[Federal Register Volume 87, Number 86 (Wednesday, May 4, 2022)]
[Rules and Regulations]
[Pages 26276-26295]
[FR Doc No: 2022-08923]

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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: Final rule.

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SUMMARY: Pursuant to the EPA's Significant New Alternatives Policy
program, this action lists 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 adopting 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
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 requiring 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 adding a reference to the Agency's
regulations under the Toxic Substances Control Act for 2,3,3,3-
tetrafluoroprop-1-ene for the listings in nonroad vehicles and previous
listings for certain onroad vehicles.

DATES: This final rule is effective on June 3, 2022. The incorporation
by reference of certain publications listed in the rule is approved by
the Director of the Federal Register as of June 3, 2022.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-HQ-OAR-2021-0347. All documents in the docket are listed on the
www.regulations.gov website. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available electronically through www.regulations.gov.

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 finalizing in this action?
    A. Listing of HFO-1234yf as Acceptable, Subject to Use
Conditions, for MVAC Systems in New 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 use conditions?
    B. Modifications to Use Conditions for MVAC Systems in Other
Vehicle Types
    C. 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 use condition?
    D. Incorporation by Reference of SAE Standards
    E. What is the relationship between this SNAP rule and other
federal rules?
    F. Response to Comments
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
    K. Congressional Review Act (CRA)
IV. References

I. General Information

A. Executive Summary and Background

    As proposed, EPA is listing 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, under
the Significant New Alternatives Policy (SNAP) program, as of 30 days
after publication of this final rule, for motor vehicle air
conditioning (MVAC) systems \1\ in the following types

of newly manufactured (hereafter ``new'') \2\ nonroad vehicles,\3\
including some vehicles that are also considered heavy-duty (HD) \4\
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 pickups, 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\ This is intended to mean a completely new refrigeration
circuit containing a new compressor, evaporator, condenser, and
refrigerant tubing.
    \3\ 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.
    \4\ 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 received four comments on the proposed rule from refrigerant
suppliers and equipment manufacturers, and all commenters strongly
supported finalizing the rule as proposed. The comment summaries and
EPA's responses to the comments are below in section II.F.
    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 pickup trucks, and complete HD vans (81 FR 86778; December 1, 2016).
The use conditions for those prior listings, which are intended to
mitigate flammability and toxicity risks, require that 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). In this action, EPA is requiring the same
use conditions, with certain updates discussed below, for MVAC systems
designed to use HFO-1234yf in certain new nonroad vehicles. EPA is
listing HFO-1234yf as acceptable, subject to use conditions, after its
evaluation of human health and environmental information on various
substitutes submitted to the SNAP program. In listing HFO-1234yf as
acceptable, subject to use conditions, this action provides additional
flexibility for industry stakeholders by expanding the list of
acceptable substitutes for certain types of nonroad vehicles.
    EPA is also adopting 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 is
also modifying the use conditions for the previous listings of HFO-
1234yf in certain onroad 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 including a use condition, which requires
unique servicing fittings, to provide for servicing MVAC systems in the
nonroad vehicles addressed in this action, including use of small
refrigerant cans (two pounds or less). For the previous listings of
HFO-1234yf in certain onroad vehicles, EPA is revising the use
conditions to require unique servicing fittings for use with small cans
(two pounds or less).
    Finally, EPA is including 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 in certain onroad vehicles. 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 (OEM).
    The Agency is not modifying regulations promulgated under section
608 of the Clean Air Act (CAA). 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 CAA
section 608, 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 40 CFR 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 40
CFR 82.154(c)(2). This action does not modify the provisions under 40
CFR 82.154, including the restriction on the sale of substitute
refrigerants and requirements for self-sealing valves.

B. SNAP Program Background

    The SNAP program implements CAA section 612. 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.\5\ The producer must

also provide the Agency with the producer's unpublished health and
safety studies on such substitutes.
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    \5\ EPA's SNAP regulations at 40 CFR 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 are 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 action, 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 pickup 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.'' \6\ The
court's decision on the 2016 Rule did not vacate the listing of HFO-
1234yf for certain types of vehicles, and this final rule is not EPA's
response to the court's decision on the 2016 Rule.
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    \6\ 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 action 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. 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.

D. 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--Air Changes Per Hour
AEM--Association of Equipment Manufacturers
ANSI--American National Standards Institute
ASHRAE--American Society of Heating, Refrigerating and Air-
Conditioning Engineers
ASTM--American Society for Testing and Materials
ATEL--Acute Toxicity Exposure Limit
CAA--Clean Air Act
CAS Reg. No.--Chemical Abstracts Service Registry Identification
Number
CBI--Confidential Business Information
CFC--Chlorofluorocarbon
CFD--Computational Fluid Dynamics
CFR--Code of Federal Regulations
CGA--Compressed Gas Association
CO2--Carbon Dioxide
CRP--Cooperative Research Project
DIY--Do-It-Yourself
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--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
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
USGCRP--U.S. Global Change Research Program
VOC--Volatile Organic Compounds
WEEL--Workplace Environmental Exposure Limit

II. What is EPA finalizing in this action?

A. Listing of HFO-1234yf as Acceptable, Subject to use Conditions, for
MVAC Systems in Certain new Nonroad Vehicles

    As proposed, (86 FR at 68968; December 6, 2021), EPA is listing
HFO-1234yf as acceptable, subject to use conditions, for MVAC systems
in several types of new 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 listing HFO-1234yf as acceptable, subject to use conditions, in
the five nonroad vehicle types. The use conditions require that MVAC
systems designed to use HFO-1234yf meet the requirements of SAE J639,
SAE J1739, and SAE J2844 to help ensure that use of HFO-1234yf does not
have a significantly greater overall impact on human health and the
environment than other alternatives for use in those vehicles. EPA is
updating the existing use conditions that are currently required for
the use of HFO-1234yf in MVAC systems in new LD vehicles, MDPVs, HD
pickup trucks, and complete HD vans and applying them to all the MVAC
systems addressed in this action. The use conditions are detailed below
in section II.A.4, ``What are the use conditions?''
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 pickups,
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).\7\ The vehicle types addressed in this action include
certain types of new nonroad vehicles, specifically:
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    \7\ 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;
8 9
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    \8\ Wagner, 2021. May 24, 2021, email from John Wagner of the
Association of Equipment Manufacturers to EPA. Available in the
docket for this rulemaking.
    \9\ 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;
\10\
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    \10\ 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; \11\
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    \11\ Ibid.
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     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; \12\ and
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    \12\ Ibid.
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     Commercial utility vehicles that are primarily used for
ranching, farming, hunting/fishing, construction, landscaping, property
maintenance, railroad maintenance, forestry, and mining.\13\
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    \13\ Ibid.
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    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.\14\ 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.15 16
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.\17\ 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.
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    \14\ 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.
    \15\ 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.
    \16\ Wagner, 2021. May 24, 2021, email from John Wagner of the
Association of Equipment Manufacturers to EPA. Available in the
docket for this rulemaking.
    \17\ 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 ANSI/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)
\18\ . 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 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.
---------------------------------------------------------------------------

    \18\ ASHRAE, 2019. ANSI/ASHRAE Standard 34-2019: Designation and
Safety Classification of Refrigerants.
[GRAPHIC] [TIFF OMITTED] TR04MY22.001

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. In the proposed rule (86 FR 68962;
December 6, 2021), EPA provided information on the environmental and
health properties of HFO-1234yf and other substitutes in these MVAC
applications and described the Agency's 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 rulemaking (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 rulemaking.19 20 21 22 23
---------------------------------------------------------------------------

    \19\ ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Agricultural Tractors Greater than
40 Horsepower) (New Equipment).
    \20\ ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Self-Propelled Agricultural
Machinery) (New Equipment).
    \21\ ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Compact Equipment) (New Equipment).
    \22\ ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining
Equipment) (New Equipment).
    \23\ 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 new nonroad vehicles, EPA considered the Agency's
analyses 24 25 26 27 28 29 30 31 32 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.33 34 35 36 37 These risk assessments are
available in the docket for this rulemaking. 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 action. In addition, EPA considered risk assessments
38 39 40 41 42 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.
---------------------------------------------------------------------------

    \24\ EPA, 2005. Risk Analysis for Alternative Refrigerant in
Motor Vehicle Air Conditioning.
    \25\ ICF, 2008a. Air Conditioning Refrigerant Charge Size to
Passenger Compartment Volume Ratio Analysis.
    \26\ ICF, 2008b. Revised Characterization of U.S. Hybrid and
Small Car Sales (Historical and Predicted) and Hybrid Vehicle
Accidents.
    \27\ 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.
    \28\ ICF, 2009b. Risk Screen on Substitutes for CFC-12 in Motor
Vehicle Air Conditioning: Substitute: HFO-1234yf.
    \29\ ICF, 2010a. Summary of HFO-1234yf Emissions Assumptions.
    \30\ ICF, 2010b. Summary of Updates to the Vintaging Model that
Impacted HFO-1234yf Emissions Estimates.
    \31\ 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.
    \32\ ICF, 2010d. Sensitivity Analysis CMAQ results on projected
maximum TFA rainwater concentrations and maximum 8-hr ozone
concentrations.
    \33\ CRP, 2008. Risk Assessment for Alternative Refrigerants
HFO-1234yf Phase II. Prepared for SAE International Cooperative
Research Program 1234 by Gradient Corporation.
    \34\ 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.
    \35\ DuPont and Honeywell. Guidelines for Use and Handling of
HFO-1234yf (v8.0).
    \36\ Exponent. 2008. HFO-1234yf Refrigerant Concentration and
Ignition Tests in Full-Scale Vehicle Passenger Cabin and Engine
Compartment.
    \37\ CRP, 2013.SAE International Cooperative Research Project
CRP1234-4 on R-1234yf Safety, Finishes Work and Presents
Conclusions. Available online at: http://www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2146.

    \38\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \39\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage
Harvesters, Sprayers, and Windrowers.
    \40\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders)
    \41\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction,
Forestry and Mining Equipment.
    \42\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commericial
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, 43 44 which is similar to or lower than the GWP of
other alternatives for the nonroad vehicles addressed in this final
rule. 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 \45\ and CO2,\46\ have GWPs of 124 and 1, respectively.
---------------------------------------------------------------------------

    \43\ 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: http://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
    \44\ 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: http://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
    \45\ 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).
    \46\ 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
this action 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''),\47\ EPA listed the use of certain
refrigerant blends, including the ones mentioned above, as unacceptable
in new LD vehicles starting in MY 2017. EPA did not propose and is not
finalizing a change of status for use of these refrigerant blends in
MVACs in nonroad vehicles. Although EPA is not aware of the use of
these refrigerant blends, they remain acceptable, subject to use
conditions, for the nonroad vehicles addressed in this action. 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 new nonroad vehicles.\48\
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.
---------------------------------------------------------------------------

    \47\ 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.
    \48\ 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           Final decision
----------------------------------------------------------------------------------------------------------------
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 IKON       933-3,337         0-0.098  Yes \2\..............  No change.
 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, and 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 EPA's regulatory definition of VOC (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.\49\ For information
on recent analyses and research that has been conducted on TFA,
including EPA's 2011 analysis, 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), see section II.A.3.a of
the proposed rule (86 FR at 68968; December 6, 2021). Taking into
consideration the 2011 analysis and the research that has been
conducted since, as discussed in section II.A.3.a in the proposed rule,
EPA concludes that the use of HFO-1234yf in the nonroad vehicles
addressed in this action does not pose a significant risk to the
environment from atmospheric decomposition to TFA.
---------------------------------------------------------------------------

    \49\ Other fluorinated compounds also decompose into TFA,
including HFC-134a.
---------------------------------------------------------------------------

    Therefore, based on the consideration of all of these environmental
impacts, EPA concludes that HFO-1234yf does not pose significantly
greater risk to the environment than the other alternatives for use in
new 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 to 12.3 percent by
volume (62,000 ppm to 123,000 ppm).\50\ 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.\51\
---------------------------------------------------------------------------

    \50\ Chemours, 2019. HFO-1234yf for Use as a Refrigerant.
Significant New Alternatives Policy Program Submission to the U.S.
Environmental Protection Agency.
    \51\ 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 of the vehicle or 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.\52\ 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.
---------------------------------------------------------------------------

    \52\ 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 by 2,100 ppm at the typical charge size (i.e., 1.3
kilograms) and exceeding both the LFL (by 95,900 ppm) and the UFL (by
34,900 ppm) at the maximum charge size (i.e., 3.2 kilograms), 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, 53 54 55 56 57 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.
---------------------------------------------------------------------------

    \53\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \54\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage
Harvesters, Sprayers, and Windrowers.
    \55\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders).
    \56\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction,
Forestry, and Mining Equipment.
    \57\ 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)
58 59 60 61 62 63 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.
---------------------------------------------------------------------------

    \58\ AEM, 2019. Risk Assessment for HFO-1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
    \59\ AEM, 2020a. Risk Assessment for HFO-1234yf in Self-
Propelled Agricultural Machinery including Combines, Forage
Harvesters, Sprayers, and Windrowers.
    \60\ AEM, 2020b. Risk Assessment for HFO-1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders).
    \61\ AEM, 2020c. Risk Assessment for HFO-1234yf in Construction,
Forestry, and Mining Equipment.
    \62\ AEM, 2020d. Risk Assessment for HFO-1234yf in Commercial
Utility Vehicles.
    \63\ 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
considers 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 new 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 concludes that the
use of HFO-1234yf in the new nonroad vehicles addressed in this action
does not pose significantly greater flammability risk than the other
alternatives when used in accordance with the 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.\64\ 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 \65\ 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
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.
---------------------------------------------------------------------------

    \64\ SAE, 2019. Standard J2772: Measurement of Passenger
Compartment Refrigerant Concentrations Under System Refrigerant
Leakage Conditions. SAE International.
    \65\ Twelve percent oxygen in air (i.e., 120,000 ppm) is the No-
Observed-Adverse-Effect-Level (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 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.\66 67 68 69 70\ 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.\71\
---------------------------------------------------------------------------

    \66\ ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Agricultural Tractors Greater than
40 Horsepower) (New Equipment).
    \67\ ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Self-Propelled Agricultural
Machinery) (New Equipment).
    \68\ ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Compact Equipment) (New Equipment).
    \69\ ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining
Equipment) (New Equipment).
    \70\ ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Commercial Utility Vehicles) (New
Equipment).
    \71\ Ibid.
---------------------------------------------------------------------------

    Servicing of the vehicles is expected to take place in high-bays
and/or outside (e.g., out in the field or other outdoor site) \72\
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.
---------------------------------------------------------------------------

    \72\ Chemours, 2019. HFO-1234yf for Use as a Refrigerant.
Significant New Alternatives Policy Program Submission to the U.S.
Environmental Protection Agency.
---------------------------------------------------------------------------

    EPA also determined that occupational exposure during disposal of
all the vehicles, except for construction, forestry, and mining
equipment, at the typical and maximum charge sizes is not likely to
exceed the long-term (8-hour) WEEL for HFO-1234yf (i.e., 500 ppm).
Under the disposal release scenarios for construction, forestry, and
mining equipment, 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 by 10 ppm. 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 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 new nonroad
vehicles addressed in this action does not pose greater toxicity risk
to workers than the other alternatives when used in accordance with the
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 new nonroad vehicles addressed
in this action. The general population is defined as non-personnel who
are subject to exposure of the substitute near industrial facilities,
including manufacturing or equipment production factories, equipment
operating locations, or recycling centers, rather than personnel at
end-use. EPA concludes that the use of HFO-1234yf in the new nonroad
vehicles addressed in this action does not pose significantly greater
toxicity risk than the other alternatives when used in accordance with
the 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 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 new
vehicles.
    EPA is listing HFO-1234yf as acceptable, subject to use conditions,
in MVAC systems in certain new 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 updating the existing use
conditions that are currently required for the use of HFO-1234yf in
MVAC systems in new LD passenger cars and trucks, MDPVs, HD pickup
trucks, and complete HD vans and then applying them to all the MVAC
systems addressed in this action. 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 use condition requires that HFO-1234yf may be used only
in new MVAC systems 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, under
this use condition, HFO-1234yf may be used only in new MVACs that have
been properly designed for its use.
    The second use condition requires that MVAC systems designed to use
HFO-1234yf in new 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.
    HFO-1234yf is mildly flammable (A2L classification) and, like other
fluorinated refrigerants, can decompose to form the toxic compound
hydrogen fluoride (HF) when exposed to flame or to sufficient heat.
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 HF generation and refrigerant ignition (March 29, 2011;
76 FR 17488) for the nonroad vehicles addressed in this action. 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 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. 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 new vehicles, EPA is modifying the use conditions to
replace the reference to older versions of SAE J639, SAE J1739, and SAE
J2844.
    First, EPA is replacing 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 replacing 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 replacing 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. Servicing Fittings for Small Cans of HFO-1234yf

    EPA is including a use condition for HFO-1234yf to provide for
servicing air conditioning systems. The 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 pickup trucks, and complete HD vans). The use
condition is discussed below in section II.C.3, ``What is the 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 rulemaking
(EPA-HQ-OAR-2021-0347) at https://www.regulations.gov. As explained in
the proposed rule (86 FR 68962; December 6, 2021) and 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 rulemaking.\73\
---------------------------------------------------------------------------

    \73\ 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
use condition, small refrigerant cans must be equipped with a Standard
Compressed Gas Association (CGA) 166 left-hand thread outlet connection
valve in accordance with SAE Standard J2844.\74\ The hose connected to
the vehicle must also use the low side service port per SAE J639.
---------------------------------------------------------------------------

    \74\ 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 in this action, the sale of such small refrigerant cans
would be subject to the regulatory requirements under CAA section 608,
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) provides 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 modifying 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 40 CFR
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?
    As proposed, EPA is listing 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 revising 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,75 76 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 regulatory definition of VOC (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.
---------------------------------------------------------------------------

    \75\ 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: http://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
    \76\ 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: http://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 \77\ compared with the LFL of 62,000 ppm for HFO-1234yf.\78\
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),\79\ respectively, over the course of 15 minutes, which
represents the approximate amount of time required to charge the MVAC
system.\80\ 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). \81\ 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.\82\ 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.\83\
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.
---------------------------------------------------------------------------

    \77\ 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).
    \78\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \79\ 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.
    \80\ 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.
    \81\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO-1234yf.
    \82\ Ibid.
    \83\ 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[hyphen]1234yf during MVAC servicing are not expected to accumulate
under the vehicle hood in concentrations above the LFL for
HFO[hyphen]1234yf.
    EPA concludes that the currently available assessments on the use
of HFO[hyphen]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[hyphen]1234yf.
Therefore, the use of HFO[hyphen]1234yf in small cans does not pose
significantly greater flammability risk than the other alternatives
when used in accordance with the 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[hyphen]1234yf, see the section II.A.3.c above. In evaluating
potential asphyxiation and toxicity impacts of HFO[hyphen]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[hyphen]1234yf for
plausible worst-case scenarios. According to the results of EPA's
asphyxiation assessment, the use of HFO[hyphen]1234yf in small
refrigerant cans does not present a significant risk of
asphyxiation.\84\ Conditions resulting in oxygen levels under 12
percent \85\ would only occur with charge sizes that are significantly
larger than the maximum charge size for

small refrigerant cans or room sizes that are unlikely for the
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.\86\
---------------------------------------------------------------------------

    \84\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO[hyphen]1234yf.
    \85\ Twelve percent oxygen in air (i.e., 120,000 ppm) is the
NOAEL for hypoxia (ICF 1997).
    \86\ 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[hyphen]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
ranging from 3,100 ppm to 11,080 ppm are all lower than the RCL (i.e.,
16,000 ppm) and ATEL (i.e., 100,000 ppm) for HFO[hyphen]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.\87\ The various scenarios investigated included
releases of 170 grams to 680 grams of refrigerant from both an inverted
and upright can.\88\ 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[hyphen]1234yf.
---------------------------------------------------------------------------

    \87\ 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.
    \88\ 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[hyphen]1234yf.\89\ EPA determined that if proper
handling and disposal guidelines are followed in accordance with good
industrial hygiene practices and the SDS for HFO[hyphen]1234yf, there
is no significant risk to workers during the disposal of
HFO[hyphen]1234yf from MVAC systems or HFO[hyphen]1234yf small
refrigerant cans.
---------------------------------------------------------------------------

    \89\ ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO[hyphen]1234yf.
---------------------------------------------------------------------------

    For potential toxicity risks of HFO[hyphen]1234yf to the general
population, EPA's analysis indicated that HFO[hyphen]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 EPA's analysis, workplace and general population
exposure to HFO[hyphen]1234yf in small cans when used according to the
use condition is not expected to exceed relevant exposure limits.
Therefore, EPA concludes that the use of HFO[hyphen]1234yf in small
cans does not pose significantly greater toxicity risks than other
acceptable refrigerants when used in accordance with the 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 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,
to 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).
    In this rule, EPA is establishing a use condition requiring that
for connections with small cans (two pounds or less) of
HFO[hyphen]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[hyphen]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. Incorporation by Reference

    As proposed, EPA is adopting 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 is also modifying the use conditions for the previous
listings of HFO[hyphen]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[hyphen]1234yf
(HFO[hyphen]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. What is the relationship between this SNAP rule and other federal
rules?

1. Significant New Use Rule for HFO[hyphen]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[hyphen]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[hyphen]1234yf
before we would be able to issue a revised rule that allows for
consumer filling, servicing, or maintenance of MVAC systems with
HFO[hyphen]1234yf'' \90\ and that use of small cans would need to be
consistent with EPA's final SNUR for HFO[hyphen]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[hyphen]1234yf other than in
passenger cars and vehicles in which the original charging of MVAC
systems with HFO[hyphen]1234yf was done by the OEM and use of
HFO[hyphen]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[hyphen]1234yf was done by
the OEM, among other things. Manufacturers of small cans of
HFO[hyphen]1234yf have also submitted a unique fitting specifically for
use with small can taps and small refrigerant cans for EPA's review.
Today's listing of HFO[hyphen]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[hyphen]1234yf, commercial use
or use in consumer products to recharge MVAC systems with
HFO[hyphen]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[hyphen]1234yf.
---------------------------------------------------------------------------

    \90\ 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 including a reference to the June 2015 SNUR (80 FR 37166) in
Appendix B subpart G of part 82, under the `Comments' column, for the
listings of HFO[hyphen]1234yf for the nonroad vehicles addressed in
this action. EPA is also modifying the existing listings of
HFO[hyphen]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
    Today's action will not have any impact on EPA's regulations under
sections 608 or 609 of the Clean Air Act. Among other things, CAA
section 608 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[hyphen]1234yf is not exempt from the venting prohibition
in any application; therefore, knowing release of HFO[hyphen]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
action does not 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 revising regulations promulgated
under CAA section 608 in this action.
    CAA section 609 establishes standards and requirements regarding
the servicing or repair of MVAC systems. 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 \91\ 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[hyphen]1234yf.
---------------------------------------------------------------------------

    \91\ Service for consideration means receiving something of
worth or value to perform service, whether in money, credit, goods,
or services.
---------------------------------------------------------------------------

3. Will this action 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 (81 FR 73478). The
nonroad vehicles for which EPA is listing HFO[hyphen]1234yf are not
regulated under the Phase 1 or Phase 2 HD GHG standards. Additionally,
today's action does not have a direct impact on the HD GHG standards,
either for Phase 1 or Phase 2.

F. Response to Comments

    EPA received four comments on the proposed rule from refrigerant
suppliers and equipment manufacturers. All commenters strongly
supported finalizing the rule as proposed, particularly the proposal to
list

HFO[hyphen]1234yf as acceptable, subject to use conditions, in certain
nonroad vehicle air conditioning systems. One commenter noted that the
similarities between the proposed use conditions for the nonroad
vehicles and those required for certain onroad vehicles ``will prevent
confusion and help harmonize the industry as [HFO-]1234yf usage expands
to nonroad vehicles.'' Another commenter stated that the proposed
listings of HFO[hyphen]1234yf in the nonroad vehicles would ``provide
manufacturers with regulatory certainty so they can design and
manufacture new equipment using HFO[hyphen]1234yf and transition to
lower GWP solutions.'' EPA acknowledges the support for the proposed
rule and is finalizing the listings and changes as proposed.
    In the proposed rule, EPA requested information on the development
of HFO[hyphen]1234yf MVAC systems for types of nonroad or onroad HD
vehicles not covered by this rulemaking, particularly onroad trucks
(i.e., Class 4-8 trucks between 14,001 and 33,000 or greater pounds).
Two commenters supported the expanded use of HFO[hyphen]1234yf in HD
onroad trucks greater than 14,000 pounds. One commenter estimated that
manufacturers would need at least five to ten years to fully transition
from HFC-134a to HFO[hyphen]1234yf and noted a few potential technical
challenges. However, the commenter stated that ``medium- and heavy-duty
truck manufacturers are addressing the challenge with urgency,'' and
encouraged EPA to initiate rulemaking to list HFO[hyphen]1234yf for HD
onroad trucks greater than 14,000 pounds. EPA acknowledges the
commenters' support for the listing of HFO[hyphen]1234yf in additional
onroad vehicles and will consider these comments as it evaluates
possible future actions.

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 final rule. Thus, the rule would not impose new costs on small
entities.

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
not economically significant as defined in Executive Order 12866, and
because EPA does not believe the environmental health or safety risks
addressed by this action present a disproportionate risk to children.
This action's health and risk assessments are contained in the
comparisons of toxicity for HFO[hyphen]1234yf, as well as in the risk
screens for HFO[hyphen]1234yf. The risk screens are in the docket for
this rulemaking.

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

    This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    This action involves technical standards. EPA is adopting 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 is also modifying the
use conditions for the previous listings of HFO[hyphen]1234yf in MVAC
systems to incorporate by reference the most current versions of the
three standards. The use conditions ensure that HFO[hyphen]1234yf does
not present significantly greater risk to human health or the
environment than other alternatives available for use in MVAC.
Specifically, the three standards are:
    1. SAE J639: Safety and Design Standards for Motor Vehicle
Refrigerant Vapor Compression Systems (revised November 2020). This
document establishes safety standards for HFO[hyphen]1234yf MVAC
systems 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
standard is available at https://www.sae.org/standards/content/j639_201112/.
    2. SAE J1739: Potential Failure Mode and Effects Analysis (FMEA)
Including Design FMEA, Supplemental FMEA-MSR, and Process FMEA (revised
January 2021). This standard describes potential FMEA in design and
potential

FMEA in manufacturing and assembly processes. It requires manufacturers
of MVAC systems and vehicles to conduct a FMEA and assists users in the
identification and mitigation of risk by providing appropriate terms,
requirements, ranking charts, and worksheets. This standard is
available at https://www.sae.org/standards/content/j1739_202101/.
    3. SAE J2844: R[hyphen]1234yf (HFO[hyphen]1234yf) New Refrigerant
Purity and Container Requirements for Use in Mobile Air-Conditioning
Systems (revised January 2013). This standard sets purity standards and
describes container requirements, including fittings for refrigerant
cylinders. For connections with refrigerant containers for use in
professional servicing, use fittings must be consistent with SAE J2844
(revised January 2013). For connections with small refrigerant cans for
consumer or professional use, use fittings must have a diameter of 0.5
inches, a thread pitch of 16 thread per inch, and a left thread
direction, consistent with SAE J2844. This standard is available at
https://www.sae.org/standards/content/j2844_201301/.
    These standards may be purchased by mail at: SAE Customer Service,
400 Commonwealth Drive, Warrendale, PA 15096-0001; by telephone: 1-877-
606-7323 in the United States or<PHONE_NUMBER> outside the United States
or in Canada. The cost of SAE J639, SAE J1739, and SAE J2844 is $85
each for an electronic or hardcopy. 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, and servicing the systems. Therefore, EPA concludes that
the use of SAE J639, SAE J1739, and SAE J2844 are reasonably available.

J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    A regulatory action may involve potential environmental justice
concerns if it could: (1) Create new disproportionate impacts on people
of color, communities of low-income, and/or indigenous peoples; (2)
exacerbate existing disproportionate impacts on people of color,
communities of low-income, and/or indigenous peoples; or (3) present
opportunities to address existing disproportionate impacts on people of
color, communities of low-income, and/or indigenous peoples through the
action under development.
    EPA believes that this action does not have disproportionately high
and adverse human health or environmental effects on people of color,
communities of low-income and/or indigenous peoples, as specified in
Executive Order 12898 (59 FR 7629, February 16, 1994). The listings for
HFO[hyphen]1234yf in the vehicle types addressed in this action would
provide additional lower-GWP alternatives for the MVAC end-use. By
providing a lower-GWP alternative for this end-use, this final rule is
also anticipated to reduce the use and eventual emissions of potent
GHGs in this end-use, which could help to reduce the effects of climate
change, including the public health and welfare effects on people of
color, communities of low-income and/or indigenous peoples. This
action's health and environmental risk assessments are contained in the
comparison of health and environmental risks for HFO[hyphen]1234yf, as
well as in the risk screens that are available in the docket for this
rulemaking. EPA's analysis indicates that other environmental impacts
and human health impacts of HFO[hyphen]1234yf are comparable to or less
than those of other substitutes that are listed as acceptable for the
same end-use. Based on these considerations, EPA expects that the
effects on people of color, communities of low-income and/or indigenous
peoples would not be disproportionately high and adverse.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and EPA will submit a rule
report to each House of the Congress and to the Comptroller General of
the United States. This action is not a ``major rule'' as defined by 5
U.S.C. 804(2).

IV. References

    Unless specified otherwise, all documents are available
electronically through the Federal Docket Management System, Docket
number EPA-HQ-OAR-2021-0347.
AEM, 2019. Risk Assessment for HFO[hyphen]1234yf in Agricultural
Tractors >= 40 HP including 2WD, MFD, 4WD and Track Type Equipment.
AEM, 2020a. Risk Assessment for HFO[hyphen]1234yf in Self-Propelled
Agricultural Machinery including Combines, Forage Harvesters,
Sprayers, and Windrowers.
AEM, 2020b. Risk Assessment for HFO[hyphen]1234yf in Compact
Equipment (Examples include Tractors <40HP, Turf Equipment, Skid
Steer, Mini-Excavators and Track Loaders)
AEM, 2020c. Risk Assessment for HFO[hyphen]1234yf in Construction,
Forestry, and Mining Equipment.
AEM, 2020d. Risk Assessment for HFO[hyphen]1234yf in Commercial
Utility Vehicles.
AEM, 2020e. CFD Leak Modeling-Supplemental Information to Compliment
AEM Machine Form RAs.
AEM, 2021. Appendix A: Machine Forms as Classified by AEM
Membership.
ASHRAE, 2019. ANSI/ASHRAE Standard 34-2019: Designation and Safety
Classification of Refrigerants.
Chemours, 2019. HFO[hyphen]1234yf for Use as a Refrigerant.
Significant New Alternatives Policy Program Submission to the U.S.
Environmental Protection Agency.
CRP, 2008. Risk Assessment for Alternative Refrigerants
HFO[hyphen]1234yf Phase II. Prepared for SAE International
Cooperative Research Program 1234 by Gradient Corporation.
CRP, 2009. Risk Assessment for Alternative Refrigerants
HFO[hyphen]1234yf and R[hyphen]744 (CO2) Phase III. Prepared for SAE
International Cooperative Research Program 1234 by Gradient
Corporation.
CRP, 2013. SAE International Cooperative Research Project
CRP1234[hyphen]4 on R[hyphen]1234yf Safety, Finishes Work and
Presents Conclusions. Available online at: http://www.sae.org/servlets/pressRoom?OBJECT_TYPE=PressReleases&PAGE=showRelease&RELEASE_ID=2146.

DuPont and Honeywell, 2008. Guidelines for Use and Handling of
HFO[hyphen]1234yf (v8.0).
EPA, 2005. Risk Analysis for Alternative Refrigerant in Motor
Vehicle Air Conditioning.
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, 2016. Protection of Stratospheric Ozone: Update to the
Refrigerant Management Requirements Under the Clean Air Act.
November 18, 2016. 81 FR 82272. Available online at: https://www.regulations.gov/document?D=EPA-HQ-OAR-2015-0453-0125.
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.
Exponent, 2008. HFO[hyphen]1234yf Refrigerant Concentration and
Ignition Tests in Full-Scale Vehicle Passenger Cabin and Engine
Compartment.
ICF, 1997. Physiological Effects of Alternative Fire Protection
Agents--Hypoxic Atmospheres Conference. Stephanie Skaggs prepared
the proceedings of the conference held May 22, 1997 in New London,
CT.
ICF, 2008a. Air Conditioning Refrigerant Charge Size to Passenger
Compartment Volume Ratio Analysis.
ICF, 2008b. Revised Characterization of U.S. Hybrid and Small Car
Sales (Historical and Predicted) and Hybrid Vehicle Accidents.
ICF, 2009a. Revised Final Draft Assessment of the Potential Impacts
of HFO[hyphen]1234yf and the Associated Production of TFA on Aquatic
Communities and Local Air Quality.
ICF, 2009b. Risk Screen on Substitutes for CFC-12 in Motor Vehicle
Air Conditioning: Substitute: HFO[hyphen]1234yf.
ICF, 2010a. Summary of HFO[hyphen]1234yf Emissions Assumptions.

ICF, 2010b. Summary of Updates to the Vintaging Model that Impacted
HFO[hyphen]1234yf Emissions Estimates.
ICF, 2010c. Revised Assessment of the Potential Impacts of
HFO[hyphen]1234yf and the Associated Production of TFA on Aquatic
Communities, Soil and Plants, and Local Air Quality.
ICF, 2010d. Sensitivity Analysis CMAQ results on projected maximum
TFA rainwater concentrations and maximum 8-hr ozone concentrations.
ICF, 2016. Technical Support Document for Acceptability Listing of
HFO[hyphen]1234yf for Motor Vehicle Air Conditioning in Limited
Heavy-Duty Applications.
ICF, 2021a. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles Agricultural Tractors Greater than 40
Horsepower) (New Equipment).
ICF, 2021b. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles Self-Propelled Agricultural
Machinery) (New Equipment).
ICF, 2021c. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles Compact Equipment) (New Equipment).
ICF, 2021d. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles--Construction, Forestry, and Mining
Equipment) (New Equipment).
ICF, 2021e. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Nonroad Vehicles Commercial Utility Vehicles) (New
Equipment).
ICF, 2021f. Risk Screen on Substitutes in Motor Vehicle Air
Conditioning (Small Cans). Substitute: HFO[hyphen]1234yf.
Kataoka, O., Yoshizawa, M., & Hirakawa, T., 2000. Allowable Charge
Limit of Flammable Refrigerants and Ventilation Requirements. Daikin
Industries. International Refrigeration and Air Conditioning
Conference. Paper 506. Available online at: http://docs.lib.purdue.edu/iracc/506.
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:
http://www.cogci.dk/network/OJN_174_CF3CF=CH2.pdf.
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: http://pubs.rsc.org/en/Content/ArticleLanding/2008/CP/b714382f.
Perrin Quarles Associates, Inc., 2007. Disposable Container Heel
Testing Study Report. Prepared for United States Environmental
Protection Agency by Perrin Quarles Associates, Inc. March 21, 2007.
SAE, 2013. Standard J2844: R[hyphen]1234yf (HFO[hyphen]1234yf) New
Refrigerant Purity and Container Requirements for Use in Mobile Air-
Conditioning Systems. (Revised January 2013).
SAE, 2019. Standard J2772: Measurement of Passenger Compartment