Air Quality: Revision to the Regulatory Definition of Volatile Organic Compounds-Exclusion of (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)), 88940-88947 [2024-25971]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 89, Number 218 (Tuesday, November 12, 2024)]
[Proposed Rules]
[Pages 88940-88947]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-25971]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[EPA-HQ-OAR-2023-0295; FRL-10823-01-OAR]
RIN 2060-AW00


Air Quality: Revision to the Regulatory Definition of Volatile 
Organic Compounds--Exclusion of (Z)-1-chloro-2,3,3,3-tetrafluoropropene 
(HCFO-1224yd(Z))

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) is proposing to 
revise the EPA's regulatory definition of volatile organic compounds 
(VOC) under the Clean Air Act (CAA). This action proposes to add (Z)-1-
chloro-2,3,3,3-tetrafluoropropene (also known as HCFO-1224yd(Z); CAS 
number 111512-60-8) to the list of compounds excluded from the 
regulatory definition on the basis that this compound makes a 
negligible contribution to tropospheric ozone (O3) 
formation.

DATES: Comments must be received on or before January 13, 2025.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2023-0295, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/ 
(our preferred method). Follow the online instructions for submitting 
comments.
     Mail: U.S. Environmental Protection Agency, EPA Docket 
Center, Docket No. EPA-HQ-OAR-2023-0295, Office of Air and Radiation 
Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 
20460.
     Hand Delivery or Courier: EPA Docket Center, WJC West 
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. 
The Docket Center's hours of operations are 8:30 a.m.-4:30 p.m., 
Monday-Friday (except Federal Holidays).
    Instructions: All submissions received must include the Docket ID 
No. for this

[[Page 88941]]

rulemaking. Comments received may be posted without change to https://www.regulations.gov/, including any personal information provided. For 
detailed instructions on sending comments and additional information on 
the rulemaking process, see the ``Public Participation'' heading of the 
SUPPLEMENTARY INFORMATION section of this document.

FOR FURTHER INFORMATION CONTACT: Dr. Souad Benromdhane, Office of Air 
Quality Planning and Standards, Health and Environmental Impacts 
Division, Mail Code C539-07, Environmental Protection Agency, P.O. Box 
12055, Research Triangle Park, NC 27711; telephone: (919) 541-4359; 
email address: [email protected].

SUPPLEMENTARY INFORMATION:

Public Participation

    Written comments: Submit your comments, identified by Docket ID No. 
EPA-HQ-OAR-2023-0295, at https://www.regulations.gov (our preferred 
method), or the other methods identified in the ADDRESSES section. Once 
submitted, comments cannot be edited or removed from the docket. The 
EPA may publish any comment received to its public docket. Do not 
submit to EPA's docket at https://www.regulations.gov any information 
you consider to be Confidential Business Information (CBI), Proprietary 
Business Information (PBI), or other information whose disclosure is 
restricted by statute. Multimedia submissions (audio, video, etc.) must 
be accompanied by a written comment. The written comment is considered 
the official comment and should include discussion of all points you 
wish to make. The EPA will generally not consider comments or comment 
contents located outside of the primary submission (i.e., on the web, 
cloud, or other file sharing system). Please visit https://www.epa.gov/dockets/commenting-epa-dockets for additional submission methods; the 
full EPA public comment policy; information about CBI, PBI, or 
multimedia submissions; and general guidance on making effective 
comments.

Table of Contents

I. Does this action apply to me?
II. Background
    A. The EPA's VOC Exemption Policy
    B. Petition To List HCFO-1224yd(Z) as an Exempt Compound
III. The EPA's Assessment of the Petition
    A. Contribution to Tropospheric Ozone Formation
    B. Potential Impacts on Other Environmental Endpoints
    1. Contribution to Stratospheric Ozone Depletion
    2. Toxicity
    3. Contribution to Climate Change
    C. Conclusions
IV. Proposed Action
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 14094: Modernizing Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    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 Concerning Regulations That 
Significantly Affect Energy Supply, Distribution or Use
    I. National Technology Transfer and Advancement Act (NTTAA)
    J. Executie Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations and Executive Order 14096: Revitalizing Our Nation's 
Commitment to Environmental Justice for All
VI. References

I. Does this action apply to me?

    Entities potentially affected by this proposed rule include, but 
are not necessarily limited to, the following: State and local air 
pollution control agencies that adopt and implement regulations to 
control air emissions of VOC; and industries manufacturing and/or using 
HCFO-1224yd(Z) for use in foam blowing, refrigeration, as well as 
applications in solvents and aerosol propellants, and other minor uses. 
Potential entities that may be affected by this action include the 
following:

     Table 1--Potentially Affected Entities by North American Industrial Classification System (NAICS) Code
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               Category                  NAICS code                Description of regulated entities
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Industry.............................          333415  Air-Conditioning and Warm Air Heating Equipment and
                                                        Commercial and Industrial Refrigeration Equipment
                                                        Manufacturing.
Industry.............................          811310  Commercial and industrial machinery and equipment (except
                                                        automotive and electronic) repair and maintenance.
Industry.............................          221116  Geothermal Electric Power Generation.
Industry.............................          221117  Biomass Electric Power Generation.
Industry.............................          221118  Other Electric Power Generation.
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    This table is not intended to be exhaustive but rather provides a 
guide for readers regarding entities that might be affected by this 
deregulatory action. This table lists the types of entities that the 
EPA is now aware of that could potentially be affected to some extent 
by this action. Other types of entities not listed in the table could 
also be affected to some extent. To determine whether your entity is 
directly or indirectly affected by this action, you should consult your 
State or local air pollution control and/or air quality management 
agencies.

II. Background

A. The EPA's VOC Exemption Policy

    Tropospheric O3, commonly known as smog, is formed when 
VOC and nitrogen oxides (NOX) react in the atmosphere in the 
presence of sunlight. Because of the harmful health effects of 
O3, the EPA and State governments limit the amount of VOC 
that can be released into the atmosphere. VOC form O3 
through atmospheric photochemical reactions, and different VOC have 
different levels of reactivity. That is, different VOC do not react to 
form O3 at the same speed or form different amounts of 
O3. Some VOC react more slowly or form less O3; 
therefore, changes in their emissions have limited effects on local or 
regional O3 pollution episodes. It has been the EPA's policy 
since 1971 that certain organic compounds with a negligible level of 
reactivity should be excluded from the regulatory definition of VOC to 
focus VOC control efforts on compounds that significantly affect 
O3 concentrations. The EPA also believes that exempting such 
compounds creates an incentive for industry to use negligibly reactive 
compounds in place of more highly reactive compounds that are regulated 
as VOC. The EPA lists compounds that

[[Page 88942]]

it has determined to be negligibly reactive in its regulations as being 
excluded from the regulatory definition of VOC (40 CFR 51.100(s)).
    The CAA requires the regulation of VOC for various purposes. 
Section 302(s) of the CAA specifies that the EPA has the authority to 
define the meaning of ``VOC'' and, hence, what compounds shall be 
treated as VOC for regulatory purposes. The policy of excluding 
negligibly reactive compounds from the regulatory definition of VOC was 
first laid out in the ``Recommended Policy on Control of Volatile 
Organic Compounds'' (42 FR 35314, July 8, 1977) (``1977 Recommended 
Policy'') and was supplemented subsequently with the ``Interim Guidance 
on Control of Volatile Organic Compounds in Ozone State Implementation 
Plans'' (70 FR 54046, September 13, 2005) (``2005 Interim Guidance''). 
The EPA uses the reactivity of ethane as the threshold for determining 
whether a compound has negligible reactivity. Compounds that are less 
reactive than, or equally reactive to, ethane under certain assumed 
conditions may be deemed negligibly reactive and, therefore, suitable 
for exemption from the regulatory definition of VOC. Compounds that are 
more reactive than ethane continue to be considered VOC for regulatory 
purposes and, therefore, are subject to control requirements. The 
selection of ethane as the threshold compound was based on a series of 
smog chamber experiments that underlay the 1977 Recommended Policy.
    The EPA has used three different metrics to compare the reactivity 
of a specific compound to that of ethane: (i) the rate constant for 
reaction with the hydroxyl radical (OH) (known as kOH); (ii) 
the maximum incremental reactivity (MIR) on a reactivity per unit mass 
basis; and (iii) the MIR expressed on a reactivity per mole basis. 
Differences between these three metrics are discussed below.
    The kOH is the rate constant of the reaction of the 
compound with the OH radical in the air. This reaction is often, but 
not always, the first and rate-limiting step in a series of chemical 
reactions by which a compound breaks down in the air and contributes to 
O3 formation. If this step is slow, the compound will likely 
not form O3 at a very fast rate. The kOH values 
have long been used by the EPA as metrics of photochemical reactivity 
and O3-forming activity, and they were the basis for most of 
the EPA's early exemptions of negligibly reactive compounds from the 
regulatory definition of VOC. The kOH metric is inherently a 
molar-based comparison, i.e., it measures the rate at which molecules 
react.
    The MIR, both by mole and by mass, is a more updated metric of 
photochemical reactivity derived from a computer-based photochemical 
model, and it has been used as a metric of reactivity since 1995. This 
metric considers the complete O3-forming activity of a 
compound over multiple hours and through multiple reaction pathways, 
not merely the first reaction step with OH. Further explanation of the 
MIR metric can be found in Carter (1994).
    The EPA has considered the choice between MIRs with a molar or mass 
basis for the comparison to ethane in past rulemakings and guidance. In 
the 2005 Interim Guidance, the EPA stated that a comparison to ethane's 
MIR on the mass basis strikes the right balance between a threshold 
that is low enough to capture chemicals that significantly affect ozone 
formation and a threshold that is high enough to allow for the 
exemption of some other chemicals that may usefully substitute for more 
reactive compounds. The guidance also stated that EPA will continue to 
compare chemicals to ethane using kOH expressed on a molar 
basis and MIR values expressed on a mass basis during the review of 
suggested chemicals for VOC-exempt status.\1\ The 2005 Interim Guidance 
notes that the EPA will consider a compound to be negligibly reactive 
if it is equally reactive as or less reactive than ethane based on 
either kOH expressed on a molar basis or MIR values 
expressed on a mass basis (70 FR 54046).
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    \1\ Interim Guidance on Control of Volatile Organic Compounds in 
Ozone State Implementation Plans, 2005, US Environmental Protection 
Agency, Document Number 05-18015 (70 FR 54046). And could be found 
at this link: https://www.govinfo.gov/content/pkg/FR-2005-09-13/pdf/05-18015.pdf.
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    The molar comparison of MIR is more consistent with the original 
smog chamber experiments, which compared equal molar concentrations of 
individual VOC, supporting the selection of ethane as the threshold, 
while the mass-based comparison of MIR is consistent with how MIR 
values and other reactivity metrics are applied in reactivity-based 
emission limits. It is, however, important to note that the mass-based 
comparison is less restrictive than the molar-based comparison in that 
more compounds would qualify as negligibly reactive.
    Given the two goals of the exemption policy articulated in the 2005 
Interim Guidance, the EPA believes that ethane continues to be an 
appropriate threshold for defining negligible reactivity. And, to 
encourage the use of environmentally beneficial substitutions, the EPA 
continues to believe that a comparison to ethane on a mass basis 
strikes the right balance between a threshold that is low enough to 
capture compounds that significantly affect O3 
concentrations and a threshold that is high enough to exempt some 
compounds that may usefully substitute for more highly reactive 
compounds.
    The 2005 Interim Guidance also noted that concerns have sometimes 
been raised about the potential impact of a VOC exemption on 
environmental endpoints other than O3 concentrations, 
including fine particle formation, air toxics exposures, stratospheric 
O3 depletion, and climate change. The EPA has recognized, 
however, that there are existing regulatory or non-regulatory programs 
that are specifically designed to address these issues, and the EPA 
continues to believe in general that the impacts of VOC exemptions on 
environmental endpoints other than O3 formation can be 
adequately addressed by these programs. The VOC exemption policy is 
intended to facilitate attainment of the O3 National Ambient 
Air Quality Standards (NAAQS), and VOC exemption decisions will 
continue to be based primarily on consideration of a compound's 
contribution to O3 formation. However, if the EPA determines 
that a particular VOC exemption is likely to result in a significant 
increase in the use of a compound and that the increased use would pose 
a significant risk to human health or the environment that would not be 
addressed adequately by existing programs or policies, then the EPA may 
exercise its judgment accordingly in deciding whether to grant an 
exemption.
    The EPA has provided the foregoing discussion of its VOC exemption 
policies as background for its assessment of the petition to list HCFO-
1224yd(z) as an exempt compound and its proposed action to grant the 
petition. However, the EPA is not reopening the 2005 Interim Guidance 
or other aspects of its VOC exemption policy in this proposed rule and 
is not seeking comment on these issues.

B. Petition To List HCFO-1224yd(Z) as an Exempt Compound

    The AGC Chemicals Americas, Inc. (``AGC'') submitted a petition to 
the EPA on July 29, 2020, requesting that (Z)-1-chloro-2,3,3,3-
tetrafluoropropene (also known as HCFO-1224yd(Z); CAS number 111512-60-
8) be exempted from the regulatory definition of VOC. The petition 
stated that HCFO-1224yd(Z) has low reactivity (i.e., 0.052  
0.011g of O3/g of HCFO-1224yd(Z))

[[Page 88943]]

compared to the MIR of ethane (0.28 g O3/g). The petitioner 
indicated that HCFO-1224yd(Z) may be used in refrigeration which uses a 
turbo-type refrigerator, a binary generator, a heat recovery heat pump, 
etc. As a refrigerant, this compound will not be generally emitted into 
the atmosphere on a continuous basis in significant amounts. 
Refrigerators will be initially charged and then serviced with HCFO-
1224yd(Z) with minimal losses of refrigerant to the atmosphere over 
time, and they will be subject to EPA's regulations related to 
servicing and ``venting.'' HCFO-1224yd(Z) has been approved by EPA 
through its Significant New Alternatives Policy (SNAP) program as an 
acceptable substitute for use in new and retrofitted centrifugal 
chillers, positive displacement chillers and industrial process 
refrigeration.\2\
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    \2\ 84 FR 64765 (Nov. 25, 2019): https://www.federalregister.gov/documents/2019/11/25/2019-25412/protection-of-stratospheric-ozone-determination-35-for-significant-new-alternatives-policy-program.
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    AGC has developed HCFO-1224yd(Z) to support reductions in emissions 
of greenhouse gases (GHGs). The global warming potential (GWP) for 
HCFO-1224yd(Z) is 0.88 for a time horizon of 100 years. HCFO-1224yd(Z) 
is relatively short-lived in the atmosphere, with a lifetime of 
approximately 20 days. HCFO-1224yd(Z)'s ODP is almost zero (0.00023) 
and, leading to an environmental impact that is estimated to be low 
especially when compared to the existing alternatives (Tokuhashi et 
al., 2018). Hence, HCFO-1224yd(Z) can serve as a replacement for 
compounds in several centrifugal and positive displacement chillers 
such as ammonia absorption, carbon dioxide, and HFO-1336mzz(Z) among 
others with GWP ranging between zero and 630. For industrial process 
refrigeration, HCFO-1224yd(Z) has a GWP lower than or comparable to 
that of acceptable existing substitutes for new or retrofit equipment 
with GWP ranging between zero and 14,800.
    Toxicity of HCFO-1224yd(Z) is comparable to or lower than that of 
other available substitutes in the same end uses. The toxicity risks 
are evaluated through the SNAP program but can also be minimized 
through the application of recommended guidance in the Occupational 
Alliance for Risk Science's Workplace Environmental Exposure Level 
(OARS WEEL), the American Society of Heating, Refrigerating and Air-
Conditioning Engineers safety standards 15 (ASHARE 15) and other 
industry standards, as well as the safety data sheet (SDS) and other 
safety precautions related to refrigeration and air conditioning 
industry.
    To support its petition, AGC provided a document on ground-level 
atmospheric ozone formation potential from the reactivity of HCFO-
1224yd(Z) with the hydroxyl OH based on calculations using SARPC-11 
atmospheric chemical mechanism.\3\ AGC's supplemental technical report 
supplied a MIR of HCFO-1224yd(Z) of 0.052  0.011 g 
O3/g HCFO-1224yd(Z) on the mass-based MIR scale. This 
reactivity is significantly lower than that of ethane (0.29  0.07 g O3/g ethane). The report also addressed 
uncertainties around the MIR value calculated and stipulated that the 
relative impact on ozone formation will be small when compared to 
variability in atmospheric conditions. The report raised a warning 
around the chemical mechanism used to predict ozone formation potential 
to caution about the need to test whether the predicted value can be 
observed in an environmental chamber experiment. The petition did not 
include a value for the rate constant kOH for the gas-phase 
reaction with OH radicals.
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    \3\ Carter, W. P. L. 2020. Estimation of the ground-level 
atmospheric ozone formation potential of isomers of 1-chloro-
2,3,3,3-tetrafluoro-1-propene, HFCO-1224YD(Z), Report to AGC 
Chemicals Americas Company, Exton, PA, USA.
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    To address the potential for stratospheric O3 impacts, 
the petitioner specified that, because the atmospheric lifetime of 
HCFO-1224yd(Z) due to loss by OH reaction was estimated to be 
relatively short, even though HCFO-1224yd(Z) contains chlorine, it is 
not expected to contribute to the depletion of the stratospheric 
O3 layer more than other alternatives listed acceptable by 
EPA's SNAP program (USEPA, 2019).

III. The EPA's Assessment of the Petition

    The EPA is proposing to respond to the petition to revise the EPA's 
regulatory definition of VOC for exemption of HCFO-1224yd(Z). This 
action is based on consideration of the compound's low contribution to 
tropospheric O3 and the low likelihood of risk to human 
health or the environment, including stratospheric O3 
depletion, toxicity, and climate change. Additional information on 
these topics is provided in the following sections.

A. Contribution to Tropospheric Ozone Formation

    The rate constant kOH for the gas-phase reaction with OH 
radicals is measured to be (5.84  0.030) 10-13 
cm\3\/molecule-sec at ~298 degrees Kelvin (K) (Tokuhashi et al., 2018). 
This kOH is more than twice the kOH of ethane 
(2.4 x 10-13 cm\3\/molecule-sec at ~298 K; Atkinson et al., 
2006) even when uncertainty is considered and, therefore, suggests that 
it is more reactive than ethane. In most cases, chemicals with high 
kOH values also have high MIR values, but the products that 
are formed here in subsequent reactions are expected to be 
polyfluorinated compounds, which do not contribute to O3 
formation (Osterstrom et al., 2017). In the case of HCFO-1224yd(Z), 
while the kOH is relatively high, the calculated maximum 
incremental reactivity MIR is very low when compared to that of ethane 
based on Carter (2020), provided by the petitioner, and reviewed by 
EPA.
    Carter (2020) estimates that HCFO-1224yd(Z) has a MIR value of 
0.052  0.011 g O3/g VOC versus 0.29  
0.07 g O3/g VOC for ethane. Therefore, the EPA considers 
HCFO-1224yd(Z) to be negligibly reactive and eligible for VOC-exempt 
status following the Agency's long-standing policy that compounds 
should so qualify where either reactivity metric (kOH 
expressed on a molar basis or MIR expressed on a mass basis) indicates 
that the compound is less reactive than ethane. While the overall 
atmospheric reactivity of HCFO-1224yd(Z) was not studied in an 
experimental smog chamber, the chemical mechanism derived from other 
chamber studies (Carter, 2011) was used to model the complete formation 
of O3 for an entire single day under realistic atmospheric 
conditions by Carter (2020). The EPA has assessed the Carter study 
provided by the petitioner and believes the calculated MIR value is 
reliable.\4\
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    \4\ Supporting memo is included in the docket.
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    Table 2 presents three reactivity metrics for HCFO-1224yd(Z) as 
they compare to ethane.

[[Page 88944]]



                               Table 2--Reactivities of Ethane and HCFO-1224yd(Z)
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                                                                                Maximum
                                                                              incremental           Maximum
                 Compound                     kOH (cm\3\/molecule-sec)     reactivity (MIR)       incremental
                                                                            (g O3/mole VOC)    reactivity (MIR)
                                                                                                 (g O3/g VOC)
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Ethane....................................  2.4 x 10-\13\...............                 8.4   0.28 
                                                                                                            0.07
HCFO-1224yd(Z)............................  (5.84  0.030) x                  7.7  0.052 
                                             10-\13\.                                                      0.011
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Notes:
kOH value at 298 K for ethane is from Atkinson et al. (2006; page 3626).
kOH value at 300 K for HCFO-1224yd(Z) is from Tokuhashi et al., 2018 (table 1).
Mass-based MIR value (g O3/g VOC) of ethane is from Carter (2011).
Mass-based MIR value (g O3/g VOC) of HCFO-1224yd(Z) is from Carter 2020.
Molar-based MIR (g O3/mole VOC) values were calculated from the mass-based MIR (g O3/g VOC) values using the
  number of moles per gram of the relevant organic compound.

    The reaction rate of HCFO-1224yd(Z) with the OH radical 
(kOH) has been measured to be (5.84  0.030) x 
10-13 cm\3\/molecule-sec (Tokuhashi et al., 2018); other 
reactions with O3 and the nitrate radical were negligibly 
small. The corresponding reaction rate of ethane with OH is 2.4 x 
10-13 cm\3\/molecule-sec (Atkinson et al., 2006). The data 
in table 2 show that HCFO-1224yd(Z) has a higher kOH value 
than ethane, meaning that it initially reacts more than twice as fast 
in the atmosphere as ethane. However, the resulting unsaturated 
fluorinated compounds in the atmosphere are short lived and react more 
slowly to form O3 (Baasandorj et al., 2011). The modeled 
reactivity based on the mechanism considered by Carter resulted in a 
very low maximum incremental reactivity on a mass basis. When compared 
to ethane, HCFO-1224yd(Z) has a MIR of 0.052  0.011 g 
O3/g VOC. Hence HCFO-1224yd(Z)'s MIR is less than the fifth 
of that of ethane at 0.28  0.07 g O3/g ethane. 
As shown in table 2, HCFO-1224yd(Z)'s MIR on a molar basis is also 
somewhat lower than that of ethane. Considering the uncertainty and 
variability in the MIR modeling, as described by Carter (2020), we are 
confident that the MIR of HCFO-1224yd(Z) is less than that of ethane.
    A molecule of HCFO-1224yd(Z) is considerably less reactive than a 
molecule of ethane in terms of complete O3-forming activity, 
as shown by the molar-based MIR (g O3/mole VOC) values. 
Likewise, one gram of HCFO-1224yd(Z) has a lower capacity than one gram 
of ethane to form O3 in terms of a mass-based MIR. Thus, 
following the 2005 Interim Guidance, the EPA finds HCFO-1224yd(Z) to be 
eligible for exemption from the regulatory definition of VOC based on 
both the molar- and mass-based MIR.

B. Potential Impacts on Other Environmental Endpoints

    The EPA's decision to exempt HCFO-1224yd(Z) from the regulatory 
definition of VOC is based on our findings above. However, as noted in 
the 2005 Interim Guidance, the EPA reserves the right to exercise its 
judgment in certain cases where an exemption is likely to result in a 
significant increase in the use of a compound and a subsequent 
significantly increased risk to human health or the environment. In 
this case, the EPA does not find that exemption of HCFO-1224yd(Z) would 
result in an increase of risk to human health or the environment, 
regarding stratospheric O3 depletion, toxicity, and climate 
change. More information on these topics is provided in the following 
sections.
1. Contribution to Stratospheric Ozone Depletion
    The SNAP program is the EPA's program to evaluate and regulate 
substitutes for end-uses historically using O3-depleting 
chemicals. Under section 612(c) of the CAA, the EPA is required to 
identify and publish lists of acceptable and unacceptable substitutes 
for class I or class II O3-depleting substances. Per the 
SNAP program findings, the ODP of HCFO-1224yd(Z) is zero, which is 
significantly less than the ODPs for the [ozone depleting substances] 
ODS subject to the phase out of production and consumption under 
regulations issued under sections 601-607 of the CAA and consistent 
with the Montreal Protocol on Substances that Deplete the Ozone Layer. 
The SNAP program has listed HCFO-1224yd(Z) as an acceptable substitute 
for chillers and other industrial process refrigeration end-uses 
provided in 84 FR 64765, November 25, 2019 (USEPA, 2019).
    HCFO-1224yd(Z) is unlikely to contribute to the depletion of the 
stratospheric O3 layer. The O3 depletion 
potential (ODP) of HCFO-1224yd(Z) is expected to be negligible based on 
several lines of evidence (Tokuhashi et al., 2018; Guo et al., 2019). 
Because HCFO-1224yd(Z)'s atmospheric lifetime is short (20 days 
according to Tokuhashi et al., 2018) compared to the timescale for 
mixing within the troposphere, it will decay before it has a chance to 
reach the stratosphere and, thus, will not participate in O3 
destruction (Guo et al., 2019).
2. Toxicity
    Based on screening assessments of the health and environmental 
risks of HCFO-1224yd(Z), the SNAP program expected that users will be 
able to use the compound without significantly greater health risks 
than presented using other available substitutes for the same end uses 
(USEPA, 2019).
    The EPA anticipates that HCFO-1224yd(Z) will be used consistent 
with the recommendations specified in the manufacturer's SDS (AGC, 
2017). According to the SDS, potential health effects from inhalation 
of HCFO-1224yd(Z) include drowsiness or dizziness, irritation of the 
skin or eyes, or frostbite. These potential health effects are common 
to many refrigerants. However, HCFO-1224yd(Z) could cause asphyxiation 
if air is displaced by vapors in a confined space. The Workplace 
Environmental Exposure Limit (WEEL) committee of the Occupational 
Alliance for Risk Science (OARS) reviewed available animal toxicity 
data and recommends a WEEL for the workplace of 1000 parts per million 
(ppm) (6700 mg/m\3\) \5\ time-weighted average (TWA) for an 8-hour 
workday, as later published in 2019 in Toxicology and Industrial Health 
(``(Z)-I-Chloro-2,3,3,3-tetrafluoropropene,'' 2020).\6\ This WEEL was 
derived based

[[Page 88945]]

on a 4-week, GLP-compliant inhalation toxicity study in rats (AGC, 
2016), based on the point of departure a NOAEL of 40,000 ppm. This was 
also the NOAEL for the developmental toxicity study where developmental 
effects were only observed in female rats. The EPA expects that users 
will be able to meet the WEEL and address potential health risks by 
following requirements and recommendations in the SDS and other safety 
precautions common to the refrigeration and air conditioning industry.
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    \5\ Occupational Alliance for Risk Science (OARS-WEELs)- HCFO-
1224yd(Z)), 2017: https://www.tera.org/OARS/PDF_documents/09_hcfo-1224yd(z)-weel-document-final-2017.pdf.
    \6\ (``(Z)-I-Chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)) 
(2017). (2019). Toxicology and Industrial Health, 36(5), 305-309. 
https://doi.org/10.1177/0748233720930548.
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    HCFO-1224yd(Z) is not regulated as a hazardous air pollutant (HAP) 
under title I of the CAA. Also, it is not listed as a toxic chemical 
under section 313 of the Emergency Planning and Community Right-to-Know 
Act (EPCRA).
    The Toxic Substances Control Act (TSCA) gives the EPA authority, 
among other things, to evaluate and, if necessary, address risks of 
injury to health or the environment from new chemical substances before 
such substances may be manufactured (including imported). Section 5 of 
TSCA requires manufacturers and importers to notify the EPA before 
manufacturing a new chemical substance or manufacturing or processing 
any chemical substance for a use which the Administrator has determined 
is a significant new use. When EPA receives such notice, it assesses 
whether sufficient information is available to permit a reasoned 
evaluation of the health and environmental effects of the substance or 
use and whether manufacturing, processing, distribution in commerce, 
use, or disposal of the substance (or any combination of such 
activities) presents, may present, or is not likely to present an 
unreasonable risk. Based on its review of a premanufacture notice (PMN) 
for HCFO-1224yd(Z), the EPA signed a consent order under TSCA section 
5(e) to protect against an unreasonable risk of injury to health or the 
environment. EPA also subsequently issued a Significant New Use Rule 
(SNUR) under TSCA that requires submission of a Significant New Use 
Notice (SNUN) to the EPA at least 90 days before manufacturing or 
processing of HCFO-1224yd(Z) for any significant new use. The required 
notification will provide the EPA with the opportunity to evaluate any 
intended significant new use before it occurs and, if necessary, to 
issue orders to address any potential unreasonable risk to human health 
or the environment.
    HCFO-1224yd(Z) is one of the class of substances generally referred 
to as per- and polyfluoroalkyl substances (PFAS). Many PFAS compounds 
represent a public health concern due to their toxicity and persistence 
in the environment. As a class, they are also highly varied, and 
variations in structure may result in (yet unknown) differences in 
environmental mobility and toxicity. The agency's ongoing work 
addressing PFAS does not currently address HCFO-1224yd(Z) specifically; 
however, the exposure limits and SNAP screening assessment noted above 
give us confidence that the use of this compound will not pose an 
unreasonable risk to human health. EPA also believes that the impacts 
of PFAS will be adequately addressed by regulatory and non-regulatory 
programs specifically designed to address those impacts.\7\
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    \7\ Interim Guidance on Control of Volatile Organic Compounds in 
Ozone State Implementation Plans, 2005, US Environmental Protection 
Agency, Document Number 05-18015 (70 FR 54046). And could be found 
at this link: https://www.govinfo.gov/content/pkg/FR-2005-09-13/pdf/05-18015.pdf.
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3. Contribution to Climate Change
    The Intergovernmental Panel on Climate Change (IPCC) Fifth 
Assessment Report (IPCC AR5) does not provide an estimate for HCFO-
1224yd(Z)'s global warming potential (GWP).\8\ The HCFO-1224yd(Z) GWP 
on a 100-year time horizon was calculated to be 5.4 in one study by 
Tokuhashi et al. (2018), but the same study reported an experimental 
chamber value of 0.88 and a lifetime of 20 days. This is consistent 
with the Scientific Assessment of Ozone Depletion by the chemical 
sciences laboratory (NOAA, 2022) where the GWP was found to be smaller 
than one under all reactivity efficiencies and recommended adjustments. 
These authors also calculated an inflated radiation or IR spectrum from 
a theoretical model using density functional theory (DFT) for HCFO-
1224yd(Z). That calculation gives a GWP of 5.4. While the theoretical 
value differs substantially on a percentage basis from the measured 
value, the GWP based on the experimental measurement is expected to be 
the more accurate given the large uncertainties in the calculated 
molecular model which tend to be unknown and high. Either value is 1-2 
orders of magnitude lower than the GWP for the refrigerant(s) that 
HCFO-1224yd(Z) is designed to replace. HCFO-1224yd(Z) has a GWP below 
one indicating that it has less radiating impact than that of 
CO2 over a 100-year time period (GWP100). Species 
with double bonds assembled in the Intergovernmental Panel on Climate 
Change Fifth Assessment Report (table 8.A.1) show lower GWP than 
species without a double bond. According to the SNAP rule, HCFO-
1224yd(Z)'s GWP is smaller than one and is comparable to or lower than 
those of some of the substitutes such as used in new chillers, ammonia 
absorption, carbon dioxide (CO2), and hydro-fluoro-olefin 
(HFO-1336mzz(Z)), and for new and retrofit chillers with GWPs ranging 
from 0 to 630. (USEPA, 2019). Both the calculated and the observed 
values of HCFO-1224yd(Z)'s GWP are lower than that of ethane determined 
to be 10.2.\9\
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    \8\ IPCC, 2013: Climate Change 2013: Chapter 8, Myhre, G., D. 
Shindell, F.-M. Br[eacute]on, W. Collins, J. Fuglestvedt, J. Huang, 
D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, 
G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and 
Natural Radiative Forcing. In: Climate Change 2013: The Physical 
Science Basis. Contribution of Working Group I to the Fifth 
Assessment Report of the Intergovernmental Panel on Climate Change 
[Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. 
Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. 
Cambridge University Press, Cambridge, United Kingdom and New York, 
NY, USA. https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter08_FINAL.pdf.
    \9\ Lifetimes, direct and indirect radiative forcing, and global 
warming potentials of ethane (C2H6), propane (C3H8), and butane 
(C4H10): https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.804.
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C. Conclusions

    The EPA finds that HCFO-1224yd(Z) is negligibly reactive with 
respect to its contribution to tropospheric O3 formation 
and, thus, may be exempted from the EPA's definition of VOC in 40 CFR 
51.100(s). HCFO-1224yd(Z) has been listed as acceptable for use in new 
and retrofitted centrifugal chillers, positive displacement chillers 
and industrial process refrigeration under the SNAP program (USEPA, 
2019). The EPA has also determined that exemption of HCFO-1224yd(Z) 
from the regulatory definition of VOC will not result in an increase of 
risk to human health and the environment, and, to the extent that use 
of this compound does have impacts on other environmental endpoints, 
those impacts are adequately managed by existing programs. For example, 
HCFO-1224yd(Z) has a similar or lower stratospheric O3 
depletion potential than available substitutes in those end-uses, and 
the toxicity risk from using HCFO-1224yd(Z) is not significantly 
greater than the risk from using other available alternatives for the 
same uses. The EPA has concluded that non-tropospheric O3-
related risks associated with potential increased use of HCFO-1224yd(Z) 
are adequately managed by SNAP. The EPA does not expect significant use 
of HCFO-1224yd(Z) in applications not covered by the SNAP program. To 
the extent that

[[Page 88946]]

the compound is used in other applications not already reviewed under 
SNAP or under the New Chemicals Program under TSCA, the SNUR in place 
under TSCA requires that any significant new use of a chemical be 
reported to the EPA using a SNUN. Any significant new use of HCFO-
1224yd(Z) would, thus, need to be evaluated by the EPA, and the EPA 
will continually review the availability of acceptable substitute 
chemicals under the SNAP program.

IV. Proposed Action

    The EPA is responding to the petition by proposing to revise its 
regulatory definition of VOC at 40 CFR 51.100(s) to add HCFO-1224yd(Z) 
to the list of compounds that are exempt from the regulatory definition 
of VOC because it is less reactive than ethane based on a comparison of 
mass-based MIR and molar-based MIR metrics and is, therefore, 
considered negligibly reactive. As a result of this action, if an 
entity uses or produces this compound and is subject to the EPA 
regulations limiting the use of VOC in a product, limiting the VOC 
emissions from a facility, or otherwise controlling the use of VOC for 
purposes related to attaining the O3 NAAQS, this compound 
will not be counted as a VOC in determining whether these regulatory 
obligations have been met. This action would affect whether this 
compound is considered a VOC for State regulatory purposes to reduce 
O3 formation, if a State relies on the EPA's regulatory 
definition of VOC. States are not bound to exclude from control as a 
VOC those compounds that the EPA has found to be negligibly reactive. 
However, no State may take credit for controlling this compound in its 
O3 control strategy. Consequently, reductions in emissions 
for this compound will not be considered or counted in determining 
whether States have met the rate of progress requirements for VOC in 
State Implementation Plans or in demonstrating attainment of the 
O3 NAAQS.

V. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 14094: Modernizing Regulatory Review

    This action is not a significant regulatory action as defined in 
Executive Order 12866, as amended by Executive Order 14094, and was 
therefore not subject to a requirement for Executive Order 12866 
review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA. It does not contain any recordkeeping or reporting 
requirements.

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. This 
action will not impose any requirements on small entities. This action 
removes HCFO-1224yd(Z) from the regulatory definition of VOC and, 
thereby, relieves manufacturers, distributers, and users of the 
compound from tropospheric O3 requirements to control 
emissions of the compound.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. This 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. This proposed rule removes HCFO-1224yd(Z) from 
the regulatory definition of VOC and, thereby, relieves manufacturers, 
distributers, and users from tropospheric O3 requirements to 
control emissions of the compound. Thus, Executive Order 13175 does not 
apply to this action.

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

    Executive Order 13045 directs Federal agencies to include an 
evaluation of the health and safety effects of the planned regulation 
on children in Federal health and safety standards and explain why the 
regulation is preferable to potentially effective and reasonably 
feasible alternatives. This action is not subject to Executive Order 
13045, because it is not economically significant as defined in 
Executive Order 12866, and because the EPA does not believe the 
environmental health or safety risks addressed by this action present a 
disproportionate risk to children. Our assessment is consistent with 
the SNAP finding that the conditional use of this chemical will 
guarantee the reduction of exposure risks to the general population 
particularly the most sensitive population (e.g., children). Since 
HCFO-1224yd(Z) is utilized in specific industrial applications where 
children are not present and dissipates quickly (e.g., lifetime of 22 
days) with short-lived end products, there is no exposure or 
disproportionate risk to children. This action removes HCFO-1224yd(Z) 
from the regulatory definition of VOC and, thereby, relieves 
manufacturers, distributers, and users from tropospheric O3 
requirements to control emissions of the compound.

H. Executive Order 13211: Actions Concerning Regulations 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 (NTTAA)

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations and 
Executive Order 14096: Revitalizing Our Nation's Commitment to 
Environmental Justice for All

    The EPA believes that the human health and environmental conditions 
that exist prior to this action do not result in disproportionate and 
adverse effects on communities with EJ concerns. As we found no data 
available to support the opposite, we addressed the human health and 
environmental risks by this proposed action to the greatest ability 
feasible. This action was developed in accordance with agency guidance 
on environmental justice.
    The EPA believes that this action in not likely to result in new 
disproportionate and adverse effects on communities with environmental 
justice concerns. This action removes HCFO-1224yd(Z) from the 
regulatory definition

[[Page 88947]]

of VOC and, thereby, relieves manufacturers, distributers, and users of 
the compound from tropospheric O3 requirements to control 
emissions of the compound. It will in fact help States focus on more 
photochemically reactive chemicals preventing more formation of Ozone 
and consequently more adverse related health and environmental effects.

K. Judicial Review

    Under section 307(b)(1) of the CAA, petitions for judicial review 
of this action must be filed in the United States Court of Appeals for 
the District of Columbia Circuit Court within 60 days from the date the 
proposed action is published in the Federal Register. Filing a petition 
for review by the Administrator of this proposed action does not affect 
the finality of this action for the purposes of judicial review nor 
does it extend the time within which a petition for judicial review 
must be filed and shall not postpone the effectiveness of such action. 
Thus, any petitions for review of this action related to the exemption 
of HCFO-1224yd(Z) from the regulatory definition of VOC must be filed 
in the Court of Appeals for the District of Columbia Circuit within 60 
days from the date proposed action is published in the Federal 
Register.

VII. References

AGC. (2016) (Z)-1-Chloro-2,3,3,3-tetrafluoropropene Refrigerant Gas 
Safety Data Sheet. ASAHI GLASS CO., LTD. Tokyo 100-8405, Japan 
August 2016.
AGC Chemicals. (2017). AMOLEA[supreg] 1224yd, Technical Information, 
ASAHI Glass Co., Ltd. (pp. 1-18).
Atkinson, R., Baulch, D.L., Cox, R.A., Crowley, J.N., Hampson, Jr., 
R.F., Hynes, R.G., Jenkin, M.E., Kerr, J.A., Rossi, M.J., and Troe, 
J. (2006) Evaluated kinetic and photochemical data for atmospheric 
chemistry: Volume II--gas phase reactions of organic species. Atmos. 
Chem. Phys. 6: 3625-4055.
Baasandorj, M., Ravishankara, A.R., Burkholder, J.B. (2011) 
Atmospheric chemistry of (Z)-CF3CH=CHCF3: OH radical reaction rate 
coefficient and global warming potential. J Phys Chem A. 2011 Sep 
29;115(38):10539-49. doi: 10.1021/jp206195g.
Carter, W.P.L. (1994) Development of ozone reactivity scales for 
volatile organic compounds. J. Air Waste Manage, 44: 881-899.
Carter, W.P.L. (2011) SAPRC Atmospheric Chemical Mechanisms and VOC 
Reactivity Scales, at https://www.engr.ucr.edu/~carter/SAPRC/. Last 
updated in Sept. 14, 2013. Tables of Maximum Incremental Reactivity 
(MIR) Values available at https://www.arb.ca.gov/regact/2009/mir2009/mir2009.htm. May 11, 2011.
Osterstrom, F.F., Andersen, S.T., S[oslash]lling, T.I., Nielsena, 
OJ., and Andersen, M.P.S. (2017) Atmospheric chemistry of Z- and E-
CF3CH--CHCF3: Phys.Chem.Chem.Phys., 2017, 19, 735.
Tokuhashi, K., Uchimaru, T., Takizawa, K., & Kondo, S. (2018). Rate 
Constants for the Reactions of OH Radical with the (E)/(Z) Isomers 
of CF3CF=CHCl and CHF2CF=CHCl. The Journal of Physical Chemistry A, 
122(12), 3120-3127. https://doi.org/10.1021/acs.jpca.7b11923.
USEPA, 2019. Protection of Stratospheric Ozone: Determination 35 for 
Significant New Alternatives Policy Program November 25, 2019. 84 FR 
64765. Available online at: https://www.govinfo.gov/content/pkg/FR-2019-11-25/pdf/2019-25412.pdf.

List of Subjects in 40 CFR Part 51

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Ozone, Reporting and recordkeeping requirements, 
Volatile organic compounds.

Michael S. Regan,
Administrator.

    For reasons stated in the preamble, title 40, chapter I of the Code 
of Federal Regulations is proposed to be amended as follows:

PART 51--REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF 
IMPLEMENTATION PLANS

0
1. The authority citation for part 51 continues to read as follows:

    Authority:  23 U.S.C. 101; 42 U.S.C. 7401-7671q.

Subpart F--Procedural Requirements

0
2. Section 51.100 is amended by revising paragraph (s)(1) introductory 
text to read as follows:


Sec.  51.100  Definitions.

* * * * *
    (s) * * *
    (1) This includes any such organic compound other than the 
following, which have been determined to have negligible photochemical 
reactivity: methane; ethane; methylene chloride (dichloromethane); 
1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-
trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11); 
dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22); 
trifluoromethane (HFC-23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC-
114); chloropentafluoroethane (CFC-115); 1,1,1-trifluoro 2,2-
dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1-
dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-difluoroethane (HCFC-
142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); pentafluoroethane 
(HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1-trifluoroethane 
(HFC-143a); 1,1-difluoroethane (HFC-152a); parachlorobenzotrifluoride 
(PCBTF); cyclic, branched, or linear completely methylated siloxanes; 
acetone; perchloroethylene (tetrachloroethylene); 3,3-dichloro-
1,1,1,2,2-pentafluoropropane (HCFC-225ca); 1,3-dichloro-1,1,2,2,3-
pentafluoropropane (HCFC-225cb); 1,1,1,2,3,4,4,5,5,5-decafluoropentane 
(HFC 43-10mee); difluoromethane (HFC-32); ethylfluoride (HFC-161); 
1,1,1,3,3,3-hexafluoropropane (HFC-236fa); 1,1,2,2,3-pentafluoropropane 
(HFC-245ca); 1,1,2,3,3-pentafluoropropane (HFC-245ea); 1,1,1,2,3-
pentafluoropropane (HFC-245eb); 1,1,1,3,3-pentafluoropropane (HFC-
245fa); 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); 1,1,1,3,3-
pentafluorobutane (HFC-365mfc); chlorofluoromethane (HCFC-31); 1 
chloro-1-fluoroethane (HCFC-151a); 1,2-dichloro-1,1,2-trifluoroethane 
(HCFC-123a); 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane 
(C4F9OCH3 or HFE-7100); 2-
(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OCH3); 1-
ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane 
(C4F9OC2H5 or HFE-7200); 2-
(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OC2H5
); methyl acetate; 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (n-
C3F7OCH3, HFE-7000); 3-ethoxy- 1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-
(trifluoromethyl) hexane (HFE-7500); 1,1,1,2,3,3,3-heptafluoropropane 
(HFC 227ea); methyl formate (HCOOCH3); 1,1,1,2,2,3,4,5,5,5-decafluoro-
3-methoxy-4-trifluoromethyl-pentane (HFE-7300); propylene carbonate; 
dimethyl carbonate; trans-1,3,3,3-tetrafluoropropene; 
HCF2OCF2H (HFE-134); 
HCF2OCF2OCF2H (HFE-236cal2); 
HCF2OCF2CF2OCF2H (HFE-
338pcc13); 
HCF2OCF2OCF2CF2OCF2
H (H-Galden 1040x or H-Galden ZT 130 (or 150 or 180)); trans 1-chloro-
3,3,3-trifluoroprop-1-ene; 2,3,3,3-tetrafluoropropene; 2-amino-2-
methyl-1-propanol; t-butyl acetate; 1,1,2,2- Tetrafluoro -1-(2,2,2-
trifluoroethoxy) ethane; cis-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-
1336mzz-Z); (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)); 
and perfluorocarbon compounds which fall into these classes:
* * * * *
[FR Doc. 2024-25971 Filed 11-8-24; 8:45 am]
BILLING CODE 6560-50-P