[Federal Register Volume 86, Number 231 (Monday, December 6, 2021)]
[Proposed Rules]
[Pages 68962-68982]
[FR Doc No: 2021-25440]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 82

[EPA-HQ-OAR-2021-0347; FRL-8470-01-OAR]
RIN 2060-AV25

Protection of Stratospheric Ozone: Listing of HFO-1234yf Under
the Significant New Alternatives Policy Program for Motor Vehicle Air
Conditioning in Nonroad Vehicles and Servicing Fittings for Small
Refrigerant Cans

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the EPA's Significant New Alternatives Policy
program, this action proposes to list the refrigerant 2,3,3,3-
tetrafluoroprop-1-ene, also known as HFO-1234yf or R-1234yf, as
acceptable, subject to use conditions, in the motor vehicle air
conditioning end-use for certain types of newly manufactured nonroad
(also called off-road) vehicles, which includes some vehicles that are
also considered heavy-duty vehicles. EPA is also proposing to adopt the
current versions of the industry safety standards SAE J639, SAE J1739,
and SAE J2844 by incorporating them by reference into the use
conditions for the proposed listings in nonroad vehicles and previous
listings for certain onroad vehicles covered in final rules issued
separately in March 2011 and December 2016. In addition, EPA is
proposing to require unique servicing fittings for use with small
refrigerant cans (two pounds or less) of 2,3,3,3-tetrafluoroprop-1-ene
that are used to service onroad and nonroad vehicles. Finally, EPA is
proposing to add a reference to the Agency's regulations under the
Toxic Substances Control Act for 2,3,3,3-tetrafluoroprop-1-ene for the
proposed listings in nonroad vehicles and previous listings for certain
onroad vehicles. Aside from the changes proposed in this action, the
Agency is not reopening for comment other portions of the March 2011
and December 2016 final rules.

DATES: Comments must be received on or before January 20, 2022. Any
party requesting a public hearing must notify the contact listed below
under FOR FURTHER INFORMATION CONTACT by 5 p.m. Eastern Daylight Time
on December 13, 2021. If a virtual public hearing is held, it will take
place on or before December 21, 2021 and further information will be
provided on EPA's Stratospheric Ozone website at www.epa.gov/ozone/snap.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2021-0347, to the Federal eRulemaking Portal: https://www.regulations.gov. Follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or withdrawn. EPA
may publish any comment received to its public docket. Do not submit
electronically any information you consider to be Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Multimedia submissions (audio, video, etc.) must be
accompanied by a written comment. The written comment is considered the
official comment and should include discussion of all points you wish
to make. EPA will generally not consider comments or comment contents
located outside of the primary submission (i.e., on the web, cloud, or
other file sharing system). For additional submission methods, EPA's
full public comment policy, information about CBI or multimedia
submissions, and general guidance on making effective comments, please
visit https://www.epa.gov/dockets/commenting-epa-dockets. The EPA is
temporarily suspending its Docket Center and Reading Room for public
visitors, with limited exceptions, to reduce the risk of transmitting
COVID-19. Our Docket Center staff will continue to provide remote
customer service via email, phone, and webform. We encourage the public
to submit comments via https://www.regulations.gov or email, as there
may be a delay in processing mail and faxes. Hand deliveries and
couriers may be received by scheduled appointment only. For further
information on EPA Docket Center services and the current status,
please visit us online at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Chenise Farquharson, Stratospheric
Protection Division, Office of Atmospheric Programs (Mail Code 6205 T),
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington,
DC 20460; telephone number:<PHONE_NUMBER>; email address:
[email protected]. Notices and rulemakings under EPA's
Significant New Alternatives Policy program are available on EPA's
Stratospheric Ozone website at www.epa.gov/snap/snap-regulations.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
    A. Executive Summary and Background
    B. SNAP Program Background
    1. Rulemaking
    2. Listing of Unacceptable/Acceptable Substitutes
    3. Petition Process
    4. 90-Day Notification
    C. Does this action apply to me?
    D. What acronyms and abbreviations are used in the preamble?
II. What is EPA proposing in this action?
    A. Proposed Listing of HFO-1234yf as Acceptable, Subject To Use
Conditions, for MVAC Systems in Newly Manufactured Nonroad Vehicles
    1. What is the affected end-use?
    2. What are the ASHRAE classifications for refrigerant
flammability?
    3. How does HFO-1234yf compare to other refrigerants for these
MVAC applications with respect to SNAP criteria?
    4. What are the proposed use conditions?
    B. Proposed Modifications to Existing Use Conditions for MVAC
Systems in Other Vehicle Types
    C. Proposed Servicing Fittings for Small Cans of HFO-1234yf
    1. What is the affected end-use?
    2. How does HFO-1234yf compare to other refrigerants for this
MVAC application with respect to SNAP criteria?
    3. What is the proposed use condition?
    D. Proposed Incorporation by Reference of SAE Standards
    E. When would the listings apply?
    F. What is the relationship between this SNAP rule and other
federal rules?
    G. On which topics is EPA specifically requesting comment?
III. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
IV. References

I. General Information

A. Executive Summary and Background

    In this action, EPA is proposing to list 2,3,3,3-tetrafluoroprop-1-
ene, also known as hydrofluoroolefin (HFO)-1234yf or R-1234yf,
hereafter referred to as ``HFO-1234yf,'' as acceptable, subject to use
conditions, as of 30 days after publication of any final rule, for MVAC

systems \1\ in the following types of newly manufactured nonroad
vehicles,\2\ including some vehicles that are also considered heavy-
duty (HD) \3\ vehicles:
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    \1\ Under the SNAP program, MVAC systems are those systems that
provide passenger comfort cooling for light-duty cars and trucks,
heavy-duty vehicles (large pick-ups, delivery trucks, recreational
vehicles, and semi-trucks), nonroad vehicles, buses, and rail
vehicles. See final rules published on March 29, 2011 (76 FR 17488)
and on December 1, 2016 (81 FR 86778). For informational purposes,
we note that this includes systems that are also included in the
definitions that apply under other provisions of EPA's regulations
under title VI of the CAA. In this regard, we note that EPA's
subpart F regulations at 40 CFR 82.152 define ``MVAC-like
appliance'' to mean ``a mechanical vapor compression, open-drive
compressor appliance with a full charge of 20 pounds or less of
refrigerant used to cool the driver's or passenger's compartment of
off-road vehicles or equipment. This includes, but is not limited
to, the air-conditioning equipment found on agricultural or
construction vehicles. This definition is not intended to cover
appliances using R-22 refrigerant.'' By contrast, EPA's subpart F
regulations at 40 CFR 82.152 define ``Motor vehicle air conditioner
(MVAC)'' as ``any appliance that is a motor vehicle air conditioner
as defined in 40 CFR part 82, subpart B.'' The subpart B regulations
at 40 CFR 82.32 provide that: ``Motor vehicle air conditioners means
mechanical vapor compression refrigeration equipment used to cool
the driver's or passenger's compartment of any motor vehicle. This
definition is not intended to encompass the hermetically sealed
refrigeration systems used on motor vehicles for refrigerated cargo
and the air conditioning systems on passenger buses using HCFC-22
refrigerant.'' Further, the subpart B regulations at 40 CFR 82.32
provide that: ``Motor vehicle as used in this subpart means any
vehicle which is self-propelled and designed for transporting
persons or property on a street or highway, including but not
limited to passenger cars, light duty vehicles, and heavy duty
vehicles. This definition does not include a vehicle where final
assembly of the vehicle has not been completed by the original
equipment manufacturer.''
    \2\ In the past, EPA has referred to these vehicles as ``off-
road vehicles'' under the SNAP program. In this action, we are
aligning our terminology with that of other EPA programs and using
the term ``nonroad vehicle,'' which is defined under CAA section 216
to mean ``a vehicle that is powered by a nonroad engine and that is
not a motor vehicle or a vehicle used solely for competition.''
EPA's regulations issued under that section of the Act defining a
nonroad engine are codified at subpart A of 40 CFR part 1068.
    \3\ Heavy-duty vehicles are often subdivided by vehicle weight
classifications, as defined by the vehicle's gross vehicle weight
rating (GVWR), which is a measure of the combined curb (empty)
weight and cargo carrying capacity of the truck. Heavy-duty vehicles
have GVWRs above 8,500. See https://www.epa.gov/emission-standards-reference-guide/vehicle-weight-classifications-emission-standards-reference-guide.
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     Agricultural tractors with greater than 40 horsepower
(HP);
     Self-propelled agricultural machinery;
     Compact equipment;
     Construction, forestry, and mining equipment; and
     Commercial utility vehicles.
    EPA has previously listed HFO-1234yf as acceptable, subject to use
conditions, in new light-duty (LD) passenger cars and trucks (76 FR
17488; March 29, 2011) and new medium-duty passenger vehicles (MDPV),
HD pick-up trucks, and complete HD vans (81 FR 86778; December 1,
2016). The use conditions for those prior listings require that motor
vehicle air conditioning (MVAC) systems designed to use HFO-1234yf meet
the requirements of three technical safety standards developed by SAE
International (SAE) (i.e., SAE J639, SAE J1739, and SAE J2844) and are
intended to mitigate flammability and toxicity risks. In this action,
EPA is proposing to require the same use conditions, with certain
updates discussed below, for MVAC systems designed to use HFO-1234yf in
certain newly manufactured nonroad vehicles. EPA is proposing to list
HFO-1234yf as acceptable, subject to use conditions, after its
evaluation of human health and environmental information on various
substitutes submitted to the Significant New Alternatives Policy (SNAP)
program. In proposing to list HFO-1234yf as acceptable, subject to use
conditions, this action would provide additional flexibility for
industry stakeholders by expanding the list of acceptable substitutes
for certain types of nonroad vehicles.
    EPA is also proposing to adopt the current versions of SAE J639,
SAE J1739, and SAE J2844 by incorporating them by reference into the
use conditions for the nonroad vehicles addressed in this action. EPA
also proposes to modify the use conditions for the previous listings of
HFO-1234yf for MVAC systems in certain vehicles to replace the
references to older versions of the three SAE standards with references
to the current versions. The current versions of the three standards
are SAE J639 (revised November 2020), ``Safety and Design Standards for
Motor Vehicle Refrigerant Vapor Compression Systems;'' SAE J1739
(revised January 2021), ``Potential Failure Mode and Effects Analysis
(FMEA) Including Design FMEA, Supplemental FMEA-MSR, and Process
FMEA;'' and SAE J2844 (revised January 2013), ``R-1234yf (HFO-1234yf)
New Refrigerant Purity and Container Requirements for Use in Mobile
Air-Conditioning Systems.''
    In addition, EPA is proposing to include a use condition for HFO-
1234yf to provide for servicing air conditioning systems in the nonroad
vehicles addressed in this action, including use of small refrigerant
cans (two pounds or less). The use condition, which would require
specific servicing fittings, would apply to the nonroad vehicles for
which we are newly proposing to list HFO-1234yf as acceptable, subject
to use conditions, as well as for all types of vehicles for which EPA
has previously listed HFO-1234yf as acceptable, subject to use
conditions. For the existing listings, EPA is proposing to revise the
existing use conditions to require unique servicing fittings for use
with small cans (two pounds or less).
    Finally, EPA is proposing to include a reference to the Agency's
Significant New Use Rule (SNUR) for HFO-1234yf under the Toxic
Substances Control Act (80 FR 37166, June 30, 2015) in Appendix B
subpart G of part 82, under the `Comments' column, for the listings of
HFO-1234yf for the nonroad vehicles addressed in this action, as well
as for all the previous listings of HFO-1234yf as acceptable, subject
to use conditions, for various vehicle types. The SNUR states that
commercial users or consumers can only recharge MVAC systems with HFO-
1234yf where the original charging of the system with HFO-1234yf was
done by the original equipment manufacturer.
    Aside from the proposed updates to refer to the most current
versions of the SAE standards, the proposed addition of a use condition
relating to servicing fittings for small cans, and the proposed
reference to the June 2015 SNUR, the Agency is not reopening for
comment other portions of the March 29, 2011, and December 1, 2016,
final rules.
    EPA notes that there are additional requirements that concern the
sale or offer for sale of refrigerants, including a sales restriction
under the regulations implementing section 608 of the CAA, which can be
found at 40 CFR part 82 subpart F. These regulations collectively
comprise the national recycling and emissions reduction program and may
be commonly referred to as the stationary refrigeration and air
conditioning management program. The general sales restriction
provisions are codified at 82.154(c) and the specifications for self-
sealing valves relevant to an exemption to the sales restriction for
small cans of MVAC refrigerant are codified at 82.154(c)(2). This
proposal does not propose to modify the provisions under 40 CFR 82.154,
including the restriction on the sale of substitute refrigerants and
requirements for self-sealing valves. The Agency is not proposing and
is not reopening for comment regulations promulgated under section CAA
608.

B. SNAP Program Background

    The SNAP program implements section 612 of the Clean Air Act (CAA).
Several major provisions of section 612 are:

1. Rulemaking
    Section 612 requires EPA to promulgate rules making it unlawful to
replace any class I (chlorofluorocarbon (CFC), halon, carbon
tetrachloride, methyl chloroform, methyl bromide fluorocarbon, and
chlorobromomethane) or class II (hydrochlorofluorocarbon (HCFC)) ozone-
depleting substances (ODS) with any substitute that the Administrator
determines may present adverse effects to human health or the
environment where the Administrator has identified an alternative that
(1) reduces the overall risk to human health and the environment and
(2) is currently or potentially available.
2. Listing of Unacceptable/Acceptable Substitutes
    Section 612(c) requires 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.
3. Petition Process
    Section 612(d) grants the right to any person to petition EPA to
add a substance to, or delete a substance from, the lists published in
accordance with section 612(c).
4. 90-Day Notification
    Section 612(e) directs 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 a new or existing chemical is introduced into
interstate commerce for significant new use as a substitute for a class
I substance.\4\ The producer must also provide the Agency with the
producer's unpublished health and safety studies on such substitutes.
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    \4\ EPA's SNAP regulations at 82.176 extend this requirement to
substitutes for class II substances, providing that ``[a]ny producer
of a new substitute must submit a notice of intent to introduce a
substitute into interstate commerce 90 days prior to such
introduction.''
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    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 has identified five types of listing decisions: Acceptable;
acceptable subject to use conditions; acceptable subject to narrowed
use limits; unacceptable; and pending (40 CFR 82.180(b)). Use
conditions and narrowed use limits are both considered ``use
restrictions,'' as described below. 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 only if certain conditions in the way
that the substitute is used are met to minimize risks to human health
and the environment. EPA describes such substitutes as ``acceptable
subject to use conditions.'' (40 CFR 82.180(b)(2)). 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. 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.'' (40 CFR 82.180(b)(3)).
    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, EPA examines
the 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.
    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, these statements
are not binding for use of the substitute under the SNAP program.
However, regulatory requirements so listed are binding as applicable
under other regulatory programs (e.g., worker protection regulations
promulgated by the U.S. Occupational Safety and Health Administration
(OSHA)). The ``further information'' classification does not
necessarily include all other legal obligations pertaining to the use
of the substitute. While the items listed are not legally binding under
the SNAP program, EPA encourages users of substitutes to apply all
statements in the ``further information'' column in their use of these
substitutes. In many instances, the information simply refers to sound
operating practices that have already been identified in existing
industry and/or building codes or standards. Thus, many of the
statements, if adopted, would not require the affected user to make
significant changes in existing operating practices.
    For additional information on the SNAP program, visit the SNAP
portion of EPA's Ozone Layer Protection website at https://www.epa.gov/snap. Copies of the full lists of acceptable substitutes for 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 published March 18,
1994 (59 FR 13044), codified at 40 CFR part 82, subpart G. SNAP
decisions and the appropriate Federal Register citations 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 to 40 CFR part 82, subpart G.
    In this proposed rule, EPA refers to listings made in a final rule
issued on December 1, 2016, at 81 FR 86778 (``2016 Rule'') in which the
Agency listed HFO-1234yf as acceptable, subject to use conditions, in
new MDPV, HD pick-up trucks, and complete HD vans. The 2016 Rule also
changed the listings for certain hydrofluorocarbons (HFCs) and blends
from acceptable to unacceptable in various end-uses in the
refrigeration and air conditioning, foam blowing, and fire suppression
sectors. After a challenge to the 2016 Rule, the United States Court of
Appeals for the District of Columbia Circuit (``the court'') issued a
partial vacatur of the 2016 Rule ``only to the extent it requires
manufacturers to replace HFCs that were previously and lawfully
installed as substitutes for ozone-depleting substances.'' \5\ The
court's decision on the 2016 Rule did not vacate the listing of HFO-
1234yf for certain types of vehicles, and this proposed rule is not
EPA's response to the court's decision on the 2016 Rule.
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    \5\ Mexichem Fluor, Inc. v. EPA, No. 17-1024, 760 Fed. Appx. 6,
9 (D.C. Cir., April 5, 2019).
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C. Does this action apply to me?

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

 All Other Basic Organic Chemical Manufacturing (NAICS 325199)
 All Other General Merchandise Stores (NAICS 452990)

 All Other Miscellaneous Chemical Product and Preparation
Manufacturing (NAICS 325998)
 Automotive Parts and Accessories Stores (NAICS 441310)
 Automotive Repair Shops Not Elsewhere Classified, Including
Air Conditioning and Radiator Specialty Shops (NAICS 811198)
 Gasoline Stations with Convenience Stores (NAICS 447110)
 General automotive repair shops (NAICS 811111)
 Heavy Duty Truck Manufacturing (NAICS 336120)
 Industrial Gas Manufacturing (NAICS 32512)
 Motor Vehicle Body Manufacturing (NAICS 336211)
 Motor Vehicle Parts Manufacturing (NAICS 3363)
 Other Automotive Repair and Maintenance (NAICS 81119)
 Other Motor Vehicle Parts Manufacturing (NAICS 336390)
 Recyclable Material Merchant Wholesalers (NAICS 423930)
 Refrigeration Equipment and Supplies Merchant Wholesalers
(NAICS 423740)

    This list is not intended to be exhaustive but provides a guide for
readers regarding types of entities likely to be regulated by this
action if it becomes final as proposed. This list includes the types of
entities that EPA is now aware could potentially be regulated by this
action. Other types of entities not listed above could also be
regulated. 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. 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.

C. What acronyms and abbreviations are used in the preamble?

    Below is a list of acronyms and abbreviations used in the preamble
of this document:

AIHA--American Industrial Hygiene Association
AC--Air Conditioning
ACH--Changes Per Hour
AEM--Association of Equipment Manufacturers
ATEL--Acute Toxicity Exposure Limit
ANSI--American National Standards Institute
ASHRAE--American Society of Heating, Refrigerating and Air-
Conditioning Engineers
ASTM--American Society for Testing and Materials
CAA--Clean Air Act
CAS Reg. No.--Chemical Abstracts Service Registry Identification
Number
CBI--Confidential Business Information
CGA--Compressed Gas Association
CFC--Chlorofluorocarbon
CFD--Computational Fluid Dynamics
CFR--Code of Federal Regulations
CO2--Carbon Dioxide
CRP--Cooperative Research Project
DIY--Do-It-Yourself
EEAP--Environmental Effects Assessment Panel
E.O.--Executive Order
EPA--United States Environmental Protection Agency
FCL--Flammability Concentration Limit
FMEA--Failure Mode and Effects Analysis
FR--Federal Register
GHG--Greenhouse Gas
GWP--Global Warming Potential
GVWR--Gross Vehicle Weight Rating
HCFC--Hydrochlorofluorocarbon
HD--Heavy-Duty
HD GHG--Heavy-Duty Greenhouse Gas
HF--Hydrogen Fluoride
HFC--Hydrofluorocarbon
HFO--Hydrofluoroolefin
HP--Horsepower
ICF--ICF International, Inc.
IPCC--Intergovernmental Panel on Climate Change
LD--Light-Duty
LD GHG--Light-Duty Greenhouse Gas
LFL--Lower Flammability Limit
MDPV--Medium-Duty Passenger Vehicle
MVAC--Motor Vehicle Air Conditioning
MY--Model Year
NAAQS--National Ambient Air Quality Standards
NAICS--North American Industrial Classification System
NOAEL--No Observed Adverse Effect Level
NRC--National Research Council
OEM--Original Equipment Manufacturer
ODP--Ozone Depletion Potential
ODS--Ozone-depleting Substance
OMB--United States Office of Management and Budget
OSHA--Occupational Safety and Health Administration
PPE--Personal Protective Equipment
ppm--Parts Per Million
PRA--Paperwork Reduction Act
RCL--Reference Concentration Limit
RFA--Regulatory Flexibility Act
SAE--SAE International
SAP--Scientific Assessment Panel
SDS--Safety Data Sheet
SIP--State Implementation Plan
SNAP--Significant New Alternatives Policy
SNUN--Significant New Use Notice
SNUR--Significant New Use Rule
STEL--Short-term Exposure Limit
TFA--Trifluoroacetic Acid
TLV--Threshold Limit Value
TSCA--Toxic Substances Control Act
TWA--Time Weighted Average
UFL--Upper Flammability Limit
UMRA--Unfunded Mandates Reform Act
UNEP--United Nations Environmental Programme
USGCRP--U.S. Global Change Research Program
VOC--Volatile Organic Compounds
WEEL--Workplace Environmental Exposure Limit
WMO--World Meteorological Organization

II. What is EPA proposing in this action?

A. Proposed Listing of HFO-1234yf as Acceptable, Subject to Use
Conditions, for MVAC Systems in Certain Newly Manufactured Nonroad
Vehicles

    EPA is proposing to list HFO-1234yf as acceptable, subject to use
conditions, for MVAC systems in several types of newly manufactured
nonroad vehicles, specifically: Agricultural tractors greater than 40
HP; self-propelled agricultural machinery; compact equipment;
construction, forestry, and mining equipment; and commercial utility
vehicles. All MVAC refrigerants listed as acceptable are subject to use
conditions requiring labeling and the use of unique fittings as
described in Appendix B to subpart G of part 82--Substitutes Subject to
Use Restrictions and Unacceptable Substitutes. EPA is proposing to list
HFO-1234yf as acceptable, subject to use conditions, in the five
nonroad vehicle types. The proposed use conditions would require that
MVAC systems designed to use HFO-1234yf meet the requirements of SAE
J639, SAE J1739, and SAE J2844 and would help to ensure that use of
HFO-1234yf will not have a significantly greater overall impact on
human health and the environment than other alternatives for use in
those vehicles. EPA is proposing to update the existing use conditions
that are currently required for the use of HFO-1234yf in MVAC systems
in newly manufactured LD vehicles, MDPVs, HD pick-up trucks, and
complete HD vans and apply them to all the MVAC systems addressed in
this proposal. The proposed use conditions are detailed below in
section II.A.4, ``What are the proposed use conditions?''
    While EPA is proposing to list HFO-1234yf as acceptable, subject to
use conditions, in certain newly manufactured nonroad vehicles,
including some vehicles that would also be considered HD vehicles, we
are requesting comment and information on development of HFO-1234yf
MVAC systems for other types of HD vehicles not covered in this
proposal, particularly HD on-road trucks (i.e., Class 4-8 trucks
between 14,001 and 33,000 or greater pounds). EPA intends to consider
these comments in determining whether to initiate a separate rulemaking
to list HFO-1234yf in these other vehicle types.
1. What is the affected end-use?
    Under SNAP, MVAC systems cool the passenger compartment of LD
passenger

vehicles and trucks, HD vehicles (e.g., large pick-ups, delivery
trucks, and semi-trucks), off[hyphen]road vehicles, buses, and
passenger rail vehicles. These systems are typically charged during
vehicle manufacture, and the main components are connected by flexible
refrigerant lines. Nonroad vehicles can be grouped into several
categories (i.e., agriculture, construction, recreation, and many other
purposes).\6\ The vehicle types addressed in today's proposal include
certain types of newly manufactured nonroad vehicles, specifically:
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    \6\ EPA, 2021. Basic Information about the Emission Standards
Reference Guide for On-road and Nonroad Vehicles and Engines.
Available online at https://www.epa.gov/emission-standards-reference-guide/basic-information-about-emission-standards-reference-guide-road and in the docket for this rulemaking at
https://nepis.epa.gov/Exe/ZyPDF.cgi/P100K5U2.PDF?Dockey=P100K5U2.PDF.
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     Agricultural tractors greater than 40 HP (including two-
wheel drive (2WD), mechanical front-wheel drive (MFD), four-wheel drive
(4WD), and track tractors) that are used for a number of agricultural
applications such as farm work, planting, landscaping, and loading;
7 8
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    \7\ Wagner, 2021. May 24, 2021, email from John Wagner of the
Association of Equipment Manufacturers to EPA. Available in the
docket for this rulemaking.
    \8\ AEM, 2021. Appendix A: Machine Forms as Classified by AEM
Membership. Available in the docket for this rulemaking.
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     Self-propelled agricultural machinery (including combines,
grain and corn harvesters, sprayers, windrowers, and floaters) that are
primarily used for harvesting, fertilizer, and herbicide operations;
\9\
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    \9\ Ibid.
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     Compact equipment (including mini excavators, turf mowers,
skid-steer loaders and tractors less than 40 HP) that are primarily
used for agricultural operations and residential, commercial, and
agricultural landscaping; \10\
---------------------------------------------------------------------------

    \10\ Ibid.
---------------------------------------------------------------------------

     Construction, forestry, and mining equipment (including
excavators, bulldozers, wheel loaders, feller bunchers, log skidders,
road graders, articulated trucks, sub-surface machines, horizontal
directional drill, trenchers, and tracked crawlers) that are primarily
used to excavate surface and subsurface materials during construction,
landscaping, and road maintenance and building; \11\ and
---------------------------------------------------------------------------

    \11\ Ibid.
---------------------------------------------------------------------------

     Commercial utility vehicles that are primarily used for
ranching, farming, hunting/fishing, construction, landscaping, property
maintenance, railroad maintenance, forestry, and mining.\12\
---------------------------------------------------------------------------

    \12\ Ibid.
---------------------------------------------------------------------------

    These nonroad vehicles are almost exclusively used and operated by
professionals (e.g., agricultural owners or skilled employees/
operators) and vary by size, weight, use, and/or horsepower.\13\ For
example, commercial utility vehicles typically weigh between 1,200 and
2,400 pounds, while agricultural tractors >40 HP typically weigh
between 39,000 and 50,000 pounds.14 15 MVAC systems in these
nonroad vehicles can have charge sizes ranging from 650 grams (23
ounces) to 3,400 grams (120 ounces) depending on the manufacturer and
cab size, compared to a range of 390 grams (14 ounces) to 1,600 grams
(56 ounces) for MVAC systems in light and medium duty passenger
vehicles, HD pickups, and complete HD vans.\16\ Additionally, unlike
onroad passenger vehicles, for example, nonroad vehicles are limited to
non-highway terrain (e.g., fields, construction sites, forests, and
mines), have more robust components, are operated at low working
speeds, and there are typically a limited number of vehicles in the
same location.
---------------------------------------------------------------------------

    \13\ EPA, 2021. Basic Information about the Emission Standards
Reference Guide for On-road and Nonroad Vehicles and Engines.
Available online at https://www.epa.gov/emission-standards-reference-guide/basic-information-about-emission-standards-reference-guide-road and in the docket for this rulemaking.
    \14\ Heavy-duty vehicles are often subdivided by vehicle weight
classifications, as defined by the vehicle's gross vehicle weight
rating (GVWR), which is a measure of the combined curb (empty)
weight and cargo carrying capacity of the truck. Heavy-duty vehicles
have GVWRs above 8,500. See https://www.epa.gov/emission-standards-reference-guide/vehicle-weight-classifications-emission-standards-reference-guide.
    \15\ Wagner, 2021. May 24, 2021, email from John Wagner of the
Association of Equipment Manufacturers to EPA. Available in the
docket for this rulemaking.
    \16\ ICF, 2016. Technical Support Document for Acceptability
Listing of HFO-1234yf for Motor Vehicle Air Conditioning in Limited
Heavy-Duty Applications. Available in the public docket for this
rulemaking.
---------------------------------------------------------------------------

2. What are the ASHRAE classifications for refrigerant flammability?
    The American National Standards Institute/American Society of
Heating, Refrigerating and Air Conditioning Engineers (ANSI/ASHRAE)
Standard 34-2019 assigns a safety group classification for each
refrigerant which consists of two to three alphanumeric characters
(e.g., A2L or B1). The initial capital letter indicates the toxicity
and the numeral 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 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.
    Refrigerants are also assigned a flammability classification 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 [deg]F (60 [deg]C) and 14.7 psia (101.3
kPa).\17\ The flammability classification ``1'' is given to
refrigerants that, when tested, show no flame propagation. The
flammability classification ``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\3\. The flammability classification ``2L'' 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.), have
an LFL greater than 0.10 kg/m\3\, and have a maximum burning velocity
of 10 cm/s or lower when tested at in dry air at 73.4 [deg]F (23.0
[deg]C) and 14.7 psia (101.3 kPa). The flammability classification
``3'' is given to refrigerants that, when tested, exhibit flame
propagation and that 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\3\ or lower.
Using these safety group classifications, ANSI/ASHRAE Standard 34-2019
categorizes HFO-1234yf in the A2L Safety Group.
---------------------------------------------------------------------------

    \17\ ASHRAE, 2019. ANSI/ASHRAE Standard 34-2019: Designation and
Safety Classification of Refrigerants.

---------------------------------------------------------------------------

[GRAPHIC] [TIFF OMITTED] TP06DE21.006

3. How does HFO-1234yf compare to other refrigerants for these MVAC
applications with respect to SNAP criteria?
    When reviewing a substitute under SNAP, EPA compares the risk posed
by that substitute to the risks posed by other alternatives and
considers whether that specific substitute under review poses
significantly more risk than other available or potentially available
alternatives for the same use. For this action, EPA performed a
comparative risk analysis, based on our criteria for review, including
an evaluation of environmental impacts, flammability, and toxicity.
Redacted submissions that do not include information claimed as CBI by
the submitter and supporting documentation for HFO-1234yf are provided
in the docket for this proposed rule (EPA-HQ-OAR-2021-0347 at https://www.regulations.gov). EPA's assessments to examine the health and
environmental risks of HFO-1234yf in each equipment type are also
available in the docket for this proposed
rule.18 19 20 21 22
---------------------------------------------------------------------------

    \18\ ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Agricultural Tractors Greater than
40 Horsepower) (New Equipment).
    \19\ ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Self-Propelled Agricultural
Machinery) (New Equipment).
    \20\ ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Compact Equipment) (New Equipment).
    \21\ ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining
Equipment) (New Equipment).
    \22\ ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Commercial Utility Vehicles) (New
Equipment).
---------------------------------------------------------------------------

    As explained more fully below, to help evaluate environmental,
flammability, and toxicity risks resulting from the use of HFO-1234yf
in certain types of newly manufactured nonroad vehicles, EPA considered
the Agency's analyses 23 24 25 26 27 28 29 30 31 conducted
in support of the 2011 (76 FR 17488; March 29, 2011) and 2016 (81 FR
86778; December 1, 2016) listing decisions for HFO-1234yf in MVAC
systems, including information submitted during the public comment
period of the proposal for the 2011 final decision (October 19, 2009;
74 FR 53445), such as the SAE Cooperative Research Project's (CRP) risk
assessments.32 33 34 35 36 These risk assessments are
available in the docket for this proposed rule. The refrigerants to
which HFO-1234yf was compared in the 2011 action for LD vehicles are
the same refrigerants available for use in the nonroad vehicle types
included in this proposal. In addition, EPA considered risk assessments
37 38 39 40 41 conducted by the Association of Equipment
Manufacturers (AEM), an industry consortium of construction and
agriculture equipment manufacturers, and found these were consistent
with the Agency's assessments to examine the health and environmental
risks of HFO-1234yf in each vehicle type.
---------------------------------------------------------------------------

    \23\ EPA, 2005. Risk Analysis for Alternative Refrigerant in
Motor Vehicle Air Conditioning.
    \24\ ICF, 2008a. Air Conditioning Refrigerant Charge Size to
Passenger Compartment Volume Ratio Analysis.
    \25\ ICF, 2008b. Revised Characterization of U.S. Hybrid and
Small Car Sales (Historical and Predicted) and Hybrid Vehicle
Accidents.
    \26\ ICF, 2009a. Revised Final Draft Assessment of the Potential
Impacts of HFO-1234yf and the Associated Production of TFA on
Aquatic Communities and Local Air Quality.
    \27\ ICF, 2009b. Risk Screen on Substitutes for CFC-12 in Motor
Vehicle Air Conditioning: Substitute: HFO-1234yf.
    \28\ ICF, 2010a. Summary of HFO-1234yf Emissions Assumptions.
    \29\ ICF, 2010b. Summary of Updates to the Vintaging Model that
Impacted HFO-1234yf Emissions Estimates.
    \30\ ICF, 2010c. Revised Assessment of the Potential Impacts of
HFO-1234yf and the Associated Production of TFA on Aquatic
Communities, Soil and Plants, and Local Air Quality.
    \31\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected
maximum TFA rainwater concentrations and maximum 8-hr ozone
concentrations.
    \32\ CRP, 2008. Risk Assessment for Alternative Refrigerants
HFO-1234yf Phase II. Prepared for SAE International Cooperative
Research Program 1234 by Gradient Corporation.
    \33\ CRP, 2009. Risk Assessment for Alternative Refrigerants
HFO-1234yf and R-744 (CO2) Phase III. Prepared for SAE International
Cooperative Research Program 1234 by Gradient Corporation.
    \34\ DuPont and Honeywell. Guidelines for Use and Handling of
HFO-1234yf (v8.0).
    \35\ Exponent. 2008. HFO-1234yf Refrigerant Concentration and
Ignition Tests in Full-Scale Vehicle Passenger Cabin and Engine
Compartment.
    \36\ CRP, 2013.SAE International Cooperative Research Project
CRP1234-4 on R-1234yf Safety, Finishes Work and Presents
Conclusions. Available online at: https://www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2146.

    \37\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \38\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage
Harvesters, Sprayers, and Windrowers.
    \39\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders).
    \40\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction,
Forestry, and Mining Equipment.
    \41\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial
Utility Vehicles.
---------------------------------------------------------------------------

(a) Environmental Impacts
    The SNAP program considers a number of environmental criteria when
evaluating substitutes: Ozone depleting potential (ODP); climate
effects, primarily based on global warming potential (GWP); local air
quality

impacts, particularly potential impacts on smog formation from
emissions of volatile organic compounds (VOC); and ecosystem effects,
particularly from negative impacts on aquatic life. These and other
environmental and health risks are discussed below.
    HFO-1234yf is chemical substance identified as 2,3,3,3-
tetrafluoroprop-1-ene (CAS Reg. No. 754-12-1). HFO-1234yf has a GWP of
four,42 43 which is similar to or lower than the GWP of
other alternatives for the nonroad vehicles addressed in this proposal.
For example, its GWP is significantly lower than that of HFC-134a, the
refrigerant most widely used in these vehicles today, which has a GWP
of 1,430. As shown in Table 1, two other alternatives, HFC-152a,\44\
and CO2 \45\ have GWPs of 124 and 1, respectively.
---------------------------------------------------------------------------

    \42\ Nielsen et al., 2007. Atmospheric chemistry of CF3CF=CH2:
Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH
radicals, and O3. Chemical Physics Letters 439, 18-22. Available
online at: https://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
    \43\ Papadimitriou et al., 2007. CF3CF=CH2 and (Z)-CF3CF=CHF:
temperature dependent OH rate coefficients and global warming
potentials. Phys. Chem. Chem. Phys., 2007, Vol. 9, p. 1-13.
Available online at: https://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
    \44\ HFC-152a is listed as acceptable, subject to use
conditions, for new vehicles only at 40 CFR part 82 subpart G; final
rule published June 12, 2008 (73 FR 33304).
    \45\ CO2 is listed as acceptable, subject to use
conditions, for new vehicles only at 40 CFR part 82 subpart G; final
rule published June 6, 2012 (77 FR 33315).
---------------------------------------------------------------------------

    Other acceptable refrigerants for the nonroad vehicles addressed in
today's proposal have GWPs ranging from 933 to 3,337. These include
several blend refrigerants that are listed as acceptable, subject to
use conditions, for these nonroad vehicles, including the HFC blends
SP34E and R-426A (also known as RS-24) and the HCFC blends, R-416A
(also known as HCFC Blend Beta or FRIGC FR12), R-406A, R-414A (also
known as HCFC Blend Xi or GHG-X4), R-414B (also known as HCFC Blend
Omicron), HCFC Blend Delta (also known as Free Zone), Freeze 12, GHG-
X5, and HCFC Blend Lambda (also known as GHG-HP). In a final rule
issued July 20, 2015, at 80 FR 42870 (``2015 Rule''),\46\ EPA listed
the use of certain refrigerant blends, including the ones mentioned
above, as unacceptable in newly manufactured LD vehicles starting in MY
2017. EPA did not propose or finalize a change of status for use of the
refrigerant blends in MVACs in nonroad vehicles. The refrigerant blends
remain acceptable, subject to use conditions, for the nonroad vehicles
addressed in this proposed rule. Also, although they are listed as
acceptable, subject to use conditions, EPA is not aware of the use or
development of HFC-152a, CO2, or any of the refrigerant
blends above in newly manufactured nonroad vehicles.\47\ Additionally,
all MVAC refrigerants are subject to use conditions requiring labeling
and the use of unique fittings, and the two lower-GWP alternatives
currently approved for use in nonroad vehicles (i.e., HFC-152a and
CO2) are subject to additional use conditions mitigating
flammability and toxicity as appropriate to the alternative.
---------------------------------------------------------------------------

    \46\ The 2015 Rule, among other things, changed the listings for
certain HFCs and blends from acceptable to unacceptable in various
end-uses in the aerosols, refrigeration and air conditioning, and
foam blowing sectors. After a challenge to the 2015 Rule, the United
States Court of Appeals for the District of Columbia Circuit (``the
court'') issued a partial vacatur of the 2015 Rule ``to the extent
it requires manufacturers to replace HFCs with a substitute
substance'' (see Mexichem Fluor, Inc. v. EPA, 866 F.3d 451, 462
(D.C. Cir. 2017) and remanded the rule to the Agency for further
proceedings. The court also upheld EPA's listing changes as being
reasonable and not ``arbitrary and capricious.'' See Mexichem Fluor,
866 F.3d at 462-63.
    \47\ The CAA and EPA's ODS regulations restrict the permissible
uses of virgin HCFCs. With respect to refrigerants, virgin HCFC-22,
HCFC-142b and blends containing HCFC-22 or HCFC-142b may now only be
used to service existing appliances. Consequently, virgin HCFC-22,
HCFC-142b and blends containing virgin HCFC-22 or HCFC-142b may no
longer be used as a refrigerant to manufacture new pre-charged
appliances or appliance components or to charge new appliances
assembled onsite.

    Table 1--GWP, ODP, and VOC Status of HFO-1234yf Compared to Other Refrigerants in MVAC Systems of Nonroad
                                                  Vehicles \1\
----------------------------------------------------------------------------------------------------------------
           Refrigerants                  GWP             ODP              VOC status              Proposal
----------------------------------------------------------------------------------------------------------------
HFO-1234yf.......................               4               0  No.....................  Acceptable, subject
                                                                                to use conditions.
CO2, HFC-152a, HFC-134a..........         1-1,430               0  No.....................  No change.
Other refrigerants, including           933-3,340         0-0.098  Yes \2\................  No change.
 IKON A, R-414B, R-416A, R-426A,
 SP34E.
----------------------------------------------------------------------------------------------------------------
\1\ The table does not include not-in-kind technologies listed as acceptable for the stated end-use.
\2\ One or more constituents of the blend are VOC.

    HFO-1234yf does not deplete the ozone layer. Similarly, HFC-134a,
HFC-152a, CO2, the HFC blends SP34E, and R-426A do not
deplete the ozone layer; however, the HCFC blends have ODPs ranging
from 0.012 to 0.056.
    HFO-1234yf, HFC-134a, HFC-152a, and CO2 are exempt from
the definition of VOC under CAA regulations (see 40 CFR 51.100(s))
addressing the development of state implementation plans (SIPs) to
attain and maintain the National Ambient Air Quality Standards (NAAQS).
The HFC blends and some of the HCFC blends have one or more components
that are VOC.
    Another potential environmental impact of HFO-1234yf is its
atmospheric decomposition to trifluoroacetic acid (TFA,
CF3COOH). TFA is a strong acid that may accumulate in soil,
plants, and aquatic ecosystems over time and may have the potential to
adversely impact plants, animals, and ecosystems.\48\ Simulations have
found that the amount of TFA in rainfall produced from a transition of
all mobile air conditioners in the continental United States to HFO-
1234yf has been estimated to be double or more the values observed in
the United States in 2009 from all sources, natural and artificial
(i.e., HFC-134a).\49\ In comparison, the amount of TFA produced from
HFO-1234yf is expected to be higher than that of other fluorinated
refrigerants in this end-use.
---------------------------------------------------------------------------

    \48\ Other fluorinated compounds also decompose into TFA,
including HFC-134a.
    \49\ Luecken et al., 2009. Ozone and TFA impacts in North
America from degradation of 2, 3, 3, 3-tetrafluoropropene (HFO-
1234yf), a potential greenhouse gas replacement. Environmental
Science & Technology 2009. Available online at: https://www.researchgate.net/profile/Robert_Waterland/publication/40481734_Ozone_and_TFA_impacts_in_North_America_from_degradation_of_2333-Tetrafluoropropene_(HFO-
1234yf)_a_potential_greenhouse_gas_replacement/links/
00b7d514ca9595bf5e000000.pdf.
---------------------------------------------------------------------------

    In support of the 2011 and 2016 listing decisions for HFO-1234yf in
certain MVAC systems, EPA analyzed potential TFA concentrations from a
full transition to HFO-1234yf in all

refrigeration and stationary AC systems including all MVAC
applications.50 51 52 53 54 EPA has also considered this
analysis in developing this proposal. The analysis found a maximum
projected concentration of TFA in rainwater of approximately 1,700 ng/
L. This maximum projected concentration identified in EPA's analysis,
1700 ng/L,\55\ was roughly 34 percent higher than that projected in a
2009 peer reviewed article.\56\ The difference in projected TFA
concentrations in water is a reflection of EPA's reliance on higher
emission estimates.\57\ Even when relying on more conservative emission
estimates, a concentration of 1700 ng/L corresponds to roughly 1/600th
of the No-Observed-Adverse-Effect-Level (NOAEL) for the most sensitive
algae species, which is also well below the NOAEL for the most
sensitive aquatic animal species.\58\
---------------------------------------------------------------------------

    \50\ ICF, 2009a. Revised Final Draft Assessment of the Potential
Impacts of HFO-1234yf and the Associated Production of TFA on
Aquatic Communities and Local Air Quality.
    \51\ ICF, 2010a. Summary of HFO-1234yf Emissions Assumptions.
    \52\ ICF, 2010b. Summary of Updates to the Vintaging Model that
Impacted HFO-1234yf Emissions Estimates.
    \53\ ICF, 2010c. Revised Assessment of the Potential Impacts of
HFO-1234yf and the Associated Production of TFA on Aquatic
Communities, Soil and Plants, and Local Air Quality.
    \54\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected
maximum TFA rainwater concentrations and maximum 8-hr ozone
concentrations.
    \55\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected
maximum TFA rainwater concentrations and maximum 8-hr ozone
concentrations.
    \56\ Luecken et al., 2009. Ozone and TFA impacts in North
America from degradation of 2,3,3,3-tetrafluoropropene (HFO-1234yf),
a potential greenhouse gas replacement. Environmental Science &
Technology 2009. Available online at: https://www.researchgate.net/profile/Robert_Waterland/publication/40481734_Ozone_and_TFA_impacts_in_North_America_from_degradation_of_2333-Tetrafluoropropene_(HFO-
1234yf)_a_potential_greenhouse_gas_replacement/links/
00b7d514ca9595bf5e000000.pdf.
    \57\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected
maximum TFA rainwater concentrations and maximum 8-hr ozone
concentrations.
    \58\ ICF, 2009a. Revised Final Draft Assessment of the Potential
Impacts of HFO-1234yf and the Associated Production of TFA on
Aquatic Communities and Local Air Quality.
---------------------------------------------------------------------------

    Since the 2011 final rule listing HFO-1234yf as acceptable for LD
vehicles, additional research on TFA has been conducted. The United
Nations Environment Programme (UNEP) Ozone Secretariat provided a
summary of key information pertaining to TFA based on the 2014
Assessment Reports of the Environmental Effects Assessment Panel (EEAP)
and the Scientific Assessment Panel (SAP) of the Montreal Protocol. The
brief states, ``While it is well established that TFA is a ubiquitous
natural component in rivers, lakes, and other surface water bodies,
uncertainties remain regarding anthropogenic sources, long-term fate
and abundances as these are linked to current and future use and
emissions of HFCs, HCFCs, and HFOs. Based on estimates to 2040,
increases are predicted to remain relatively low and are therefore not
expected to be a significant risk to human health or detrimental to the
environment. Projected future increased loadings of TFA to playas,
land-locked lakes, and the oceans due to continued use of HCFCs, HFCs,
and replacement products such as HFOs are still judged to present
negligible risks for aquatic organisms and humans.'' \59\ This UNEP
brief also states that TFA and its salts ``do not bioconcentrate in
aquatic organisms, and do not biomagnify in the food chain. Thus, they
present negligible risk to organisms higher on the food chain,
including humans.'' The 2018 Assessment Report of the EEAP reiterated
that ``[overall], there is no new evidence that contradicts the
conclusion of our previous Assessments that exposure to current and
projected concentrations of salts of TFA in surface waters present a
minimal risk to the health of humans and the environment.'' \60\ EEAP
also referred to a 2017 review of this topic \61\ which reached a
similar conclusion.
---------------------------------------------------------------------------

    \59\ UNEP, 2015. Ecological Issues on the Feasibility of
Managing HFCs: Focus on TFA. Inter-sessional Informal Meeting, 12-13
June 2015. This document accessible at: https://ozone.unep.org/sites/default/files/2020-06/informal%20brief_ecological%20effects_intersessional_June%202015_final%20%281%29.docx.
    \60\ EEAP, 2019. Environmental Effects and Interactions of
Stratospheric Ozone Depletion, UV Radiation, and Climate Change.
2018 Assessment Report. Nairobi: Environmental Effects Assessment
Panel, United Nations Environment Programme (UNEP) 390 pp. Available
online at: https://ozone.unep.org/science/assessment/eeap.
    \61\ Norwegian Environment Agency, 2017. Study on Environmental
and Health Effects of HFO Refrigerants, Norwegian Environment Agency
Report No. No. M-9172017, Oslo, Norway, p. 349.
---------------------------------------------------------------------------

    A 2014 study by Kazil, et al.\62\ analyzed TFA deposition in the
United States assuming 100 percent of all MVAC systems use HFO-1234yf.
The results indicated that rainwater TFA concentrations, while varying
strongly geographically, will be orders of magnitude lower compared to
the levels at which toxic effects are observed in aquatic systems. More
recently, the World Meteorological Organization (WMO) concluded that
``[t]here is increased confidence that [TFA] produced from degradation
of HFCs, HCFCs, and HFOs will not harm the environment over the next
few decades,'' \63\ while also calling for periodic reevaluation of
this conclusion. EPA likewise finds that the data on TFA are not
sufficient to propose or establish additional restrictions under SNAP
at this time. In sum, based on our consideration of these documents,
the additional information available since our 2011 listing decision
shows no greater risk than our earlier analysis. We further note that
the requirements for the safe disposal of appliances and the venting
prohibition under section 608 of the CAA, codified at 40 CFR 82.155 and
40 CFR 82.154(a), respectively, and accompanying refrigerant management
requirements reduce emissions of these refrigerants. EPA intends to
continue reviewing the research on potential impacts from TFA in the
future and may consider taking additional action in the future if
warranted.
---------------------------------------------------------------------------

    \62\ Kazil et al., 2014. Deposition and rainwater concentrations
of trifluoroacetic acid in the United States from the use of HFO-
1234yf. JGR-Atmospheres, 2014.
    \63\ WMO, 2018. Executive Summary: Scientific Assessment of
Ozone Depletion: 2018, World Meteorological Organization, Global
Ozone Research and Monitoring Project--Report No. 58, 67 pp.,
Geneva, Switzerland, 2018.
---------------------------------------------------------------------------

    Taking into consideration the analysis conducted in support of the
2011 listing decision, which was based on conservative emissions
assumptions and a transition from HFC-134a to HFO-1234yf for all MVAC
systems (not limited to LD vehicles), and the research that has been
conducted since, EPA proposes that the use of HFO-1234yf in the nonroad
vehicles addressed in this action will not pose a significant risk to
the environment from atmospheric decomposition to TFA.
    Based on the consideration of all of these environmental impacts,
EPA proposes that HFO-1234yf does not pose significantly greater risk
to the environment than the other alternatives for use in newly
manufactured nonroad vehicles addressed in this action, and it poses
significantly less risk than several of the alternatives with higher
GWPs and ODPs.
(b) Flammability
    HFO-1234yf is a flammable refrigerant classified as A2L under
ASHRAE 34-2013. HFC-134a, CO2, and the refrigerant blends
SP34E and R-426A (also known as RS-24) and the HCFC blends, R-416A
(also known as HCFC Blend Beta or FRIGC FR12), R-414A (also known as
HCFC Blend Xi or GHG-X4), R-414B (also known as HCFC Blend Omicron),
HCFC Blend Delta (also known as Free Zone), Freeze 12, GHG-X5, and HCFC
Blend Lambda (also known as GHG-HP) are nonflammable refrigerants,
while HFC-152a and R-406A are slightly more

flammable than HFO-1234yf with an ASHRAE classification of A2. HFO-
1234yf is flammable when its concentration in air is in the range of
6.2 percent and 12.3 percent by volume (62,000 ppm to 123,000 ppm).\64\
In the presence of an ignition source (e.g., static electricity, a
spark resulting from a switch malfunction, or a cigarette), an
explosion or a fire could occur when the concentration of HFO-1234yf
exceeds its LFL of 62,000 ppm, posing a significant safety concern for
workers and consumers if it is not handled carefully. However, HFO-
1234yf is difficult to ignite and, in the event of ignition, the flames
would propagate slowly.\65\
---------------------------------------------------------------------------

    \64\ Chemours, 2019. HFO-1234yf for Use as a Refrigerant.
Significant New Alternatives Policy Program Submission to the U.S.
Environmental Protection Agency.
    \65\ HFO-1234yf has a high minimum ignition energy of 5,000-
10,000 mJ and a low burning velocity of 1.5 cm/s (Koban, 2011).
---------------------------------------------------------------------------

    With regards to flammability risks to workers, EPA's risk screens
evaluated the potential for a fire from release and ignition in
workplace situations and work-site operations, such as during equipment
manufacture, servicing and disposal or recycling of vehicle end-of-life
for the five nonroad vehicles. EPA considered the characteristics that
could be different from LD and other HD vehicles, such as differences
in the engine compartment size, passenger cabins, and operating
conditions, and how those might impact risks. In order to determine the
potential flammability risks during servicing or end-use in case of a
release of refrigerant into the cab, concentrations of HFO-1234yf
immediately following a 60 percent release of refrigerant over a period
of one minute into the cab were compared to the LFL and upper
flammability limit (UFL) for HFO-1234yf reported by ASHRAE Standard 34
(i.e., 62,000 ppm and 123,000 ppm, respectively). The one-minute time
duration is most appropriate for determining the risks of flammable
refrigerants because the potential maximum instantaneous concentration
can be estimated and compared to the LFL. Two key inputs to the models
were the cab volume (i.e., the space into which the refrigerant would
leak) and the refrigerant charge size. Because passenger compartment
volumes and refrigerant charge sizes can vary widely from model to
model, the highest ratio of charge size to compartment volume
identified was used as the input into the models.
    In the event of a leak, SAE Standard J2772 specifies that nonroad
vehicles be manufactured such that the pressure differential between
the air conditioning system and the cab allows only up to 60 percent of
the refrigerant charge to be released into the cab.\66\ Independent
testing of refrigerant releases from nonroad vehicles, according to SAE
Standard J2772, found that the amount of refrigerant released following
a line leak was much lower than 60 percent.
---------------------------------------------------------------------------

    \66\ SAE, 2019. Standard J2772: Measurement of Passenger
Compartment Refrigerant Concentrations Under System Refrigerant
Leakage Conditions. SAE International.
---------------------------------------------------------------------------

    To represent a plausible worst-case scenario, EPA's box modeling
assumed that 60 percent of the charge of the air conditioning systems
for the five nonroad vehicles is released into the cab of the vehicles
over a period of one minute. EPA's worst-case scenario box modeling
resulted in the concentration of HFO-1234yf in the cab exceeding the
LFL of 62,000 ppm, for the five nonroad vehicles. However, the
estimated exposures were derived using conservative assumptions and
represent worst-case scenarios with a low probability of occurrence, as
the analyses assume a rapid release of refrigerant (i.e., one minute),
assume the minimum required fresh air intake, and do not consider the
air recirculation rate for the nonroad vehicles or other variables that
would potentially reduce the concentration levels in the air to below
the flammable range for HFO-1234yf. Additionally, flammability concerns
are further reduced due to the design of MVAC systems for the five
vehicle types as described above in section II.A.1 and the low
probability of collisions for these nonroad vehicles. MVAC systems in
the nonroad vehicles are robust and made to withstand strenuous
operation, which lowers the potential for line leaks due to wear.
According to AEM, 67 68 69 70 71 the operator's compartment
in agricultural tractors greater than 40 HP; self-propelled
agricultural machinery; compact equipment; and construction, forestry,
and mining equipment is a completely self-contained unit which provides
an additional level of safety in a collision event. For commercial
utility vehicles, which are smaller than the other four nonroad vehicle
types, AEM noted that the engine compartment is contained in the rear
of the vehicle, under the cargo bed, with the main components of the
MVAC system in the front of the cabin with only the compressor and two
lines near the engine. The potential for collisions is also less likely
because most of the vehicles are operated by trained professionals,
typically at low speed, and are only driven on the highway to move from
one site or nonroad location to another.
---------------------------------------------------------------------------

    \67\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \68\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage
Harvesters, Sprayers, and Windrowers.
    \69\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders).
    \70\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction,
Forestry, and Mining Equipment.
    \71\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial
Utility Vehicles.
---------------------------------------------------------------------------

    In addition to the plausible worst-case scenario analysis, which
employs a simple box model, EPA's risk screens reference modeling
conducted by AEM in the flammability assessments. The AEM consortium
used two different models in its assessments: (1) A box model to
examine worst-case scenarios for a wide variety of nonroad vehicles
addressed in this proposal and (2) a computational fluid dynamics (CFD)
72 73 74 75 76 77 model to more realistically represent the
behavior of the leaked refrigerant in an nonroad vehicle.The AEM box
model modeled the release of 60 percent of the refrigerant charge in
the vehicles with varying charge and cab sizes and assumed a near-
instantaneous leak of refrigerant over a period of 10 seconds. Six of
the scenarios modeled in the box model resulted in the concentration of
HFO-1234yf in the cab being equal to or exceeding the LFL; the
concentrations from the remaining six scenarios were below the LFL.
Similar to EPA's box modeling, the estimated exposures were derived
using conservative assumptions and represent worst-case scenarios with
a low probability of occurrence, as the analyses assume a rapid release
of refrigerant, assume the minimum required fresh air intake (i.e., 43
m\3\/hour), and do not consider the air recirculation rate for the
nonroad vehicles or other variables that would potentially reduce the
concentration levels in the air to below the flammable range for HFO-
1234yf.
---------------------------------------------------------------------------

    \72\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \73\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage
Harvesters, Sprayers, and Windrowers.
    \74\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders).
    \75\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction,
Forestry, and Mining Equipment.
    \76\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial
Utility Vehicles.
    \77\ AEM, 2020e. CFD Leak Modeling-Supplemental Information to
Compliment AEM Machine Form RAs.

---------------------------------------------------------------------------

    Conversely, the maximum concentration reached in the AEM CFD model,
which models a realistic leak scenario with the release of 60 percent
of the refrigerant charge released in the nonroad vehicles for 1000
seconds of simulation, was significantly below the LFL for HFO-1234yf
of 62,000 ppm. Construction, forestry, and mining vehicles were modeled
to represent the five nonroad vehicles as they had the highest ratio of
refrigerant charge to cabin volume among the five nonroad vehicles. AEM
found that the maximum concentration of HFO-1234yf reached in the cab
(i.e., 25,700 ppm) is not likely to exceed the LFL for the five nonroad
vehicles. The AEM CFD model reflects the real-world behavior of
refrigerant in the cab given a worst-case leak scenario because it
takes into account the refrigerant entry and exit points and assumes
worst-case scenario conditions, including the most likely scenario
where an operator is likely to ignite a cigarette, the highest charge-
to-cab ratio, minimal fresh air flow, and maximum air velocity and
refrigerant penetration. Additionally, the CFD modeling demonstrates
the conservativeness of the worst-case scenario box modeling and how
unlikely its results are; therefore, the worst-case scenario box models
may be overstating the true risks associated with the use of HFO-1234yf
in MVAC systems in the nonroad vehicles compared to real-world
conditions as presented in the CFD model.
    For these reasons, EPA concludes that the currently available
assessments on the use of HFO-1234yf in newly manufactured nonroad
vehicles addressed in this action are sufficiently conservative to
account for all probable flammability risks from the use of HFO-1234yf.
Relying on a similar analysis considered in support of the 2011 and
2016 SNAP listings of HFO-1234yf in certain MVAC systems, verifying
that more recent information is consistent with that analysis, and
considering unique factors for the nonroad vehicle types, EPA proposes
to conclude that the use of HFO-1234yf in the newly manufactured
nonroad vehicles addressed in this action does not pose significantly
greater flammability risk than the other alternatives when used in
accordance with the proposed use conditions described below in section
II.A.4, which are intended to mitigate flammability risks, and
recommendations in the safety data sheet (SDS) and EPA's risk screens.
(c) Toxicity
    Potential health effects of exposure to HFO-1234yf include
drowsiness or dizziness. HFO-1234yf may also irritate the skin or eyes
or cause frostbite, and at sufficiently high concentrations, HFO-1234yf
may cause irregular heartbeat. HFO-1234yf could cause asphyxiation if
air is displaced by vapors in a confined space. These potential health
effects are common to many refrigerants.
    The American Industrial Hygiene Association (AIHA) has established
a Workplace Environmental Exposure Level (WEEL) of 500 ppm as an 8-hr
TWA for HFO-1234yf. HFO-1234yf also has an acute toxicity exposure
limit (ATEL) of 100,000 ppm and a refrigerant concentration limit (RCL)
of 16,000 ppm, which are both established by ASHRAE. EPA anticipates
that users will be able to meet the AIHA WEEL and ASHRAE ATEL and RCL,
limits intended to reduce the risks of flammability in normally
occupied, enclosed spaces, and address potential health risks by
following requirements and recommendations in the manufacturer's SDSs
and other safety precautions common to the refrigerant industry.
    To evaluate human health and safety impacts, including asphyxiation
and toxicity risks, from the use of HFO-1234yf in the five types of
nonroad vehicles, the Agency estimated the potential exposures to HFO-
1234yf in the event of a 60 percent release of refrigerant from the
vehicles under reasonable worst-case scenarios described in the risk
screens. In the event of a leak, SAE Standard J2772 specifies that
nonroad vehicles be manufactured such that the pressure differential
between the air conditioning system and the cab allows only up to 60
percent of the refrigerant charge to be released into the cab.\78\ The
analysis of asphyxiation risks considered whether a worst-case release
of refrigerant under the cab would result in oxygen concentrations of
12 percent or less. The analysis found that impacts on oxygen
concentrations did not present a significant risk of asphyxiation at
the typical charge sizes, and that a 60 percent leak of refrigerant at
the maximum charge sizes could result in an oxygen concentration below
19.5 percent but above 12 percent. The estimated exposures were derived
using conservative assumptions, however, and conditions resulting in
oxygen levels under 12 percent \79\ are only predicted to occur with
charge sizes that are significantly larger than the maximum charge
sizes provided by the submitter or cab sizes that are unlikely for the
proposed applications. Additionally, the worst-case scenarios did not
consider conditions that are likely to occur that would increase oxygen
levels to which individuals would be exposed, such as fresh air flow
into the cab.
---------------------------------------------------------------------------

    \78\ SAE, 2019. Standard J2772: Measurement of Passenger
Compartment Refrigerant Concentrations Under System Refrigerant
Leakage Conditions. SAE International.
    \79\ Twelve percent oxygen in air (i.e., 120,000 ppm) is the
NOAEL for hypoxia (ICF, 1997).
---------------------------------------------------------------------------

    To assess the toxicity risks to end-users, 15-minute and 30-minute
TWA exposures were estimated and compared to the standard toxicity
limits. The estimated TWA exposures were fairly conservative as the
analyses assume a rapid release of refrigerant (i.e., one minute and 10
seconds for EPA's and AEM's box models, respectively), assume the
minimum required ventilation rate (i.e., 43 m\3\/hour), and do not
consider the air recirculation rate for the vehicles or other variables
that would potentially reduce the concentration levels in the air. EPA
found that the estimated 15-minute and 30-minute TWA exposures for HFO-
1234yf in MVAC systems in the nonroad vehicles are not likely to exceed
the ATEL for HFO-1234yf of 100,000 ppm in a one-minute release scenario
under EPA's worst-case scenario modeling assumptions. The end-use
exposures estimated by AEM across all scenarios were also well below
the ATEL for HFO-1234yf. Furthermore, these exposure estimates were
derived using conservative assumptions that do not necessarily reflect
a real-world leak scenario or the larger cab size where MVAC systems
using HFO-1234yf would typically be installed.
    Additionally, the estimated TWA exposure for HFO-1234yf determined
from AEM's CFD modeling, which models a realistic leak scenario for the
nonroad vehicles, was significantly below the ATEL for HFO-1234yf of
100,000 ppm. Construction, forestry, and mining vehicles were modeled
to represent the five nonroad vehicles. As noted above, these vehicles
are a more conservative and an approximately equivalent proxy for the
other four nonroad vehicle types because they have the highest ratio of
refrigerant charge to cabin volume among the five nonroad vehicles.
Therefore, the toxicity risks from using HFO-1234yf in the five nonroad
vehicles is not likely to exceed the ATEL for the five nonroad
vehicles.
    Concerning workplace exposure during charging, servicing, and
disposal of the nonroad vehicles addressed in this proposal, we expect
that professional technicians have proper training and certification
and have the proper equipment and knowledge to minimize their risks due
to exposure to refrigerant from an MVAC system. Thus,

worker exposure to HFO-1234yf is expected to be low. The vehicles are
typically charged by the Original Equipment Manufacturer (OEM). During
air conditioning system manufacture (i.e., charging at OEM location),
points of release would be from connection/disconnection of temporary
lines for charging and recovery equipment, although exposure during
these activities is expected to be minimal due to the use of left-hand
threaded fittings on storage cylinders, as specified in SAE Standard
J2844, intended to help mitigate any releases and restrict the
possibility of cross-contamination with other
refrigerants.80 81 82 83 84 Furthermore, equipment
containing HFO-1234yf is expected to be equipped with unique fittings
for the low-side and high-side service ports of the MVAC system,
according to SAE Standard J639, also intended to help mitigate any
releases and restrict the possibility of cross-contamination with other
refrigerants.\85\
---------------------------------------------------------------------------

    \80\ ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Agricultural Tractors Greater than
40 Horsepower) (New Equipment).
    \81\ ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Self-Propelled Agricultural
Machinery) (New Equipment).
    \82\ ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Compact Equipment) (New Equipment).
    \83\ ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining
Equipment) (New Equipment).
    \84\ ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Commercial Utility Vehicles) (New
Equipment).
    \85\ Ibid.
---------------------------------------------------------------------------

    Servicing of the vehicles is expected to take place outside (e.g.,
out in the field or other outdoor site) rather than at a typical
servicing center for LD vehicles, for example; therefore, exposure
during servicing is expected to be less than during charging the MVAC
system during manufacture. Therefore, occupational exposure during
these activities was conservatively modeled based on charging. The
modeled maximum 15-minute TWA exposures for HFO-1234yf during charging
were compared to the short-term exposure limit (STEL) of 1,500 ppm.
EPA's modeling indicated that the short-term (15-minute) worker
exposure concentrations of HFO-1234yf are not likely to exceed its STEL
for the typical or maximum charge size in the vehicles during charging
or servicing. Additionally, these exposure estimates are significantly
lower than the RCL and ATEL of 16,000 ppm and 100,000 ppm,
respectively, for HFO-1234yf, which are limits intended to reduce the
risks of asphyxiation and acute toxicity hazards in normally occupied,
enclosed spaces according to ASHRAE Standard 34.
    EPA also determined that occupational exposure during disposal of
the vehicles at the typical charge size is not likely to exceed the
long-term (8-hour) WEEL for HFO-1234yf (i.e., 500 ppm). However, under
the disposal release scenarios, the modeling showed that occupational
exposure during disposal of MVAC systems containing HFO-1234yf at the
maximum charge size (i.e., 3.4 kilograms (120 ounces)) could
potentially exceed the 8-hour long-term exposure limit. The estimated
exposures, however, were well below the RCL of 16,000 ppm for HFO-
1234yf and were derived using conservative assumptions and represent a
worst-case scenario with a low probability of occurrence. These MVAC
systems are also typically disposed of by CAA section 608-certified
personnel using proper industrial hygiene techniques while wearing PPE
to maximize recovery efficiency and limit releases. EPA concludes that
the manufacture, use, servicing or disposal of HFO-1234yf MVAC systems
in the newly manufactured nonroad vehicles addressed in this action
does not pose greater risk toxicity risk to workers than the other
alternatives when used in accordance with the proposed use conditions.
    Additionally, EPA's review of potential toxicity risks of HFO-
1234yf to the general population indicated that HFO-1234yf is not
expected to pose significantly greater toxicity risk than other
alternatives for the MVAC systems in the newly manufactured nonroad
vehicles addressed in this action. The general population is defined as
non-personnel who are subject to exposure of the proposed substitute
near industrial facilities, including manufacturing or equipment
production factories, equipment operating locations, or recycling
centers, rather than personnel at end-use. EPA proposes to conclude
that the use of HFO-1234yf in the newly manufactured nonroad vehicles
addressed in this action does not pose significantly greater toxicity
risk than the other alternatives when used in accordance with the
proposed use conditions described below in section II.A.4, which are
intended to mitigate toxicity risks, and recommendations in the SDS and
EPA's risk screens.
4. What are the proposed use conditions?
    All MVAC refrigerants listed as acceptable are subject to use
conditions requiring labeling and the use of unique fittings. HFC-152a
and CO2 are subject to additional use conditions mitigating
flammability and toxicity as appropriate to the alternative. Neither
HFC-152a nor CO2 can simply be ``dropped'' into existing
MVAC systems because they are listed as acceptable only for newly
manufactured vehicles.
    EPA is proposing to list HFO-1234yf as acceptable, subject to use
conditions, in MVAC systems in certain newly manufactured nonroad
vehicles because the use conditions are necessary to ensure that use of
HFO-1234yf will not have a significantly greater overall impact on
human health and the environment than other alternatives. EPA is
proposing to update the existing use conditions that are currently
required for the use of HFO-1234yf in MVAC systems in newly
manufactured LD passenger cars and trucks, MDPVs, HD pick-up trucks,
and complete HD vans and then apply them to all the MVAC systems
addressed in this proposal. Manufacturing and service personnel or
consumers may not be familiar with refrigeration or AC equipment
containing a flammable refrigerant. These use conditions will be
sufficiently protective to ensure use of HFO-1234yf in these nonroad
vehicles does not pose significantly greater risk than use of other
alternatives.
    The first proposed use condition requires that HFO-1234yf may be
used only in new MVAC systems \86\ which have been designed to address
concerns unique to flammable refrigerants--i.e., HFO-1234yf may not be
used as a conversion or ``retrofit'' refrigerant for existing MVACs
designed for other refrigerants. HFO-1234yf was not submitted under the
SNAP program for use in retrofitted MVAC systems, and no information
was provided on how to address hazards if HFO-1234yf were to be used in
MVAC systems that were not designed for a flammable refrigerant.
Therefore, EPA is only proposing that HFO-1234yf may be used in new
MVACs that have been properly designed for its use.
---------------------------------------------------------------------------

    \86\ This is intended to mean a completely new refrigeration
circuit containing a new compressor, evaporator, condenser, and
refrigerant tubing.
---------------------------------------------------------------------------

    The second proposed use condition requires that MVAC systems
designed to use HFO-1234yf in newly manufactured agricultural tractors
greater than 40 HP; self-propelled agricultural machinery; compact
equipment; construction, forestry, and mining equipment; and commercial
utility vehicles must meet the requirements of SAE J639 (revised
November 2020), ``Safety Standards for Motor Vehicle Refrigerant Vapor
Compression Systems.'' This standard

sets safety standards that include unique fittings; a warning label
indicating the refrigerant's identity and that it is a flammable
refrigerant; and requirements for engineering design strategies that
include a high-pressure compressor cutoff switch and pressure relief
devices. This use condition also requires that for connections with
refrigerant containers for use in professional servicing, use fittings
must be consistent with SAE J2844 (revised January 2013), ``R-1234yf
(HFO-1234yf) New Refrigerant Purity and Container Requirements for Use
in Mobile Air-Conditioning Systems,'' which specifies quick-connect
fittings that are different from those for any other refrigerant. The
low-side service port and connections will have an outside diameter of
14 mm (0.551 inches), and the high-side service port will have an
outside diameter of 17 mm (0.669 inches), both accurate to within 2 mm.
Under SAE J2844 (revised January 2013), containers of HFO-1234yf for
use in professional servicing of MVAC systems must have a left-handed
screw valve with a diameter of 0.5 inches and Acme (trapezoidal) thread
with 16 threads per inch.
    Consistent with the conclusion EPA drew at the time of the Agency's
listing decision for HFO-1234yf in LD vehicles, EPA believes that the
safety requirements that are included in SAE J639 sufficiently mitigate
risks of both hydrogen fluoride (HF) generation and refrigerant
ignition (March 29, 2011; 76 FR 17488) for the nonroad vehicles
addressed in this proposed action. HFO-1234yf is mildly flammable (A2L
classification) and, like other fluorinated refrigerants, can decompose
to form the toxic compound HF when exposed to flame or to sufficient
heat. The SAE J639 standard can also address flammability and HF risks
of HFO-1234yf for the nonroad vehicles. For example, SAE J639 provides
for a pressure relief device designed to minimize direct impingement of
the refrigerant and oil on hot surfaces and for design of the
refrigerant circuit and connections to avoid refrigerant entering the
passenger cabin. The pressure release device ensures that pressure in
the system will not reach an unsafe level that might cause an
uncontrolled leak of refrigerant, such as if the MVAC system is
overcharged. The pressure release device will reduce the likelihood
that refrigerant leaks would reach hot surfaces that might lead to
either ignition or formation of HF. These elements of the refrigerant
circuit and connections are designed to prevent refrigerant from
entering the passenger cabin if there is a leak. Keeping refrigerant
out of the passenger cabin minimizes the possibility that there would
be sufficient levels of refrigerant to reach flammable concentrations
or that HF would be formed and transported where passengers might be
exposed.
    The third proposed use condition requires the manufacturer of MVAC
systems and vehicles to conduct Failure Mode and Effects Analysis
(FMEA) as provided in SAE J1739 (revised January 2021), ``Potential
Failure Mode and Effects Analysis (FMEA) Including Design FMEA,
Supplemental FMEA-MSR, and Process FMEA,'' and keep records of the FMEA
on file for three years from the date of creation. SAE J1739 (revised
January 2021) describes a FMEA as ``a systematic group of activities
intended to: (a) Recognize and evaluate the potential failure of a
product/process and the effects and causes of that failure, (b)
identify actions that could eliminate or reduce the change of the
potential failure occurring, and (c) document the process.'' Through
the FMEA, OEMs determine the appropriate protective strategies
necessary to ensure the safe use of HFO-1234yf across their vehicle
fleet. It is standard industry practice to perform the FMEA and to keep
it on file while the vehicle is in production and for several years
afterwards. As with the previous use condition, this use condition is
intended to ensure that agricultural tractors greater than 40 HP; self-
propelled agricultural machinery; compact equipment; construction,
forestry, and mining equipment; and commercial utility vehicles
manufactured with HFO-1234yf MVACs are specifically designed to
minimize release of the refrigerant into the passenger cabin or onto
hot surfaces that might result in ignition or in generation of HF.

B. Proposed Modifications To Use Conditions for MVAC Systems in Other
Vehicle Types

    For the previous listings of HFO-1234yf in the March 29, 2011 (76
FR 17488), and December 1, 2016 (81 FR 86778), final rules for MVAC
systems in certain newly manufactured vehicles, EPA is proposing to
modify the use conditions to replace the reference to older versions of
SAE J639, SAE J1739, and SAE J2844.
    First, EPA is proposing to replace the reference to SAE J639
(revised 2011) in the March 2011 and December 2016 final rules with a
reference to the 2020 version of the standard, ``Safety and Design
Standards for Motor Vehicle Refrigerant Vapor Compression Systems.''
This is the most recent version of the SAE J639 standard, which was
updated to include system design and safety- related requirements for
secondary loop HFC-152a MVAC systems, and to make general improvements
for clarity.
    Second, EPA is proposing to replace the reference to SAE J1739
(adopted 2009) in the March 2011 and December 2016 final rules with a
reference to the 2021 version of the standard, ``Potential Failure Mode
and Effects Analysis (FMEA) Including Design FMEA, Supplemental FMEA-
MSR, and Process FMEA.'' The 2021 version is the most recent version of
the SAE J1739 standard; it was revised to emphasize the process of FMEA
selection, creation, documentation, reporting, and change management.
    Finally, EPA is proposing to replace the reference to SAE J2844
(revised 2011) in the March 2011 final rule with a reference to the
2013 version of the standard, ``R-1234yf (HFO-1234yf) New Refrigerant
Purity and Container Requirements for Use in Mobile Air-Conditioning
Systems.'' This is the most recent version of the SAE J2844 standard;
it was updated to add the requirements for certification according to
SAE J2911, ``Procedure for Certification that Requirements for Mobile
Air Conditioning System Components, Service Equipment, and Service
Technician Training Meet SAE J Standards.''

C. Proposed Servicing Fittings for Small Cans of HFO-1234yf

    EPA is proposing to include a use condition for HFO-1234yf to
provide for servicing air conditioning systems. The proposed use
condition would require unique servicing fittings for use with small
cans (two pounds or less) for servicing of MVAC systems containing HFO-
1234yf in the nonroad vehicles addressed in this action, as well as
servicing of the MVAC systems in the vehicles for which HFO-1234yf has
already been listed as acceptable, subject to use conditions (i.e., new
LD passenger cars and trucks and new MDPVs, HD pick-up trucks, and
complete HD vans). The use condition is discussed below in section
II.C.3., ``What is the proposed use condition?'' EPA previously listed
HFO-1234yf as acceptable, subject to use conditions, for large
containers of HFO-1234yf for professional servicing of MVAC systems (76
FR 17488, March 29, 2011; 77 FR 17344, March 26, 2012). Redacted
submissions and supporting documentation for HFO-1234yf in small cans
are provided in the docket for this proposed rule (EPA-HQ-OAR-2021-
0347) at https://www.regulations.gov. As

explained more fully below, to help evaluate environmental,
flammability, and toxicity risks resulting from the use of HFO-1234yf
in small cans for MVAC servicing, EPA conducted a risk screen which is
available in the docket for this proposed rule.\87\
---------------------------------------------------------------------------

    \87\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO-1234yf.
---------------------------------------------------------------------------

    Servicing of MVAC systems containing HFO-1234yf with small
refrigerant cans is expected to take place in a variety of locations,
including professional and residential garages with differing sizes and
ventilation rates. As discussed below in section II.C.3 regarding the
proposed use condition, the small refrigerant cans would need to be
equipped with a Standard Compressed Gas Association (CGA) 166 left-hand
thread outlet connection valve in accordance with SAE Standard
J2844.\88\ The hose connected to the vehicle would also use the low
side service port per SAE J639.
---------------------------------------------------------------------------

    \88\ SAE J2844 container valve requirements are for HFO-1234yf
service cylinders with a volume less than or equal to 23 kilograms.
---------------------------------------------------------------------------

    For additional context, we further note that separate from the
requirements proposed in this rulemaking, the sale of such small
refrigerant cans would be subject to the regulatory requirements under
section 608 of the CAA, codified at 40 CFR 82.154. These regulations
restrict the sale, distribution, and offer for sale or distribution of
refrigerants, including non-exempt substitute refrigerants, like HFO-
1234yf, to circumstances where certain requirements are met. Specific
to the sale of small cans of refrigerant, 40 CFR 82.154(c)(1)(ix)
states that non-exempt substitute refrigerant for use in an MVAC, e.g.,
HFO-1234yf, may be sold, including to DIYers, if it is in a container
designed to hold two pounds or less of refrigerant which has a unique
fitting, and, if manufactured or imported on or after January 1, 2018,
has a self-sealing valve that complies with the self-sealing valve
specifications codified at 40 CFR 82.154(c)(2). EPA is not proposing to
modify the existing CAA section 608 provisions under 40 CFR 82.154,
including the restriction on sale of substitute refrigerants and
requirements for self-sealing valves. For additional information, EPA
directs readers to 82.152, where EPA defines a self-sealing valve as
``a valve affixed to a container of refrigerant that automatically
seals when not actively dispensing refrigerant and that meets or
exceeds established performance criteria as identified in Sec.
82.154(c)(2).''
1. What is the affected end-use?
    EPA is proposing to list HFO-1234yf as acceptable, subject to a use
condition, in small cans (two pounds or less) for servicing of MVAC
systems in the nonroad vehicles addressed in this action, as well as in
MVAC systems in the vehicles for which HFO-1234yf has already been
listed as acceptable, subject to use conditions. For the existing
listings in the March 29, 2011 (76 FR 17488), and December 1, 2016 (81
FR 86778), final rules, EPA is proposing to revise the use conditions
to require unique servicing fittings for use with small cans.
2. How does HFO-1234yf compare to other refrigerants for these MVAC
applications with respect to SNAP criteria?
(a) Environmental Impacts
    HFO-1234yf has a GWP of four,89 90 which is similar to
or lower than the GWP of the other acceptable alternatives for use in
small cans (i.e., HFC-134a and CO2). HFO-1234yf, HFC-134a,
and CO2 do not deplete the ozone layer, and are all exempt
from the definition of VOC under CAA regulations (see 40 CFR 51.100(s))
addressing the development of SIPs to attain and maintain the NAAQS.
For additional information on the environmental impacts of HFO-1234yf,
see the discussion above in section II.A.3.a.
---------------------------------------------------------------------------

    \89\ Nielsen et al., 2007. Atmospheric chemistry of CF3CF=CH2:
Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH
radicals, and O3. Chemical Physics Letters 439, 18-22. Available
online at: https://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
    \90\ Papadimitriou et al., 2007. CF3CF=CH2 and (Z)-CF3CF=CHF:
Temperature dependent OH rate coefficients and global warming
potentials. Phys. Chem. Chem. Phys., 2007, Vol. 9, p. 1-13.
Available online at: https://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
---------------------------------------------------------------------------

(b) Flammability
    As discussed above in section II.A.3.b, HFO-1234yf is classified as
A2L under ASHRAE 34-2013, while HFC-134a and CO2 are
nonflammable refrigerants. HFO-1234yf is flammable when its
concentration in air is in the range of 6.2 percent and 12.3 percent by
volume (62,000 ppm to 123,000 ppm). Due to its flammability, small cans
of HFO-1234yf for MVAC system servicing could pose a safety concern for
workers and service personnel or consumers if they are not properly
handled.
    Servicing of MVAC systems with small refrigerant cans containing
HFO-1234yf is expected to take place in either a professional garage
bay or a residential garage. To determine the potential flammability
risks of a catastrophic release of refrigerant during professional and
DIY MVAC system servicing using a small refrigerant can, EPA analyzed
plausible worst-case scenarios to model a catastrophic release of HFO-
1234yf \91\ compared with the LFL of 62,000 ppm for HFO-1234yf.\92\
Under these plausible worst-case scenarios, the full charge of the
refrigerant can is assumed to be emitted into the professional garage
bay and residential garage with 4.0 and 3.1 air changes per hour
(ACH),\93\ respectively, over the course of 15 minutes, which
represents the approximate amount of time required to charge the MVAC
system.\94\ EPA found that the maximum instantaneous concentrations of
HFO-1234yf in the lower 0.4 meters of the room did not exceed the LFL
for HFO-1234yf (i.e., 62,000 ppm) for small refrigerant cans (charge
size of around 1kg (2 pounds) or less).\95\ EPA also found that the
maximum instantaneous concentration exceeded 25 percent (15,500 ppm) of
the LFL for HFO-1234yf for DIY servicing under one of the
scenarios.\96\ However, the scenario was derived using conservative
assumptions (e.g., minimum room volume, vertical concentration
gradient). Furthermore, small refrigerant cans are not likely to be
used in spaces significantly smaller than those modeled in EPA's
assessment, which are expected to be large enough to accommodate a
vehicle and adequate space surrounding the vehicle for the user to
access the MVAC unit. Finally, HFO-1234yf is difficult to ignite and,
in the event of ignition, the flames would

propagate slowly.\97\ Therefore, the risk of fire is minimal if small
refrigerant cans containing HFO-1234yf meet and are used to service
vehicles in rooms with volumes in accordance with relevant safety
standards as described below in section II.C.3.
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    \91\ In order to simulate the vertical concentration gradient of
refrigerant following release, it is assumed that 95 percent of the
leaked refrigerant mixes evenly into the lower 0.4 meters (1.3 feet)
of the room, and the rest of the refrigerant mixes evenly in the
remaining volume (Kataoka 2000).
    \92\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \93\ The air exchange rates were derived from the requirements
in ANSI/ASHRAE Standard 62.1-2019, Table 6.1 (ANSI/ASHRAE 2019c).
Ventilation requirements (presented as cubic feet per minute in the
standard) were converted to ACH using the assumed room size in the
residential garage scenario.
    \94\ Perrin Quarles Associates, Inc. (2007) suggests charging
for up to 15 minutes to fully empty the contents of the refrigerant
can is a best practice for DIY servicing of an MVAC system. This
study also indicates that the transfer procedure used for a small
refrigerant can (e.g., holding upright, rotation method, and other
flow control methods) influences the transfer time and resulting
heel remaining in the can.
    \95\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \96\ Ibid.
    \97\ HFO-1234yf has a high minimum ignition energy of 5,000-
10,000 mJ and a low burning velocity of 1.5 cm/s (Koban, 2011).
---------------------------------------------------------------------------

    Additionally, EPA considered the submitters' detailed assessments
of the probability of events that might create a fire and approaches to
mitigate risks. A CFD modeling was conducted by a submitter to simulate
a severe refrigerant line leak from a 600-gram MVAC system in a garage
bay of 84 m\3\ without forced ventilation and found that the flammable
region of the refrigerant plume under the hood of the vehicle was
small, ranging from 2 inches to a maximum of 10 inches, which quickly
dispersed. Similarly, leaks from a small refrigerant can containing
HFO-1234yf during MVAC servicing are not expected to accumulate under
the vehicle hood in concentrations above the LFL for HFO-1234yf.
    EPA proposes to conclude that the currently available assessments
on the use of HFO-1234yf in small cans for professional and DIY
servicing of MVAC systems are sufficiently conservative to account for
all probable flammability risks from the use of HFO-1234yf. Therefore,
the use of HFO-1234yf in small cans does not pose significantly greater
flammability risk than the other alternatives when used in accordance
with the proposed use condition described below in section II.C.3,
which is intended to mitigate flammability risks, and recommendations
in the SDS and EPA's risk screen.
(c) Toxicity
    For a discussion of the potential health effects of HFO-1234yf, see
the section II.A.3.c above. In evaluating potential asphyxiation and
toxicity impacts of HFO-1234yf in small cans on human health, EPA
considered both occupational risk and risk to the general population.
EPA investigated the risk of asphyxiation and of exposure to toxic
levels of HFO-1234yf for plausible worst-case scenarios. According to
the results of EPA's asphyxiation assessment, the use of HFO-1234yf in
small refrigerant cans does not present a significant risk of
asphyxiation.\98\ Conditions resulting in oxygen levels under 12
percent \99\ would only occur with charge sizes that are significantly
larger than the maximum charge size proposed for small refrigerant cans
or room sizes that are unlikely for the proposed application. In
addition, the charge sizes at which an asphyxiation concern would exist
are also significantly larger (about 18 times) than the average charge
size of an MVAC system.\100\
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    \98\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \99\ Twelve percent oxygen in air (i.e., 120,000 ppm) is the
NOAEL for hypoxia (ICF 1997).
    \100\ EPA's Vintaging Model (EPA 2020) assumes the refrigerant
charge size for MVACs to be 0.555-1 kilograms in light-duty vehicles
and 0.79-1.14 kilograms in light-duty trucks.
---------------------------------------------------------------------------

    To evaluate toxicity risks, EPA estimated 15-minute TWA exposures
for HFO-1234yf in small cans and compared them to the standard toxicity
limits. The estimated TWA values were conservative as the analysis did
not consider opened windows or doors, fans operating, conditioned
airflow (either heated or cooled), or other variables that would reduce
the levels to which individuals would be exposed. The modeling results
showed that the estimated 15-minute TWA exposures are not likely to
exceed the ATEL (i.e., 100,000 ppm) and are all lower than the RCL
(i.e., 16,000 ppm) for HFO-1234yf.
    EPA also considered testing and air sampling conducted by a
submitter to determine potential refrigerant exposure to professional
servicing technicians or DIY users due to leakage of refrigerant cans
in a small, closed garage with the condenser fan off and the vehicle
hood partly open.\101\ The various scenarios investigated included
releases of 170 grams to 680 grams of refrigerant from both an inverted
and upright can.\102\ Refrigerant samples were taken under the vehicle
at 0.15 meters above the floor (representing the potential breathing
area of a technician present in that space) and in the engine
compartment. The experimentally derived exposure estimates are also
significantly lower than the RCL (i.e., 16,000 ppm) and ATEL (i.e.,
100,000 ppm) for HFO-1234yf.
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    \101\ Honeywell International, Inc. 2012. Refrigerant exposure
to service personnel or DIYers due to leakage of 12 oz charging cans
or ``small cans.'' Experiments Conducted at Honeywell's Research
Laboratory in Buffalo, NY USA. January 2012.
    \102\ The orientation of the can during servicing determines the
phase (i.e., liquid or gas) of the refrigerant that is being
transferred into the MVAC system. When the can is upright, the
refrigerant transfers as a gas and when the can is inverted, the
refrigerant transfers as a liquid (Perrin Quarles Associates, Inc.,
2007). Refrigerant can instructions often direct users to hold the
can upright or rotate its position during servicing.
---------------------------------------------------------------------------

    Additionally, EPA assessed the potential exposures to workers
during disposal (e.g., collection, transportation) of small refrigerant
cans containing HFO-1234yf.\103\ EPA determined that if proper handling
and disposal guidelines are followed in accordance with good industrial
hygiene practices and the SDS for HFO-1234yf, there is no significant
risk to workers during the disposal of HFO-1234yf from MVAC systems or
HFO-1234yf small refrigerant cans.
---------------------------------------------------------------------------

    \103\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle
Air Conditioning (Small Cans). Substitute: HFO-1234yf.
---------------------------------------------------------------------------

    For potential toxicity risks of HFO-1234yf to the general
population, our analysis indicated that HFO-1234yf is not expected to
present an unreasonable risk to human health in the general population
when used as a refrigerant in small cans for MVAC servicing.
    Based upon our analysis, workplace and general population exposure
to HFO-1234yf in small cans when used according to the proposed use
condition is not expected to exceed relevant exposure limits.
Therefore, we propose to conclude that the use of HFO-1234yf in small
cans does not pose significantly greater toxicity risks than other
acceptable refrigerants when used in accordance with the proposed use
condition described below in section II.C.3 which is intended to
mitigate toxicity risks, and recommendations in the SDS and EPA's risk
screen.
3. What is the proposed use condition?
    EPA's SNAP program has a longstanding approach of requiring unique
fittings for use with each refrigerant substitute in MVAC systems. This
is intended to prevent cross contamination of different refrigerants,
preserve the purity of recycled refrigerants, and ultimately to avoid
venting of refrigerant consistent with requirements under CAA section
608(c), codified at 40 CFR 82.154(a). In the 1996 SNAP rule requiring
the use of fittings on all refrigerants submitted for use in MVAC
systems, EPA urged industry to develop mechanisms to ensure that the
refrigerant venting prohibition under CAA section 608 and the
implementing regulations at 40 CFR 82.154 are observed (61 FR 54032;
October 16, 1996). EPA has issued multiple SNAP rules codified in the
CFR requiring the use of fittings unique to a refrigerant for use on
``containers of the refrigerant, on can taps, on recovery, recycling,
and charging equipment, and on all [motor vehicle] air conditioning
system service ports.'' (See appendices C and D to subpart G of 40 CFR
part 82).
    EPA is proposing that for connections with small cans (two pounds
or less) of

HFO-1234yf use fittings must be consistent with SAE J2844 (revised
January 2013), which specifies quick-connect fittings that are
different from those for any other refrigerant. The low-side service
port and connections will have an outside diameter of 14 mm (0.551
inches), and the high-side service port will have an outside diameter
of 17 mm (0.669 inches), both accurate to within 2 mm. Under SAE J2844
(revised January 2013), small cans of HFO-1234yf (e.g., for use in DIY
servicing of MVAC systems) must have a left-handed screw valve with a
diameter of 0.5 inches and Acme (trapezoidal) thread with 16 threads
per inch.

D. Proposed Incorporation by Reference

    EPA is proposing to adopt the current versions of three technical
safety standards developed by SAE by incorporating them by reference
into the use conditions for the nonroad vehicles addressed in this
action. EPA also proposes to modify the use conditions for the previous
listings of HFO-1234yf in certain MVAC systems to incorporate by
reference the most current versions of the three standards. The three
standards are SAE J639 (revised November 2020), ``Safety and Design
Standards for Motor Vehicle Refrigerant Vapor Compression Systems;''
SAE J1739 (revised January 2021), ``Potential Failure Mode and Effects
Analysis (FMEA) Including Design FMEA, Supplemental FMEA-MSR, and
Process FMEA;'' and SAE J2844 (revised January 2013), ``R-1234yf (HFO-
1234yf) New Refrigerant Purity and Container Requirements for Use in
Mobile Air-Conditioning Systems.'' Section II.A.4 of this preamble
discusses these standards in greater detail.
    EPA finds, as in past rules, that it is appropriate to reference
consensus standards that set conditions to reduce risk. As in past
listings of flammable refrigerants, we find that such standards have
already gone through a development phase that incorporates the latest
findings and research. Likewise, such standards have gone through a
vetting and refinement process that provides the affected parties an
opportunity to comment. For the U.S. MVAC industry, EPA sees SAE
standards in general as a pervasively used body of work to address
risks, and these standards are the most applicable and recognized by
the U.S. market.
    Incorporation by reference allows federal agencies to comply with
the requirement to publish rules in the Federal Register and the Code
of Federal Regulations by referring to material already published
elsewhere. The legal effect of incorporation by reference is that the
material is treated as if it were published in the Federal Register and
Code of Federal Regulations.
    SAE J639, J1739, and J2844 are available for purchase by mail at:
SAE Customer Service, 400 Commonwealth Drive, Warrendale, PA 15096-
0001; Telephone: 1-877-606-7323 in the U.S. or Canada (other countries
dial 1-724-776-4970); internet address for SAE J639: https://www.sae.org/standards/content/j639_201112/; internet address for SAE
J1739: https://www.sae.org/standards/content/j1739_202101/; internet
address for SAE J2844: https://www.sae.org/standards/content/j2844_201301/. The cost of SAE J639, J1739, and J2844 is $85 each for
an electronic or hard copy. The cost of obtaining these standards is
not a significant financial burden for manufacturers of MVAC systems,
and purchase is not required for those selling, installing, or
servicing the MVAC systems covered by these standards. Therefore, the
EPA concludes that SAE J639, J1739, and J2844 are reasonably available.

E. When would the listings apply?

    EPA proposes that all the proposed listings, if finalized, would
apply 30 days after the date of publication of a final rule. This date,
the same as the proposed effective date of this regulation, supports
the safe use of this substitute without undue delay.

F. What is the relationship between this SNAP rule and other federal
rules?

1. Significant New Use Rule for HFO-1234yf Under the Toxic Substances
Control Act
    In a Final Rule published on March 29, 2011 (76 FR 17488), EPA
noted that the listing of HFO-1234yf as acceptable, subject to use
conditions, in new passenger cars and trucks did not apply to small
cans. EPA stated that the Agency ``would require additional information
on consumer risk and a set of unique fittings from the refrigerant
manufacturer for use with small cans or containers of HFO-1234yf before
we would be able to issue a revised rule that allows for consumer
filling, servicing, or maintenance of MVAC systems with HFO-1234yf''
\104\ and that use of small cans would need to be consistent with EPA's
final SNUR for HFO-1234yf under TSCA (October 27, 2010; 75 FR 65987).
EPA has since revised the SNUR (80 FR 37166, June 30, 2015) to require
the submission of a significant new use notice (SNUN) for commercial
use of HFO-1234yf other than in passenger cars and vehicles in which
the original charging of MVAC systems with HFO-1234yf was done by the
OEM and use of HFO-1234yf in consumer products other than products used
to recharge the MVAC systems in passenger cars and vehicles in which
the original charging of MVAC systems with HFO-1234yf was done by the
OEM, among other things. Manufacturers of small cans of HFO-1234yf have
also submitted a unique fitting specifically for use with small can
taps and small refrigerant cans for EPA's review. Today's proposed
listing of HFO-1234yf would apply to small cans, weighing two pounds or
less, for DIY or professional use. Consistent with the revised June
2015 SNUR for HFO-1234yf, commercial use or use in consumer products to
recharge MVAC systems with HFO-1234yf in passenger cars and vehicles
may only occur without submission of a SNUN and review by EPA if the
OEM originally charged the system with HFO-12324yf.
---------------------------------------------------------------------------

    \104\ EPA, 2011. Protection of Stratospheric Ozone: New
Substitute in the Motor Vehicle Air Conditioning Sector Under the
Significant New Alternatives Policy (SNAP) Program; Final Rule.
March 29, 2011 (76 FR 17488). Available online at: https://www.govinfo.gov/content/pkg/FR-2011-03-29/pdf/2011-6268.pdf.
---------------------------------------------------------------------------

    EPA is proposing to include a reference to the June 30, 2015 SNUR
(80 FR 37166) in Appendix B subpart G of part 82, under the `Comments'
column, for the listings of HFO-1234yf for the nonroad vehicles
addressed in this action. EPA is also proposing to modify the existing
listings of HFO-1234yf as acceptable, subject to use conditions, for
various vehicle types, by including the reference to the June 2015 SNUR
in the Comments column in Appendix B subpart G of part 82.
2. CAA Sections 608 and 609
    Among other things, section 608 of the CAA prohibits individuals
from knowingly venting or otherwise releasing into the environment any
refrigerants except those specifically exempted in certain end uses,
while maintaining, servicing, repairing, or disposing of air
conditioning or refrigeration equipment. HFO-1234yf is not exempt from
the venting prohibition in any application; therefore, knowing release
of HFO-1234yf from MVAC systems in the nonroad vehicles addressed in
this action, or any other MVAC system, by any person maintaining,
servicing, repairing, or disposing of such systems is prohibited. MVAC
end-of-life disposal and recycling specifications are also covered
under CAA section 608 and EPA's regulations issued under that section
of the Act, which are codified at subpart F of 40 CFR part 82. In
addition, as mentioned above in sections I.A and

II.C, there are additional requirements that concern the sale or offer
for sale of refrigerants, including a sales restriction under 40 CFR
subpart F and specifically at 82.154(c)(1) and related specifications
for self-sealing valves at 82.154(c)(2). This proposal does not propose
to modify the provisions under 40 CFR 82.154, including the restriction
on sale of substitute refrigerants and requirements for self-sealing
valves. The Agency is not proposing to revise, and is not reopening for
comment, regulations promulgated under section CAA 608 in this action.
    CAA section 609 establishes standards and requirements regarding
the servicing or repair of MVAC systems.\105\ EPA has issued
regulations implementing this statutory requirement and those
regulations are codified at subpart B of 40 CFR part 82. Under section
609 and its implementing regulations, no person repairing or servicing
motor vehicles for consideration \106\ may perform any service on an
MVAC that involves the refrigerant without properly using approved
refrigerant recovery or recovery and recycling equipment, and no such
person may perform such service unless such person has been properly
trained and certified. Refrigerant handling equipment must be certified
by EPA or an independent organization approved by EPA. The statutory
and regulatory provisions regarding MVAC servicing apply to all
refrigerants, including HFO-1234yf. Today's proposal will not have any
impact on EPA's regulations under sections 608 or 609 of the Clean Air
Act.
---------------------------------------------------------------------------

    \105\ Under the SNAP program, MVAC systems are those systems
that provide passenger comfort cooling for light-duty cars and
trucks, heavy-duty vehicles (large pick-ups, delivery trucks,
recreational vehicles, and semi-trucks), nonroad vehicles, buses,
and rail vehicles. See final rules published on March 29, 2011 (76
FR 17488) and on December 1, 2016 (81 FR 86778). For informational
purposes, we note that this includes systems that are also included
in the definitions that apply under other provisions of EPA's
regulations under title VI of the CAA. In this regard, we note that
EPA's regulations at 40 CFR 82.152 define ``MVAC-like appliance'' to
mean ``a mechanical vapor compression, open-drive compressor
appliance with a full charge of 20 pounds or less of refrigerant
used to cool the driver's or passenger's compartment of nonroad
vehicles or equipment. This includes, but is not limited to, the
air-conditioning equipment found on agricultural or construction
vehicles. This definition is not intended to cover appliances using
R-22 refrigerant.'' By contrast, EPA's regulations at 40 CFR 82.152
define ``Motor vehicle air conditioner (MVAC)'' as ``any appliance
that is a motor vehicle air conditioner as defined in 40 CFR part
82, subpart B.'' The subpart B regulations at 40 CFR 82.32 provide
that: ``Motor vehicle air conditioners means mechanical vapor
compression refrigeration equipment used to cool the driver's or
passenger's compartment of any motor vehicle. This definition is not
intended to encompass the hermetically sealed refrigeration systems
used on motor vehicles for refrigerated cargo and the air
conditioning systems on passenger buses using HCFC-22 refrigerant.''
Further, the subpart B regulations at 40 CFR 82.32 provide that:
``Motor vehicle as used in this subpart means any vehicle which is
self-propelled and designed for transporting persons or property on
a street or highway, including but not limited to passenger cars,
light duty vehicles, and heavy duty vehicles. This definition does
not include a vehicle where final assembly of the vehicle has not
been completed by the original equipment manufacturer.''
    \106\ Service for consideration means receiving something of
worth or value to perform service, whether in money, credit, goods,
or services.
---------------------------------------------------------------------------

3. Would this action listing HFO-1234yf as acceptable, subject to use
conditions, for certain nonroad vehicles and small cans affect EPA's HD
greenhouse gas standards?
    The Phase 1 HD Greenhouse Gas (GHG) rule (76 FR 57106; September
15, 2011) set GHG standards for the HD industry in three discrete
categories--combination tractors, HD pickups and vans, and vocational
vehicles. The Phase 1 rule also set separate standards for engines that
power vocational vehicles and combination tractors--based on the
relative degree of homogeneity among vehicles within each category. As
part of the Phase 1 HD GHG standards, EPA finalized a low leakage
standard of 1.50 percent leakage per year for AC systems installed in
HD pickup trucks and vans and combination tractors for model years 2014
and later. On October 25, 2016, EPA finalized Phase 2 HD GHG standards
that built on the existing Phase 1 HD GHG standards, and also finalized
GHG standards for certain trailers used in combination with HD tractors
(81 FR 73478). The nonroad vehicles for which EPA is proposing to list
HFO-1234yf are not regulated under the Phase 1 or Phase 2 HD GHG
standards. Additionally, today's proposal, should EPA adopt it, will
have no direct effect on the HD GHG standards, either for Phase 1 or
Phase 2.

G. On which topics is EPA specifically requesting comment?

    EPA requests comment on all aspects of this proposal, including
proposed decisions to list HFO-1234yf as acceptable, subject to use
conditions, in MVAC systems in certain newly manufactured nonroad
vehicles and small cans, the proposed incorporation of the latest
versions of the relevant SAE standards, and the proposed dates when the
proposed listings would apply if finalized.
    EPA also requests information on development of HFO-1234yf MVAC
systems for other types of HD or nonroad vehicles, particularly on-road
trucks (i.e., Class 4-8 trucks between 14,001 and 33,000 or greater
pounds). EPA will consider these comments in determining whether to
initiate a separate rulemaking to list HFO-1234yf in other
applications.

III. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.

B. Paperwork Reduction Act (PRA)

    This action does not impose any new information collection burden
under the PRA. OMB has previously approved the information collection
activities contained in the existing regulations and has assigned OMB
control number 2060-0226. The approved Information Collection Request
includes five types of respondent reporting and recordkeeping
activities pursuant to SNAP regulations: Submission of a SNAP petition,
filing a TSCA/SNAP Addendum, notification for test marketing activity,
recordkeeping for substitutes acceptable subject to use restrictions,
and recordkeeping for small volume uses. This rule contains no new
requirements for reporting or recordkeeping.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. In
making this determination, EPA concludes that the impact of concern for
this rule is any significant adverse economic impact on small entities
and that the agency is certifying that this rule will not have a
significant economic impact on a substantial number of small entities
if the rule has no net burden on the small entities subject to the
rule. Because the use conditions are consistent with industry consensus
standards, no change in business practice is required to meet the use
conditions, resulting in no adverse impact compared to the absence of
this proposed rule. Thus, the rule would not impose new costs on small
entities if finalized as proposed.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no

enforceable duty on any state, local or tribal governments or the
private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications as specified in
Executive Order 13175. It will not have substantial direct effects on
tribal governments, on the relationship between the Federal government
and Indian tribes, or on the distribution of power and responsibilities
between the Federal government and Indian tribes, as specified in
Executive Order 13175. Thus, Executive Order 13175 does not apply to
this action.

G. Executive Order 13045: Protection of Children From Environmental
Health and Safety Risks

    This action is not subject to Executive Order 13045 because it is