[Federal Register Volume 87, Number 82 (Thursday, April 28, 2022)]
[Proposed Rules]
[Pages 25170-25178]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-08922]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[EPA-HQ-OAR-2021-0420; FRL-8371-02-OAR]
RIN 2060-AV24


Air Quality: Revision to the Regulatory Definition of Volatile 
Organic Compounds--Exclusion of (2E)-1,1,1,4,4,4-hexafluorobut-2-ene 
(HFO-1336mzz(E))

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 (2E)-
1,1,1,4,4,4-hexafluorobut-2-ene (also known as trans-1,1,1,4,4,4-
hexafluorobut-2-ene, and HFO-1336mzz(E); CAS number 66711-86-2) to the 
list of compounds

[[Page 25171]]

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 June 27, 2022.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2021-0420, 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-2021-0420, Office of Air and Radiation 
Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 
20460.
     Hand Delivery or Courier (by scheduled appointment only): 
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 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. Out 
of an abundance of caution for members of the public and our staff, the 
EPA Docket Center and Reading Room are open to the public by 
appointment only to reduce the risk of transmitting COVID-19. Our 
Docket Center staff also continues to provide remote customer service 
via email, phone, and webform. Hand deliveries and couriers may be 
received by scheduled appointment only. For further information on EPA 
Docket Center services and the current status, please visit us online 
at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Dr. Souad Benromdhane, Office of Air 
Quality Planning and Standards, Health and Environmental Impacts 
Division, Mail Code C539-07, Environmental Protection Agency, Research 
Triangle Park, NC 27711; telephone: (919) 541-4359; fax number: (919) 
541-5315; email address: [email protected].

SUPPLEMENTARY INFORMATION: 

General Information

    Written comments: Submit your comments, identified by Docket ID No. 
EPA-HQ-OAR-2021-0420, 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) 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). For additional submission methods, the full EPA public comment 
policy, information about CBI or multimedia submissions, and general 
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Due to public health concerns related to COVID-19, the EPA Docket 
Center and Reading Room are open to the public by appointment only. Our 
Docket Center staff also continues to provide remote customer service 
via email, phone, and webform. Hand deliveries or couriers will be 
received by scheduled appointment only. For further information and 
updates on EPA Docket Center services, please visit us online at 
https://www.epa.gov/dockets.
    The EPA continues to monitor information carefully and continuously 
from the Centers for Disease Control and Prevention (CDC), local area 
health departments, and our Federal partners so that we can respond 
rapidly as conditions change regarding COVID-19.

Table of Contents

I. Does this action apply to me?
II. Background
    A. The EPA's VOC Exemption Policy
    B. Petition To List HFO-1336mzz(E) 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 13563: Improving Regulation and 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. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Judicial Review
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 
HFO-1336mzz(E) 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........................................       325120  Industrial Gas Manufacturing.
Industry........................................       333242  Semiconductor Machinery Manufacturing.
Industry........................................       325998  All Other Miscellaneous Chemical Product and
                                                                Preparation Manufacturing.
Industry........................................       326140  Polystyrene Foam Product Manufacturing.
Industry........................................       326150  Urethane and Other Foam Product (except
                                                                Polystyrene) Manufacturing.

[[Page 25172]]

 
Industry........................................       333415  Air-Conditioning and Warm Air Heating Equipment
                                                                and Commercial and Industrial Refrigeration
                                                                Equipment Manufacturing.
Industry........................................         3363  Motor Vehicle Parts Manufacturing.
Industry........................................       336611  Ship Building and Repairing.
Industry........................................       336612  Boat Building.
Industry........................................       339999  All other Miscellaneous Manufacturing.
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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. Volatile organic compounds 
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 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:

[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 ozone concentrations and a threshold that is 
high enough to exempt some compounds that may usefully substitute 
for more highly reactive compounds.
    When reviewing compounds that have been suggested for VOC-exempt 
status, EPA will continue to compare them to ethane using 
kOH expressed on a molar basis and MIR values expressed 
on a mass basis.\1\
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    \1\ Interim Guidance on Control of Volatile Organic Compounds in 
Ozone State Implementation Plans, 2005, US Environmental Protection 
Agency, Document # 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.

    The 2005 Interim Guidance notes that the EPA will consider a 
compound to be negligibly reactive if it is equally 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).
    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,

[[Page 25173]]

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 
believes 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.

B. Petition To List HFO-1336mzz(E) as an Exempt Compound

    The Chemours Company submitted a petition to the EPA on November 
30, 2016, requesting that (2E)-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-
1336mzz(E); CAS number 66711-86-2) be exempted from the regulatory 
definition of VOC. The petition was based on the argument that HFO-
1336mzz(E) has low reactivity (i.e., 0.011 g of O3/g of HFO-
1336mzz(E)) relative to the MIR of ethane (0.28 g O3/g). The 
petitioner indicated that HFO-1336mzz(E) may be used in a variety of 
applications in foam expansion or blowing agents where it has 
significant performance and energy-saving advantages. Chemours has 
developed HFO-1336mzz(E) to support reductions in emissions of 
greenhouse gases (GHGs). The global warming potentials GWP for HFO-
1336mzz(E) are estimated as 26, 7, and 2 for time horizons of 20, 100, 
and 500 years, respectively as estimated by (Osterstrom et al., 2017). 
The World Meteorological Organization provided a 100-year GWP of 16 in 
its scientific assessment of O3 depletion under the global 
ozone research and monitoring project.\2\ Hence, HFO-1336mzz(E) can 
serve as a replacement for several higher global warming potential 
(>700 GWP) compounds for use in polyurethane rigid insulating foams, 
among others, many of which were removed from Significant New 
Alternatives Policy (SNAP) acceptable lists beginning on January 1, 
2017, or January 1, 2020. The Petitioner stated that manufacturers and 
formulators of polyurethane foams and refrigeration equipment need 
access to HFO-1336mzz(E) to meet VOC limits on their products without 
impairing performance.
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    \2\ WMO, 2018. World Meteorological Organization, Scientific 
Assessment of Ozone Depletion: 2018, Global Ozone Research and 
Monitoring Project--Report No. 58, 588 pp., Geneva, Switzerland, 
2018. Available online at: https://ozone.unep.org/sites/default/files/2019-05/SAP-2018-Assessment-report.pdf.
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    To support its petition, Chemours referenced several documents, 
including one peer-reviewed journal article on HFO-1336mzz(E) reaction 
rates (Osterstrom et al., 2017). Chemours also provided a supplemental 
technical report on the MIR of HFO-1336mzz(E) (Carter, 2011a). Per this 
report, the MIR of HFO-1336mzz(E) is 0.011 g O3/g HFO-
1336mzz(E) on the mass-based MIR scale. This reactivity rate is much 
lower than that of ethane (0.28 g O3/g ethane). The 
reactivity rate kOH for the gas-phase reaction of OH 
radicals with HFO-1336mzz(E) (kOH) has been measured to be 
1.72  0.42 x 10-\13\ centimeter (cm)\3\/
molecule-seconds at ~300 degrees Kelvin (K) (Osterstrom et al., 2017). 
This kOH rate is lower than that of ethane (kOH 
of ethane = 2.4 x 10-\13\ cm\3\/molecule-sec at ~298 K) even 
when uncertainty is considered and, therefore, suggests that HFO-
1336mzz(E) is less or equally reactive than ethane. In most cases, 
chemicals with high kOH values also have high MIR values, 
but for HFO-1336mzz(E), the products that are formed in subsequent 
reactions are expected to be poly fluorinated compounds, which do not 
contribute to O3 formation (Osterstrom et al., 2017; Carter 
2011a). Based on the current scientific understanding of 
tetrafluoroalkene reactions in the atmosphere, it is unlikely that the 
actual O3 impact on a mass basis would equal or exceed that 
of ethane in the scenarios used to calculate VOC reactivity in 
Osterstrom et al. (2017), in line with Baasandorj et al. (2011) and 
Carter (2011a).
    To address the potential for stratospheric O3 impacts, 
the petitioner contended that, because the atmospheric lifetime of HFO-
1336mzz(E) due to loss by OH reaction was estimated to be relatively 
short and it does not contain chlorine or bromine, it is not expected 
to contribute to the depletion of the stratospheric O3 layer 
(Osterstrom et al., 2017; Baasandorj et al., 2011).

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 HFO-1336mzz(E). 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

    As noted in studies cited by the petitioner, HFO-1336mzz(E) has a 
MIR value of 0.011 g O3/g VOC for ``averaged conditions,'' 
versus 0.28 g O3/g VOC for ethane (Carter, 2011). Therefore, 
the EPA considers HFO-1336mzz(E) to be negligibly reactive and eligible 
for VOC-exempt status in accordance with 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 HFO-1336mzz(E) 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 (Carter, 2011a). Therefore, the EPA believes that the MIR 
value calculated in the Carter study submitted by the petitioner is 
reliable as

[[Page 25174]]

it was supported by Osterstrom et al. (2017).
    Table 2 presents three reactivity metrics for HFO-1336mzz(E) as 
they compare to ethane.

                               Table 2--Reactivities of Ethane and HFO-1336mzz(E)
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                                                                                      Maximum
                                                                                    incremental       Maximum
                                                          kOH  (cm\3\/molecule-     reactivity      incremental
                        Compound                                   sec)            (MIR)  (g O3/    reactivity
                                                                                     mole VOC)    (MIR)  (g O3/g
                                                                                                       VOC)
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Ethane.................................................            2.4 x 10-\13\             8.4            0.28
HFO-1336mzz(E).........................................           1.72 x 10-\13\             1.8           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 HFO-1336mzz(E) is from Osterstrom (2017) and Baasandorj (2011).
Mass-based MIR value (g O3/g VOC) of ethane is from Carter (2011).
Mass-based MIR value (g O3/g VOC) of HFO-1336mzz(E) is from a supplemental report by Carter (2011a).
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 HFO-1336mzz(E) with the OH radical 
(kOH) has been measured to be 1.72 x 10-13 cm\3\/
molecule-sec (Osterstrom et al., 2017); 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 HFO-1336mzz(E) has a lower kOH value than ethane, 
meaning that it initially reacts slower or 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 
(Osterstrom et al., 2017; Baasandorj et al., 2011). The mass-based MIR 
is 0.011 g O3/g VOC and much lower than that of ethane.
    A molecule of HFO-1336mzz(E) is much 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 HFO-1336mzz(E) 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 proposes to find HFO-1336mzz(E) 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 proposed decision to exempt HFO-1336mzz(E) 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 HFO-
1336mzz(E) would result in an increase of risk to human health or the 
environment, regarding stratospheric O3 depletion, toxicity, 
and climate change. Additional 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 HFO-1336mzz(E) is zero. The SNAP 
program has listed HFO-1336mzz(E) as an acceptable substitute for a 
number of foam-blowing end-uses provided in 85 FR 79863, December 11, 
2020 (USEPA, 2020).
    HFO-1336mzz(E) is unlikely to contribute to the depletion of the 
stratospheric O3 layer. The O3 depletion 
potential (ODP) of HFO-1336mzz(E) is expected to be negligible based on 
several lines of evidence: the absence of chlorine or bromine in the 
compound and the atmospheric reactions described in Carter (2008). 
Because HFO-1336mzz(E)'s atmospheric lifetime is short relative to the 
time scale 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.
2. Toxicity
    Based on screening assessments of the health and environmental 
risks of HFO-1336mzz(E), the SNAP program anticipated that users will 
be able to use the compound without significantly greater health risks 
than presented by the use of other available substitutes for the same 
end uses (USEPA, 2020).
    The EPA anticipates that HFO-1336mzz(E) will be used consistent 
with the recommendations specified in the manufacturer's safety data 
sheet (SDS) (Chemours, 2016). According to the SDS, potential health 
effects from inhalation of HFO-1336mzz(E) include skin or eye 
irritation or frostbite. Exposure to high concentrations of HFO-
1336mzz(E) from misuse or intentional inhalation abuse may cause 
irregular heartbeat. In addition, HFO-1336mzz(E) 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 400 parts per 
million (ppm) (2680 mg/m\3\) \3\ time-weighted average (TWA) for an 8-
hour workday, as later published in 2019 in Toxicology and Industrial 
Health (``Trans-1,1,1,4,4,4-hexafluoro-2-butene,'' 2019).\4\ This WEEL 
was derived based on reduced male body weight gain in the 13-week rat 
inhalation toxicity study (TNO, 2016a, and TNO, 2016b), based on the 
point of departure of NOAEL of 7500 ppm. This was also the NOAEL for 
the developmental toxicity study where developmental effects were only

[[Page 25175]]

observed at maternally toxic levels. The EPA anticipates 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.
---------------------------------------------------------------------------

    \3\ Occupational Alliance for Risk Science (OARS-WEELs)- HFO-
1336mzz(E), 2018: https://www.tera.org/OARS/PDF_documents/03_trans-1-1-1-4-4-4-hexafluoro-2-butene-(hfo-1336mzz-e).pdf.
    \4\ Trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(E)) 
(2018). (2019). Toxicology and Industrial Health, 35(3), 204-210. 
https://doi.org/10.1177/0748233719825529.
---------------------------------------------------------------------------

    HFO-1336mzz(E) 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 to 
assess and prevent potential unreasonable risks to human health and the 
environment before a new chemical substance is introduced into 
commerce. Section 5 of TSCA requires manufacturers and importers to 
notify the EPA before manufacturing or importing a nonexempt new 
chemical substance by submitting a Premanufacture Notice (PMN) prior to 
the manufacture (including import) of the chemical substance. Under the 
TSCA New Chemicals Program, the EPA then assesses whether an 
unreasonable risk may, or will, be presented by the expected 
manufacturing, processing, distribution in commerce, use, and disposal 
of the new substance. Based on its review of a PMN and a Significant 
New Use Notice (SNUN) for HFO-1336mzz(E), the EPA has determined that 
use of HFO-1336mzz(E) in consumer products or use other than as 
described in the PMN and SNUN, may cause serious chronic health 
effects. To address concerns identified during the PMN review of HFO-
1336mzz(E), the EPA issued a Significant New Use Rule (SNUR) under TSCA 
on May 16, 2016, to require submission of a SNUN to the EPA at least 90 
days before manufacturing or processing of HFO-1336mzz(E) for any uses 
in consumer products or any use other than as described in the PMN (81 
FR 30451, 30462, May 16, 2016). The required notification will provide 
the EPA with the opportunity to evaluate the intended use before it 
occurs and, if necessary, to prohibit or limit that activity to protect 
against an unreasonable risk. The EPA received a SNUN for a significant 
new use of HFO-1336mzz(E) in 2017 and modified the SNUR in June 2021 
based on its determination for the SNUN (86 FR 30210, 30215, June 7, 
2021).\5\ The EPA, therefore, believes that existing programs address 
the risk of toxicity associated with the use of HFO-1336mzz(E).
---------------------------------------------------------------------------

    \5\ https://www.govinfo.gov/content/pkg/FR-2021-06-07/html/2021-11768.htm.
---------------------------------------------------------------------------

    The EPA recognizes that both HFO-1336mmz(E) and its atmospheric 
breakdown product trifluoroacetic acid (TFA) are members of the broad 
class of compounds known as per- and poly-fluoroalkyl substances 
(PFAS), even though they are not among the PFAS currently listed or 
targeted for specific Agency action. Many PFAS are highly mobile in 
various media, some are volatile and can be transported long distances 
in air and/or in water and widely distributed in the environment. Some 
studies suggest that PFAS emitted to air can result in human exposures 
in other media such as source/surface or drinking waters even though 
the emissions origin may be distant from receptor water bodies.\6\ Some 
PFAS are persistent in the environment and in the human body and can 
accumulate over time. There is evidence that exposure to certain PFAS 
can lead to adverse human health effects (e.g., low infant birth 
weights, immune system effects, cancer, and thyroid disruption). 
Numerous states have developed health-based (e.g., drinking water) 
standards for various PFAS. The Environmental Effects Assessment Panel 
for the Montreal Protocol (EEAP) has considered the production of TFA 
as a breakdown product of HFCs and HFOs and has found, ``Projected 
future increased loadings of TFA to playas, land-locked lakes, and the 
oceans due to continued use of HCFCs, HFCs, and replacement products 
such as HFOs are still judged to present negligible risks for aquatic 
organisms and humans.'' \7\ In its most recent assessment report (2018 
Assessment Report), EEAP found, ``Overall, there is no new evidence 
that contradicts the conclusion of our previous Assessments that 
exposure to current and projected concentrations of salts of TFA in 
surface waters present a minimal risk to the health of humans and the 
environment.'' \8\
---------------------------------------------------------------------------

    \6\ https://pubs.acs.org/doi/abs/10.1021/acs.est.0c06580.
    \7\ UNEP, 2015. Environmental Effects Of Ozone Depletion And Its 
Interactions With Climate Change: 2014 Assessment of the Montreal 
Protocol. United Nations Environment Programme (UNEP), Nairobi. This 
document accessible at: https://ozone.unep.org/sites/default/files/2019-05/eeap_report_2014.pdf.
    \8\ UNEP, 2019. Environmental Effects and Interactions of 
Stratospheric Ozone Depletion, UV Radiation, and Climate Change: 
2018 Assessment Report of the Montreal Protocol. United Nations 
Environment Programme (UNEP), Nairobi. This document accessible at: 
https://ozone.unep.org/sites/default/files/2019-04/EEAP_assessment-report-2018%20%282%29.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 HFO-
1336mzz(E) global warming potential (GWP).\9\ The HFO-1336mzz(E) GWP on 
a 100-year time horizon was calculated to be 7 in 1 study by Osterstrom 
et al. (2017) and 32 (atmospherically well-mixed) and 14 (lifetime-
adjusted) in another study by Baasandorj et al. (2018). However, the 
WMO (2018) calculated the 100-year GWP for HFO-1336mzz(E) as 16. 
Species with double bonds assembled in the Intergovernmental Panel on 
Climate Change Fifth Assessment Report (Table 8.A.1) indicate lower GWP 
than species without a double bond. However, the GWP of 14 approximated 
by (Baasandorj et al., 2018), and the gas-phase degradation of HFO-
1336-mzz(E) is not expected to lead to a significant formation of 
atmospherically long-lived species. According to the SNAP rule, HFO-
1336mzz(E)'s GWP of 16 is lower than those of some of the substitutes 
in a variety of foam blowing and refrigeration end-uses, solvents, and 
aerosol propellants (USEPA, 2020). HFO-1336mzz(E) was developed to 
replace other chemicals used for similar end-uses with GWP ranging from 
1 to 1,300 such as the refrigerant 1,1,1,2-tetrafluoroethane (R-134a), 
among others. The petitioner claims that HFO-1336mzz(E) is a better 
alternative to other substitutes in foam expansion or blowing agents 
for use in polyurethane rigid insulating foams. Specifically, HFO-
1336mzz(E) will provide significant performance and energy saving 
advantages and reduce climate change impacts both directly by its 
relatively low GWP and indirectly by decreasing energy consumption 
throughout the lifecycle of insulated foams in several applications.
---------------------------------------------------------------------------

    \9\ 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.
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C. Conclusions

    The EPA proposes that HFO-1336mzz(E) is negligibly reactive with 
respect to its contribution to tropospheric O3 formation 
and, thus,

[[Page 25176]]

may be exempted from the EPA's definition of VOC in 40 CFR 51.100(s). 
HFO-1336mzz(E) has been listed as acceptable for use as a blowing agent 
in several end-uses under the SNAP program (USEPA, 2020). The EPA has 
also determined that exemption of HFO-1336mzz(E) 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, HFO-
1336mzz(E) has a similar or lower stratospheric O3 depletion 
potential than available substitutes in those end-uses, and the 
toxicity risk from using HFO-1336mzz(E) 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 HFO-1336mzz(E) are 
adequately managed by SNAP. The EPA does not expect significant use of 
HFO-1336mzz(E) in applications not covered by the SNAP program. To the 
extent that 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 Significant New Use Notice 
(SNUN). Any significant new use of HFO-1336mzz(E) 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.
    This class of PFAS is highly varied, and variations in structure 
may result in (yet unknown) differences in environmental mobility and 
toxicity. The agency's ongoing work in PFAS is based on the recent PFAS 
Strategic Roadmap: EPA's Commitments to Action 2021-2024, which lays 
out an agenda and actions that have yet to be fully realized. Part of 
that plan is to better understand the environmental mobility, toxicity, 
and treatability of various congeners. There is much that we do not 
know about PFAS in general and for specific compounds. Therefore, EPA 
is seeking public comment on whether and how EPA should consider 
information on and properties of PFAS compounds beyond those properties 
related to the VOC exemption program and how it might impact the VOC 
delisting decision.

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 HFO-1336mzz(E) 
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 obligated 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

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 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 HFO-1336mzz(E) 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 any 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 HFO-1336mzz(E) 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

    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. Since HFO-1336mzz(E) 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 HFO-
1336mzz(E) 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

[[Page 25177]]

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

    The EPA believes that this action does not have disproportionately 
high and adverse human health or environmental effects on minority 
populations, low-income populations and/or indigenous peoples, as 
specified in Executive Order 12898 (59 FR 7629, February 16, 1994). 
This action removes HFO-1336mzz(E) 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.

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 HFO-1336mzz(E) 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

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[boxH]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.
Baasandorj, M., Marshall, P., Waterland, R.L., Ravishankara, A.R. & 
Burkholder, J.B. Rate Coefficient Measurements and Theoretical 
Analysis of the OH + (E)-CF3CH[boxH]CHCF3 Reaction. The Journal of 
Physical Chemistry A 122, 4635-4646, doi:10.1021/acs.jpca.8b02771 
(2018).
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. (2008) Reactivity Estimates for Selected Consumer 
Product Compounds, Final Report to California Air Resources Board 
Contract No. 06-408, February 19, 2008. http://www.arb.ca.gov/research/reactivity/consumer_products.pdf.
Carter, W.P.L. (2011) SAPRC Atmospheric Chemical Mechanisms and VOC 
Reactivity Scales, at http://www.engr.ucr.edu/~carter/SAPRC/. Last 
updated in Sept. 14, 2013. Tables of Maximum Incremental Reactivity 
(MIR) Values available at http://www.arb.ca.gov/regact/2009/mir2009/mir2009.htm. May 11, 2011.
Carter, W.P.L. (2011a) Estimation of the ground-level atmospheric 
ozone formation potentials of Cis 1,1,1,4,4,4-HexaFluoro-2-Butene, 
August 8, 2011.
Chemours. (2016) CD-59 Foam Expansion Agent Safety Data Sheet. 
Version 4.1. The Chemours Company FC, LLC, Wilmington, DE December 
2016.
Osterstrom, F.F., Andersen, S.T., S[oslash]lling, T.I., Nielsena, O 
J., and Andersen, M.P.S. (2017) Atmospheric chemistry of Z- and E-
CF3CH--CHCF3: Phys.Chem.Chem.Phys., 2017, 19, 735
TNO (Netherlands Organization for Applied Scientific Research). 
(2016a) Sub-chronic (13-week) inhalation toxicity study with HFO-
1336mzz(E) in rats. Report No. V20686. TNO Company, Netherlands. 
Unpublished report.
TNO (Netherlands Organization for Applied Scientific Research). 
(2016b) Inhalation prenatal developmental toxicity study with HFO-
1336mzz(E)in rats. Report No. V20685. TNO Company, Netherlands.
Pitts, J.N. Jr., Winer, A.M., Aschmann, S.M., Carter, W.P.L., and 
Atkinson, K. (1983), Experimental Protocol for Determining Hydroxyl 
Radical Reaction Rate Constants Environmental Science Research 
Laboratory, ORD, USEPA. EPA600/3-82-038.
USEPA, 2020. Protection of Stratospheric Ozone: Determination 36 for 
Significant New Alternatives Policy Program December 11, 2020. 85 FR 
79863. Available online at: https://www.govinfo.gov/content/pkg/FR-2020-12-11/pdf/2020-23861.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, part 51 of chapter I of title 
40 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 the introductory text of 
paragraph (s)(1).


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)-

[[Page 25178]]

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); trans-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzz(E)); and 
perfluorocarbon compounds which fall into these classes:
* * * * *
[FR Doc. 2022-08922 Filed 4-27-22; 8:45 am]
BILLING CODE 6560-50-P