[Federal Register Volume 83, Number 84 (Tuesday, May 1, 2018)]
[Proposed Rules]
[Pages 19026-19033]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-09079]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[EPA-HQ-OAR-2017-0175; FRL-9977-28-OAR]
RIN 2060-AT52


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

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
revise the regulatory definition of volatile organic compounds (VOC) 
under the Clean Air Act (CAA). This action proposes to add cis-
1,1,1,4,4,4-hexafluorobut-2-ene (also known as HFO-1336mzz-Z; CAS 
number 692-49-9) to the list of compounds excluded from the regulatory 
definition of VOC on the basis that this compound makes a negligible 
contribution to tropospheric ozone (O3) formation.

[[Page 19027]]


DATES: Written comments must be received on or before July 2, 2018.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2017-0175, at http://www.regulations.gov. Follow the online 
instructions for submitting comments. Once submitted, comments cannot 
be edited or removed from Regulations.gov. The EPA may publish any 
comment received to its public docket. Do not submit electronically any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. 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 http://www2.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: 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: 
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2017-0175. All documents in the docket are 
listed in the Regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the internet and will be 
publicly available only in hard copy. Publicly available docket 
materials are available either electronically in Regulations.gov or in 
hard copy at the EPA Docket Center, Room 3334, EPA WJC West Building, 
1301 Constitution Avenue NW, Washington, DC. The Public Reading Room is 
open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding 
legal holidays. The telephone number for the Public Reading Room is 
(202) 566-1744, and the telephone number for the EPA Docket Center is 
(202) 566-1742.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2017-0175. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at http://www.regulations.gov, including any personal 
information provided, unless the comment includes information claimed 
to be CBI or other information whose disclosure is restricted by 
statute. Do not submit information that you consider to be CBI or 
otherwise protected through http://www.regulations.gov or email. The 
http://www.regulations.gov website is an ``anonymous access'' system, 
which means the EPA will not know your identity or contact information 
unless you provide it in the body of your comment. If you send an email 
comment directly to the EPA without going through http://www.regulations.gov, your email address will be automatically captured 
and included as part of the comment that is placed in the public docket 
and made available on the internet. If you submit an electronic 
comment, the EPA recommends that you include your name and other 
contact information in the body of your comment and with any disk or 
CD-ROM you submit. If the EPA cannot read your comment due to technical 
difficulties and cannot contact you for clarification, the EPA may not 
be able to consider your comment. Electronic files should not include 
special characters or any form of encryption and be free of any defects 
or viruses. For additional information about the EPA's public docket, 
visit the EPA Docket Center homepage at http://www.epa.gov/dockets.

Table of Contents

I. General Information
    A. Does this action apply to me?
    B. What should I consider as I prepare my comments for the EPA?
II. Background
    A. The EPA's VOC Exemption Policy
    B. Petition To List HFO-1336mzz-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. The Significant New Alternatives Policy (SNAP) Program 
Acceptability Findings
    3. Toxicity
    4. Contribution to Climate Change
    C. Conclusions
IV. Proposed Rule
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulations and Controlling 
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution or Use
    J. National Technology Transfer and Advancement Act (NTTAA)
    K. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    L. Judicial Review
VI. References

I. General Information

A. 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-Z for use in polyurethane rigid insulating foams, and 
refrigeration and air conditioning. Potential entities that may be 
affected by this action include:

   Table 1--Potentially Affected Entities by North American Industrial
                   Classification System (NAICS) Code
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                                              Description of regulated
         Category             NAICS code              entities
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Industry..................          326140  Polystyrene Foam Product
                                             Manufacturing.
Industry..................          326150  Urethane and Other Foam
                                             Product (except
                                             Polystyrene) Manufacturing.
Industry..................          333415  Air-Conditioning and Warm
                                             Air Heating Equipment and
                                             Commercial and Industrial
                                             Refrigeration Equipment
                                             Manufacturing.

[[Page 19028]]

 
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.

B. What should I consider as I prepare my comments for the EPA?

    Submitting CBI. Do not submit information containing CBI to the EPA 
through http://www.regulations.gov or email. Clearly mark the part or 
all of the information that you claim to be CBI. For CBI information on 
a disk or CD-ROM that you mail to the EPA, mark the outside of the disk 
or CD-ROM as CBI and then identify electronically within the disk or 
CD-ROM the specific information that is claimed as CBI. In addition to 
one complete version of the comments that includes information claimed 
as CBI, you must submit a copy of the comments that does not contain 
the information claimed as CBI for inclusion in the public docket. If 
you submit a CD-ROM or disk that does not contain CBI, mark the outside 
of the disk or CD-ROM clearly that it does not contain CBI. Information 
not marked as CBI will be included in the public docket and the EPA's 
electronic public docket without prior notice. Information marked as 
CBI will not be disclosed except in accordance with procedures set 
forth in 40 Code of Federal Regulations (CFR) part 2. Send or deliver 
information identified as CBI only to the following address: OAQPS 
Document Control Officer (C404-02), OAQPS, U.S. Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711, 
Attention Docket ID No. EPA-HQ-OAR-2017-0175.

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 do not form 
O3 to the same extent. Some VOC react 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 in order 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) (from here forward 
referred to as the 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) (from here forward referred to as the 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

[[Page 19029]]

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.

    The 2005 Interim Guidance notes that the EPA will consider a 
compound to be negligibly reactive if it is equal to or less reactive 
than ethane based on either kOH expressed on a molar basis 
or MIR values expressed on a mass basis.
    The molar comparison of MIR is more consistent with the original 
smog chamber experiments, which compared equal molar concentrations of 
individual VOCs, 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 slightly less restrictive than the molar-based comparison 
in that a few more compounds would qualify as negligibly reactive.
    Given the two goals of the exemption policy articulated in the 2005 
Interim Guidance, the Agency 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 ozone 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-Z as an Exempt Compound

    DuPont Chemicals & Fluoroproducts (DuPont) submitted a petition to 
the EPA on February 14, 2014, requesting that cis-1,1,1,4,4,4-
hexafluorobut-2-ene (HFO-1336mzz-Z; CAS number 692-49-9) be exempted 
from the regulatory definition of VOC. The petition was based on the 
argument that HFO-1336mzz-Z has low reactivity relative to ethane. The 
petitioner indicated that HFO-1336mzz-Z may be used in a variety of 
applications as a replacement for foam expansion or blowing agents with 
higher global warming potential (GWP) (>700 GWP) for use in 
polyurethane rigid insulating foams, among others. It is also a new 
developmental refrigerant as a potential working fluid for Organic 
Rankine Cycles (ORC).\1\
---------------------------------------------------------------------------

    \1\ Konstantinos Kontomaris, 2014, HFO-1336mzz-Z High 
Temperature Chemical Stability and Use as a Working Fluid in Organic 
Rankine Cycles. International Refrigeration and Air Conditioning 
Conference. Perdue University: https://www.chemours.com/Refrigerants/en_US/products/Opteon/Stationary_Refrigeration/assets/downloads/2014_Purdue-Paper-Opteon-MZ.pdf.
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    To support its petition, DuPont referenced several documents, 
including one peer-reviewed journal article on HFO-1336mzz-Z reaction 
rates (Baasandorj, M. et al., 2011). DuPont also provided a 
supplemental technical report on the MIR of HFO-1336mzz-Z (Carter, 
2011a). Per this report, the MIR of HFO-1336mzz-Z is 0.04 gram (g) 
O3/g HFO-1336mzz-Z on the mass-based MIR scale. This 
reactivity rate is 86 percent 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-Z (kOH) 
has been measured to be 4.91 x 10-13 centimeter (cm)\3\/
molecule-seconds at ~296 degrees Kelvin (K) (Pitts et al., 1983, 
Baasandorj et al., 2011). This kOH rate is twice as high as 
that of ethane (kOH of ethane = 2.4 x 10-13 
cm\3\/molecule-sec at ~298 K) and, therefore, suggests that HFO-
1336mzz-Z is twice as reactive as ethane. In most cases, chemicals with 
high kOH values also have high MIR values, but for HFO-
1336mzz-Z, the products that are formed are expected to be mostly 
smaller perfluorinated compounds, which are not reactive in the 
atmosphere and do not form ozone (Baasandorj et al., 2011). 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 (Baasandorj et al., 2011; Carter, 2011a).
    To address the potential for stratospheric O3 impacts, 
the petitioner contended that, because the atmospheric lifetime of HFO-
1336mzz-Z due to loss by OH reaction was estimated to be ~20 days and 
it does not contain chlorine or bromine, it is not expected to 
contribute to the depletion of the stratospheric O3 layer.

III. The EPA's Assessment of the Petition

    The EPA is responding to the petition by proposing to exempt HFO-
1336mzz-Z from the regulatory definition of VOC. 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-Z has a 
MIR value of 0.04 g O3/g VOC for ``averaged conditions,'' 
versus 0.28 g O3/g VOC for ethane (Carter, 2011). Therefore, 
the EPA considers HFO-1336mzz-Z 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-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

[[Page 19030]]

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.
    Table 2 presents three reactivity metrics for HFO-1336mzz-Z as they 
compare to ethane.

                                Table 2--Reactivities of Ethane and HFO-1336mzz-Z
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                                                                                      Maximum
                                                                                    incremental       Maximum
                                                                   kOH  (cm\3\/     reactivity      incremental
                            Compound                               molecule-sec)   (MIR) (g O3/     reactivity
                                                                                     mole VOC)     (MIR) (g O3/g
                                                                                                       VOC)
----------------------------------------------------------------------------------------------------------------
Ethane..........................................................     2.4 x 10-13             8.4            0.28
HFO-1336mzz-Z...................................................    4.91 x 10-13             6.6            0.04
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Notes:
1. kOH value at 298 K for ethane is from Atkinson et al., 2006 (page 3626).
2. kOH value at 296 K for HFO-1336mzz-Z is from Baasandorj, 2011.
3. Mass-based MIR value (g O3/g VOC) of ethane is from Carter, 2011.
4. Mass-based MIR value (g O3/g VOC) of HFO-1336mzz-Z is from a supplemental report by Carter, 2011a.
5. 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-Z with the OH radical 
(kOH) has been measured to be 4.91 x 10-13 cm\3\/
molecule-sec (Baasandorj et al., 2011); 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-Z has a slightly higher kOH value than 
ethane, meaning that it initially reacts faster in the atmosphere than 
ethane. However, a molecule of HFO-1336mzz-Z is 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. 
Additionally, one gram of HFO-1336mzz-Z has a lower capacity than one 
gram of ethane to form O3. Thus, following the 2005 Interim 
Guidance, HFO-1336mzz-Z is eligible to be exempted 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-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 is proposing to find that exemption 
of HFO-1336mzz-Z would not result in an increase of risk to human 
health or the environment, with regard to stratospheric O3 
depletion, toxicity and climate change. Additional information on these 
topics is provided in the following sections.
1. Contribution to Stratospheric Ozone Depletion
    HFO-1336mzz-Z is unlikely to contribute to the depletion of the 
stratospheric O3 layer. The O3 depletion 
potential (ODP) of HFO-1336mzz-Z 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-Z has a kOH value that is twice as high 
as that of ethane (see section III.A ``Contribution to Tropospheric 
Ozone Formation''), it will decay before it has a chance to reach the 
stratosphere and, thus, will not participate in O3 
destruction.
2. The Significant New Alternatives Policy (SNAP) Program Acceptability 
Findings
    The SNAP program is the EPA's program to evaluate and regulate 
substitutes for end-uses historically using ozone-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 ozone-depleting substances. Per the SNAP program findings, the 
ODP of HFO-1336mzz-Z is zero. The SNAP program has listed HFO-1336mzz-Z 
as an acceptable substitute for a number of foam blowing end-uses 
provided in 79 FR 62863, October 21, 2014 (USEPA, 2014), and as an 
acceptable substitute in the refrigeration and air conditioning sector 
in heat transfer, as well as in chillers and industrial process air 
conditioning provided in 81 FR 32241, May 23, 2016 (USEPA, 2016).
3. Toxicity
    Based on screening assessments of the health and environmental 
risks of HFO-1336mzz-Z, the SNAP program anticipated that users will be 
able to use the compound without significantly greater health risks 
than presented by use of other available substitutes for the same uses 
(USEPA, 2014, 2016).
    The EPA anticipates that HFO-1336mzz-Z will be used consistent with 
the recommendations specified in the manufacturer's safety data sheet 
(SDS) (DuPont, 2011). According to the SDS, potential health effects 
from inhalation of HFO-1336mzz-Z include skin or eye irritation or 
frostbite. Exposure to high concentrations of HFO-1336mzz-Z from misuse 
or intentional inhalation abuse may cause irregular heartbeat. In 
addition, HFO-1336mzz-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 500 parts per million (ppm) (3350 mg/m\3\) time-weighted 
average (TWA) for an 8-hour workday (OARS, 2014). This WEEL was derived 
based on reduced male body weight in the 13-week rat inhalation 
toxicity study (Dupont, 2011). The WEEL is also protective against 
skeletal fluorosis, which may occur at higher exposures because of 
metabolism. 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.
    HFO-1336mzz-Z is not regulated as a hazardous air pollutant (HAP) 
under

[[Page 19031]]

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 new chemical 
substance by submitting a Premanufacture Notice (PMN) prior to the 
manufacture (including import) of the chemical. 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. The 
EPA has determined, however, that domestic manufacturing, use in non-
industrial products, or use other than as described in the PMN may 
cause serious chronic health effects. To mitigate risks identified 
during the PMN review of HFO-1336mzz-Z, the EPA issued a Significant 
New Use Rule (SNUR) under TSCA on June 5, 2015, to require persons to 
submit a Significant New Use Notice to the EPA at least 90 days before 
they manufacture or process HFO-1336mzz-Z for uses other than those 
described in the PMN (80 FR 32003, 32005, June 5, 2015). The required 
notification will provide the EPA with the opportunity to evaluate the 
intended use and, if necessary, to prohibit or limit that activity 
before it occurs. The EPA, therefore, believes that existing programs 
address the risk of toxicity associated with the use of HFO-1336mzz-Z.
4. Contribution to Climate Change
    The Intergovernmental Panel on Climate Change (IPCC) Fifth 
Assessment Report (IPCC AR5) estimated the lifetime of HFO-1336mzz-Z to 
be approximately 22 days (Baasandorj et al., 2011), and the gas-phase 
degradation of HFO-1336-mzz-Z is not expected to lead to a significant 
formation of atmospherically long-lived species. The radiative 
efficiency of HFO-1336-mzz-Z was calculated to be 0.38 watts per square 
meter at the earth's surface per part per billion concentration of the 
material (W m-2 ppb-1) based on Baasandorj et 
al., 2011. The report estimated the resulting 100-year GWP to be 9, 
meaning that, over a 100-year period, one ton of HFO-1336mzz-Z traps 9 
times as much warming energy as one ton of carbon dioxide 
(CO2) (IPCC, 2013). HFO-1336mzz-Z's GWP of 9 is lower than 
those of some of the substitutes in a variety of foam blowing end-uses 
and in centrifugal and positive displacement chillers, heat transfer, 
and industrial process air conditioning. HFO-1336mzz-Z was developed to 
replace other chemicals used for similar end-uses with GWP ranging from 
725 to 5,750 such as CFC-11, CFC-113, HCFC-141b and HCFC-22. The 
petitioner claims that HFO-1336mzz-Z is a better alternative to other 
substitutes in foam expansion or blowing agents for use in polyurethane 
rigid insulating foams. Thermal test data and energy efficiency trials 
indicate that HFO-1336mzz-Z will provide superior insulating value and, 
thus, reduces climate change impacts both directly by its low GWP and 
indirectly by decreasing energy consumption throughout the lifecycle of 
insulated foams in appliances, buildings, refrigerated storage and 
transportation.

C. Conclusions

    The EPA finds that HFO-1336mzz-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). HFO-1336mzz-Z has been listed as acceptable for use in 
several industrial and commercial refrigeration and air conditioning 
end-uses, as well as for use as a blowing agent under the SNAP program 
(USEPA, 2014, 2016). The EPA has also determined that exemption of HFO-
1336mzz-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, HFO-1336mzz-Z has a similar or lower 
stratospheric O3 depletion potential than available 
substitutes in those end-uses, and the toxicity risk from using HFO-
1336mzz-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 HFO-1336mzz-Z are adequately managed by SNAP. The EPA 
does not expect significant use of HFO-1336mzz-Z 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-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 Rule

    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-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. If finalized, then for an entity which 
uses or produces any of this compound and is subject to 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. Also if finalized, 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 (SIPs) 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. Executive Order 13771: Reducing Regulations and Controlling 
Regulatory Costs

    This action is expected to be an Executive Order 13771 deregulatory

[[Page 19032]]

action. This proposed rule is expected to provide meaningful burden 
reduction by exempting HFO-1336mzz-Z from the VOC regulatory definition 
and relieving manufacturers, distributers, and users from recordkeeping 
or reporting requirements. This action is voluntary in nature and has 
non-quantifiable cost savings given unpredictability in who or how much 
of it will be used.

C. 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.

D. 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, 
if finalized, removes HFO-1336mzz-Z from the regulatory definition of 
VOC and, thereby, would relieve manufacturers, distributers, and users 
of the compound from tropospheric ozone requirements to control 
emissions of the compound.

E. 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.

F. 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.

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

    This action does not have tribal implications, as specified in 
Executive Order 13175. This action proposes to remove HFO-1336mzz-Z 
from the regulatory definition of VOC and, if finalized, would relieve 
manufacturers, distributers and users from tropospheric ozone 
requirements to control emissions of the compound. Thus, Executive 
Order 13175 does not apply to this action.

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

    This action is not subject to Executive Order 13045, because it is 
not economically significant as defined in Executive Order 12866, and 
because EPA does not believe the environmental health or safety risks 
addressed by this action present a disproportionate risk to children. 
Since HFO-1336mzz-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 proposes to remove HFO-
1336mzz-Z from the regulatory definition of VOC and, if finalized, 
would relieve manufacturers, distributers and users from tropospheric 
ozone requirements to control emissions of the compound.

I. 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.

J. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

K. 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 proposes to remove HFO-1336mzz-Z from the regulatory 
definition of VOC and, if finalized, would relieve manufacturers, 
distributers, and users of the compound from tropospheric ozone 
requirements to control emissions of the compound.

L. Judicial Review

    Section 307(b)(1) of the CAA indicates which Federal Courts of 
Appeal have venue for petitions of review of final actions by EPA. This 
section provides, in part, that petitions for review must be filed in 
the Courts of Appeals for the District of Columbia Circuit if (i) the 
agency action consists of ``nationally applicable regulations 
promulgated, or final action taken, by the Administrator,'' or (ii) 
such action is locally or regionally applicable, if ``such action is 
based on a determination of nationwide scope or effect and if in taking 
such action the Administrator finds and publishes that such action is 
based on such a determination.''
    The EPA proposes to find that any final action related to this 
rulemaking is ``nationally applicable'' or of ``nationwide scope and 
effect'' within the meaning of CAA section 307(b)(1). Through this 
rulemaking action, the EPA interprets section 302 of the CAA, a 
provision which has nationwide applicability. The EPA's proposed change 
to the regulatory definition of VOC would affect implementation plans 
and national regulatory programs implicating this pollutant. For this 
reason, the Administrator proposes to determine that any final action 
related to the proposed rule is of nationwide scope and effect for 
purposes of CAA section 307(b)(1). Thus, pursuant to CAA section 307(b) 
any petitions for review of any final actions regarding the rulemaking 
would be filed in the United States Court of Appeals for the District 
of Columbia Circuit within 60 days from the date of any final action 
published in the Federal Register.

VI. 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.
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.

[[Page 19033]]

DuPont Haskell. FEA-1100: 90-day inhalation toxicity study in rats; 
Unpublished Report DuPont-17453-785-1; Haskell Laboratory of 
Industrial Toxicology: Newark, DE, 2011.
IPCC, 2007: Climate Change 2007: The Physical Science Basis. 
Contribution of Working Group I to the Fourth Assessment Report of 
the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, 
M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. 
Miller (eds.)]. Cambridge University Press, Cambridge, United 
Kingdom and New York, NY, USA, 996 pp.
IPCC, 2013: 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, 1535 pp.
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, 2014. Significant New Alternatives Policy Program; Foam 
Blowing Sector; Risk Screen on Substitutes in Rigid Polyurethane 
Appliance Foam; Rigid Polyurethane and Polyisocyanurate Laminated 
Boardstock; Rigid Polyurethane Commercial Refrigeration and Sandwich 
Panels; Rigid Polyurethane Slabstock and Other; Flexible 
Polyurethane; Integral Skin Polyurethane; and Phenolic Insulation 
Board and Bunstock. Substitute: HFO-1336mzz(Z) (Formacel[supreg] 
1100); October 10, 2014. Available online at: https://www.gpo.gov/fdsys/pkg/FR-2014-10-21/pdf/2014-24989.pdf.
USEPA, 2016. Significant New Alternatives Policy Program; 
Refrigeration and Air Conditioning Sector; Risk Screen on 
Substitutes for Use in Chillers and Industrial Process Air 
Conditioning Substitute: HFO-1336mzz(Z) (Opteon[supreg] MZ); May 23, 
2016. Available online at: https://www.gpo.gov/fdsys/pkg/FR-2016-05-23/pdf/2016-12117.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.

    Dated: April 23, 2018.
E. Scott Pruitt,
Administrator.

    For reasons set forth in the preamble, EPA proposes to amend part 
51 of chapter I of title 40 of the Code of Federal Regulations 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: 3 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); and perfluorocarbon compounds which fall into these 
classes:
* * * * *
[FR Doc. 2018-09079 Filed 4-30-18; 8:45 am]
BILLING CODE 6560-50-P