SUPPORTING ANALYSIS
FOR
MANDATORY REPORTING OF GREENHOUSE GASES: NOTICE OF PRELIMINARY DETERMINATIONS REGARDING REQUESTS TO USE PROVISIONAL G LOBAL W ARMING P OTENTIALS UNDER THE FLUORINATED GAS PRODUCTION CATEGORY OF THE GREENHOUSE GAS REPORTING RULE
Off ice of Air and Radiation U.S. Environmental Protection Agency January 23 , 2011Page 2 of 10 

## Table of Contents

Introduction

................................ ................................ ................................ ................................ ................... 3 Background

................................ ................................ ................................ ................................ ................... 3 Estimating Global Warming Potentials

................................ ................................ ................................ ......... 4 Summary of Information Submitted to EPA

................................ ................................ ................................ . 6 Preliminary Determinations and Their Rationale

................................ ................................ ......................... 9Page 3 of 10 

## Introduction This Supporting Analysis provides background and rationale for the preliminary determinations regarding the provisional Global Warming Potentials (GWPs ) for fluorinated greenhouse gases (GHG s ) submitted to EPA by DuPont de Nemours, Inc. and Honeywell International for the purposes of the calculations in 98.123(c)(1) of subpart L

— Fluorinated Gas Production of the Mandatory Reporting of Greenhouse Gases (4 0 CFR part 98). 

## Background Under 98.123(c)(1) , fluorinated gas producers that wish to use 98.123(c) (the Emission Factor Method or Emission Calculation Factor Method) to estimate emissions from a continuous process must make a preliminary estimate of the a nnual CO 2 e emissions of fluorinated GHGs f rom each process vent . They are required to do so using the engineering calculations or assessments specified in the rule. If the preliminary estimate indicates that a vent emits 10,000 mtCO 2 e or more, facilities must use stack testing to establish an emission factor for that vent. If the preliminary estimate indicates that a vent emits less than 10,000 mtCO 2 e, facilities may use engineering calculations or assessments to establish an emission calculation factor. Under 98.123(c)(1)(v) , t o convert the fluorinated GHG emissions to CO 2 e, fluorinated gas producers must use Equation A

– 1 of § 98.2. For fluorinated GHGs whose GWPs are not listed in Table A

– 1 to subpart A of part 98 , producers must use a default GWP of 2 ,000 unless they submit a request to use other GWPs for those fluorinated GHGs in that process under paragraph (c)(1)(vi) , and EPA approve s that request

. Under 98.123(c)(1)(vi), fluorinated gas producers may submit a r equest to use a GWP other than 2,000 for fluorinated GHGs whose GWPs are not listed in Table A

– 1 to subpart A if t heir process vent emits one or more fluorinated GHGs (1) whose GWPs are not listed in Table A

– 1 to subpart A, (2) that are emitted in quantities that, with a default GWP of 2,000, result in total calculated annual emissions equal to or greater than 10,000 metric tons CO 2 e for the vent, and (3) that t hey believe have GWPs that would result in total calculated annual emissions less than 10,000 m etric t ons CO 2 e. Under 98.123(c)(1)(vi )(B), EPA reviews each request to determine whether it is complete, substantiates each of the provisional GWPs, and demonstrates that the process vents are calculated to emit less than 10,000 metric tons CO 2 e of fluorinated GHGs only when the proposed prov isional GWPs, not the default GWP of 2,000, are used for the fluorinated GHGs for which the provisional GWPs are requested

. If EPA makes a preliminary determination that each of these criteria is met, EPA publishes a notice for public comment including the determination and the data and analysis submitted by the producers under paragraphs (c)(1)(vi)(A)(1) through (3).
Under paragraphs (c)(1)(vi)(A)(1) through (3) , fluorinated gas producers must include the following information in the request for each fluo rinated GHG that does not have a GWP listed in Table A

– 1 to subpart A of part 98 and that constitutes more than one percent by mass of the stream emitted from the vent:Page 4 of 10 (1) The identity of the fluorinated GHG, including its chemical formula and, if available, CAS number. (2) The estimated GWP of the fluorinated GHG. (3) The data and analysis that supports the estimate of the GWP of the fluorinated GHG, including:

(i) Data and analysis related to the low

- pressure gas phase infrared absorption spectrum of the fluorinated GHG

. (ii) Data and analysis related to the estimated atmospheric lifetime of the fluorinated GHG (reaction mechanisms and rates, including e.g., photolysis and reaction with atmospheric components such as OH, O 3 , CO, and water). (iii) The radiative transfer analysis tha t integrates the lifetime and infrared absorption spectrum data to calculate the GWP. (iv) Any published or unpublished studies of the GWP of the gas. On February 25, 2011, Honeywell International (Honeywell) requested to use alternative GWPs for two fluorinat ed GHGs for the purposes of calculations in paragraph (c)(1) of 40 CFR 98.123. Honeywell requested to use alternate (i.e., lower) GWPs for two commercial chemicals produced at their Buffalo Research Laboratory: HFC

- 1234ze and HFC

- 1234yf. Honeywell included published scientific papers and other information to fulfill the requirements under paragraphs (c)(1)(vi)(A)(1) through (3)

. On February 28, 2011, E. DuPont de Nemours, Inc. (DuPont) requested to use alternative GWPs for six fluorinated GHGs for the purp oses of calculations in paragraph (c)(1) of 40 CFR 98.123. DuPont requested to use alternate (i.e., lower) GWPs for six chemicals at DuPont plant sites subject to subpart L: hexafluoropropylene (HFP), perfluoromethyl vinyl ether (PMVE), tetrafluoroethylene (TFE), 3,3,3

- trifluoropropene (TFP), vinyl fluoride (VF), and vinylidine fluoride (VF2). For each chemical, DuPont included peer

- reviewed scientific data and other information to fulfill the requirements under paragraphs (c)(1)(vi)(A)(1) through (3)

.


## Est **imating Global Warming Potentials** For a compound that one know s will be a gas in the atmosphere and will absorb at infrared wavelengths , the key component of the Global Warming Potential ( GWP ) calculation is the integration of the radiative forcing for the compound over the 100

- year integration time. In turn, the accuracy of the radiative forcing calculation depends on the scientific capabilities of the radiative transfer calculation, using the infrared absorption cross

- sections for the compound being exami ned and the atmospheric lifetime of the compound (as a function of where it is emitted) . The lifetime and radiative forcing are in turn affected by the compound’s distribution in the atmosphere with al titude, latitude and longitude. Estimating GWPS depend s on:

 Accurate knowledge of the reactivity of the compound to derive its lifetime and spatial distribution. For most compounds of interest this will depend on the compound’s rate of reaction with OH or rate of photolysis. Note that these can be strongly te mperature dependent and for ph oto lysis, can also be pressure dependent. Other reactants (e.g.,Page 5 of 10 excited oxygen atoms, ozone, chlorine atoms) can be important, but are usually much less important.

 Accurate derivation of the lifetime of the compound. This mea ns having a strong understanding of how temperatures and pressures vary spatially, especially with altitude , how atmospheric concentrations of OH vary spatially and over time (i.e., daily and seasonally), and in cases where photolysis is an important remov al mechanism, a strong knowledge on the absorption cross

- sections and the quantum yield as well as an accurate derivation of the photolysis rates spatially. Th e spatial and temporal variation in atmospheric concentrations for other reactants is also import ant if reactions with those gases are relevant.

 Accurate knowledge of the spatial distribution of the compound , and its emissions, with latitude, longitude and altitude. Long

- lived gases are generally well mixed, especially in the troposphere, but short

- li ved gases are not well

- mixed in either the troposphere or the stratosphere . (Short

- lived gases simply do not last long enough to become well mixed

. ) This is especially important for the radiative forcing analysis but can also be very relevant to the lifeti me derivation.

 Accurate knowledge of the infrared absorption cross

- sections. These can either be obtained from laboratory measurements or from ab initio theoretical approaches. In practice, if only a very roughly estimated GWP is needed, one can approximat e to another compound with similar chemical structure.

 Accurate knowledge of the radiative forcing of the compound, which requires an accurate radiative transfer modeling capability that represents the effects of the atmospheric distribution of temperature , pressure, clouds, water vapor, ozone and other key constituents. It must also consider possible overlaps of the cross

- sections with those for other gases and particles in the background atmosphere.
The most accurate approach to derive a GWP is to use a f ull three

- dimensional model of the global atmosphere where emissions are assumed at the locations of interest for the derived GWPs. These studies are computationally expensive. To get around this, alternative estimation approaches have been developed. Howe ver, these alternative approaches typically assume that the gases are well mixed in the atmosphere (that is, distributed evenly over all longitudes, latitudes, and altitudes). These approaches therefore do not fully reflect the radiative behavior of gases that are not well mixed, such as short

- lived gases. W hile the methods themselves allow for a radiative forcing analysis that accounts for variation with altitude , in practice, a number of physical chemists who have estimated GWPs assume that the gas is w ell mixed with altitude

. While this is never a completely accurate assumption except for extremely long

- lived gases (lifetime much greater than 200 years), th e assumption is particularly inaccurate for short

- lived compound s , that is, compounds with lifetim es of less than a year. This issue is discussed in more detail by Patten et al. (2011). 1

1 K

. O. Patten, V

. G. Khamaganov, V

. L. Orkin, S

. L. Baughcum, and D

. J. Wuebbles , 2011, OH reaction rate constant, IR absorption spectrum, o zone depletion potentials and global warming potentials of 2

- bromo

- 3,3,3

- t rifluoropropene , Journal of Geophysical Research 116: D24307, doi:10.1029/2011JD016518

.Page 6 of 10 

## Summary of Information Submitted to EPA On February 25, 2011, Honeywell Int ernational (Honeywell) requested to use alternative GWPs for fluorinated GHGs for the purpos es of calculations in paragraph (c)(1) of 40 CFR 98.123(c)(1). Honeywell requested to use alternate (i.e., lower) GWPs for two commercial chemicals produced at their Buffalo Research Laboratory: HFC

- 1234ze (CAS # 29118

- 24

- 9) ( CF 3 CH=CHF ) 2 and HFC

- 1234yf (CA S # 754

- 12

- 1) ( CF 3 CF=CH 2 )

. 3 Honeywell included published scientific papers and other information to fulfill the requirements requested under paragraphs (c)(1)(vi)(A)(1) through (3). Honeywell provided three scientific papers (and other materials referencin g the results of these studies published by EPA) to fulfill the requirements under 98.123 (c)(1)(vi)(A)(1) through (3) : (1) Vassileios C. Papadimitriou, Ranajit K. Talukdar, R. W. Portmann, A. R. Rabvishankara, and James B. Burkholder, 2008, CF 3 CF=CH 2 and (Z)

- C F 3 CF=CHF: temperature dependent OH rate coefficients and global warming potentials, Physical Chemistry Chemical Physics 10:808

– 820. (2) R. Søndergarrd, O. J. Nielsen, M. D. Hurley, T.J. Wallington, and R. Singh, 2007, Atmospheric chemistry of trans

- CF 3 CH=CHF: Kinetics of the gas

- phase reactions with Cl atoms, OH radicals, and O 3 , Chemical Physical Letters 443:199

– 204. (3) O. J. Nielsen, M. S. Javadi, M. P. Sulbaek, M. D. Hurley, T.J. Wallington, and R. Singh, 2007, Atmospheric chemistry of CF 3 CF=CH 2 : Kinetics and m echanisms of gas

- phase reactions with Cl atoms, OH radicals, and O 3 , Chemical Physical Letters 439:18

– 22. Papadimitriou et al. (2008) estimate that the GWP of HFC

- 1234yf ( CF 3 CF=CH 2 ) is less than 4.4, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ), and using the infrared absorption cross

- sections measured in their study. In addition, they also estimate that that HFC

- 1234yf has an estimated local atmospheric lifetime of 12 days based solely on OH reactive loss. However, the authors acknowledge that the constant mixing profiles of HFC

1234yf assumed in the GWP calculation is likely to overestimate the radiative efficiency of the short

- lived compound; and therefore, the GWP estimate should be taken as an upper estimate.
Similar ly, Nielsen et al. (2007) estimate that HFC

- 1234yf ( CF 3 CF=CH 2 ) has an atmospheric lifetime of approximately 11 days with respect to reaction with OH radicals, and a GWP of 4, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ) . However, the authors acknowledge that the quoted lifetime is a global average, and the local lifetimes could be significantly shorter or longer. The authors subsequently use this quoted lifetime and the scaling method outlined by Pinnock et al. (1995) to estimate the GWP. 4 Again, the approach used is likely to lead to an overestimate of the actual GWP values.

2 HFC

- 1234ze (CAS # 29118

- 24

- 9) is also known as trans

- 1,3,3,3

- tetrafluoroprop

- 1

- ene (CF 3 CH=CHF)

3 HFC

- 1234yf (CAS # 754

- 12

- 1) is also known as 2,3,3,3

- tetrafluoroprop

- 1

- ene (CF 3 CF=CH 2 ).

4 S. Pinnock, M. D. Hurley, K. P. Shine, T. J. Wallington, and T. J. Smyth, 1995, J. Geophys. Res. 100:23227.Page 7 of 10 By comparison, Søndergarrd et al. (2007) estimate that HFC

- 1234ze ( CF 3 CH=CHF ) has an atmospheric lifetime of approximately 2 weeks with respect to r eaction with OH radicals, and a GWP of approximately 6, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). A number of the co

- authors (O. J. Nielsen, M. D. Hurley, T.J. Wallington, and R. Singh) of the Nielsen et al. (2007) paper are also co

- authors of the Søndergarrd et al. (2007) paper, and similar methods to those previously described were used to estimate the atmospheric lifetime and GWP values. On June 27, 2011, E. DuPont de Nemours, Inc. (DuPont) requested to use altern ative GWPs for fluorinated GHGs for the purposes of calculations in paragraph (c)(1) of 40 CFR 98.123(c)(1). DuPont requested to use alternate (i.e., lower) GWPs for six chemicals at DuPont plant sites subject to subpart L: hexafluoropropylene (HFP) (CAS # 116

- 15

- 4 ) , perfluoromethyl vinyl ether (PMVE) (CAS # 1187

- 93

- 5 ) , tetrafluoroethylene (TFE) (CAS # 116

- 1 4

- 3 ) , 3,3,3

- trifluoropropene (TFP) (CAS # 677

- 21

- 4 ) , vinyl fluoride (VF) (CAS # 75

- 02

- 5 ) , and vinylidine fluoride (VF2) (CAS # 75

- 38

- 7 ) . For each chemic al, DuPont included peer

- reviewed scientific data and other information to fulfill the requirements requested under paragraphs (c)(1)(vi)(A)(1) through (3).
For hexafluoro propylene (HFP) and tetrafluoroethylene (TFE) , DuPont referred to a study conducted b y Acerboni et al. (2001), 5 which estimated the global and yearly averaged lifetime as 6 days for HEP and 1.9 days for TFE , and a GWP of 0.25 for HEP and 0.021 for TFE , both based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). The study applied a chemical transport model to estimate the atmospheric distributions and lifetime, and radiative forcing calculations were performed using a radiative transfer model assuming either constant vertical concentration profiles or the distribu tions derived from the chemical transport model.
For perfluoromethyl vinyl ether (PMVE) , DuPont referred to a study conducted by Mashino et al. (2000), 6 which estimated the global and yearly averaged lifetime as 8 days with respect to reaction with OH, and a GWP of 2, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). The study estimated the atmospheric lifetime by scaling to the know lifetime of methyl chloroform, and radiative forcing calculations were performed using the
a pproximation method developed by Pinnock et al. (1995). 4

For 3,3,3

- trifluoropropene (TFP) , DuPont referred to a study conducted by Anderson et al. (2005), 7 which estimated the overall global and yearly averaged lifetime as 7.0 days with respect to reaction with OH and O 3 , and a GWP of 3, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). The study estimated the atmospheric lifetime by assuming

5 G. Acerboni, et al., 2001, Atmospheric degradation and global warming poten tials of three perfluoroalkenes, Atmospheric Envir onment 35(24): 4113

– 4123

.
6 M. Mashino, et al., 2000, Atmospheric Degradation of CF 3 OCFCF 2 : Kinetics and Mechanism of Its Reactio n with OH Radicals and Cl Atoms, The Journal of Physical Chemistry A 104(13): 2925

– 2930

.
7 M. P. S. Andersen, et al., 2005, Atm ospheric chemistry of C x F 2x+1 CH=CH2 (x=1, 2, 4, 6, and 8): Kinetics of gas

phase reactions with Cl atoms, OH radicals, and O 3 , Journal of Photochemistry and Photobiology, A: Chemistry , 176(1

– 3):124

– 128

.Page 8 of 10 global weighted average concentration s of OH and O 3 , and radiative forcing calculations were performed using the approximation method developed by Pinnock et al. (1995). 4

For vinyl fluoride (VF) and vinylidine fluoride (VF2) , DuPont referred to a study conducted by Baasandorj et al. (2010), 8 which estimated the overall global and yearly averaged lifetime as 2 days for VF and 4 days for VF2, both with respect to reaction with OH, and a GWP of 0.7 for VF and 0.9 for VF2 , both based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). Radiative forcing calculations were performed using the approximation method developed by Pinnock et al. (1995). 4
In addition, DuPont included informat ion on three additional chemicals whose calculated emission rates, using a GWP of 2000, do not currently equal or exceed 10,000 mtCO 2 e for any vent, but may in the future: carbonyl fluoride (CAS # 353

- 50

- 4) , perfluoropropyl vinyl ether (CAS # 1623

- 05

- 8) , a nd perfluoroethyl vinyl ether (CAS # 10493

- 43

- 3)

. For carbonyl fluoride , DuPont referred to a study conducted by Kanakidou et al. (1995), 9 which estimated the overall global and yearly averaged lifetime to lie in the range of 3.9 to 7.1 days, and a GWP of 2, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). The study estimated the atmospheric lifetime by embedding experimentally determined Henry’s law coefficients and hydrolysis rate constants into a global tropospheric chem ical transport model , and radiative forcing calculations were performed using the approximation method developed by Pinnock et al. (1995). 4

For perfluoropropyl vinyl ether , DuPont estimated the overall global a nd yearly averaged lifetime as 8.077 days, and a GWP of 3, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). The atmospheric lifetime was estimated using the AOPWIN module of E PA’s EPI SuiteTM v4.10 exposure assessment modeling tool, and radiative forcing calculations were performed using the approximation method developed by Pinnock et al. (1995). 4

For perfluoro eth yl vinyl ether , DuP ont estimated the overall global and yearly averaged lifetime as 8.077 days, and a GWP of 3, based on a 100 year time horizon, compared to value of 1 for carbon dioxide (CO 2 ). The atmospheric lifetime was again estimated using the AOPWIN module of EPA’s EP I SuiteTM v4.10 exposure assessment modeling tool, and radiative forcing calculations were again performed using the approximation method developed by Pinnock et al. (1995). 4 The GWP values for all of the compo unds discussed above are all likely to be upper limits because of the assumption in the derivations that the gases are well mixed .

8 M. Baasandorj, et al., 2010, Rate Coefficients for the Gas

- Phase Reaction of the Hydroxyl Radical with CH2═CHF and CH2═CF2. The Journal of Physical Chemistry A 114(13): 4619

– 4633

.
9 M. Kanakidou, F.J. Dentener, and P.J. Crutzen , 1995, A global three

- dimensional study of the fate of HCFCs and HFC

- 134a in th e troposphere , Journal of Geophysical Research 100(D9)

.Page 9 of 10 

## Preliminary Determinations and Their Rationale In accordance with 98.123(c)(1)(vi)(B), EPA review ed the requests from both Honeywell and DuPont to determine whether each wa s complete, substantiate d each of the provisional GWPs, and demonstrate d that the process vents we re calculated to emit less than 10,000 metric tons CO 2 e of fluorinated GHGs only when the proposed provisiona l GWPs, not the default GWP of 2,000, we re used for the fluorinated GHGs for which the p rovisional GWPs were requested.
EPA ma d e a preliminary determination that each of these criteria wa s met for the requests submitted by both Honeywell and DuPont, with one exception. (The exception was for HFC

1234yf , which was emitted in quantities that, with a default GWP of 2,000, result ed in total calculated annual emissions of less than10,000 mtCO 2 e.) The remainder of this section includ es a summary of the determi nation and the data and analysis submitted by the producers under paragraphs (c)(1)(vi)(A)(1) through (3). EPA’s preliminary determination included review of the submitted information by a leading subject matter expert on GWP estimation who was also a co
- developer of the GWP concept. EPA concluded that the methods overall were likely to overestimate GWPs (maybe by an order of magnitude or more) rather than underestimate them. Because 98.123(c)(1) allows the use of engineering calculations only when estima ted emissions fall below 10,000 metric tons CO 2 e, an overestimated GWP is considered acceptable by EPA in the context of 98.123(c)(1). Therefore, the conclusion of EPA’s review was that the background information was adequate and that it justified the use of the alternative GWPs in the context of 98.123(c)(1)(vi). The overestimation of the GWPs submitted by both Honeywell and DuPont results from the fact that the commonly

- used estimation techniques employed in the analyses cited by both companies use simpl ifying assumptions that are not fully applicable to compounds that are short

- lived in the atmosphere

— defined here as any compound with an atmospheric lifetime less than 1 year. (All of the compounds for which provisional GWPs were requested are short

- lived based on this definition.) Essentially, the estimation techniques assume that the compounds are well

- mixed in the atmosphere, but short

- lived compounds do not last long enough to become well mixed (i.e., spread evenly over all longitudes, latitudes, and a ltitudes). Instead, their concentrations decrease rapidly with distance from their emission point, particularly with changing latitude and altitude. The assumption that the compounds are well mixed affects the estimates of both of the primary components o f GWPs: atmospheric lifetime and radiative forcing. In the analyses cited by the companies, atmospheric lifetimes are estimated either by assuming that the short

- lived compound is exposed to the global average concentration of hydroxyl radicals (OH) , or by deriving the lifetime of the short

- lived (i.e., not well

- mixed) compound from the known lifetime of a long

- lived (i.e., well

- mixed) reference compound based on the compounds’ respective reaction rates with OH. Both approaches are likely to overestimate th e lifetime (and therefore the GWP) of the short

- lived compound because they essentially assume that the concentration of the short

- lived compound remains constant with altitude. This overestimates the share of the short

lived compound that resides higher i n the atmosphere, where lower OH concentrations, temperatures, and pressures slow reaction rates and lengthen lifetimes. Radiative forcing is also estimated based on the assumption that the concentration of the short

- lived compound remains constant with al titude. This assumption is likely to overestimate the radiative forcing (andPage 10 of 10 therefore the GWP) of short

- lived compounds because, again, it overestimates the share of the short

- lived compound that resides higher in the atmosphere. GHGs higher in the atmosp here (i.e., near the tropopause) are responsible for more radiative forcing than the same GHGs lower in the atmosphere. Radiative forcing is most sensitive to GHG changes in the vicinity of the tropopause, where the atmospheric temperature minimum occurs. These expectations are born out in radiative transfer calculations where it is found that radiative forcing is most sensitive to concentration changes at the tropopause level. Together, these assumptions may result in overestimates of the GWP by a factor o f ten or more. The provisional GWPs are shown in Table 1

. Table 1 : Provision al Global Warming Potentials for fluorinated greenhouse gases for which EPA has made preliminary determinations that all approval criteria have been met for the purposes of the calculations in 98.123(c)(1) of subpart L.

Fluorinated GHG CAS # Provisional GWP

HFC

- 1234ze 29118

- 24

- 9 6
hexafluoropropylene (HFP) 116

- 15

- 4 0.25
perfluoromethyl vinyl ether (PMVE) 1187

- 93

- 5 3

tetrafluor oethylene (TFE) 116

- 14

- 3 0.02
trifluoro propene (TFP) 677

- 21

- 4 3
vinyl fluoride (VF) 75

- 02

- 5 0.7
vinylidine fluoride (VF2) 75

- 38

- 7 0.9

As noted above, DuPont also included provisional GWPs and data and analysis for three other fluorinated GHGs, includ ing c arbonyl fluoride (CAS # 353

- 50

- 4) , perfluoropropyl vinyl ether (CAS # 1623

- 05

- 8) , and perfluoroethyl vinyl ether (CAS # 10493

- 43

- 3) . Dupont noted that the calculated emissions of these chemicals from particular process vents did not currently exceed 10,000 metric tons of CO2e, but may exceed 10,000 metric tons CO 2 e in the future. In response to these submissions and to Honeywell’s submission of a provisional GWP and data and analysis for HFC

- 1234yf , EPA noted that it would consider the information as Table A

- 1 of 40 CFR Part 98 is updated.