles of the SNAP program and what are the SNAP criteria for evaluating substitutes?

IV. Residential and Light Commercial Air Conditioning and Heat Pumps

A. What is the EPA proposing in this action?

B. Background on Residential and Light Commercial AC and Heat Pumps

C. What are the ASHRAE groups for refrigerant flammability and toxicity?

D. What are the refrigerants the EPA is proposing to list as acceptable in the residential and light commercial AC and heat pumps end-use and how do they compare to other refrigerants in this end-use?

E. What are the refrigerants for which the EPA is proposing to update use conditions and how do they compare to other refrigerants in the residential and light commercial AC and heat pumps end-use?

F. What use conditions is the EPA proposing in this action for new and updated listings in this residential and light commercial AC and heat pumps end-use?

G. What additional information is the EPA including in these proposed listings?

V. Household Refrigerators and Freezers

A. What is the EPA proposing in this action?

B. Background on Household Refrigerators and Freezers

C. What are the ASHRAE groups for refrigerant flammability and toxicity?

D. What is HCR 4141 and how does it compare to other refrigerants in the household refrigerators and freezers end-use?

E. What use conditions is the EPA proposing in this action for the new listing for HCR 4141 in new household refrigerators and freezers?

F. What additional information is the EPA including in this proposed listing?

VI. Water Coolers

A. What is the EPA proposing in this action?

B. Background on Water Coolers

C. What are the ASHRAE groups for refrigerant flammability and toxicity?

D. What is R-290 and how does it compare to other refrigerants in the water coolers end-use?

E. What use conditions is the EPA proposing in this action for the updated listing for R-290 in new water coolers?

F. What additional information is the EPA including in this proposed listing?

VII. Chillers

A. What is the EPA proposing in this action?

B. Background on Centrifugal Chillers and Positive Displacement Chillers

C. What are the ASHRAE classifications for refrigerant flammability and toxicity?

D. What is R-516A and how does it compare to other refrigerants in the centrifugal chillers and positive displacement chillers end-uses?

E. What use conditions is the EPA proposing in this action for the new listing for R-516A in new centrifugal chillers and positive displacement chillers?

F. What additional information is the EPA including in this proposed listing?

VIII. Motor Vehicle Air Conditioning

A. What is the EPA proposing in this action?

B. Background on Motor Vehicle Air Conditioning

C. What are the ASHRAE classifications for refrigerant flammability and toxicity used in MVACs?

D. What are refrigerants HFO-1234yf, R-444A, R-453A, R-456A, and R-480A and how do they compare to other refrigerants in the same end-use?

E. What use conditions is the EPA proposing in this action that apply to proposed listings in this end-use?

F. Modification of “unacceptability” Listing Applicable to Flammable Refrigerants in MVAC

G. Modifications to MVAC SNAP Requirements

IX. Fire Suppression and Explosion Protection

A. What is the EPA proposing in this action?

B. Background on Total Flooding Fire Suppression

C. What is 2-BTP/CO

and how does it compare to other fire suppressants in the same end-use?

D. What use conditions is the EPA proposing?

E. Why is the EPA proposing these specific use conditions?

F. What Additional Information Is the EPA Including in This proposed listing?

X. On Which Topics Is the EPA Specifically Requesting Comment?

A. Residential and Light Commercial AC and Heat Pumps, Household Refrigerators and Freezers, and Water Coolers

B. Chillers

C. Motor Vehicle Air Conditioning

D. Fire Suppression and Explosion Protection

XI. 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 and Safety Risks

I. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use

J. National Technology Transfer and Advancement Act

XII. References

I. Executive Summary

A. Purpose of the Regulatory Action

The EPA is proposing new and revised listings after our evaluation of human health and environmental information for certain substitutes under Clean Air Act (CAA) section 612, Significant New Alternatives Policy (SNAP) program. The Agency is proposing action on these new listings in the refrigeration and air conditioning (AC), and fire suppression and explosion protection sectors based on the information that the EPA has included in the docket. This proposed action would provide new refrigerant and fire suppressant options in specific uses, thereby increasing flexibility for industry. It also would revise certain existing requirements under the SNAP program to allow for greater consistency and compatibility with current industry

safety standards such as those for AC equipment and for water coolers.

B. Summary of the Major Provisions of the Regulatory Action

This action proposes to list new alternatives as well as to revise use conditions for existing alternatives for the refrigeration and AC sector and to list a new alternative for the fire suppression and explosion protection sector. Specifically, the EPA is proposing to:

• Update existing use conditions for hydrofluorocarbon (HFC)-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A in residential and light commercial AC and heat pumps;

• List the hydrocarbon refrigerant (HCR) blend HCR 4141, hydrofluoroolefin (HFO)-1234ze(E), and the HFO/HFC blend R-516A as acceptable, subject to use conditions, in residential and light commercial AC and heat pumps;

• List HCR 4141 as acceptable, subject to use conditions, in household refrigerators and freezers;

• Update existing use conditions for R-290 in water coolers;

• List R-516A as acceptable, subject to use conditions, in positive displacement chillers and centrifugal chillers;

• List HFO-1234yf as acceptable, subject to use conditions, in retrofit light- and medium-duty vehicle (LMDV) motor vehicle air conditioning (MVAC), in new MVACs on buses, and in new MVACs in heavy-duty on-highway (HDOH) vehicles;

• List the blend R-444A as acceptable, subject to use conditions, in retrofit LMDV MVACs and retrofit heavy-duty (HD) pickup trucks and van MVACs (complete and incomplete);

• List the blend R-456A as acceptable, subject to use conditions, in retrofit LMDV MVACs, retrofit HD pickup trucks and van MVACs (complete and incomplete), retrofit HDOH MVACs, and retrofit MVACs on buses and trains;

• List the blend R-480A as acceptable, subject to use conditions, in retrofit LMDV MVACs, retrofit MVACs on HD pickup trucks and vans (complete and incomplete), retrofit HDOH MVACs, and retrofit MVACs on buses and trains;

• List the blend R-453A as acceptable, subject to use conditions, in retrofit MVACs on buses and trains; and

• List 2-bromo-3,3,3-trifluoropropene/carbon dioxide (2-BTP/CO

) as acceptable, subject to use conditions, as a total flooding agent in fire suppression for use in normally unoccupied spaces onboard aircraft including engine nacelles, auxiliary power units (APUs), and cargo bays.

In summary, the common use conditions proposed for new household refrigerators and freezers, residential and light commercial AC and heat pumps, water coolers, and chillers are as follows:

(1) These refrigerants may be used only in new equipment, designed specifically and clearly identified for use with the refrigerant. None of these substitutes may be used as a conversion or “retrofit” refrigerant for existing equipment.

(2) These refrigerants must be used with warning labels on the equipment and packaging that are similar to or match verbatim those required by the relevant Underwriters Laboratories (UL) standard.

(3) Equipment must be marked with distinguishing red color-coded hoses and piping to indicate use of a flammable refrigerant and marked service ports, pipes, hoses, and other devices through which the refrigerant is serviced.

Additional use conditions specific to particular end-uses also apply and are discussed with each proposed listing. The regulatory text of the proposed listings, including the proposed use conditions and further information, appears in tables in the docket for this rulemaking under the title “Proposed Regulatory Text for SNAP Rule 27.” All proposed new listings appear in proposed appendix Z of 40 Code of Federal Regulations (CFR) part 82, subpart G. The proposed updated listings for HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A in residential and light commercial AC and heat pumps and for R-290 in new water coolers appear as proposed changes in appendix R, appendix W, and appendix V of 40 CFR part 82, subpart G.

II. Public Participation

A. Written Comments

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2024-0503 at

https://www.regulations.gov

(our preferred method), or the other methods identified in the

ADDRESSES

section. Once submitted, comments cannot be edited or removed from the docket. The EPA may publish any comment received to its public docket. Do not submit to the EPA's docket at

https://www.regulations.gov

any information you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (

i.e.,

on the web, cloud, or other file sharing system). Please visit

https://www.epa.gov/dockets/commenting-epa-dockets

for additional submission methods; the full EPA public comment policy; information about CBI, PBI, or multimedia submissions; and general guidance on making effective comments.

B. Participation in Virtual Public Hearing

The EPA may hold a virtual public hearing if the agency receives a request to hold one. Any party requesting a public hearing must notify the contact listed in the

FOR FURTHER INFORMATION CONTACT

section, which is Emily Maruyama at email address:

maruyama.emily@epa.gov

by 5 p.m. Eastern Daylight Time on or before November 17, 2025. If a virtual public hearing is held, it will take place on or around November 25, 2025 and further information will be provided on the EPA's Stratospheric Ozone website at

https://www.epa.gov/snap.

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 3-5 minutes to provide oral testimony. The EPA encourages commenters to provide a copy of their oral testimony electronically by emailing it to

maruyama.emily@epa.gov.

The EPA also recommends submitting the text of your oral comments as written comments to the rulemaking docket EPA-HQ-OAR-2024-0503. Written statements and supporting information submitted during the comment period will be considered with the same weight as oral comments and supporting information presented at the public hearing. The EPA may ask clarifying questions during the oral presentations but will not respond to the presentations at that time.

Please note that any updates made to any aspect of the hearing are posted online at

https://www.epa.gov/snap.

While the EPA expects the hearing to go forward as set forth above, please monitor our website or contact Emily Maruyama, 202-564-2809,

maruyama.emily@epa.gov

to determine if there are any updates. The EPA does

not intend to publish a document in the

Federal Register

announcing updates.

C. Public Access to Voluntary Consensus Safety Standards

The EPA is proposing to incorporate by reference the American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers (ANSI/ASHRAE) Standard 15-2024, “Safety Standard for Refrigeration Systems” (hereafter “ASHRAE 15-2024”) in the use conditions for one refrigerant proposed to be listed for use in chillers. The standard concerns the safe design, construction, installation, and operation of refrigeration systems. This standard is available at

https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources

and may be purchased by mail at: 180 Technology Parkway NW, Peachtree Corners, Georgia 30092; by telephone: 1-800-527-4723 in the United States or Canada. ASHRAE 15-2024 and ASHRAE 34-2024 are available as a bundle costing $178.00 for an electronic copy or hard copy. The cost of obtaining this standard is not a significant financial burden for equipment manufacturers or for those selling, installing, and servicing the equipment. Therefore, the ASHRAE standard the EPA is proposing to incorporate by reference is reasonably available.

As one of two co-proposed options for use conditions for listings in the residential and light commercial AC and heat pumps, household refrigerators and freezers, and water coolers end-uses, the EPA proposes to incorporate by reference several industry safety standards from UL. The EPA is also proposing to incorporate by reference an industry safety standard from UL in the use conditions for one refrigerant proposed to be listed for use in chillers. The 2022 revision of the standard UL 60335-2-40, “Household And Similar Electrical Appliances—Safety—Part 2-40: Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers” (hereafter “UL 60335-2-40”), 4th edition, December 15, 2022 is available at:

https://www.shopulstandards.com/ProductDetail.aspx?UniqueKey=43802,

and may be purchased by mail at: COMM 2000, 151 Eastern Avenue, Bensenville, IL 60106; Email:

orders@shopulstandards.com;

Telephone: 1-888-853-3503 in the United States or Canada (other countries dial 1-415-352-2178); internet address:

https://ulstandards.ul.com

https://www.shopulstandards.com.

The cost of the 2022 revision to UL 60335-2-40 is $521 for an electronic copy and $652 for a hard copy.

The 2024 revision of the standard UL 60335-2-24, “Household And Similar Electrical Appliances—Safety—Part 2-24: Particular Requirements for Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers,” (hereafter “UL 60335-2-24”), 3rd edition, July 29, 2022, and revisions through February 29, 2024, is available at:

https://www.shopulstandards.com/ProductDetail.aspx?productId=UL60335-2-24_3_S_20220729.

It may be purchased by mail, email, or telephone as described in the previous paragraph for UL 60335-2-40. The cost of the 2024 revision to the 3rd edition of UL 60335-2-24 is $555 for an electronic copy and $694 for a hard copy.

The February 2024 revision of the standard UL 399, “Drinking Water Coolers” (hereafter “UL 399”), 8th edition, March 30, 2017, and revisions through February 28, 2024, is available at:

https://www.shopulstandards.com/ProductDetail.aspx?productId=UL399_8_S_20170330.

It may be purchased by mail, email, or telephone as described in the previous paragraphs for UL 60335-2-40 and UL 60335-2-24. The cost of the February 2024 revision to the 8th edition of UL 399 is $798 for an electronic copy and $998 for a hard copy.

UL also offers a subscription service to the Standards Certification Customer Library that allows unlimited access to their standards and related documents. The cost of obtaining these standards is not a significant financial burden for equipment manufacturers and purchase is not necessary for those selling, installing, and servicing the equipment. Therefore, the UL standards the EPA is proposing to incorporate by reference are reasonably available.

III. General Information

A. Does this action apply to me?

The following list identifies regulated entities that may be affected by this rule and their respective North American Industrial Classification System (NAICS) codes:

• New Single-Family Housing Construction (except For-Sale Builders) (236115).

• Commercial and Institutional Building Construction (236220).

• Plumbing, Heating, and Air Conditioning Contractors (238220).

• All Other Basic Organic Chemical Manufacturing (325199).

• Air Conditioning and Warm Air Heating Equipment and Commercial and Industrial Refrigeration Equipment Manufacturing (333415).

• Aircraft Manufacturing (336411).

• Motor Vehicle Manufacturing (3361).

• Motor Vehicle Parts Manufacturing (3363).

• Refrigeration Equipment and Supplies Merchant Wholesalers (423740).

• Recyclable Material Merchant Wholesalers (423930).

• Convenience Stores (445120).

• General Automotive Repair (811111).

• Appliance Repair and Maintenance (811412).

• Fire Protection (922160).

This list is not intended to be exhaustive, but rather to provide a guide for readers regarding entities likely to be affected by this action. To determine whether your facility, company, business, or organization could be affected by this action, you should carefully examine the regulations at 40 CFR part 82, subpart G, and the proposed revisions. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the

FOR FURTHER INFORMATION CONTACT

section.

B. What action is the Agency proposing to take?

The EPA is proposing to list new alternatives for the refrigeration and AC sector and for the fire suppression and explosion protection sector. The Agency also proposes to revise use conditions for existing alternatives for the refrigeration and AC sector and list a new alternative for the fire suppression and explosion protection sector.

C. What is the Agency's authority for taking this action?

This action is based upon the EPA's authority under CAA section 612. The SNAP program implements CAA section 612. The first SNAP rulemaking was promulgated in 1994, and set forth the framework for the program in addition to finalizing listings for a number of alternatives as acceptable. Since that time, EPA has issued 26 final rules and 39

Federal Register

notices under the SNAP program. Several major provisions of CAA section 612 are as follows:

CAA section 612(c) requires the EPA to promulgate rules making it unlawful to “replace any class I [(chlorofluorocarbon (CFC), halon, carbon tetrachloride, methyl chloroform, methyl bromide, hydrobromofluorocarbon, and chlorobromomethane)] or class II [(hydrochlorofluorocarbon (HCFC))] substance with any substitute substance which the Administrator determines

may present adverse effects to human health or the environment, where the Administrator has identified an alternative to such replacement that (1) reduces the overall risk to human health and the environment; and (2) is currently or potentially available.” CAA section 612(c) requires the EPA to publish a list of the substitutes that it finds to be unacceptable for specific uses and to publish a corresponding list of acceptable substitutes for specific uses. Since its inception, the SNAP program has continually responded to petitions and submissions using either a rulemaking or notice to convey listing decisions.

CAA section 612(d) grants the right to any person to petition the Administrator to add a substance to, or delete a substance from, the lists published in accordance with section 612(c).

CAA section 612(e) directs the EPA to require “any person who produces a chemical substitute for a class I substance . . . to notify the [Agency] not less than 90 days before new or existing chemicals are introduced into interstate commerce for significant new use as substitutes for a class I substance.” The producer must also provide the Agency with the producer's unpublished health and safety studies on such substitutes.

The regulations for the SNAP program are promulgated at 40 CFR part 82, subpart G, and the Agency's process for reviewing SNAP submissions is described in regulations at 40 CFR 82.180. Under these rules, the Agency identified five types of listing decisions: acceptable; acceptable, subject to use conditions; acceptable, subject to narrowed use limits; unacceptable; and pending. Use conditions and narrowed use limits are both considered “use restrictions.” Substitutes that are deemed acceptable with no use restrictions (no use conditions or narrowed use limits) can be used for all applications within the relevant end-uses in the sector. After reviewing a substitute, the Agency may determine that a substitute is acceptable if certain conditions in the way that the substitute is used are met to minimize risks to human health and the environment. The EPA describes such substitutes as “acceptable, subject to use conditions.”

For some substitutes, the Agency may permit a narrowed range of use within an end-use or sector. For example, the Agency may limit the use of a substitute to certain end-uses or specific applications within an industry sector. The EPA describes these substitutes as “acceptable subject to narrowed use limits.”

Under the narrowed use limit, users intending to adopt these substitutes “must ascertain that other alternatives are not technically feasible.”

CAA section 612 and the EPA regulations do not allow the introduction of substitutes on the “unacceptable” list into interstate commerce unless and until the effective date of a final rule that changes an unacceptable listing to acceptable, acceptable subject to use conditions, or acceptable subject to narrowed use limits.

40 CFR 82.180(b)(2).

40 CFR 82.180(b)(3).

Id.

Many SNAP listings include “comments” or “further information” to provide additional information on substitutes. Since this additional information is not part of the regulatory decision under SNAP, these statements are not binding for use of the substitute under the SNAP program. The EPA encourages users of substitutes to apply all statements in the “Further Information” column in their use of these substitutes. Regulatory requirements so listed may be binding under other regulatory programs (

e.g.,

worker protection regulations promulgated by United States Occupational Safety and Health Administration (OSHA) or Department of Transportation (DOT) requirements for transport of flammable gases). In many instances, the information simply refers to sound operating practices that have already been identified in existing industry and/or building codes or safety standards. Thus, many of the statements, if adopted, would not require the affected user to make significant changes in existing operating practices.

The “Further Information” column also does not necessarily include all other legal obligations pertaining to the manufacture, use, handling, and disposal of the listed substitute. Flammable refrigerants being recovered or otherwise disposed of from commercial or industrial air conditioning equipment are likely to be considered hazardous waste under the Resource Conservation and Recovery Act (RCRA).

Lower flammability ignitable spent refrigerants that are recycled for reuse can follow alternative safety standards under 40 CFR part 266, subpart Q, instead of the full RCRA Subtitle C hazardous waste requirements.

40 CFR parts 260-270.

For additional information on the SNAP program, visit the EPA's SNAP website at

https://www.epa.gov/snap.

The lists of acceptable substitutes for Ozone-Depleting Substances (ODS) in all industrial sectors are available at

https://www.epa.gov/snap/snap-substitutes-sector.

For more information on the Agency's process for administering the SNAP program or criteria for evaluation of substitutes, refer to the initial SNAP rulemaking, codified at 40 CFR part 82, subpart G.

SNAP decisions and the appropriate

Federal Register

(FR) citations can be found at

https://www.epa.gov/snap/snap-regulations.

Substitutes listed as unacceptable; acceptable, subject to narrowed use limits; or acceptable, subject to use conditions, are also listed in the appendices of 40 CFR part 82, subpart G.

See 59 FR 13044; March 18, 1994.

D. What are the guiding principles of the SNAP program and what are the SNAP criteria for evaluating substitutes?

The guiding principles of the SNAP program are described in the preamble to the first SNAP rule.

These principles, reiterated and described in many subsequent SNAP rulemakings, are:

Ibid.

1. Evaluate substitutes within a comparative risk framework: The SNAP program evaluates the risk of substitutes compared to available or potentially available substitutes which the new substitutes are intended to replace.

2. Do not require that substitutes be risk free to be found acceptable: Substitutes found to be acceptable must not pose significantly greater risk than other substitutes, but they do not have to be risk free.

3. Restrict those substitutes that are significantly worse: The EPA does not intend to restrict a substitute if it has only marginally greater risk.

4. Evaluate risks by use: Central to SNAP's evaluations is the intersection between the characteristics of the substitute itself and its specific end-use application.

5. Provide the regulated community with information as soon as possible.

6. Do not endorse products manufactured by specific companies.

7. Defer to other environmental regulations when warranted: In some cases, the EPA and other federal agencies have developed extensive regulations under other sections of the CAA or other statutes that address potential environmental or human health effects that may result from the use of certain substitutes. The SNAP program takes existing regulations under other programs into account when reviewing substitutes.

In making decisions regarding whether a substitute is acceptable or unacceptable, and whether substitutes present risks that are lower than or comparable to risks from other substitutes that are currently or potentially available in the end-uses under consideration, the EPA examines the following criteria in 40 CFR 82.180(a)(7): “(i) atmospheric effects and related health and environmental impacts; (ii) general population risks from ambient exposure to compounds with direct toxicity and to increased ground-level ozone; (iii) ecosystem risks; (iv) occupational risks; (v) consumer risks; (vi) flammability; and (vii) cost and availability of the substitute.” To enable the EPA to assess these criteria, we require submitters to include various information including but not limited to ozone depletion potential (ODP), flammability, and the potential for human exposure. The EPA applies the same criteria to all evaluations; however, the Agency notes, for different sectors, the relevance of the factors may vary. For example, for the fire suppression sector, flammability would be considered differently than for the other sectors.

To assess atmospheric effects, the EPA uses both the ODP of class I and class II ODS in appendix A of 40 CFR part 82, subpart A and where appropriate the exchange values for HFCs listed in the American Innovation and Manufacturing (AIM) Act and codified at 40 CFR part 84, subpart A. For both ODP and exchange values, there are equivalent values listed in

Montreal Protocol on Substances that Deplete the Ozone Layer

(Montreal Protocol) annexes.

For substitute compounds without these values, the Agency uses information provided in the World Meteorological Organization (WMO) 2022 assessment,

and other relevant sources. For chemical blends, such as the fire suppressant blend proposed as acceptable in this document, the EPA calculates atmospheric effects values as a mass weighted average of each component of the blend.

https://ozone.unep.org/treaties/montreal-protocol/montreal-protocol-substances-deplete-ozone-layer.

WMO,

Scientific Assessment of Ozone Depletion: 2022,

GAW Report No. 278, 509 pp.; WMO: Geneva, 2022. Available at:

https://ozone.unep.org/system/files/documents/Scientific-Assessment-of-Ozone-Depletion-2022.pdf.

(WMO, 2022).

In a future notice and comment rulemaking, the EPA plans to revisit the criteria used for these evaluations particularly regarding atmospheric effects. The EPA acknowledges that there is an important relationship between ODS and HFCs. Therefore, this future rulemaking may be combined with other relevant proposals in order to consider the provisions regarding substitutes under CAA Title VI and the AIM Act subsection (i) paragraph (5) holistically. The Agency is not proposing or seeking comment on these topics in this rulemaking.

The SNAP program uses exposure assessments to estimate concentration levels of substitutes to which workers, consumers, the general population, and environmental receptors may be exposed over a determined period of time. These assessments are based on personal monitoring data or area sampling data if available. Exposure assessments may be conducted for many types of releases including: (1) releases in the workplace and in homes; (2) releases to ambient air and surface water; (3) releases from the management of solid wastes.

The SNAP program uses toxicity data to assess the possible health and environmental effects of exposure to substitutes. We use broad health-based criteria such as: (1) Permissible Exposure Limits (PELs) for occupational exposure; (2) inhalation reference concentrations (RfCs) for noncarcinogenic effects on the general population; and (3) cancer slope factors for carcinogenic risk to members of the general population. When considering risks in the workplace, if OSHA has not issued a PEL for a compound, the EPA then considers Recommended Exposure Limits from the National Institute for Occupational Safety and Health, Workplace Environmental Exposure Limits (WEELs) set by the American Industrial Hygiene Association (AIHA), or Threshold Limit Values (TLVs) set by the American Conference of Governmental Industrial Hygienists. If limits for occupational exposure or exposure to the general population are not already established, then the EPA derives these values following the Agency's peer reviewed guidelines. Exposure information is combined with toxicity information to explore any basis for concern. Toxicity data are used with existing EPA guidelines to develop health-based limits for interim use in these risk characterizations.

The SNAP program examines flammability as a safety concern for workers and consumers. The EPA assesses flammability risk using data on: (1) flash point and flammability limits (

e.g.,

OSHA flammability/combustibility classifications); (2) data on testing of blends with flammable components; (3) test data on flammability in consumer applications conducted by independent laboratories; and (4) information on flammability risk mitigation techniques.

The SNAP program also examines other potential environmental impacts such as ecotoxicity and local air quality impacts. A compound that is likely to be discharged to water may be evaluated for impacts on aquatic life. Some substitutes are volatile organic compounds (VOC). The EPA also notes whenever a potential substitute is considered a hazardous or toxic air pollutant (under CAA sections 112(b) and 202(l)) or hazardous waste under the RCRA subtitle C regulations.

The EPA also notes that the U.S. government has not adopted a single definition of per- and polyfluoroalkyl substances (PFAS) and has not included HFCs, HFOs, 2-BTP, or trifluoroacetic acid (TFA) in any PFAS-related restrictions. There also is no consensus definition of PFAS as a class of chemicals, and different definitions can result in more or fewer chemicals being classified as PFAS. There are several HFCs and HFOs, among other chemicals such as 2-BTP and TFA, that are defined as PFAS by some states and other jurisdictions. The EPA is not proposing or seeking comment on any definitions of PFAS in this rulemaking.

As described above, the proposed listing decisions consider whether substitutes present risks that are lower than or comparable to risks from other substitutes that are currently or potentially available in the end-uses under consideration. The EPA does not assume any substitute is risk free.

IV. Residential and Light Commercial Air Conditioning and Heat Pumps

A. What is the EPA proposing in this action?

The EPA is proposing to list R-516A and HFO-1234ze(E) as acceptable, subject to use conditions, for use in all applications under the residential and light commercial AC and heat pumps end-use. The EPA is also proposing to list HCR 4141 as acceptable, subject to use conditions, for use in self-contained room AC, a limited subset of equipment covered by this end-use.

SNAP use conditions are designed to ensure that refrigerants are listed for specific end-uses and in a way that mitigates risks to human health and the environment. The use conditions proposed for these new listings are discussed in Section IV.F. They include a requirement that these refrigerants be used in new equipment only and specific requirements for warning labels and markings. The EPA is also co-proposing two options for an additional use condition related to equipment

certification or industry safety standard requirements. These options are described in detail in Section IV.F.4. One option would incorporate by reference a new edition of the safety standard for this end-use. The second option would require residential and light commercial AC and heat pump equipment to be certified to a U.S. industry consensus safety standard by an organization that is recognized as a Nationally Recognized Testing Laboratory (NRTL).

The proposed regulatory text for listings using the third-party certification option can be found in the docket for this rulemaking under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Third-Party Certification Option (co-proposed as an alternative to Section III).” The proposed regulatory text for listings using the incorporate by reference option can be found in the docket for this rulemaking under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Incorporate by Reference Option.” If one of the use condition options is finalized, the EPA would publish corresponding finalized listings for R-516A, HCR 4141, and HFO-1234ze(E) in new residential and light commercial AC and heat pump equipment in appendix Z of 40 CFR part 82, subpart G.

The EPA is also proposing to update use conditions for the previously listed refrigerants HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A for use in the residential and light commercial AC and heat pumps end-use. Information on the previous listing locations and the existing use conditions for these refrigerants can be found in Section IV.E.

The EPA proposes that the same use conditions described previously in this section for the new listings in this end-use would also apply to these updated listings. The EPA is also co-proposing the same two options for a use condition related to equipment certification or industry safety standard requirements. For these updated listings, the EPA intends to finalize one of these co-proposed options along with an appropriate transition period to provide manufacturers with opportunity for a smooth transition between the existing and updated use conditions. Throughout Sections IV. and VI. in this document, the term “updated use conditions” refers to the set of use conditions being proposed that would apply to new equipment manufactured after the effective date of a final rule. The updated use conditions would neither apply to nor affect equipment manufactured before the effective date of the final rule. All the proposed use conditions are described in detail in Section IV.F. The EPA would update the existing listings for these substitutes in the following locations:

• HFC-32 in new residential and light commercial AC and heat pumps—self-contained room AC only in appendix R of 40 CFR part 82, subpart G;

• HFC-32 in new residential and light commercial AC and heat pumps excluding self-contained room AC in appendix W of 40 CFR part 82, subpart G;

• R-452B, R-454A, R-454B, R-454C, and R-457A in new residential and light commercial AC and heat pumps in appendix W of 40 CFR part 82, subpart G; and

• R-290 and R-441A in new residential and light commercial AC and heat pumps—self-contained room AC only in appendix R of 40 CFR part 82, subpart G.

This proposal would also add listing numbers to each row in the end-use column of appendix W in the table “Refrigerants—Substitutes Acceptable Subject to Use Conditions.” Additionally, this proposal would fix a typographical error in appendix R and appendix V where the name of a standard was written as “UL 60355-2-89” instead of “UL 60335-2-89” in the “Further information” column. These formatting and typographical edits would not substantively change any listings in the tables and would improve clarity and readability.

B. Background on Residential and Light Commercial AC and Heat Pumps

The residential and light commercial AC and heat pumps end-use includes equipment for cooling air in individual rooms, single-family homes, and small commercial buildings. Heat pumps are equipment types that offer both air heating and cooling options for such locations. This end-use differs from commercial comfort AC, which uses chillers to cool water that is then circulated to cool air throughout a large commercial building, such as an office building or hotel. This end-use includes both self-contained and split systems. Self-contained systems include some rooftop AC units (

e.g.,

those ducted to supply conditioned air to multiple spaces) and many types of room ACs, including packaged terminal air conditioners (PTACs), packaged terminal heat pumps (PTHPs), window AC units, portable room AC units, and wall-mounted self-contained ACs, designed for use in a single room. The EPA refers to the variety of self-contained equipment for cooling a single room using the phrase “residential and light commercial AC and heat pumps—self-contained room AC,” irrespective of whether they are air conditioners, providing space cooling, or heat pumps that can either heat or cool a space. Split systems include ducted and non-ducted mini-splits (which might also be designed for use in a single room), multi-splits and variable refrigerant flow (VRF) systems, and ducted unitary splits. Water-source and ground-source heat pumps (WSHPs/GSHPs) often are packaged systems similar to self-contained equipment but could be applied with the condenser separated from the other components similar to split systems. Examples of equipment for residential and light commercial AC and heat pumps include:

•

Unitary AC or unitary split systems, also called central air conditioners:

These systems include an outdoor unit with a condenser and a compressor, refrigerant lines, an indoor unit with an evaporator, and ducts to carry cooled air throughout a building. Central heat pumps are similar but offer the choice to either heat or cool the indoor space.

•

Multi-split and mini-split air conditioners and heat pumps:

Multi-split systems include one or more outdoor unit(s) with a condenser and compressor, and multiple indoor units, each of which is connected to the outdoor unit by refrigerant lines. Mini-split systems are similar to multi-split systems, but they have only a single outdoor unit and a single indoor unit, and they cool a single room. Non-ducted multi-splits and mini-splits provide cooled or heated air directly from the indoor unit rather than providing the air through ducts.

•

Rooftop AC units:

These are units that combine the compressor, condenser, and evaporator in a single package and may contain additional components for filtration and dehumidification. Most units also include dampers to control air intake. Rooftop AC units cool or heat outside air that is then delivered to the space directly through the ceiling or a duct network. Rooftop AC units are common in small commercial buildings such as a single store in a mall with no indoor passageways between stores (

e.g.,

a “strip-mall”). They can also be set up in an array to provide cooling or heating throughout a larger commercial establishment such as a department store or supermarket.

•

Window air conditioners:

These are self-contained units that fit in a window with the condenser extending outside the window.

•

PTACs and PTHPs:

These are self-contained units that consist of a separate, un-encased combination of heating and cooling assemblies mounted through a wall. PTACs and PTHPs are intended for use in a single room and use no ducts to carry cooled air and no external refrigerant lines. Typical applications include motel or dormitory air conditioners.

•

Portable room air conditioners:

These are self-contained units that usually have wheels and are designed to be moved easily from room to room. They may contain an exhaust hose that can be placed through a window or door to eject heat to the outside.

•

WSHPs and GSHPs:

These are similar to unitary split systems except that, when in cooling mode, heat is ejected from the condenser through a second circuit rather than directly with outside air. The second circuit transfers the heat to the ground, ground water, or another body of water such as a lake. Water is used for this transfer, but brine can be used if temperatures would risk freezing. Some systems can perform heating in a similar matter with the refrigerant circuit running in reverse. Regardless, the term “heat pump” is most often used.

Unless specified, all these types of AC and heat pump equipment would be subject to the listing decisions under this rule for the identified substitutes. Of these types of equipment, window air conditioners, PTACs, PTHPs, rooftop AC units, portable room air conditioners, and often GSHPs and WSHPs are self-contained equipment with the condenser, compressor, evaporator, and tubing all within a single unit casing. In contrast, unitary split systems, multi-split systems, and mini-split systems have an outdoor condenser that is separate from an indoor unit. Compared to these split systems, self-contained equipment typically has smaller charge sizes, fewer locations that are prone to leak, and is less likely to require servicing by a technician. These types of AC and heat pump equipment, both self-contained and split systems, typically fall under the scope of UL 60335-2-40.

C. What are the ASHRAE groups for refrigerant flammability and toxicity?

ASHRAE 34-2024 assigns a safety group for each refrigerant, which consists of two to three alphanumeric characters (

e.g.,

A2L or B1).

The initial character indicates the toxicity, and the numeral, with or without suffix letter, denotes the flammability. ASHRAE classifies Class A refrigerants as refrigerants for which toxicity has not been identified at concentrations less than or equal to 400 parts per million (ppm) by volume, based on data used to determine threshold limit value-time-weighted average (TLV-TWA) or consistent indices. Class B signifies refrigerants for which there is evidence of toxicity at concentrations below 400 ppm by volume, based on data used to determine TLV-TWA or consistent indices.

ASHRAE, 2024b. ANSI/ASHRAE Standard 34-2024: Designation and Safety Classification of Refrigerants.

ASHRAE 34-2024 also assigns refrigerants a flammability class of 1, 2, 2L, or 3. Tests for flammability are conducted in accordance with American Society for Testing and Materials (ASTM) E681 using a spark ignition source at 140 °F (60 °C) and 14.7 psia (101.3 kPa). The flammability class “1” is given to refrigerants that, when tested, show no flame propagation. The flammability class “2” is given to refrigerants that, when tested, exhibit flame propagation, have a heat of combustion less than 19,000 kJ/kg (8,169 BTU/lb), and have a lower flammability limit (LFL) greater than 0.10 kg/m

. The flammability class “2L” is given to refrigerants that meet the requirements of the “2” class and have a maximum burning velocity of 10 cm/s or lower when tested in dry air at 73.4 °F (23.0 °C) and 14.7 psia (101.3 kPa). Throughout this document, refrigerants in the flammability class of “2L” are referred to as lower flammability refrigerants. The flammability class “3” is given to refrigerants that, when tested, exhibit flame propagation and either have a heat of combustion of 19,000 kJ/kg (8,169 BTU/lb) or greater or have an LFL of 0.10 kg/m

or lower. Throughout this document, refrigerants in the flammability class of “3” are referred to as higher flammability refrigerants.

Flammability for refrigerant blends are designated based on the worst case of formulation for flammability and the worst case of fractionation for flammability determined for the blend. Information about refrigerant safety groups is consistent with that in prior rules under the SNAP program. See Section II.A.2. of SNAP Rule 26

for more detail. Using these safety groups, HFO-1234ze(E), HFC-32 and the refrigerant blends R-452B, R-454A, R-454B, R-454C, R-457A, and R-516A are in the A2L Safety Group, while R-290, R-441A, and the components of HCR 4141 are in the A3 Safety Group.

To see a diagram depicting these classifications, see SNAP Rule 26, 89 FR 50417; June 13, 2024.

See 89 FR 50410; June 13, 2024.

The EPA is proposing to list HCR 4141, HFO-1234ze(E), and R-516A as acceptable, subject to use conditions, for this end-use. HCR 4141 is a higher flammability refrigerant blend with each component in the A3 Safety Group. HFO-1234ze(E) and R-516A are lower flammability refrigerants, both in the A2L Safety Group. HCR 4141 is a blend of the saturated hydrocarbons (HCs) isobutane (R-600a), n-butane (R-600), and propane (R-290); the percentages of each component in the blend are claimed as CBI. The respective Chemical Abstracts Service Registry Identification Numbers (CAS Reg. Nos.) of R-600a, R-600, and R-290 are 75-28-5, 106-97-8, and 74-98-6. HFO-1234ze(E), also known by the trade names “Solstice® ze and Solstice® 1234ze,” is also known as

trans

-1,3,3,3-tetrafluoroprop-1-ene (CAS Reg. No. 29118-24-9). R-516A, also known by the trade name “Forane® 516A,” is a blend consisting of 77.5 percent HFO-1234yf (also known as 2,3,3,3-tetrafluoroprop-1-ene, CAS Reg. No. 754-12-1), 14 percent HFC-152a (also known as 1,1-difluoroethane, CAS Reg. No. 75-37-6), and 8.5 percent HFC-134a (also known as 1,1,1,2-tetrafluoroethane, CAS Reg. No. 811-97-2).

Redacted submissions and supporting documentation for HCR 4141, HFO-1234ze(E), and R-516A are provided in the docket. The EPA performed a risk screening assessment to examine the human health and environmental risks of each of these substitutes which are available in the docket.

ICF, 2025a. Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps (New Equipment); Substitute: HCR 4141.

ICF, 2025b. Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps (New Equipment); Substitute: HFO-1234ze(E) (Solstice® ze, Solstice® 1234ze).

ICF, 2025c. Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps (New Equipment); Substitute: R-516A (Forane® 516A).

Environmental information:

The specific atmospheric effects values can be found in the individual risk screens for HCR 4141, HFO-1234ze(E), and R-

516A. These were determined consistent with the source information noted in Section III.C. above as well as using the methodology for determining values for blends of chemicals (

i.e.,

determined by the percentage of each component). HFO-1234ze(E) and the components of R-516A—HFC-134a, HFC-152a, and HFO-1234yf—are excluded from the EPA's regulatory definition of VOC

addressing the development of State Implementation Plans (SIPs) to attain and maintain the National Ambient Air Quality Standards (NAAQS).

40 CFR 51.100(s).

40 CFR 51.100(s) states that “any compound of carbon” which “participates in atmospheric photochemical reactions” is considered a VOC unless expressly excluded in that provision based on a determination of “negligible photochemical reactivity” when compared to ethane's photochemical reactivity.

HCR 4141 is a blend of saturated HCs, all of which fall under the EPA's regulatory definition of VOC

for the purpose of developing SIPs to attain and maintain the NAAQS. The maximum incremental reactivities (MIRs)

of the components of this blend are as high or higher and more reactive than that of ethane (MIR of 0.26 g O

/g ethane), which the EPA uses as a threshold to determine whether substances may have negligible photochemical reactivity in the lower atmosphere (troposphere). The MIR of the blend HCR 4141 is expected to be less than that of R-600a (MIR of 1.23 g O

/g isobutane) and R-290 (MIR of 0.49 g O

/g propane). The EPA has previously listed R-290 as acceptable, subject to use conditions, in residential and light commercial AC and heat pumps—self-contained room AC.

40 CFR 51.100(s).

MIR values are from “Development of the SAPRC-07 Chemical Mechanism and Updated Ozone Reactivity Scales,” Report to the California Air Resources Board by William P.L. Carter. Revised January 27, 2010. (Carter, 2010).

The EPA has previously performed air quality modeling on various scenarios to determine whether emissions of HC refrigerants could have a significant impact on local air quality, particularly in certain cities with challenges in achieving attainment of the NAAQS for ground-level ozone. The EPA prepared an analysis in 2014

and a follow-on analysis in 2016

to evaluate the potential impact of the use of HC refrigerants on ground-level ozone concentrations in the United States. These analyses estimated refrigerant emissions from refrigeration and AC equipment which were all assumed to contain propylene, R-600a, R-290, and/or the HC blends R-441A and R-443A under different scenarios. The EPA concluded that potential emissions of saturated HC refrigerants used in refrigeration and AC equipment, such as R-290 and R-600a, do not have a significant impact on local air quality and would not have a greater overall impact on human health and the environment than other acceptable refrigerants, even if their market share grew much greater than anticipated.

ICF, 2014. Assessment of the Potential Impact of Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. February, 2014.

ICF, 2016. Additional Follow-on Assessment of the Potential Impact of Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. September, 2016.

ICF, 2014.

The analysis evaluated HC refrigerant in the following end-uses: cold storage warehouses, chillers, residential and light commercial AC and heat pumps, and specific small, self-contained refrigeration and air-conditioning units. The EPA considered it possible that HC refrigerants may be used in those end-uses because either SNAP had received applications for HCs in these end-uses or UL standards that specifically address higher flammability refrigerants existed for these end-uses, showing industry interest in using HC refrigerants. The scenarios for these end-uses were modeled to consider whether they were or were not exempted from the CAA section 608 venting prohibition.

The HC emissions used for these scenarios were estimated based on the EPA's Vintaging Model, and their potential contributions to ozone concentrations were assessed using the EPA's Community Multiscale Air Quality (CMAQ) model.

ICF, 2016.

CMAQ modeling was performed for the Atlanta, Houston, and Los Angeles regions, due to their distinctive geographic settings and chronic high levels of ground-level ozone. Their ozone concentrations were used to estimate and scale for national emission estimates. Ozone concentrations due to HC refrigerant emissions were compared to 70 ppb for the purposes of illustrating that even under a worst-case scenario, the projected impacts on ground-level ozone would be small.

We found that even if all the HC refrigerants in appliances in end-uses listed as acceptable, subject to use conditions, and listed as acceptable in previous rules were to be emitted, as well as two unsaturated HC refrigerants that the EPA ultimately listed as unacceptable in certain end-uses, there would be a worst-case impact of less than 0.15 ppb for ground-level ozone in the Los Angeles area.

The current NAAQS for ozone and other photochemical oxidants is 0.070 ppm, as the fourth-highest daily maximum 8-hour concentration, averaged across three consecutive years. The level of the NAAQS, 0.070 ppm, is equivalent to 70 ppb.

ICF, 2016.

Op cit.

In 2022, the EPA conducted a more recent air quality analysis, which considered additional end-uses and recently listed acceptable refrigerants (

e.g.,

R-1150 [ethylene] in very low temperature refrigeration). This analysis did not include the refrigerants propylene and R-443A due to the EPA's listing of these refrigerants as unacceptable in certain end-uses, citing their potential for local air quality impacts.

The analysis utilized updated models and projected future impacts out to 2040.

The EPA found that the revised air quality models showed slightly greater impacts compared to our 2014 and 2016 analyses when using the same refrigerants in the same end-uses. For example, when looking at a worst-case scenario where the most reactive HC refrigerant analyzed, propylene, was used broadly in all refrigeration and AC end-uses, the largest incremental amount of O

generated was 7.80 ppb in the 2016 analysis, which increased to 8.62 ppb in the 2022 analysis. Changes to the CMAQ model, more updated refrigerant emissions estimates from the EPA's Vintaging Model, as well as the longer time-period considered, resulted in the changes in impacts. However, the 2022 analysis also included analyses that accounted for updates in the SNAP listings since the prior analysis. In the 2022 analysis scenarios that estimated emissions if HC refrigerants then listed as acceptable, subject to use conditions, reached 100 percent market penetration in the end-uses in SNAP Rule 25, the worst-case increase in ground-level ozone in Los Angeles was 0.012 ppb, in Houston was 0.009 ppb, and in Atlanta was 0.006 ppb. Unlike the 2016 analysis, the 2022 analysis only examined impacts of propylene in the worst-case scenario and did not otherwise model propylene or the propylene blend R-443A in the more reasonable scenarios, as those refrigerants were listed as unacceptable in SNAP Rule 21.

Because propylene and R-443A had a much higher potential impact on local air quality than the saturated HCs, removing propylene and R-443A from the modeling resulted in lower projected impacts on local air quality in the 2022 analysis compared to the 2016 analysis in the more reasonable scenarios. The

EPA considers the 2022 modeling to further support the Agency's earlier conclusions in 2015 and 2016 that use of saturated HCs as refrigerants would not result in a significant increase in ground-level ozone.

See SNAP Rule 21, 81 FR 86778; December 1, 2016.

ICF, 2022. Additional Assessment of the Potential Impact of Hydrocarbon Refrigerants on Ground Level Ozone Concentrations. May 2022.

See 81 FR 86778; December 1, 2016.

HCR 4141 is a blend of saturated HCs. The potential of this refrigerant blend to form ground-level ozone, as determined by the MIRs of its components, is expected to be less than that of R-600a or the blend R-441A, and greater than that of R-290, as mentioned earlier in this section. The EPA is proposing to list HCR 4141 as acceptable, subject to use conditions, for use in household refrigerators and freezers, where other HC refrigerants with comparable MIRs are listed as acceptable, subject to use conditions, and for use in residential and light commercial AC and heat pumps—self-contained room AC. Thus, the EPA considers the potential impacts of HCR 4141 on local air quality, as well as the overall risk to human health and the environment, to be no greater than that of other substitutes available and already listed as acceptable in the same end-uses.

Flammability information:

HCR 4141 has higher flammability, with all its components having an ASHRAE flammability classification of 3. HFO-1234ze(E) and R-516A have lower flammability, with an ASHRAE flammability classification of 2L.

Toxicity and exposure data:

HFO-1234ze(E) and R-516A have an ASHRAE toxicity classification of A (lower toxicity). HCR 4141 has not yet been reviewed by ASHRAE's committee that develops the ASHRAE 34 standard, “Refrigerant Designation and Safety Classification;” however, its components all have an ASHRAE toxicity classification of A.

Potential health effects of exposure to these substitutes include drowsiness or dizziness. The substitutes may also irritate the skin or eyes or cause frostbite. At sufficiently high concentrations, the substitutes may cause irregular heartbeat. The substitutes could cause asphyxiation if air is displaced by vapors in a confined space. These potential health effects are common to many refrigerants.

The AIHA has established WEELs of 1,000 ppm as an 8-hr TWA for HFC-134a and HFC-152a and 500 ppm as an 8-hr TWA for HFO-1234yf. ASHRAE has adopted an Occupational Exposure Limit (OEL) of 800 ppm as an 8-hr TWA for HFO-1234ze(E). ASHRAE also has adopted an OEL of 590 ppm as an 8-hr TWA for R-516A.

ASHRAE has adopted OELs of 1,000 ppm for each of the components of HCR 4141. The EPA anticipates that users can meet the AIHA WEELs and ASHRAE OELs and address potential health risks by following requirements and recommendations in the manufacturers' safety data sheets (SDSs), the proposed use conditions, and other safety precautions common to the refrigeration and AC industry.

ANSI/ASHRAE Standard 34-2024. Designation and Safety Classification of Refrigerants.

Comparison to other substitutes in this end-use:

The atmospheric effects for HCR 4141, HFO-1234ze(E), and R-516A are overall better than or comparable to many of the substitutes currently listed as acceptable in this end-use such as R-290, R-457A, R-454C, R-454A, R-454B, or R-513A. More specifically, for new residential and light commercial AC and heat pump applications, R-516A, HFO-1234ze(E), and HCR 4141 have better than or comparable profiles to other acceptable substitutes already listed in this end-use such as R-457A, R-454C, R-454A, R-454B, R-513A, and HFC-32. The EPA acknowledges that the atmospheric effects of ammonia absorption, acceptable in this end-use, may be lower than R-516A, HFO-1234ze(E), and HCR 4141; however, the EPA is unaware of any ammonia absorption systems that are being used in the United States for this end-use. Other regulations also may limit the use of ammonia absorption; therefore, the SNAP program does not consider this substitute to be available or potentially available for new equipment in the affected applications. Furthermore, as noted above, the EPA does not intend to restrict a substitute if it has only marginally greater risk. The EPA does not consider the atmospheric effects of these three substitutes to be significantly greater and the Agency recognizes that they can provide an additional option for situations where other refrigerants are not viable, such as for use in split-systems and equipment requiring larger charge sizes, or where equipment using other generally available alternatives may be restricted in some jurisdictions. For new residential and light commercial AC and heat pumps—self-contained room AC, the atmospheric effects of HCR 4141 are comparable to or lower than that of other acceptable substitutes in this end-use category such as HFC-32, R-290, R-441A, and R-454B.

Toxicity risks of use, determined by the likelihood of exceeding the exposure limit of these refrigerants in this end-use, are evaluated in the previously referenced risk screens. The toxicity risks of using HCR 4141, HFO-1234ze(E), and R-516A are comparable to or lower than toxicity risks of other available substitutes in the same end-use.

Toxicity risks of the proposed refrigerants can be minimized by use consistent with the proposed use conditions and best industry practices.

See previous listing decisions for information regarding the toxicity of other available alternatives (see

https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps

The flammability risks associated with HCR 4141, HFO-1234ze(E), and R-516A in this end-use, determined by the likelihood of exceeding their respective LFLs, are evaluated in the risk screens referenced earlier in this section. While these refrigerants are more flammable than available, acceptable A1 refrigerants in the same end-use, this risk can be minimized by use consistent with the proposed use conditions, as well as recommendations in the manufacturers' SDS and other safety precautions common in the refrigeration and AC industry. The flammability risks of these refrigerants are comparable to or less than other available lower flammability (

e.g.,

HFC-32, R-454B) or higher flammability refrigerants (

e.g.,

R-290) that the EPA has previously listed as acceptable, subject to use conditions. The EPA is proposing use conditions that mitigate human health and environmental risks associated with the flammability of these alternatives so that they will not pose greater overall risk than other acceptable substitutes in this end-use category.

The EPA is proposing to list R-516A, HCR 4141, and HFO-1234ze(E) as acceptable, subject to use conditions. Given the wide range of applications for residential and light commercial AC and heat pumps, not all refrigerants listed as acceptable under SNAP will be suitable for the full range of equipment in this end-use. This proposal would provide additional refrigerant options for the full range of residential and light commercial AC and heat pump equipment.

E. What are the refrigerants for which the EPA is proposing to update use conditions and how do they compare to other refrigerants in the residential and light commercial AC and heat pumps end-use?

The EPA is proposing to update the use conditions for eight previously listed refrigerants in the residential and light commercial AC and heat pumps end-use. The EPA previously listed HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A as acceptable, subject to use conditions, for use in all residential and light commercial AC and heat pump applications, and R-290 and R-441A as acceptable, subject to use

conditions, for use in residential and light commercial AC and heat pumps—self-contained room AC.

R-290 is a HC refrigerant with three carbons and the formula C

. R-441A is a HC blend

consisting of 55 percent R-290, 36 percent R-600, six percent R-600a, and three percent R-170 (ethane) by weight. R-290 and R-441A are higher flammability refrigerants in the A3 Safety Group.

The EPA notes that under the SNAP program, we review and list refrigerants with specific compositions (59 FR 13044; March 18, 1994). To the extent possible, we follow ASHRAE's designations for refrigerants. Blends of refrigerants must be reviewed separately. For example, we consider each blend of R-290 with R-600a to be a different and unique refrigerant, and each would require separate submission, review and listing. Thus, blends of the refrigerants that we are listing as acceptable, subject to use conditions, in this rule are not acceptable.

HFC-32 is also known as difluoromethane. R-452B, also known by the trade names “Opteon

XL 55,” and “Solstice® L41y,” is a blend consisting of 67 percent by weight HFC-32; seven percent HFC-125, also known as 1,1,1,2,2-pentafluoroethane; and 26 percent HFO-1234yf. R-457A, also known by the trade name “Forane® 457A,” is a blend consisting of 18 percent HFC-32, 12 percent HFC-152a, and 70 percent HFO-1234yf. R-454A, also known by the trade name “Opteon

XL 40,” is a blend consisting of 35 percent HFC-32 and 65 percent HFO-1234yf. R-454B, also known by the trade names “Opteon

XL 41” and “Puron Advance

,” is a blend consisting of 68.9 percent HFC-32 and 31.1 percent HFO-1234yf. R-454C, also known by the trade name “Opteon

XL 20,” is a blend consisting of 21.5 percent HFC-32 and 78.5 percent HFO-1234yf. R-457A, also known by the trade name “Forane® 457A,” is a blend consisting of 70 percent HFO-1234yf, 18 percent HFC-32, and 12 percent HFC-152a.

HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A are lower flammability refrigerant blends in the A2L Safety Group. Additional information on the refrigerants and their components can be found in the docket for this rulemaking under the title “Section IV.E. Information on Refrigerants and Their Components—Residential and Light Commercial AC and Heat Pumps.”

Redacted submissions and supporting documentation for HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A are provided in the docket. The EPA performed updated risk screening for two proposed updated A2L listings, R-454C and R-457A, and one proposed updated A3 listing, R-441A, to examine the human health and environmental risks of these substitutes and to evaluate the impact of applying the 4th edition of UL 60335-2-40. The EPA chose these three representative substitutes which had the most conservative (lowest) LFLs and most conservative short- and long-term exposure limits among the group of refrigerants proposed for updated use conditions. These representative refrigerants were selected because it was presumed that substances with higher LFLs and exposure limits that were modeled for the same scenarios and end-uses would also pass the risk screens. The EPA proposes to conclude from these comparisons that while some calculated concentrations changed due to different assumptions and requirements, the refrigerants still could be used without exceeding the LFL and therefore did not increase flammability or exposure risks compared to the EPA's previous risk screens that assumed equipment followed UL 60335-2-40, 3rd edition. Thus, the risk screens demonstrated no greater overall risk to human health and the environment than other refrigerants being used when considering the impact of the co-proposed use conditions requiring use that meets the requirements of UL 60335-2-40, 4th edition. These risk screens are available in the docket.

ICF, 2025e. Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps (New Equipment); Substitute: R-441A.

ICF, 2025f. Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps (New Equipment); Substitute: R-454C (Opteon

XL20).

ICF, 2025g. Risk Screen on Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps (New Equipment); Substitute: R-457A (Forane® 457A).

Environmental information:

The specific atmospheric effects values can be found in the individual risk screens for HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A. These were determined consistent with the source information noted in Section III.C. above (

e.g.,

CAA, the AIM Act) as well as using the methodology used for determining values for blends of chemicals (

i.e.,

determined by the percentage of each component).

The refrigerant blends R-452B, R-454A, R-454B, R-454C, and R-457A are made up of the components HFC-125, HFC-32, HFC-152a, and HFO-1234yf. R-441A is made up of HC components and R-290 is a neat HC refrigerant.

The components of the refrigerant blends, HFC-125, HFO-1234yf, HFC-152a, and HFC-32, are excluded from the EPA's regulatory definition of VOC

for the purpose of addressing the development of SIPs to attain and maintain the NAAQS. See Section IV.D. for discussion of air quality analysis that was performed, which the EPA used to evaluate potential air quality impacts due to emissions of R-290, R-441A, and other HC refrigerants that are VOC under the EPA's regulatory definition of VOC.

The EPA has also established certain exemptions to the CAA section 608 venting prohibition, as listed in 40 CFR 82.154(a)(1), and none of those exemptions apply to HFC-32, R-452B, R-454A, R-454B, R-454C, or R-457A. The EPA previously exempted R-290 and R-441A in self-contained room air conditioners for residential and light commercial AC and heat pumps from the venting prohibition under CAA section 608(c)(2), finding that such venting, release, or disposal does not pose a threat to the environment.

The EPA is not proposing to change either of these decisions and is not reopening them for comment.

40 CFR 51.100(s).

Id.

See 80 FR 19454; April 10, 2015.

Flammability information:

HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A have lower flammability, with an ASHRAE flammability classification of 2L. R-290 and R-441A have higher flammability, with an ASHRAE flammability classification of 3.

Toxicity and exposure data:

HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A have an ASHRAE toxicity classification of A (lower toxicity). Potential health effects of exposure to these substitutes include drowsiness or dizziness. The substitutes may also irritate the skin or eyes or cause frostbite. At sufficiently high concentrations, the substitutes may cause irregular heartbeat. The substitutes could cause asphyxiation if air is displaced by vapors in a confined space. These potential health effects are common to many refrigerants.

The AIHA has established WEELs of 1,000 ppm as an 8-hr TWA for HFC-32, HFC-125, HFC-134a, and HFC-152a and 500 ppm as an 8-hr TWA for HFO-1234yf. ASHRAE also has adopted OELs of 1,000, 1,000, 870, 690, 850, 620, and 650 ppm as an 8-hr TWA for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A, respectively.

The EPA anticipates that users can meet the AIHA WEELs and ASHRAE OELs and address potential health risks by following requirements and recommendations in the manufacturers'

SDS, the proposed use conditions, and other safety precautions common to the refrigeration and AC industry.

OELs are those in ASHRAE 34-2024, “Designation and Safety Classification of Refrigerants.”

Comparison to other substitutes in this end-use:

The atmospheric effects for HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A are overall better than or comparable to many of the substitutes currently listed as acceptable. For new residential and light commercial AC and heat pump applications (the full category), HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A have comparable or higher individual values than some other substitutes listed as acceptable in part of this end-use such as R-290 and ammonia absorption and lower values than other acceptable substitutes listed in this end-use (

e.g.,

the exchange value of HFC-32 is lower than HFC-134a, R-407C, and R-410A). However, the EPA is unaware of any ammonia absorption systems being used in the United States for this end-use and due to its flammability, R-290 is listed as acceptable for use in self-contained room AC only and is not an available substitute for any of the other end-uses within the sector. As noted above, the EPA does not intend to restrict a substitute if it has only marginally greater risk. The EPA does not consider the atmospheric effects of these proposed substitutes to be significantly greater than other acceptable substitutes and the Agency recognizes that they can provide an additional option for situations where other refrigerants are not viable.

Toxicity risks of HFC-32, R-290, R-441A, R-452B, R-454A, R-452B, R-454C, and R-457A in this end-use, determined by the likelihood of exceeding their respective exposure limits, are evaluated in the previously referenced risk screens. The toxicity risks of using HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A are comparable to or lower than toxicity risks of other available substitutes in the same end-use.

Toxicity risks of the proposed refrigerants can be minimized by use consistent with the proposed use conditions and best industry practices.

See previous listing decisions for information regarding the toxicity of other available alternatives (

https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps

The flammability risks of HFC-32, R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in this end-use, determined by the likelihood of exceeding their respective LFLs, are evaluated in the previously referenced risk screens. While these refrigerants may pose greater flammability risk than other available substitutes in the same end-use, this risk can be minimized by use consistent with the proposed use conditions, as well as recommendations in the manufacturers' SDS and other safety precautions common in the refrigeration and AC industry. The EPA is proposing use conditions that maintain the low potential risk associated with the flammability of these alternatives so that they will not pose greater overall risk than other acceptable substitutes in this end-use category. A full discussion of the proposed use conditions may be found in Section IV.F.

While R-290 and R-441A have higher flammability than many substitutes listed as acceptable in this end-use, the proposed updated use conditions would reduce the potential risk associated with the flammability of these alternatives so that they would not pose greater overall risk than other acceptable substitutes in this end-use. The proposed substitutes HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A would provide additional options for situations where other refrigerants are not viable, such as for use in split-systems or equipment requiring larger charge sizes, or where equipment using other generally available alternatives may be restricted in some jurisdictions.

The EPA proposes to find that updating the use conditions for the existing listings for HFC-32, R-452B, R-454A, R-454B, R-454C, and R-457A as acceptable, subject to use conditions, for use in all types of residential and light commercial AC and heat pumps and for R-290 and R-441A in residential and light commercial AC and heat pumps—self-contained room AC, is appropriate to maintain a broad list of acceptable substitutes available for the full range of applications under this end-use and to continue safe use of these refrigerants. These updated listings would help establish and maintain an equal playing field for substitutes used in the market.

HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A are currently listed as acceptable, subject to use conditions, for use in the residential and light commercial AC and heat pumps end-use. The EPA is not proposing to move any of these listings to any other listing category (

e.g.,

unacceptable). Rather, the EPA is proposing to update the use conditions because the industry consensus safety standards that were incorporated by reference at the time of the listing have since been either updated

or superseded.

UL 60335-2-40.

UL 484.

This list provides a summary of the existing listings for each refrigerant in the residential and light commercial AC and heat pumps end-use that the EPA is proposing to update:

• HFC-32 is listed as acceptable, subject to use conditions, in all new residential and light commercial AC and heat pump applications. The current use conditions incorporate by reference UL 60335-2-40, 3rd edition. Previous listings for this refrigerant in this end-use and detailed information on the use conditions, listing decision, and rationale for these previous listings can be found in SNAP Rule 19,

SNAP Rule 23,

and SNAP Rule 25.

See 80 FR 19454; April 10, 2015.

See 86 FR 24444; May 6, 2021.

See 88 FR 26382; April 28, 2023.

• R-452B, R-454A, R-454B, R-454C, and R-457A are listed as acceptable, subject to use conditions, in all new residential and light commercial AC and heat pump applications. The current use conditions incorporate by reference UL 60335-2-40, 3rd edition. Previous listings for these refrigerants in this end-use and detailed information on the use conditions, listing decision, and rationale for these previous listings can be found in SNAP Rule 23.

See 86 FR 24444; May 6, 2021.

• R-290 and R-441A are listed as acceptable, subject to use conditions, in new residential and light commercial AC and heat pumps—self-contained room AC only. The current use conditions incorporate by reference Supplement SA and Appendices B through F of the 8th edition of UL 484. Previous listings for these refrigerants in this end-use and detailed information on the use conditions, listing decision, and rationale for these previous listings can be found in SNAP Rule 19.

See 80 FR 19454; April 10, 2015.

F. What use conditions is the EPA proposing in this action for new and updated listings in this residential and light commercial AC and heat pumps end-use?

The proposed use conditions described in this section would apply to newly listed refrigerants HCR 4141, HFO-1234ze(E), and R-516A in this end-use and to previously listed refrigerants HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A in this end-use. For these eight previously listed refrigerants, the proposed use conditions would apply to new equipment manufactured after the effective date of the final rule. The proposed updated use conditions would neither apply to nor affect equipment

manufactured before the effective date of the final rule.

Many of the proposed use conditions described in this section mirror the SNAP program's historical approach to requirements for lower flammability and higher flammability refrigerants. For example, the proposed use condition related to use only in new equipment is consistent with previously listed lower flammability and higher flammability refrigerants in this end-use. The proposed use conditions related to labels and markings are very similar to previous requirements for lower and higher flammability refrigerants in this end-use, with a few changes to better align the EPA's requirements with updated industry consensus safety standards. The co-proposed option that would incorporate by reference UL 60335-2-40 described in Section IV.F.4.a. would simply update the required safety standard to the latest edition in a manner consistent with the EPA's historical practice of incorporating portions of or entire industry consensus safety standards by reference. The other co-proposed option described in Section IV.F.4.b., while different than the EPA's historical practice, would address situations where agency regulations require adherence to editions of industry consensus safety standards that have been updated and replaced subsequent to the issuance of a final rule.

The EPA is proposing to remove the existing use conditions specific to refrigerant charge size limits for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in residential and light commercial AC and heat pump applications. SNAP Rule 19

included a specific use condition for R-290 and R-441A in self-contained room AC for refrigerant charge size limits based on cooling capacity and type of equipment. SNAP Rule 23

included a specific use condition for R-452B, R-454A, R-454B, R-454C, and R-457A in all residential and light commercial AC and heat pump applications for charge size based on UL 60335-2-40 and the room size where the equipment is used. The EPA is not proposing to eliminate charge size restrictions. Rather, the EPA is co-proposing two use condition options related to equipment certification or industry consensus safety standards, which both include requirements to ensure that equipment is designed using safe refrigerant charge sizes. The EPA is proposing to rely on the charge size restrictions inherent in that proposed requirement rather than duplicate charge size restrictions in a separate use condition. The EPA proposes the following use conditions:

See 80 FR 19454; April 10, 2015.

See 86 FR 24444; May 6, 2021.

1. New Equipment Only; Not Intended for Use as a Retrofit Alternative

The EPA is proposing that all refrigerants covered by this action in the residential and light commercial AC and heat pumps end-use, including the applicable applications (

e.g.,

unitary split AC systems, mini-splits, and heat pumps), may be used only in new equipment designed to address concerns unique to lower and higher flammability refrigerants. In other words, none of these substitutes may be used as a conversion or “retrofit” refrigerant for existing equipment. These lower and higher flammability refrigerants were not submitted under the SNAP program to be used in retrofitted equipment, and no information was provided on how to address hazards if they were to be used in equipment that was designed for nonflammable refrigerants.

2. Labels

The EPA is proposing to require labels for residential and light commercial AC and heat pump equipment. These labels would need to be permanently attached at the locations provided. The following text would be required for residential and light commercial AC and heat pump equipment containing an A2L refrigerant that is proposed to be listed in this rule:

a. On the outside of the equipment: “WARNING—Risk of Fire. Flammable Refrigerant Used. To Be Repaired Only by Trained Service Personnel. Do Not Puncture Refrigerant Tubing.”

b. On the outside of the equipment: “WARNING—Risk of Fire. Dispose of Properly in Accordance with Federal or Local Regulations. Flammable Refrigerant Used.”

c. On the inside of the equipment near the compressor: “WARNING—Risk of Fire. Flammable Refrigerant Used. Consult Repair Manual/Owner's Guide Before Attempting to Service This Product. All Safety Precautions Must be Followed.”

d. For any equipment pre-charged at the factory, on the equipment packaging: “WARNING—Risk of Fire due to Flammable Refrigerant Used. Follow Handling Instructions Carefully in Compliance with National Regulations”

e. On the indoor unit near the nameplate: A label stating the minimum installation height (if applicable), in m and ft, and the minimum room area (operating or storage), in m

and ft

. These values shall be calculated according to a U.S. industry consensus safety standard for AC and heat pump equipment.

f. On the outside of non-fixed equipment, such as portable air conditioners and window air conditioners and heat pumps: “WARNING—Risk of Fire—Store in a well ventilated room without continuously operating flames or other potential ignition.”

g. For fixed equipment such as packed terminal air conditioners, packaged terminal heat pumps, rooftop units, and split air conditioners: “WARNING—Risk of Fire—Auxiliary devices which may be ignition sources shall not be installed in the ductwork, other than auxiliary devices listed for use with the specific appliance. See instructions.”

The EPA has previously stated that it would be difficult to see warning labels with the minimum lettering height requirement for A2L refrigerants of

1/8

inch as required by the UL standard. Therefore, as in previous rules,

the EPA is proposing that the minimum height for lettering be

1/4

inch (6.4 mm) as opposed to

1/8

inch, which would make it easier for technicians, consumers, retail storeowners, first responders, and those disposing of the appliance to view the warning labels. Other than the proposed label under paragraph e, the text of the labels is similar or verbatim in language to those required by the 4th edition of UL 60335-2-40. They are also aligned with labeling requirements for A2L refrigerants in previous SNAP Rules 23

and 25.

See 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.

See 86 FR 24444, May 6, 2021.

See 88 FR 26382, April 28, 2023.

The proposed label under paragraph e describes the required content of a label rather than exact language that the label would need to contain. The same change is being proposed for one of the labels for equipment using A3 refrigerants, see paragraph l, later in this section. This proposed change would allow the EPA's use conditions to remain consistent with the requirements of the latest edition of UL 60335-2-40 while giving flexibility for the use condition to remain applicable even if the third-party certification option described in Section IV.F.4.b. is finalized, and the UL standard is not incorporated by reference. This proposed change is intended to avoid potential conflict between the regulatory requirements and the industry safety standards if the specific requirements in those standards are changed.

The EPA is also proposing labels for residential and light commercial AC and

heat pump equipment using A3 refrigerants proposed in this rule. The following text would need to be permanently attached at the locations provided:

h. On the outside of the equipment: “DANGER—Risk of Fire or Explosion. Flammable Refrigerant Used. To Be Repaired Only by Trained Service Personnel. Do Not Puncture Refrigerant Tubing.”

i. On the outside of the equipment: “WARNING—Risk of Fire or Explosion. Dispose Of Properly in Accordance with Federal or Local Regulations. Flammable Refrigerant Used.”

j. On the inside of the equipment near the compressor: “DANGER—Risk of Fire or Explosion. Flammable Refrigerant Used. Consult Repair Manual/Owner's Guide Before Attempting to Service This Product. All Safety Precautions Must Be Followed.”

k. For any equipment pre-charged at the factory, on the equipment packaging: “DANGER—Risk of Fire or Explosion due to Flammable Refrigerant Used. Follow Handling Instructions Carefully in Compliance with National Regulations.”

l. On an indoor unit near the nameplate: A label stating the minimum installation height (if applicable), in m and ft, and the minimum room area (operating or storage), in m

and ft

. These values shall be calculated according to a U.S. industry consensus safety standard for AC and heat pump equipment.

m. On the outside of non-fixed equipment, such as portable air conditioners and window air conditioners and heat pumps: “WARNING—Risk of Fire or Explosion—Store in a well ventilated room without continuously operating flames or other potential ignition.”

The EPA is proposing that the minimum height for lettering be at least

1/4

inch (6.4 mm), consistent with the labeling requirements for A3 refrigerants under the 4th edition of UL 60335-2-40. This text size makes it easier for technicians, consumers, retail storeowners, first responders, and those disposing the appliance to view the warning labels. The text of the proposed labels is similar or verbatim in language to those that required by the 4th edition of UL 60335-2-40. This proposed text differs from that in SNAP Rule 19

for A3 refrigerants in this end-use. For example, the proposed labels under paragraphs k and m do not currently exist as use conditions for R-290 and R-441A but are consistent with the latest labeling requirements for A3 refrigerants under the 4th edition of UL 60335-2-40. Additionally, the proposed labels under paragraphs i and j use the words “WARNING” and “DANGER” in lieu of “CAUTION.” The EPA proposes these updates to the labeling requirements to be consistent with the 4th edition of UL 60335-2-40 and with the SNAP labeling requirements for other higher flammability refrigerants. The EPA proposes to find that using a common set of labels would aid in compliance, especially for a manufacturer that uses more than one of these refrigerants or produces both self-contained room ACs and heat pumps and other types of residential and light commercial AC and heat pumps. The labels for residential and light commercial AC and heat pump equipment using A3 refrigerants are listed in paragraphs a through f in appendices R and Z in the proposed regulatory text for the A3 listings in this end-use. The proposed regulatory text can be found in the docket for this rulemaking under the title “Proposed Regulatory Text for SNAP Rule 27” in the sections “Proposed revisions to Appendices R, V, W, and new Appendix Z—Incorporate by Reference Option” and “Proposed revisions to Appendices R, V, W, and new Appendix Z—Third-Party Certification Option (co-proposed as an alternative to Section III).” The proposed labeling requirements are identical in both sections.

See 80 FR 19454; April 10, 2015.

3. Color-Coded Hoses and Piping

The EPA is proposing to require that equipment have distinguishing red (Pantone® Matching System [PMS] #185 or “Reichs-Ausschuß für Lieferbedingungen und Gütesicherung,” [RAL] 3020 from Germany's National Commission for Delivery Terms and Quality Assurance) color-coded hoses and piping to indicate use of a flammable refrigerant. The equipment would need to have red marked service ports, pipes, hoses, and other devices through which the refrigerant is serviced. This color would need to be present at all service ports and where service puncturing or otherwise creating an opening from the refrigerant circuit to the atmosphere might be expected. Markings would need to extend at least one inch (25 mm) from the servicing port and would need to be replaced if removed. The EPA has applied this proposed use condition in past actions for lower and higher flammability refrigerants.

The EPA is proposing that such markings apply to both A2L and A3 refrigerants to establish a common, familiar, and standard means of identifying the use of a lower or higher flammability refrigerant. Being able to immediately identify the use of a lower or higher flammability refrigerant would reduce the risk of a technician using sparking equipment or otherwise having an ignition source nearby. The AC and refrigeration industry currently uses red-colored hoses and piping as means for identifying the use of a lower or higher flammability refrigerant based on previous SNAP listings. Likewise, distinguishing coloring is used elsewhere to indicate an unusual and potentially dangerous situation, for example in the use of orange-insulated wires in hybrid electric vehicles.

See 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.

The use of color-coded hoses and piping would be in addition to the proposed use of warning labels. Having two such warning methods is reasonable and consistent with other general industry practices. This approach is the same as in our previous rules on A2L and A3 refrigerants.

See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10, 2015; 88 FR 26382, April 28, 2023.

4. Use Condition Options Related to Equipment Certification or Industry Safety Standard Requirements

The EPA is co-proposing two options for a use condition related to equipment certification or industry safety standard requirements. Under the first option, the EPA would incorporate by reference a new edition of the industry consensus safety standard for this end-use. Under the second option, the EPA would require residential and light commercial AC and heat pump equipment to be certified by an organization that is recognized as an NRTL to a U.S. industry consensus safety standard that is designed to allow for safe use of flammable refrigerants and mitigates risks such that the listed refrigerants can be used in a manner that does not pose a greater overall risk to human health and the environment than other substitutes in this end-use.

a. Incorporate by Reference UL 60335-2-40, 4th Edition Option

Since 2008, the EPA has listed numerous A2, A2L, and A3 refrigerants as acceptable, subject to use conditions, addressing use of lower and higher flammability refrigerants in end-uses where the EPA has determined it is necessary to mitigate risks. Most often, the EPA has relied in part on incorporating by reference industry consensus safety standards to ensure these risks are mitigated. Industry consensus safety standards are developed in cooperation with parties with an interest in participating in the

development or use of the standard. For example, UL uses a process where experts with various interests, including manufacturers, government agencies, and academia, come together to agree on the safety requirements for a product, resulting in a standard that reflects a collective consensus on best practices for safety. These standards are typically under continuous maintenance, meaning that they are updated and superseded by newer editions. This often means that regulations and safety standards are out of step; and thus, the EPA often updates its regulations to incorporate the newer version of the standard. The revision cycle for the 4th edition of UL 60335-2-40, including final recirculation, concluded with its publication on December 15, 2022.

Under this first option, the EPA is proposing to set a use condition consistent with the latest version of UL standards through incorporation by reference. Thus, the EPA proposes to list new refrigerants and update existing listings for refrigerants in the relevant end-use covered by this action with a use condition that these refrigerants may be used only in equipment that meets all requirements in UL 60335-2-40, 4th edition. This option continues the practice of updating regulations to align with newer editions of standards.

Specifically, the EPA is proposing to update the condition to meet all requirements listed in UL 60335-2-40, 3rd edition, “Household and Similar Electrical Appliances—Safety—Part 2-40: Particular Requirements for Electrical Heat Pumps, Air Conditioners and Dehumidifiers,” dated November 1, 2019 (for A2L refrigerants), or Supplement SA and Appendices B through F of UL Standard 484 8th edition, “Room Air Conditioners,” dated August 2, 2012 (for R-290 and R-441A), with the proposed condition to meet all requirements listed in the 4th edition of UL 60335-2-40, “Household and Similar Electrical Appliances—Safety—Part 2-40: Particular Requirements for Electrical Heat Pumps, Air Conditioners and Dehumidifiers,” dated December 15, 2022. This proposed use condition incorporating the 4th edition would apply to new equipment manufactured after the effective date of any final action. In cases where this rule includes requirements that are different than those of UL 60335-2-40 (

e.g.,

font size), the EPA is proposing that the requirements of this rule apply.

UL 60335-2-40 applies to the SNAP applications of window unit room air conditioners, PTACs and PTHPs, portable air conditioners, central air conditioners, non-ducted AC systems, packaged rooftop units, WSHPs, GSHPs, and other products. This UL standard indicates that refrigerant charges greater than a specific amount (called “m3” in the UL standard and based on the refrigerant's LFL) are beyond its scope and that national safety standards might apply, such as ANSI or ASHRAE 15.2. Because the EPA has not evaluated such situations, this proposal only covers residential and light commercial AC and heat pump equipment that fits within the scope of the UL standard.

UL 60335-2-40 was developed in an open and consensus-based approach, with the assistance of experts in the refrigeration and AC industry as well as experts involved in assessing the safety of products. Participants of the UL 60335-2-40 consensus standard process reviewed results of testing on equipment for flammability risk in residential applications and evaluated the relevant scientific studies. Further, UL has developed safety standards for construction and system design, markings, and performance tests concerning refrigerant leakage, ignition of switching components, surface temperature of parts, and component strength after being scratched. Aspects of system construction and design, including charge size, ventilation, and installation space, and greater detail on markings, are discussed later in this section. While similar safety standards exist from other bodies, such as the International Electrotechnical Commission (IEC), we are proposing in this option to use specific UL standards that are most applicable and used by U.S. manufacturers. The EPA used this approach in previous SNAP rules concerning lower and higher flammability refrigerants.

See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10, 2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.

The EPA has evaluated the revisions and proposes to find that construction and use of equipment in accordance with the 4th edition would not pose greater overall risk to human health and the environment than use in accordance with the 3rd edition. The 4th edition makes changes that address potential hazards of flammable refrigerants including refined requirements for leak detection systems to accommodate various methods, increase robustness and reliability, and account for deviation and drift over the system life cycle.

The requirements in UL 60335-2-40 would reduce the risk to workers and consumers. Incorporating the latest edition of the UL standard as a use condition would also reduce conflict between federal regulations, building codes, and other authorities that require compliance with the latest version of the UL standard. This section summarizes relevant aspects of UL 60335-2-40 for information only and is not meant to be a complete review of the standard or how it is applied.

UL 60335-2-40 limits the amount of refrigerant allowed in each type of appliance based on several factors explained in that standard. The EPA is proposing to require charge size limits for each of the proposed refrigerants by equipment type in accordance with UL 60335-2-40, 4th edition. Annex GG of the standard provides the charge limits, ventilation requirements, and requirements for secondary circuits. The standard specifies requirements for installation space of an appliance (

i.e.,

room floor area) and/or ventilation or other requirements which are determined according to the refrigerant charge used in the appliance, the installation location, and the type of ventilation of the location or of the appliance. Within Annex GG, table GG.1DV provides guidance on how to apply the requirements to address the potential flammability hazards of flammable refrigerants.

UL 60335-2-40, 4th edition also contains new specific requirements for determining releasable charge. As opposed to total refrigerant charge, which is the actual refrigerant charge of a single refrigerating system, releasable charge is the mass of refrigerant that can be released into the indoor space from a refrigerating system in the event of a leak. While accounting for releasable charge results in larger total refrigerant charges allowed under the 4th edition when compared to the 3rd edition, the EPA proposes to find that the mitigation requirements in the 4th edition of the standard, such as leak detection systems and safety shutoff valves, effectively reduce risk and address the hazards of flammable refrigerants even at larger total charge sizes.

UL 60335-2-40, 4th edition contains provisions for safety mitigation that were developed to ensure the safe use of flammable refrigerants over a range of appliances. In general, as larger charge sizes are used, more stringent mitigation requirements apply. In certain applications, refrigerant detection systems (as described in Annex LL, Refrigerant detection systems for A2L refrigerants), refrigerant sensors (as described in Annex MM, Refrigerant sensor location confirmation test), and safety alarms are required. The 4th edition includes significantly improved requirements for refrigerant detection systems, including clarified sensor

location requirements and better test methods for leak simulation tests.

Where mechanical ventilation (

i.e.,

fans) is required in accordance with Annex GG, it must be initiated by a separate refrigerant detection system either as part of the appliance or installed separately. In a room with no mechanical ventilation, Annex GG provides requirements for openings to rooms based on several factors including the charge size and the room area. The minimum opening is intended to be sufficient so that natural ventilation would reduce the risk of using a flammable refrigerant. The standard also includes specific requirements for split system appliances covering construction, instruction manuals, and allowable charge sizes, mechanical ventilation, safety alarms, and shut off valves for A2L refrigerants.

In addition to Annex GG and table GG.1DV, UL 60335-2-40 has a requirement for the maximum charge for an appliance using an A2L refrigerant, such as HFC-32, HFO-1234ze(E), R-452B, R-454A, R-454B, R-454C, R-457A, and R-516A. The 4th edition sets more comprehensive requirements on A2L refrigerants than the 3rd edition, and the EPA proposes to consider these additional safety mechanisms, including charge size limitations, to be more protective of human health and the environment. If the appliance is a portable appliance, a non-fixed factory-sealed single package, or a cord-connected appliance, which may be periodically or seasonally relocated (excluding servicing) by the end user, there are no additional requirements for room area, ventilation, or other risk mitigation if the charge is sufficiently small—under three times the LFL. Additional requirements exist for charge sizes exceeding three times the LFL.

For A3 refrigerants, including R-290, R-441A, and HCR 4141, UL 60335-2-40 requires a maximum charge of three times the LFL for an appliance that is a portable appliance, a non-fixed factory-sealed single package, or a cord-connected appliance which may be periodically or seasonally relocated (excluding servicing) by the end user. For example, for R-290 this maximum charge for non-fixed appliances would be 114 g.

The EPA compared the effect that requirements from previous standards (UL 484 and UL 60335-2-40, 3rd edition) versus UL 60335-2-40, 4th edition, would have on the results of the EPA's comparative risk screens, which are included in the docket. The EPA conducted updated risk screening on two proposed A2L listings and one proposed A3 listing, which had the most conservative (lowest) LFLs and most conservative short- and long-term exposure limits among the proposed alternatives. As discussed in Section IV.E., these risk screens demonstrated that use of these refrigerants in the residential and light commercial AC and heat pumps end-use would not pose greater overall risk to human health and the environment than other refrigerants being used when considering the impact of the co-proposed use condition requiring use that meets the requirements of UL 60335-2-40, 4th edition.

As discussed earlier in this section, the EPA is proposing to remove the existing use conditions specific to refrigerant charge size limits for R-290, R-441A, R-452B, R-454A, R-454B, R-454C, and R-457A in residential and light commercial AC and heat pump applications. Rather than duplicate charge size restrictions in a separate use condition, the EPA is proposing to rely on the charge size restrictions inherent in the requirements of UL 60335-2-40, 4th edition. Consistent with previous listings for other lower and higher flammability refrigerants in this end-use, the EPA is not proposing to include a use condition related to adherence to ASHRAE 15 or ASHRAE 15.2. As discussed in this section, the 4th edition of UL 60335-2-40 includes changes from the 3rd edition that specifically address the potential flammability hazards of lower and higher flammability refrigerants. The EPA proposes to find that these refrigerants can be used safely provided the use conditions in this proposed rule are followed, including compliance with the 4th edition of UL 60335-2-40. The EPA recognizes that in certain clauses, UL 60335-2-40 refers to ASHRAE 15 and ASHRAE 15.2 for compliance. We also note that other authorities might impose additional requirements, such as the adoption of ASHRAE 15 and 15.2 in building codes, that would provide an additional layer of safety above what the EPA is proposing to require under SNAP.

Under this incorporate by reference option, all three of the new refrigerant listings and the eight updated refrigerant listings proposed for this end-use would include the use conditions described in Sections IV.F.1., IV.F.2., and IV.F.3., as well as a use condition that the refrigerant may only be used in equipment that meets all the requirements of UL 60335-2-40, 4th edition.

The EPA performed assessments to examine the human health and environmental risks of each of these substitutes. These assessments are available in the docket.

The proposed regulatory text for new and updated listings under this option can be found in the docket under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Incorporate by Reference Option.”

See in section XII., “References”: ICF, 2025a; ICF, 2025b; ICF, 2025c; ICF, 2025e; ICF, 2025f; and ICF, 2025g.

b. Third-Party Certification Option

As noted elsewhere, in recent rulemakings for listings of lower and higher flammability refrigerants, the EPA has incorporated by reference portions of or entire industry consensus safety standards as use conditions for SNAP listings. The Agency recognizes that these standards are under continuous maintenance, meaning that they are updated and superseded by newer editions. This often means that regulations and safety standards are out of step; and thus, the EPA often updates its regulations to incorporate the newer version of the standard and to avoid directing regulated entities to editions of standards that have been updated and replaced subsequent to the issuance of a final rule. This is time-consuming, increases administrative burden, and there is often time between the issuance of a new edition of a standard and a later revised regulation which could result in confusion for the regulated community as well as slowing down adoption of revised requirements based upon the most recent science and industry experience.

This approach also may result in the EPA's requirements including sections of standards that are not needed to address the flammability risks of refrigerants. For example, UL 60335-2-40 includes certain tests that apply to all parts of the equipment, not just to the refrigerating system, and specifications about leakage current and electrical strength, which are not needed specifically to address flammability of refrigerants. Therefore, the EPA is proposing another option to streamline use conditions and to maintain consistency with the latest version of the relevant standards. This option allows for the EPA to address flammability risks while recognizing that a specific edition of a relevant standard applicable for the residential and light commercial AC and heat pumps end-use may be replaced by a later edition. This option is described in this Section IV.F.4.b.

Under this potential option, the EPA proposes that all residential and light commercial AC and heat pump

equipment using the refrigerants listed in this rulemaking would need to be certified by an OSHA-recognized NRTL to a U.S. industry consensus safety standard that is designed to allow for safe use of flammable refrigerants in residential and light commercial AC and heat pump equipment, and mitigates risks such that the listed refrigerants can be used in a manner that does not pose a greater overall risk to human health and the environment than other substitutes in this end-use. For listings in this end-use under this option, the EPA is proposing replacing the practice of incorporating by reference portions of or entire industry consensus safety standards with a use condition that relies on NRTLs certifying equipment to a U.S. industry consensus safety standard that mitigates risks. The industry consensus safety standard would need to be designed for use in the United States and be consistent with best industry safety practices (

e.g.,

UL 60335-2-40). The EPA proposes that an industry consensus safety standard used to meet this use condition would need to contain requirements for:

• Refrigerant charge sizes and risk mitigation measures that are designed to allow for safe use of flammable refrigerants (

e.g.,

refrigerant detection systems, ventilation to maintain refrigerant concentrations below the LFL in the case of a leak); and

• Markings that communicate the risks.

Definitions and requirements for the OSHA NRTL Program can be found at 29 CFR 1910.7. The term “NRTL” means an organization recognized by OSHA in accordance with appendix A to 29 CFR 1910.7, and which tests for safety, lists or labels or accepts equipment or materials, and meets the criteria described in 29 CFR 1910.7. Any testing agency or organization considering itself to meet the definition of an NRTL as specified in § 1910.7 may apply for OSHA recognition.

While the EPA is proposing reliance on certification by these NRTLs, the EPA is not opening OSHA's regulations at 29 CFR 1910.7 for comment, including definitions or requirements, nor is the EPA seeking comment on the OSHA program itself. For listings in this end-use under this option, the EPA is proposing a use condition based on certification by NRTLs instead of incorporation by reference of portions of or entire industry consensus safety standards. In addition to meeting the requirements laid out above, the U.S. industry consensus safety standard used to meet this requirement would also need to be deemed an appropriate test standard and approved by OSHA. The NRTL Program regulation at 29 CFR 1910.7(c) sets forth the criteria for determining whether a test standard is appropriate. An appropriate test standard is a document which specifies the safety requirements for specific equipment or class of equipment and is (1) recognized in the United States as a safety standard providing an adequate level of safety; (2) compatible with and maintained current with periodic revisions of applicable national codes and installation standards; and (3) developed by a standards developing organization under a method providing for input and consideration of views of industry groups, experts, users, consumers, governmental authorities, and others having broad experience in the safety field involved; or (4) in lieu of paragraphs (c) (1), (2), and (3), the standard is currently designated as an ANSI safety-designated product standard or an ASTM test standard used for evaluation of products or materials. The various procedures for approval of appropriate test standards are found in the OSHA NRTL Program Policies, Procedures, and Guidelines CPL-01-00-004 (Program Directive). NRTLs and a list of appropriate test standards that are recognized by OSHA are publicly available, and updated periodically, on OSHA's website.

https://www.osha.gov/nationally-recognized-testing-laboratory-program/current-list-of-nrtls

and

https://www.osha.gov/nationally-recognized-testing-laboratory-program/list-standards.

As discussed earlier in Section IV.F.4.a., industry consensus safety standards are developed in cooperation with parties with an interest in participating in the development or use of the standard. The EPA has confidence in this safety standards development process, as it relies on consensus built by the industry. For example, UL uses a process where experts with various interests, including manufacturers, government agencies, and academia, come together to agree on the safety requirements for a product, resulting in a standard that reflects a collective consensus on best practices for safety.

One example of an appropriate test standard for equipment in the residential and light commercial AC and heat pumps end-use is UL 60335-2-40. UL 60335-2-40 was developed in an open and consensus-based approach. The EPA proposes to view this standard as one example of a U.S. industry consensus safety standard that could be used to meet this requirement, as the requirements of the standard align with the levels of safety that the EPA expects in terms of mitigating risks to human health and the environment. As mentioned in Sections IV.D. and IV.E., the EPA performed risk screening assessments to examine the human health and environmental risks of the refrigerants being proposed in this action for this end-use. These risk screens demonstrated that use of these refrigerants in the residential and light commercial AC and heat pumps end-use consistent with the latest edition of UL 60335-2-40 would not pose greater overall risk to human health and the environment than other acceptable substitutes for new equipment in this end-use.

One potential downside of this third-party certification option is that future revisions could be made to OSHA-recognized appropriate test standards that do not align with the SNAP program's criteria for mitigating risks to human health and the environment. However, the EPA already monitors the development and revision process for industry consensus safety standards that apply to equipment in the residential and light commercial AC and heat pumps end-use and other end-uses. If this option is finalized, the EPA would continue monitoring these standards, and if revisions are made to industry safety standards that impact their alignment with the SNAP program's risk mitigation criteria, the EPA would raise concerns and could revisit and propose changes to refrigerant listing categories and/or use conditions through rulemaking.

OSHA recognizes NRTLs at the organizational-level as opposed to the laboratory-level. Therefore, the laboratory that performs the equipment testing would need to be part of an NRTL that is recognized by OSHA and have the necessary equipment and training required to test to a specific standard that would be most applicable to the equipment applications in this section.

OSHA requires all electrical equipment used in the workplace to be tested and certified by an NRTL or otherwise determined to be “acceptable” as defined in 29 CFR 1910.399. The EPA is proposing that equipment in the residential and light commercial AC and heat pumps end-use using the refrigerants proposed in this action would need to be certified to a U.S. industry consensus safety standard by an OSHA-recognized NRTL. In accordance with Annex B of the OSHA NRTL Program Directive and section 4 of ISO/IEC 17065:2012, NRTLs shall maintain registration of a certification mark with the U.S. Patent and Trademark Office, and an NRTL's procedures shall require clients to apply the NRTL's registered certification mark

to the certified equipment to signify that the equipment is certified by an NRTL and complies with the requirements of an appropriate safety test standard. In addition, the test standard(s), certification category, or a symbol or code that identifies the test standard(s) to which the unit is certified shall be shown adjacent to the NRTL's mark. These markings provide users with evidence that the equipment complies with applicable safety test standard requirements and is safe for use.

The EPA is not proposing to establish specific requirements or protocols for laboratories because OSHA already has established such requirements and performs detailed reviews of equipment certification entities. OSHA's review of NRTLs includes a thorough evaluation of application materials, assessments of the organization's programs and facilities, publication of findings in the

Federal Register

, response to public comments, and announcement of a final decision on NRTLs. OSHA also performs ongoing evaluations of NRTLs and responds to safety concerns that occur in the field. Because NRTLs must be recognized to test to a specific safety standard, all of the requirements of that particular safety standard are adopted by the NRTL, which is similar to SNAP's current use condition approach for HFC-32, R-452B, R-454A, R-454B, R-454C, R-457A, R-290, and R-441A that incorporates by reference a particular safety standard.

By not incorporating by reference a specific edition of a relevant safety standard in this use condition option, the EPA intends to increase efficiencies by not having to propose a new rule each time a safety standard is updated and to leverage OSHA's NRTL Program. The EPA does not expect this option to pose significant additional burden on manufacturers or NRTLs because most manufacturers of residential and light commercial AC and heat pump equipment have their equipment certified by an NRTL already. Manufacturers that do not already certify their equipment through an OSHA-recognized NRTL would need to do so beginning two years after the effective date of the final rule.

The EPA is aware of three entities, UL, Intertek, and CSA Group, that are currently NRTLs and test and certify equipment to industry consensus safety standards for equipment in the residential and light commercial AC and heat pumps end-use. The EPA understands there may be additional entities now or in the future.

As noted previously, the current SNAP regulations incorporate by reference UL 60335-2-40, 3rd edition, which is no longer the latest edition of a standard that is publicly available and applicable to this end-use. OSHA regulations do not specify specific editions of standards. Rather, an NRTL recognized for an ANSI-approved test standard may use either the latest proprietary version or the latest ANSI version of the standard, regardless of which version appears in its list of test standards on OSHA's web page for the NRTL. When an NRTL applies to be recognized to test to a particular standard, they must submit the specific standard to which they aim to test. If an NRTL is found to be testing and certifying equipment to a standard they are not recognized for, OSHA may act.

Under this third-party certification option, all three of the new refrigerant listings and eight updated refrigerant listings proposed for this end-use would include the use conditions described in Sections IV.F.1., IV.F.2., and IV.F.3. There would also be a condition that equipment be certified by an OSHA-recognized NRTL to a U.S. industry consensus safety standard that is designed to allow for safe use of flammable refrigerants in residential and light commercial AC and heat pump equipment.

The EPA performed an assessment to examine the human health and environmental risks of each of the proposed new substitutes. These assessments are available in the docket.

As discussed in Section IV.E., the EPA also conducted updated analyses for three representative substitutes for the updated listings to evaluate the health and safety implications of designing and using AC equipment in accordance with the latest edition of UL 60335-2-40, which the EPA proposes to view as one example of a U.S. industry consensus safety standard that could be used to meet this third-party certification requirement. These analyses found that use of these proposed refrigerants in accordance with this standard would not pose greater overall risk to human health and the environment than other acceptable substitutes for new equipment in this end-use. These assessments are available in the docket.

Proposed regulatory text for these new and updated listings under this potential option can be found in the docket under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Third-Party Certification Option (co-proposed as an alternative to Section III).”

See in section XII., “References”: ICF, 2025a; ICF, 2025b; and ICF, 2025c.

See in section XII., “References”: ICF, 2025e; ICF, 2025f; and ICF, 2025g.

5. When would the use conditions take effect?

For the newly listed refrigerants in this end-use, the use conditions would take effect on the effective date of a final rule based upon this proposal. For the refrigerants for which the EPA is proposing to update use conditions in this end-use, the EPA is proposing to allow regulated entities to follow either the existing use conditions or the proposed updated use conditions from the effective date of a final rule until two years after the effective date of the final rule.

If the EPA finalizes the third-party certification option, equipment manufactured between the effective date of the final rule and two years after that effective date could follow either the existing use conditions that include use of either UL 60335-2-40, 3rd edition

or the updated use conditions that would include certification of equipment by an OSHA-recognized NRTL. The updated use conditions would neither apply to nor affect equipment manufactured before the effective date of the final rule.

Or UL 484, 8th edition for R-290 and R-441A.

G. What additional information is the EPA including in these proposed listings?

For all proposed listings in this end-use, the EPA is including recommendations, found in the “Further Information” column of the proposed listings, to protect personnel from the risks of using flammable refrigerants. Similar to our previous listings of flammable refrigerants, the EPA is including information on the OSHA requirements at 29 CFR part 1910, proper ventilation, personal protective equipment (PPE), fire extinguishers, use of spark-proof tools

and equipment designed for flammable refrigerants, and training.

If the third-party certification option described in Section IV.F.4.b. is finalized, the EPA would also include a sentence in the “Further Information” column stating that the EPA views UL 60335-2-40 to be an example of an appropriate U.S. industry consensus safety standard that mitigates risks.

Since this additional information is not part of the regulatory decision under SNAP, these statements are not binding for use of the substitute under the SNAP program. While the statements in the “Further Information” column are not legally binding under the SNAP program, the EPA encourages users of substitutes to apply all statements in the “Further Information” column in their use of these substitutes.

V. Household Refrigerators and Freezers

A. What is the EPA proposing in this action?

The EPA is proposing to list HCR 4141 as acceptable, subject to use conditions, for use in new household refrigerators and freezers. The EPA would list HCR 4141 in a table in the new appendix Z of 40 CFR part 82, subpart G.

The EPA is proposing several use conditions for the use of HCR 4141 in the household refrigerators and freezers end-use. SNAP use conditions are designed to ensure that refrigerants are listed for specific end-uses and in a way that mitigates risks to human health and the environment. In summary, the EPA is co-proposing two options for use conditions to address flammability risks of the refrigerant HCR 4141 in household refrigerators and freezers similar to the two options discussed in Section IV.F.4. for the residential and light commercial AC and heat pumps end-use. The key difference between the two options in the household refrigerators and freezers end-use and the two options in the residential and light commercial AC and heat pumps end-use is the industry safety standard that the EPA would incorporate by reference or would describe as being a relevant industry consensus safety standard for third-party certification. In the household refrigerators and freezers end-use the relevant U.S. industry consensus safety standard that addresses safe use of flammable refrigerant is UL 60335-2-24, “Household and Similar Electrical Appliances—Safety—Part 2-24: Particular Requirements for Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers,” rather than UL 60335-2-40.

Under both options, the EPA proposes the same use conditions that would restrict the use of the refrigerant HCR 4141 to new equipment that is specifically designed for that refrigerant and that would require warning labels and markings on equipment to inform consumers, technicians, and first responders of potential flammability hazards. Those common use conditions are described in Section V.E.

The two co-proposed options take two different potential approaches to proposed use conditions addressing design safety requirements for household refrigerators and freezers and in particular, charge size. These options are described in detail in Sections V.E.4.a. and V.E.4.b. Section V.E.4.a. describes an option in which the EPA would incorporate by reference UL 60335-2-24, 3rd edition, including testing and charge sizes. Section V.E.4.b. describes an option in which the EPA would require household refrigerators and freezers to be certified to a U.S. industry consensus safety standard such as UL 60335-2-24 by an organization that OSHA recognizes as an NRTL. The EPA will consider comments and available information and could finalize either of these two co-proposals.

The common use conditions are described in Sections V.E.1., V.E.2., and V.E.3. The use condition option requiring household refrigerators and freezers using HCR 4141 to meet a specific edition of UL 60335-2-24 is described in Section V.E.4.a. The option for a use condition requiring third-party certification of household refrigerators and freezers using HCR 4141 is described in Section V.E.4.b.

The proposed regulatory text for this listing using the third-party certification option appears in the docket for this rulemaking under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Third-Party Certification Option (co-proposed as an alternative to Section III).” The proposed regulatory text for this listing using the incorporate by reference option can be found in the docket for this rulemaking under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Incorporate by Reference Option.” If one of the use condition options is finalized, the EPA would publish a corresponding finalized listing for HCR 4141 in new household refrigerators and freezers in appendix Z of 40 CFR part 82, subpart G.

B. Background on Household Refrigerators and Freezers

Household refrigerators, freezers, and combination refrigerators and freezers are intended primarily for residential use, although they may be used outside the home (

e.g.,

workplace kitchen pantries). The designs and refrigeration capacities of equipment vary widely. This equipment is composed of three main categories: household freezers only offer storage space at freezing temperatures, household refrigerators only offer storage space at non-freezing temperatures, and products with both a refrigerator and freezer in a single unit which are most common and are referred to as combination refrigerators and freezers. Small refrigerated household appliances (

e.g.,

chilled kitchen drawers, wine coolers, mini-fridges, stand-alone ice makers, home ice cream makers) are also within this end-use. In addition, refrigerators or freezers that are designed for consumer, but not commercial or professional, use and that are merely situated on a moving vehicle (

e.g.,

personal vehicle, recreational vehicle, or boat for leisure purposes) are within the scope of the household refrigerators and freezers end-use for purposes of the SNAP program. These uses are within the scope of the relevant U.S. industry safety standard, UL 60335-2-24. Throughout this document, we refer to all these uses with the phrase “household refrigerators and freezers.” Refrigerators or freezers in a commercial kitchen such as onboard a cruise ship or on aircraft are not household refrigerators or freezers for purposes of the SNAP program and such equipment is outside the scope of UL 60335-2-24. Household refrigerators and freezers have all refrigeration components integrated, and for the smallest types, the refrigeration circuit is entirely brazed or welded. These systems are charged with refrigerant at the factory and typically require only an electricity supply to begin operation.

ASHRAE's Handbook of Refrigeration provides an overview of food preservation regarding household refrigerators and freezers. Generally, a storage temperature between 32 and 39 °F (0 to 3.9 °C) is desirable for preserving fresh food. Humidity and higher or lower temperatures are more suitable for certain foods and beverages. Wine chillers, for example, are frequently used for storing wine, and have slightly higher optimal temperatures from 45 to 65 °F (7.2 to 18.3 °C). Freezers and combination refrigerators and freezers that are designed to store food for long durations

have temperatures below 8 °F (−13.3 °C) and are designed to hold temperatures near 0 to 5 °F (−17.7 to −15 °C). In single-door refrigerators, the optimum conditions for food preservation are typically warmer than this because food storage is not intended for long-term storage.

C. What are the ASHRAE groups for refrigerant flammability and toxicity?

See Section IV.C. for information on ASHRAE groups for refrigerant flammability and toxicity.

D. What is HCR 4141 and how does it compare to other refrigerants in the household refrigerators and freezers end-use?

HCR 4141 is a blend of the saturated HCs R-600a, R-600, and R-290, all of which are higher flammability refrigerants having an ASHRAE safety group of A3; the percentage of each component in the blend is claimed as CBI. See Section IV.D. for environmental information, flammability information, and toxicity and exposure information on HCR 4141. The redacted submission and supporting documentation for HCR 4141 in household refrigerators and freezers are provided in the docket. The EPA performed a risk screening assessment to examine the human health and environmental risks of this substitute which also is available in the docket.

ICF, 2025h. Risk Screen on Substitutes in Household Refrigerators and Freezers (New Equipment); Substitute: HCR 4141.

Comparison to other substitutes in the household refrigerators and freezers end-use:

The specific atmospheric effects values can be found in the individual risk screen for HCR 4141. The values were determined consistent with the source information noted in Section III.C. above (

e.g.,

CAA; the AIM Act; WMO, 2022) as well as using the methodology for determining values for blends of chemicals (

i.e.,

determined by the percentage of each component). The EPA compared HCR-4141 to other A3 refrigerants listed as acceptable subject to use conditions for the same end-use. The MIR of the blend HCR 4141 is expected to be less than that of R-600a (MIR of 1.23 g O

/g isobutane) and greater than that of R-290 (MIR of 0.49 g O

/g propane). The MIR of HCR 4141 is greater than that of compounds that have been excluded from the EPA's regulatory definition of VOC

addressing the development of SIPs to attain and maintain the NAAQS, such as HFC-152a.

40 CFR 51.100(s).

The EPA's risk screen for HCR 4141 in new household refrigerators and freezers

found that HCR 4141 can be used without exceeding its recommended OEL of 1,000 ppm (8-hr TWA); thus, the toxicity risks of HCR 4141 are comparable to those of other acceptable substitutes in new household refrigerators and freezers, which also are used without exceeding their OELs.

ICF, 2025h.

Op. cit.

Although we noted that the flammability of HCR 4141 may be greater than that of other available substitutes that have ASHRAE 1, 2 or 2L flammability classifications in the same end-use, we found its flammability risk to be not significant even under worst-case assumptions in this end-use when following the proposed use conditions.

Further, its flammability risk is comparable to that of other A3 refrigerants that the EPA has previously listed as acceptable in this end-use. We note that flammability risk can be minimized by use consistent with industry safety standards such as UL 60335-2-24—which would be required by the proposed use conditions—as well as recommendations in the manufacturers' SDS and other safety precautions common in the refrigeration and air conditioning industry. The proposed use conditions for household refrigerators and freezers would maintain low potential risk associated with the flammability of this alternative so that it would not pose greater overall risk than other acceptable substitutes in this end-use.

ICF, 2025h.

Op. cit.

E. What use conditions is the EPA proposing in this action for the new listing for HCR 4141 in new household refrigerators and freezers?

The proposed use conditions described in this section would apply to new household refrigerators and freezers using HCR 4141. Many of the proposed use conditions mirror the SNAP program's historical approach to requirements for flammable refrigerants in this end-use. The proposed use condition related to use in new equipment only is consistent with previously listed higher flammability refrigerants in this end-use. The proposed use conditions related to labels and markings are very similar to what has previously been required by SNAP for higher flammability refrigerants in this end-use, with a few updates made specifically to better align the EPA requirements with updated industry safety standards. A use condition option that proposes to incorporate by reference the latest edition of UL 60335-2-24 is consistent with the EPA's historical practice for listing flammable refrigerants in this end-use. The other co-proposed option, while different from the EPA's historical practice of incorporating portions of or entire industry consensus safety standards by reference, would address situations where the EPA's regulations require adherence to editions of industry consensus safety standards that have been updated and replaced subsequent to the issuance of a final rule. The EPA proposes the following use conditions:

1. New Equipment Only; Not Intended for Use as a Retrofit Alternative

The EPA is proposing that HCR 4141 may be used only in new equipment designed specifically and clearly identified for the refrigerant. In other words, this substitute must not be used as a conversion or “retrofit”

refrigerant for existing equipment designed for another refrigerant. The EPA has established this same requirement for other A3 refrigerants in this end-use and in certain other refrigeration and AC end-uses, such as vending machines, retail food refrigeration—stand-alone units, and very low temperature refrigeration. This requirement is intended to ensure that equipment using a higher flammability refrigerant is specifically designed to address flammability risks.

Sometimes conversion refrigerant substitutes are inaccurately referred to as “drop in” replacements.

2. Labels

The EPA is proposing to require labeling of household refrigerators and freezers using HCR 4141. The following markings, or the equivalent, would need to be provided and be permanent:

a. “DANGER—Risk of fire or explosion. Flammable refrigerant used. Do not use mechanical devices to defrost refrigerator. Do not puncture refrigerant tubing.” This marking would need to be located on or near any evaporators that can be contacted by the consumer.

b. “DANGER—Risk of fire or explosion. Flammable refrigerant used. To be repaired only by trained service personnel. Use only manufacturer-authorized service parts. Any repair equipment used must be designed for flammable refrigerants. Follow all manufacturer repair instructions. Do not puncture refrigerant tubing.” This marking would need to be located near the machine compartment.

c. “CAUTION

—Risk of fire or explosion. Dispose of refrigerator

properly in accordance with the applicable federal or local regulations. Flammable refrigerant used.” This marking would need to be located on the exterior of the refrigeration equipment.

The word “CAUTION” may be substituted with the word “WARNING.”

d. “CAUTION

—Risk of fire or explosion due to puncture of refrigerant tubing; follow handling instructions carefully. Flammable refrigerant used.” This marking would need to be located near all exposed refrigerant tubing.

The word “CAUTION” may be substituted with the word “WARNING.”

Both the 3rd and 2nd editions of UL 60335-2-24 have required labels with the above text as a hazard warning on refrigerated equipment that uses a flammable refrigerant. The 3rd edition of UL 60335-2-24 has revised two requirements in the 2nd edition concerning warning labels. The first change was that one marking would no longer be required that stated, “CAUTION—Risk of fire or explosion. Flammable refrigerant used. Consult repair manual/owner's guide before attempting to service this product. All safety precautions must be followed.” The EPA also would not require this marking in the proposed use conditions.

The second change to the labels in the 3rd edition of UL 60335-2-24 is that the height of the letters on the warning labels have changed from no less than 6.4 mm (

1/4

inch) to no less than 3.2 mm (

1/8

inch), with the signal words “DANGER,” “WARNING,” and “CAUTION” being no less than 5.0 mm (0.2 inch). This would be a smaller font size that would allow for smaller labels that would be more convenient for manufacturers to apply. The EPA is instead proposing that the label text size be no less than 6.4 mm (

1/4

inch) to allow for greater visibility for technicians, consumers, recyclers, and first responders. The larger font size is also consistent with the font size that the EPA has previously required for these labels in other SNAP rules for refrigeration or AC equipment using flammable refrigerants.

3. Color-Coded Hoses and Piping

The EPA is proposing to require that equipment have distinguishing red (PMS #185 or RAL 3020) color-coded hoses and piping to indicate use of a flammable refrigerant. This color would need to be present at all service ports and other parts of the system where service puncturing or other actions creating an opening from the refrigerant circuit to the atmosphere might be expected, would need to extend a minimum of one inch (25 mm) in both directions from such locations, and would need to be replaced if removed. The EPA has applied this proposed use condition in past actions for flammable refrigerants.

See 86 FR 24444, May 6, 2021, and 88 FR 26382, April 28, 2023.

Red markings are a requirement of the 3rd edition of UL 60335-2-24. The standard allows for an exception if the labels are visible when a technician attempts to access a process tube. In addition, the 3rd edition of UL 60335-2-24 calls for red markings but does not specify any particular shade of red. The EPA's proposal would not allow for this exception and is specifying particular shades of red, as in previous rules.

4. Use Condition Options Related to Equipment Certification or Industry Safety Standard Requirements

The EPA is co-proposing two options for a use condition related to equipment certification or industry safety standard requirements for equipment that uses HCR 4141 in household refrigerators and freezers. Under the first option, the EPA would incorporate by reference a new edition of the safety standard for this end-use. Under the second option, the EPA would require household refrigerators and freezers to be certified by an organization that is recognized as an NRTL to a U.S. industry consensus safety standard that is designed to allow for safe use of flammable refrigerants in household refrigerators and freezers. This is the same proposed approach discussed in Section IV.F.4.a.

For the most recent listings of flammable refrigerants used in household refrigerators and freezers, the EPA addressed design elements to reduce flammability risks by incorporating by reference the 2nd edition of UL 60335-2-24, “Household and Similar Electrical Appliances—Safety—Part 2-24: Particular Requirements for Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers.”

The EPA is co-proposing an option to incorporate by reference UL 60335-2-24, 3rd edition (dated July 29, 2022, with revisions through February 29, 2024). As discussed in Section IV.F.4.b., the Agency recognizes that certain standards, including UL 60335-2-24, are under continuous maintenance, meaning that they are updated and superseded by newer editions. This often means that regulations and safety standards are out of step. Therefore, the EPA is proposing another option to streamline use conditions and to maintain consistency with the most current version of the relevant standards. This potential option is discussed in Section V.E.4.b.

Dated April 28, 2017. See 83 FR 38969; August 8, 2018.

Each co-proposal in Sections IV.F.4.a. and IV.F.4.b. would include certain use conditions in addition to the common use conditions in Sections V.E.1., V.E.2., and V.E.3. (

i.e.,

for use in new equipment only, labels, and color-coded hoses and piping). The use conditions for HCR 4141 would apply to household refrigerators and freezers manufactured on and after the effective date of the final rule. The use conditions would be in a new appendix Z of 40 CFR part 82, subpart G.

a. Incorporate by Reference UL 60335-2-24, 3rd Edition Option

In this first co-proposal, the EPA proposes that the refrigerant HCR 4141 may be used only in equipment that meets all the requirements in UL 60335-2-24.

The EPA has set a similar requirement for the use of R-290, R-600a, and R-441A in household refrigerators and freezers,

where the Agency's regulations require that those refrigerants be used only in equipment meeting the requirements of the 2nd edition

of UL 60335-2-24, rather than the 3rd edition of that standard. In this proposed new listing for HCR 4141 in new household refrigerators and freezers, the EPA would incorporate by reference the standard UL 60335-2-24, “Safety Requirements for Household and Similar Electrical Appliances, Part 2: Particular Requirements for Refrigerating Appliances, Ice-Cream Appliances and Ice-Makers.”

This safety standard establishes requirements for the evaluation of household and similar electrical appliances, and safe use of flammable refrigerants. The EPA previously incorporated by reference UL 60335-2-24, 2nd edition for R-290, R-441A, and R-600a in our most recent rule on flammable refrigerants in household refrigerators and freezers.

This proposal would incorporate by reference the latest edition and revisions to that safety standard. Where the rule includes requirements that are different than those of UL 60335-2-24 (

e.g.,

font size), the EPA is proposing that the appliance would need to meet the requirements of the rule. UL 60335-2-24 establishes requirements for the evaluation of household and similar electrical appliances and the safe use of

A2, A2L, or A3 refrigerants. The charge size limit for each separate refrigerant circuit (

i.e.,

compressor, condenser, evaporator, and refrigerant piping) is 150 grams (5.3 ounces), remaining the same in the 3rd edition as in the 2nd edition.

3rd edition, July 29, 2022, with revisions through February 29, 2024.

See 83 FR 38969; August 8, 2018, and appendix R of 40 CFR part 82, subpart G.

2nd edition of UL 60335-2-24 dated April 28, 2017.

3rd edition, July 29, 2022, with revisions through February 29, 2024.

See 83 FR 38969; August 8, 2018.

Both the 2nd and 3rd editions require testing of refrigeration appliances containing flammable refrigerants, including leakage tests, temperature and scratch tests, and heat testing requirements to address the hazards due to ignition of leaked refrigerant by potential ignition sources associated with the appliance. These tests are intended, among other things, to ensure that any leaks will result in concentrations well below the LFL, and that potential ignition sources will not be able to create temperatures high enough to start a fire. Specifically, the leakage test ensures that refrigerant concentrations do not reach or exceed 75 percent of the LFL inside any internal or external electrical component compartments. Appliances that comply with UL 60335-2-24 have passed appropriate ignition or leakage tests as stipulated in the standard. In addition, UL 60335-2-24, 3rd edition, includes labels and markings, as discussed in Sections V.E.2. and V.E.3. UL standard 60335-2-24 was developed using a consensus-based approach developed in cooperation with parties with an interest in participating in the development or use of the standard. For example, UL uses a process where experts with various interests, including manufacturers, experts in assessing the safety of products, government agencies, and academia, come together to agree on the safety requirements for a product, resulting in a standard that reflects a collective consensus on best practices for safety. While similar standards exist from other bodies such as the IEC, we are proposing in this option to use specific UL standards that are most applicable and used by U.S. manufacturers. The EPA used this approach in previous SNAP rules concerning lower and higher flammability refrigerants.

UL standard 60335-2-24 was developed using a consensus-based approach developed in cooperation with parties with an interest in participating in the development or use of the standard. For example, UL uses a process where experts with various interests, including manufacturers, experts in assessing the safety of products, government agencies, and academia, come together to agree on the safety requirements for a product, resulting in a standard that reflects a collective consensus on best practices for safety. While similar standards exist from other bodies such as the IEC, we are proposing in this option to rely on specific UL standards that are most applicable and used by U.S. manufacturers. The approach of incorporating a UL standard by reference is the same as that in our previous rules on flammable refrigerants.

See 76 FR 78832, December 20, 2011; 80 FR 19454, April 10, 2015; 86 FR 24444, May 6, 2021; 88 FR 26382, April 28, 2023.

Under this incorporate by reference option, this listing would include the use conditions described in Sections V.E.1., V.E.2., and V.E.3. as well as a use condition that the refrigerant may only be used in equipment that meets all the requirements of UL 60335-2-24, 3rd edition.

The EPA performed an assessment to examine the human health and environmental risks of HCR 4141 in household refrigerators and freezers. This assessment is available in the docket.

The proposed regulatory text for this new listing under this option can be found in the docket under the title “Proposed Regulatory Text for SNAP Rule 27” in the section “Proposed revisions to Appendices R, V, W, and new Appendix Z—Incorporate by Reference Option.”

ICF, 2025h. Risk Screen on Substitutes in Household Refrigerators and Freezers (New Equipment); Substitute: HCR 4141. 2025.

b. Third-Party Certification Option

Under this second co-proposal, the EPA is proposing a use condition where all household refrigerators and freezers using HCR 4141 must be certified by an OSHA-recognized NRTL to a U.S. industry consensus safety standard that is designed to allow for safe use of flammable refrigerants in household refrigerators and freezers and mitigates risks such that the listed refrigerant can be used in a manner that does not pose a greater overall risk to human health and the environment than other substitutes in this end-use. The industry consensus safety standard must be designed for use in the United States and be consistent with best industry safety practices.

For further detail on requirements of applicable industry consensus safety standards that the EPA proposes to find necessary to sufficiently mitigate risks, see Section IV.F.4.b. While the EPA is proposing reliance on certification by these NRTLs, the EPA is not opening OSHA's regulations at 29 CFR 1910.7 for comment, including definitions or requirements, nor is the EPA seeking comment on the OSHA program itself. For further information on OSHA's NRTL Program, see Section I

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