[Federal Register Volume 83, Number 229 (Wednesday, November 28, 2018)]
[Rules and Regulations]
[Pages 61127-61134]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-25891]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[EPA-HQ-OAR-2017-0175; FRL-9987-02-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: Final rule.

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SUMMARY: On May 1, 2018, the U.S. Environmental Protection Agency (EPA) 
published a proposed rule seeking comments in response to a petition 
requesting the revision of the EPA's regulatory definition of volatile 
organic compounds (VOC) to exempt cis-1,1,1,4,4,4-hexafluorobut-2-ene 
(also known as HFO-1336mzz-Z; CAS number 692-49-9). The EPA is now 
taking final action to revise the regulatory definition of VOC under 
the Clean Air Act (CAA). This final action adds HFO-1336mzz-Z 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.

DATES: This final rule is effective on January 28, 2019.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-HQ-OAR-2017-0175. All documents in the docket are 
listed on the https://www.regulations.gov website. Although listed in 
the index, some information is not publicly available, e.g., 
Confidential Business Information or other information whose disclosure 
is restricted by statute. Certain other material, such as copyrighted 
materials, is not placed on the internet and will be publicly available 
only in hard copy form. Publicly available docket materials are 
available electronically through https://www.regulations.gov.

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:

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-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. Response to Comments and Conclusion
IV. Final 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. 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. Congressional Review Act (CRA)
    M. Judicial Review

I. Does this action apply to me?

    Entities potentially affected by this final 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, 
refrigeration, and air conditioning. Potential entities that may be 
affected by this action include:

[[Page 61128]]



   Table 1--Potentially Affected Entities by North American Industrial
                   Classification System (NAICS) Code
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                                                      Description of
            Category               NAICS code       regulated 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.
Industry.......................            3363  Motor Vehicle Parts
                                                  Manufacturing.
Industry.......................          336611  Ship Building and
                                                  Repairing.
Industry.......................          336612  Boat Building.
Industry.......................          339999  All other Miscellaneous
                                                  Manufacturing.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities that might be affected by this 
deregulatory action. This table lists the types of entities that the 
EPA is now aware of that could potentially be affected to some extent 
by this action. Other types of entities not listed in the table could 
also be affected to some extent. To determine whether your entity is 
directly or indirectly affected by this action, you should consult your 
state or local air pollution control and/or air quality management 
agencies.

II. Background

A. The EPA's VOC Exemption Policy

    Tropospheric O3, commonly known as smog, is formed when VOC and 
nitrogen oxides (NOX) react in the atmosphere in the presence of 
sunlight. Because of the harmful health effects of O3, the EPA and 
state governments limit the amount of VOC that can be released into the 
atmosphere. VOC form O3 through atmospheric photochemical reactions, 
and different VOC have different levels of reactivity. That is, 
different VOC do not react to form O3 at the same speed or 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 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 equally as 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

[[Page 61129]]

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 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-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\
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    \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. Purdue 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 in subsequent reactions are 
expected to be poly fluorinated compounds, which do not contribute to 
O3 formation (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

    On May 1, 2018, the EPA published a proposed rulemaking (83 FR 
19026) seeking comments in response to the petition to revise the EPA's 
regulatory definition of VOC for exemption of HFO-1336mzz-Z. The EPA is 
taking final action to respond to the petition by exempting 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 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.

[[Page 61130]]



                                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)
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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 
10-13cm\3\/molecule-sec (Atkinson et al., 2006). The data in 
Table 2 show that HFO-1336mzz-Z has a higher kOH value than 
ethane, meaning that it initially reacts twice as fast in the 
atmosphere as ethane. However, the resulting unsaturated fluorinated 
compounds in the atmosphere are short lived and react more slowly to 
form O3 (Baasandorj et al., 2011). The mass based MIR is 
0.04 g O3/g VOC and much lower than that of ethane.
    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. One gram of HFO-
1336mzz-Z has a lower capacity than one gram of ethane to form 
O3 in terms of a mass-based MIR. Thus, following the 2005 
Interim Guidance in striking a balance between reactivity on a molar 
basis as well as a gram basis, the EPA finds HFO-1336mzz-Z to be 
eligible for exemption from the regulatory definition of VOC based on 
both the molar- and mass-based MIR.

B. Potential Impacts on Other Environmental Endpoints

    The EPA's decision to exempt 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 does not find that exemption of HFO-1336mzz-Z would 
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 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-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 material 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 as provided in the OARS (OARS, 
2014).\2\ 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.
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    \2\ Occupational Alliance for Risk Science (OARS-WEELs)--HFO-
1336mzz-Z, 2014: https://www.tera.org/OARS/HFO-1336mzz-Z%20WEEL%20FINAL.pdf.

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[[Page 61131]]

    HFO-1336mzz-Z is not regulated as a hazardous air pollutant (HAP) 
under title I of the CAA. Also, it is not listed as a toxic chemical 
under section 313 of the Emergency Planning and Community Right-to-Know 
Act (EPCRA).
    The Toxic Substances Control Act (TSCA) gives the EPA authority 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 (SNUN) 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 relatively 
low GWP and indirectly by decreasing energy consumption throughout the 
lifecycle of insulated foams in appliances, buildings, refrigerated 
storage and transportation.

C. Response to Comments and Conclusion

    The EPA received five comments on the May 1, 2018, notice of 
proposed rulemaking. One commenter supported the proposed action to 
exempt HFO-1336mzz-Z from the EPA's definition of VOC in 40 CFR 
51.100(s), one opposed the proposed action, and three raised issues 
that were outside the scope of this rulemaking including a discussion 
about air and water quality in Asia and Mexico, and climate change. 
These three anonymous comments failed to identify any specific issue 
that is germane to our proposal to exempt HFO-1336mzz-Z. Substantial 
comments and the EPA's responses are provided below.
    Comment: One commenter (ID: EPA-HQ-OAR-2017-0175-0010) expressed 
concern that ``the EPA should not exempt HFO-1336mzz-Z . . . [and that] 
. . . surely there is a reason it was . . . [regulated as a VOC] in the 
first place.'' The commenter expressed skepticism that ``other 
regulatory groups outside of the EPA'' would prevent the compound from 
being used, if there were other environmental impacts than 
O3, once the EPA exempted this compound. This commenter also 
expressed concern that the petitioner's data ``could potentially be 
biased'' and they ``. . . would like to read a proposal that gets its 
information from a more unbiased source and considers how it will deal 
with possible drawbacks of deregulating HFO-1336mzz-Z.''
    Response: The commenter appears to state that HFO-1336mzz-Z should 
not be exempted from the definition of VOC simply because it is 
currently included in the definition of VOC. This is a circular 
argument, and, if followed, the EPA would never be able to exempt any 
substances from the definition of VOC, even where, as here, scientific 
data supported such an exemption. The commenter does not provide any 
scientific evidence that rebuts the petitioner's data supporting the 
demonstration that HFO-1336mzz-Z is eligible for this exemption.
    The reason HFO-1336mzz-Z is currently regulated as a VOC is because 
it meets the EPA's definition of VOC in 40 CFR 51.100(s) as ``any 
compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic 
acid . . . which participates in atmospheric photochemical reactions.'' 
[emphasis added] The petitioner submitted data to the EPA that show 
HFO-1336mzz-Z negligibly participates in atmospheric photochemical 
reactions, presenting a better environmental alternative for similar 
industrial applications, and therefore should be excluded from the 
definition of VOC. As explained above, our approval would allow states 
to encourage VOC substitutions with negligibly reactive compounds that 
would reduce O3 formation.
    The EPA would like to clarify the statement in the proposal which 
referred to ``existing regulatory or non-regulatory programs that are 
specifically designed to address'' other environmental issues besides 
tropospheric O3 formation, such as fine particle formation, 
air toxics exposures, stratospheric O3 depletion, and 
climate change. When referring to existing regulatory or non-regulatory 
programs, the EPA was not referring to ``other regulatory groups 
outside of the EPA,'' as the commenter suggested. Rather, Congress has 
granted the EPA with other authorities under the CAA that allow the 
Agency to address these issues specifically (e.g., NAAQS program for 
fine particle pollution; section 112 for air toxics). As stated in the 
2005 Interim Guidance, 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, the 
EPA reserves the right to exercise its judgment and choose not to grant 
a petition for an exemption from the definition of VOC, even where the 
substance meets the reactivity metrics. However, as explained in 
section III.B. of this final rule, the EPA does not believe an 
exemption of HFO-1336mzz-

[[Page 61132]]

Z will lead to significant environmental impacts.
    To the extent the commenter is raising concerns that the EPA's 
action will result in non-EPA organizations treating HFO-1336mzz-Z 
differently, we note that this action does not prohibit state and local 
air pollution regulatory agencies from regulating HFO-1336mzz-Z. Some 
local agencies continue restrictions on the use of certain compounds 
that have been excluded from the definition of VOC by the EPA.
    With respect to the comment that the petitioner's data could 
potentially be biased, the EPA uses credible, peer-reviewed information 
in its review of VOC exemption petitions. In this regard, and as 
discussed in our proposed rule and in this action, we note that the 
journal article submitted by DuPont on HFO-1336mzz-Z reaction rates was 
performed by the National Oceanic and Atmospheric Administration and 
published in The Journal of Physical Chemistry, a peer-reviewed 
journal. The other primary document relied on to support the exemption 
petition was authored by the researcher who developed the MIR scale 
(Carter, 2011a). Staff in the EPA's Office of Research and Development 
reviewed these documents as part of the petition assessment process and 
find that they are consistent with current understanding of atmospheric 
chemistry. We are not aware of information that would indicate they are 
biased.
    Therefore, for reasons discussed above, the EPA is finalizing this 
rule with no changes. 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 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. Final Action

    The EPA is responding to the petition by revising 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. As a result of this action, if an entity which 
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

    Additional information about these statutes and Executive Orders 
can be found at https://www2.epa.gov/laws-regulations/laws-and-executive-orders.

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 considered an Executive Order 13771 deregulatory 
action. This final rule provides 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 the 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 
removes HFO-1336mzz-Z from the regulatory definition of VOC and, 
thereby, relieves manufacturers, distributers, and users of the 
compound from tropospheric O3 requirements to control 
emissions of the compound.

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.

[[Page 61133]]

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 final rule removes HFO-1336mzz-Z from the 
regulatory definition of VOC and, thereby, relieves manufacturers, 
distributers and users from tropospheric O3 requirements to 
control emissions of the compound. Thus, Executive Order 13175 does not 
apply to this action.

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 the 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 removes HFO-
1336mzz-Z from the regulatory definition of VOC and, thereby, relieves 
manufacturers, distributers and users from tropospheric O3 
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 removes HFO-1336mzz-Z from the regulatory definition of VOC and, 
thereby, relieves manufacturers, distributers, and users of the 
compound from tropospheric O3 requirements to control 
emissions of the compound.

L. Congressional Review Act (CRA)

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

M. 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 
final action is published in the Federal Register. Filing a petition 
for review by the Administrator of this final 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-Z from the regulatory definition of VOC must be filed in 
the Court of Appeals for the District of Columbia Circuit within 60 
days from the date the final action is published in the Federal 
Register.

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.
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/FR2016-05-23/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: November 16, 2018.
Andrew R. Wheeler,
Acting Administrator.

    For reasons stated in the preamble, part 51 of chapter I of title 
40 of the Code of Federal Regulations is amended as follows:

[[Page 61134]]

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

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

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

Subpart F--Procedural Requirements

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


Sec.  51.100   Definitions.

* * * * *
    (s) * * *
    (1) This includes any such organic compound other than the 
following, which have been determined to have negligible photochemical 
reactivity: Methane; ethane; methylene chloride (dichloromethane); 
1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-
trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11); 
dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22); 
trifluoromethane (HFC-23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC-
114); chloropentafluoroethane (CFC-115); 1,1,1-trifluoro 2,2-
dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1-
dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-difluoroethane (HCFC-
142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); pentafluoroethane 
(HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1-trifluoroethane 
(HFC-143a); 1,1-difluoroethane (HFC-152a); parachlorobenzotrifluoride 
(PCBTF); cyclic, branched, or linear completely methylated siloxanes; 
acetone; perchloroethylene (tetrachloroethylene); 3,3-dichloro-
1,1,1,2,2-pentafluoropropane (HCFC-225ca); 1,3-dichloro-1,1,2,2,3-
pentafluoropropane (HCFC-225cb); 1,1,1,2,3,4,4,5,5,5-decafluoropentane 
(HFC 43-10mee); difluoromethane (HFC-32); ethylfluoride (HFC-161); 
1,1,1,3,3,3-hexafluoropropane (HFC-236fa); 1,1,2,2,3-pentafluoropropane 
(HFC-245ca); 1,1,2,3,3-pentafluoropropane (HFC-245ea); 1,1,1,2,3-
pentafluoropropane (HFC-245eb); 1,1,1,3,3-pentafluoropropane (HFC-
245fa); 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); 1,1,1,3,3-
pentafluorobutane (HFC-365mfc); chlorofluoromethane (HCFC-31); 1 
chloro-1-fluoroethane (HCFC-151a); 1,2-dichloro-1,1,2-trifluoroethane 
(HCFC-123a); 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane 
(C4F9OCH3 or HFE-7100); 2-
(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OCH3); 1-
ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane 
(C4F9OC2H5 or HFE-7200); 2-
(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane 
((CF3)2CFCF2OC2H5
); methyl acetate; 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (n-
C3F7OCH3, HFE-7000); 3-ethoxy- 1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-
(trifluoromethyl) hexane (HFE-7500); 1,1,1,2,3,3,3-heptafluoropropane 
(HFC 227ea); methyl formate (HCOOCH3); 1,1,1,2,2,3,4,5,5,5-decafluoro-
3-methoxy-4-trifluoromethyl-pentane (HFE-7300); propylene carbonate; 
dimethyl carbonate; trans-1,3,3,3-tetrafluoropropene; 
HCF2OCF2H (HFE-134); 
HCF2OCF2OCF2H (HFE-236cal2); 
HCF2OCF2CF2OCF2H (HFE-
338pcc13); 
HCF2OCF2OCF2CF2OCF2
H (H-Galden 1040x or H-Galden ZT 130 (or 150 or 180)); trans 1-chloro-
3,3,3-trifluoroprop-1-ene; 2,3,3,3-tetrafluoropropene; 2-amino-2-
methyl-1-propanol; t-butyl acetate; 1,1,2,2- Tetrafluoro -1-(2,2,2-
trifluoroethoxy) ethane; cis-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-
1336mzz-Z); and perfluorocarbon compounds which fall into these 
classes:
* * * * *
[FR Doc. 2018-25891 Filed 11-27-18; 8:45 am]
 BILLING CODE 6560-50-P