Federal Register / Vol. 76, No. 200 / Monday, October 17, 2011 / Proposed Rules 64059 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 51 

[EPA–HQ–OAR–2010–0605; FRL–9480–4] 

RIN 2060–AQ38 

Air Quality: Revision to Definition of 

Volatile Organic Compounds— 

Exclusion of trans-1,3,3,3- 

tetrafluoropropene and 2,3,3,3- 

tetrafluoropropene 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The EPA is proposing to 

revise the agency’s definition of volatile 

organic compounds (VOCs) for purposes 

of preparing state implementation plans 

(SIPs) to attain the national ambient air 

quality standards (NAAQS) for ozone 

under Title I of the Clean Air Act (CAA). 

This proposed revision would add 

2,3,3,3-tetrafluoropropene (also known 

as HFO–1234yf) and trans-1,3,3,3- 

tetrafluoropropene (also known as 

HFO–1234ze) to the list of compounds 

excluded from the definition of VOC on 

the basis that these compounds make a 

negligible contribution to tropospheric 

ozone formation. 

DATES: Comments must be received on 

or before November 16, 2011. 

Public Hearing: If anyone contacts us 

requesting to speak at a public hearing 

on or before November 1, 2011, we will 

hold a public hearing. Additional 

information about the hearing would be 

published in a subsequent Federal 

Register notice. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–HQ– 

OAR–2010–0605, by one of the 

following methods: 

• http://www.regulations.gov. Follow 

the on-line instructions for submitting 

comments. 

• E-mail: a-and-rDocket@epamail.epa.gov, Attention 

Docket ID No. EPA–HQ–OAR–2010– 

0605. 

• Fax: 202–566–1541, Attention 

Docket ID No. EPA–HQ–OAR–2010– 

0605. 

• Mail: Docket ID No. EPA–HQ– 

OAR–2010–0605, Environmental 

Protection Agency, Mailcode: 6102T, 

1200 Pennsylvania Ave., NW., 

Washington, DC 20460. 

• Hand Delivery: EPA Docket Center, 

U.S. Environmental Protection Agency, 

1301 Constitution Avenue, NW., Room: 

3334, Mail Code: 6102T, Washington, 

DC 20460, Attention Docket ID No. 

EPA–HQ–OAR–2010–0605. Such 

deliveries are only accepted during the 

Docket’s normal hours of operation, and 

special arrangements should be made 

for deliveries of boxed information. 

Instructions: Direct your comments to 

Docket ID No. EPA–HQ–OAR–2010– 

0605. 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 Confidential 

Business Information (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 e-mail. The 

http://www.regulations.gov Web site 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 e-mail 

comment directly to the EPA without 

going through http:// 

www.regulations.gov, your e-mail 

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 avoid the use of 

special characters, 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/epahome/ 

dockets.htm. 

Docket: All documents in the docket 

are listed in the http:// 

www.regulations.gov index. Although 

listed in the index, some information is 

not publicly available, i.e., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

will be publicly available only in hard 

copy. Publicly available docket 

materials are available either 

electronically in http:// 

www.regulations.gov or in hard copy at 

the EPA, EPA/DC, EPA West, Room 

3334, 1301 Constitution Ave., 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 is (202) 566–1742. 

FOR FURTHER INFORMATION CONTACT: 

David Sanders, Office of Air Quality 

Planning and Standards, Air Quality 

Policy Division, Mail Code C539–01, 

Research Triangle Park, NC 27711; 

telephone: (919) 541–3356; fax number: 

(919) 541–0824; e-mail address: 

sanders.dave@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. General Information 

A. Does this action apply to me? 

Entities potentially affected by this 

proposed rule include, but are not 

necessarily limited to, states (typically 

state air pollution control agencies) that 

control VOCs, and industries involved 

in the manufacture or use of 

refrigerants, aerosol propellants, and 

blowing agents for insulating foams. 

Industry group SIC a NAICSb

Refrigerants ............................................................................................................................ 2869, 3585 ..................... 238220, 336111, 

336391. 

Aerosol propellants ................................................................................................................. 2869 ............................... 325998. 

Blowing agents ....................................................................................................................... 2869, 3086 ..................... 326140, 326150. 

aStandard Industrial Classification. 

b North American Industry Classification System. 

This proposed rule is applicable to all 

manufacturers, distributors, and users of 

these chemical compounds. The use of 

these compounds is subject to 

restrictions under the CAA and the 

Toxic Substances Control Act (TSCA). 

Specifically, the use of these 

compounds as aerosol propellants, 

blowing agents, or refrigerants, or any 

other use in which they would 

substitute for chlorofluorocarbons, 

hydrochlorofluorocarbons, or their 


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substitutes, is subject to restrictions 

under the Significant New Alternatives 

Policy (SNAP) program (CAA § 612; 40 

CFR 82 subpart G). The SNAP program 

has issued a final approval for HFO– 

1234yf as a substitute for use in the 

motor vehicle air conditioning end-use 

as a replacement for ozone depleting 

substances (76 FR 17488, March 29, 

2011), and final approvals for HFO– 

1234ze as a suitable foam and 

refrigerant substitute and as a propellant 

(74 FR 50129, September 30, 2009; 75 

FR 34017, June 16, 2010). Furthermore, 

HFO–1234yf is subject to a Significant 

New Use Rule (SNUR) under TSCA. (75 

FR 65987, October 27, 2010). The 

implications of these other regulations 

are discussed in more detail in Section 

III. 

B. What should I consider as I prepare 

my comments for the EPA? 

Submitting CBI: Do not submit this 

information to the EPA through http:// 

www.regulations.gov or e-mail. Clearly 

mark the part or all of the information 

that you claim to be CBI. For CBI 

information in 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 comment that 

includes information claimed as CBI, a 

copy of the comment that does not 

contain the information claimed as CBI 

must be submitted for inclusion in the 

public docket. Information so marked 

will not be disclosed except in 

accordance with procedures set forth in 

40 CFR part 2. 

C. How can I find information about a 

possible public hearing? 

Public Hearing: To request a public 

hearing or information pertaining to a 

public hearing on this document, 

contact Ms. Pamela S. Long, Air Quality 

Policy Division, Mail code C504–01, 

U.S. Environmental Protection Agency, 

Research Triangle Park, NC 27711, 

telephone (919) 541–0641, facsimile 

number (919) 541–5509, e-mail address: 

long.pam@epa.gov. 

D. How is this preamble organized? 

The information presented in this 

preamble is organized as follows: 

I. General Information 

A. Does this action apply to me? 

B. What should I consider as I prepare my 

comments for the EPA? 

C. How can I find information about a 

possible public hearing? 

D. How is this preamble organized? 

II. Background 

A. Petition To List HFO–1234yf 

B. Petition To list HFO–1234ze 

III. The EPA’s Proposed Responses to the 

Petitions 

A. Contribution to Tropospheric Ozone 

B. Likelihood of Risk to Human Health or 

the Environment 

C. Conclusions 

IV. Proposed Action 

V. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Executive Order 13563: 

Improving Regulation and Regulatory 

Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act 

D. Unfunded Mandates Reform Act 

E. Executive Order 13132: Federalism 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer and 

Advancement Act 

J. Executive Order 12898: Federal Actions 

To Address Environmental Justice in 

Minority Populations and Low-Income 

Populations. 

II. Background 

Tropospheric ozone, commonly 

known as smog, is formed when VOCs 

and nitrogen oxides (NOX) react in the 

atmosphere in the presence of sunlight. 

Because of the harmful health effects of 

ozone, the EPA and state governments 

limit the amount of VOCs that can be 

released into the atmosphere. The VOCs 

are those organic compounds of carbon 

which form ozone through atmospheric 

photochemical reactions. Different 

VOCs have different levels of 

reactivity—that is, they do not react to 

form ozone at the same speed or do not 

form ozone to the same extent. Some 

VOCs react slowly, or form less ozone; 

therefore, changes in their emissions 

have limited effects on local or regional 

ozone pollution episodes. It has been 

the EPA’s policy that organic 

compounds with a negligible level of 

reactivity should be excluded from the 

regulatory definition of VOC so as to 

focus VOC control efforts on 

compounds that do significantly 

increase ozone 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 VOCs. The EPA lists these negligibly 

reactive compounds in its regulations 

(at 40 CFR 51.100(s)) and excludes them 

from the definition of VOC. 

The CAA requires the regulation of 

VOCs 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 VOCs for regulatory 

purposes. The policy of excluding 

negligibly reactive compounds from the 

VOC definition was first laid out in the 

‘‘Recommended Policy on Control of 

Volatile Organic Compounds’’ (42 FR 

35314, July 8, 1977) and was 

supplemented most recently with the 

‘‘Interim Guidance on Control of 

Volatile Organic Compounds in Ozone 

State Implementation Plans’’ (Interim 

Guidance) (70 FR 54046, September 13, 

2005). 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 VOCs for regulatory 

purposes and therefore 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 

policy. 

The EPA has used three different 

metrics to compare the reactivity of a 

specific compound to that of ethane: (i) 

the reaction rate constant (known as 

kOH) with the hydroxyl radical (OH); (ii) 

the maximum incremental reactivities 

(MIR) of ethane and the compound in 

question expressed on a reactivity per 

unit mass basis; and (iii) the MIR of 

ethane and the compound in question 

expressed on a reactivity per mole basis. 

Differences between these three metrics 

are discussed below. 

The kOH is the reaction rate constant 

of the compound with the OH radical in 

the air. This reaction is typically the 

first step in a series of chemical 

reactions by which a compound breaks 

down in the air and participates in the 

ozone-forming process. If this step is 

slow, the compound will likely not form 

ozone at a very fast rate. The kOH values 

have long been used by the EPA as a 

measure of photochemical reactivity 

and ozone-forming activity, and they 

have been the basis for most of the 

EPA’s previous exemptions of negligibly 

reactive compounds from the regulatory 

definition of VOC. The kOH metric is 

inherently a molar comparison, i.e., it 

measures the rate at which molecules 

react. 

The MIR values, both by mole and by 

mass, are a more recently developed 

measure of photochemical reactivity 

derived from a computer-based 

photochemical model. This 


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measurement considers the complete 

ozone forming activity of a compound, 

not merely the first reaction step. 

Further explanation of the MIR metric 

can be found in: W. P. L. Carter, 

‘‘Development of Ozone Reactivity 

Scales for Volatile Organic 

Compositions,’’ Journal of the Air & 

Waste Management Association, Vol. 

44, 881–899, July 1994. 

The MIR values for compounds are 

typically expressed as grams of ozone 

formed per gram of VOC (mass basis), 

but may also be expressed as grams of 

ozone formed per mole of VOC (molar 

basis). For comparing the reactivities of 

two compounds, using the molar MIR 

values considers an equal number of 

molecules of the two compounds. 

Alternatively, using the mass MIR 

values compares an equal mass of the 

two compounds, which will involve 

different numbers of molecules, 

depending on the relative molecular 

weights. The molar MIR comparison is 

consistent with the original smog 

chamber experiments that underlie the 

original selection of ethane as the 

threshold compound and compared 

equal molar concentrations of 

individual VOCs. It is also consistent 

with previous reactivity determinations 

based on inherently molar kOH values. 

By contrast, the mass MIR comparison 

is more consistent with how MIR values 

and other reactivity metrics have been 

applied in reactivity-based emission 

limits, such as the national VOC 

emissions standards for aerosol coatings 

(73 FR 15604). Many other VOC 

regulations contain limits based upon a 

weight of VOC per volume of product, 

such as the EPA’s regulations for 

limiting VOC emissions from 

architectural and industrial 

maintenance coatings (65 FR 7736). 

However, the fact that regulations are 

structured to measure VOC content by 

weight for ease of implementation and 

enforcement does not necessarily 

control whether VOC exemption 

decisions should be made on a weight 

basis as well. 

The choice of the molar basis versus 

the mass basis for the ethane 

comparison can be significant. Given 

the relatively low molecular weight of 

ethane, use of the mass basis tends to 

result in more VOCs being classified as 

‘‘negligibly reactive’’ than in the case of 

the molar basis. In some cases, a 

compound might be considered less 

reactive than ethane and eligible for 

VOC exemption under the mass basis 

but not under the molar basis. The 

compounds considered in this proposal, 

HFO–1234yf and HFO–1234ze, fall into 

this category, where the molar MIR 

value is greater than that of ethane, but 

the mass MIR value is equal to or less 

than that of ethane. However, for both 

compounds, both MIR values fall in the 

lower portion of the very wide range of 

VOC reactivities. 

The EPA has considered the choice 

between a molar or mass basis for the 

comparison to ethane in past 

rulemakings and guidance. Most 

recently, in the 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. 

In this action, the EPA is proposing to 

exempt these compounds using the 

comparison to ethane on the mass basis 

MIR value, because MIR values are 

available for these compounds and the 

EPA believes that this comparison is 

appropriate. 

The EPA’s 2005 Interim Guidance 

also notes that concerns have sometimes 

been raised about the potential impact 

of a VOC exemption on environmental 

endpoints other than ozone 

concentrations, including fine particle 

formation, air toxics exposures, 

stratospheric ozone depletion, and 

climate change. The EPA has 

recognized, however, that there are 

existing regulatory and non-regulatory 

programs that are specifically designed 

to address these issues, and the agency 

continues to believe that the impacts of 

VOC exemptions on environmental 

endpoints other than ozone formation 

will be adequately addressed by these 

programs. The VOC exemption policy is 

intended to facilitate attainment of the 

ozone NAAQS, and questions have been 

raised as to whether the agency has 

authority to use its VOC exemption 

policy to address concerns that are 

unrelated to ground-level ozone. Thus, 

in general, VOC exemption decisions 

will continue to be based solely on 

consideration of a compound’s 

contribution to ozone formation. 

However, if the agency 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, the EPA 

reserves the right to exercise its 

judgment in deciding whether to grant 

an exemption. 

In this case, the agency has examined 

available information on the risks to 

human health and the environment and 

applicability of other regulatory 

programs; that information for the two 

compounds considered here is 

discussed further in Section III. 

A. Petition to List HFO–1234yf 

Honeywell, Inc. submitted a petition 

to the EPA on June 29, 2009, requesting 

that HFO–1234yf (CAS 754–12–1) be 

exempted from VOC control based on its 

low reactivity relative to ethane. The 

petitioner indicated that HFO–1234yf 

may be used as a refrigerant for 

refrigeration and air-conditioning. 

Honeywell also indicated that it expects 

HFO–1234yf to be widely used as a 

replacement for HFC–134a in motor 

vehicle air-conditioners (MVAC), and 

that HFO–1234yf has been specifically 

developed for this purpose. Honeywell 

argues that as a replacement for use in 

motor vehicle air conditioners there will 

be an environmental advantage in that 

the global warming potential (GWP) of 

HFO–1234yf is 4, which is substantially 

lower than the GWP for HFC–134a (100- 

year GWP = 1430) which HFO–1234yf is 

designed to replace. Honeywell 

submitted several documents, including 

several peer-reviewed journal articles, to 

support this petition that have been 

added to the docket for this action. 

B. Petition to List HFO–1234ze 

Honeywell, Inc. also submitted a 

petition to the EPA on December 2, 

2009, requesting that HFO–1234ze (CAS 

29118–24–9) be exempted from VOC 

control based on its low reactivity 

relative to ethane. The petitioner 

indicated that HFO–1234ze may be used 

in a variety of applications including as 

a refrigerant, an aerosol propellant, and 

a blowing agent for insulating foam. 

Honeywell submitted several 

documents, including several peerreviewed journal articles, to support its 

petition, all of which have been added 

to the docket for this action. 

III. The EPA’s Proposed Responses to 

the Petitions 

Consistent with the Interim Guidance, 

the EPA’s proposed responses to the 

petitions are based on a consideration of 

the contribution that each chemical 

makes to tropospheric ozone formation 

based on a comparison of reactivity 

metrics, and our assessment that 

existing programs or policies already 

adequately address the possibility that 

granting each petition would pose a 

significant risk to human health or the 

environment. We also believe that the 


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64062 Federal Register / Vol. 76, No. 200 / Monday, October 17, 2011 / Proposed Rules 

1 D. Luecken, R. Waterland, S. Papasavva, K. 

Taddonio, W. Hutzell, J. Rugh, and S. Andersen. 

Ozone and TFA Impacts in North America from 

Degradation of 2,3,3,3–Tetrafluoropropene (HFO– 

1234yf), A Potential Greenhouse Gas Replacement. 

Environ. Sci. Technol. 44, pp. 343–349. 

2The study also noted that if 2,3,3,3- 

tetrafluoropropene were used in additional 

applications that are currently not legal in the U.S, 

e.g., non-vehicle refrigerant applications, its 

contribution to ozone formation would be greater, 

but did not quantify this potential contribution. 

3U.S. EPA. Assessment of the Impacts of Global 

Change on Regional U.S. Air Quality: A Synthesis 

of Climate Change Impacts on Ground-Level Ozone 

(An Interim Report of the U.S. EPA Global Change 

Research Program). U.S. Environmental Protection 

Agency, Washington, D.C., EPA/600/R–07/094F, 

2009. 

4 Jacob, Daniel J. and Darrell A. Winner (2009). 

Effect of climate change on air quality, Atmospheric 

Environment, 43:51–63. 

much lower global warming potential of 

HFO–1234yf compared to the 

compound HFC–134a for which it will 

substitute, as described in Section III.B, 

is an additional reason to approve the 

HFO–1234yf petition in particular, 

given that applying the Interim 

Guidance itself supports such approval. 

Information on these topics is given 

below. 

A. Contribution to Tropospheric Ozone 

Table 1 presents three reactivity 

metrics for ethane (the benchmark 

compound) and for HFO–1234yf and 

HFO–1234ze which are proposed for 

exemption from the VOC definition in 

this proposed rule. 

TABLE 1—REACTIVITIES OF ETHANE, HFO–1234ZE AND HFO–1234YF

Compound kOH

(cm3/molecule-sec) 

MIR 

(g O3/mole VOC) 

MIR 

(g O3/gram VOC) 

Ethane ....................................................................... 2.4 × 10¥13 .............................................................. 8 .4 0 .28 

HFO–1234yf .............................................................. 10.5 × 10¥13 ............................................................ 31 .92 0 .28 

HFO–1234ze ............................................................. 9.25 × 10¥13 ............................................................ 11 .2 0 .098 

Notes: 

1. kOH value for ethane is from: R. Atkinson, D. L. Baulch, R. A. Cox, J. N. Crowley, R. F. Hampson, Jr., R. G. Hynes, M. E. Jenkin, J. A. Kerr, 

M. J. Rossi, and J. Troe (2004), Summary of evaluated kinetic and photochemical data for atmospheric chemistry. 

2. kOH value for HFO–1234ze is from: R. Sondergaard, O. J. Nielsen, M. D. Hurley, T. J. Wallington, and R. Singh, ‘‘Atmospheric chemistry of 

trans-CF3CH=CHF: kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3.’’ Chemical Physics Letters, 443 (2007) 199–204. 

3. kOH value for HFO–1234yf is from: O.J. Nielson, M.S. Javadi, M.P. Sulbaek Anderson, M.D. Hurley, T.J. Wallington, R. Singh, ‘‘Atmospheric 

Chemistry of CF3CF=CH2: kinetics and mechanisms of gas-phase reactions with Cl atoms, OH Radicals, and O3,’’ Chemical Physical Letters, 

439 (2007) 18–22. 

4. Maximum incremental reactivity or MIR (g O3/g VOC) values of ethane, HFO–1234ze and HFO–1234yf are from: William P. L. Carter, ‘‘Development of the SAPRC–07 chemical mechanism and updated ozone reactivity scales’’ (updated 1/27/10). http://www.engr.ucr.edu/carter/

SAPRC/saprc07.pdf. 

5. Molar MIR (g O3/mole VOC) values were calculated from the mass MIR (g O3/g VOC) values by determining the number of moles per gram 

of the relevant organic compound. 

From the data in Table 1, it can be 

seen that HFO–1234yf has a higher kOH

value than ethane, meaning that it 

initially reacts more quickly in the 

atmosphere than ethane. A molecule of 

HFO–1234yf is also more reactive than 

a molecule of ethane, as shown by the 

molar MIR (g O3/mole VOC) values, 

because equal numbers of moles have 

equal numbers of molecules. However, 

a gram of HFO–1234yf has the same 

reactivity as a gram of ethane. This is 

because HFO–1234yf has a molecular 

weight (114) that is more than three 

times that of ethane (molecular weight 

30), and thus requires less than a third 

the number of molecules of HFO–1234yf 

per gram than the number of molecules 

of ethane per gram. 

From the data in Table 1, it also can 

be seen that HFO–1234ze has a higher 

kOH value than ethane, meaning that it 

initially reacts more quickly in the 

atmosphere than ethane. A molecule of 

HFO–1234ze is also more reactive than 

a molecule of ethane, as shown by the 

molar MIR (g O3/mole VOC) values, 

since equal numbers of moles have 

equal numbers of molecules. However, 

a gram of HFO–1234ze is less reactive, 

or creates less ozone on the day of its 

emission to the atmosphere, than a gram 

of ethane. This is because HFO–1234ze 

has a molecular weight (114) that is 

more than three times that of ethane 

(molecular weight 30), and thus requires 

less than a third the number of 

molecules of HFO–1234ze per gram 

than the number of molecules of ethane 

needed per gram. 

Thus, for both of the petitions 

submitted by Honeywell, the data 

supports the contention that the 

reactivity of the compound in the 

petition is equal to or lower than that of 

ethane on a mass MIR basis. 

We anticipate that one of these 

compounds, HFO–1234yf, will be used 

in automobiles as a replacement for the 

current refrigerant HFC–134a, which is 

the only use for which HFO–1234yf has 

been approved to date under the SNAP 

program. Given this one-for-one 

substitution situation, it is informative 

to compare the ozone forming potential 

of HFO–1234yf to that of HFC–134a, 

which has a gram MIR of only 0.0007 

and thus contributes very little to ozone 

formation. The EPA has considered the 

results of a recent peer-reviewed study 

of the increase in ozone that may occur 

as result of the substitution of HFO– 

1234yf for HFC–134a.1 Based on air 

quality modeling, this study found that 

if HFO–1234yf was used in all 

automobiles but not in any other 

application, the incremental amount of 

ozone formed from its degradation in 

the atmosphere was only 0.01% of total 

ozone formed during the simulation due 

to emissions from all sources. This 

portion of ozone formation due to 

automobiles is slightly more than the 

current baseline, where the refrigerant 

used is HCF–134a.2 Thus, the additional 

information from this study shows that, 

under the assumptions used in the air 

quality modeling, the use of HFO– 

1234yf would produce more ozone than 

continued use of HFC–134a, but the 

increase is unlikely to have a significant 

impact on local air quality. One of the 

assumptions used in the modeling was 

that the substitution of one refrigerant 

for the other would not affect 

meteorological conditions that also 

influence ozone formation. 

However, as stated in Section II.A, 

HFO–1234yf has a much lower GWP 

than HFC–134a. Global warming is 

predicted to exacerbate high ozone 

concentrations 3,4, so directionally the 

lower GWP of HFO–1234yf will offset at 

least some of the ozone increase 

predicted by the modeling that assumed 

identical meteorological conditions. The 

EPA believes the very small increase in 

ozone concentrations that may result 

from encouraging the use of HFO– 

1234yf via an exemption from the 


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5HFC–134a, which is not an ozone depleting 

substance, has already largely replaced CFC–12 in 

motor vehicle air conditioners. 

6While use by vehicle owners is not illegal, the 

SNAP conditions prevent the sale of HFO–1234yf 

in containers of the size that would be attractive to 

individual vehicle owners, and also include 

requirements for special connecting equipment for 

the large containers that are legal for sale. In 

addition, as described later in this notice, under a 

recent Significant New Use Rule anyone planning 

to distribute HFO–1234yf for use by a consumer 

would be required to notify the EPA before doing 

so. 

7 In support of this conclusion, the final SNAP 

rule preamble cited two air quality modeling 

studies in addition to Luecken et al. These studies 

focused on air quality in Los Angeles, as a worst 

case scenario. 

8The EPA considered the results of 

developmental testing available at the time of the 

final SNUR action to be of some concern, but not 

a sufficient basis to find HFO–1234yf unacceptable 

under the SNUR determination. As a result, The 

EPA requested additional toxicity testing and 

issued the SNUR for HFO–1234yf. The EPA has 

received and is presently reviewing the results of 

the additional toxicity testing. The EPA continues 

to believe that HFO–1234yf, when used in new 

automobile air conditioning systems in accordance 

with the use conditions under the SNAP rule, does 

not result in significantly greater risks to human 

health than the use of other available substitutes. 

definition of VOC does not constitute a 

sufficient reason to depart from the 

Interim Guidance’s reliance on MIR 

comparisons to ethane as the basis for 

approving VOC exemption requests. 

In summary, for both HFO–1234yf 

and HFO–1234ze, the EPA believes that 

these chemicals qualify as negligibly 

reactive with respect to their 

contribution to tropospheric ozone 

formation. 

B. Likelihood of Risk to Human Health 

or the Environment 

Additionally, we examined and 

present available information on the 

likelihood of risk to human health or the 

environment from increased use of the 

chemicals considered here. We believe 

that current regulation of these 

compounds under other EPA programs 

adequately protects human health and 

the environment. 

The only currently known or potential 

uses for the chemicals being considered 

here are as substitutes for stratospheric 

ozone-depleting substances (ODS), and 

any such use is regulated under the 

SNAP program. Under SNAP, the EPA 

reviews all new substitutes for ODS and 

allows their use in specific applications 

where the overall risks to human health 

and the environment associated with 

their use are comparable to or less than 

those of other compounds used in the 

same manner. 

After reviewing available information 

and public comments regarding its 

safety, health, and environmental risks 

and benefits under the SNAP program, 

the EPA issued a final approval on 

March 29, 2011 (76 FR 174888) for 

HFO–1234yf as an acceptable ODS 

substitute for use in MVAC, subject to 

specific use conditions, in place of 

CFC–12 and HFC–134a.5 The use 

conditions in the SNAP approval have 

the effect of making it illegal to use 

HFO–1234yf in the air conditioning 

systems of heavy-duty trucks, 

refrigerated transport, or off-road 

vehicles such as agricultural or 

construction equipment. The use 

restrictions also have the effect of 

making use of the compound other than 

by manufacturers of automobiles and 

light-duty trucks or by commercial 

automotive service centers either illegal 

or highly unlikely.6

In the SNAP review, the EPA found 

that the use of HFO–1234yf in new 

passenger vehicle and light-duty truck 

MVAC systems, subject to the use 

conditions, does not present a 

significantly greater risk to human 

health and the environment compared 

to the currently approved MVAC 

alternatives. In summary, the EPA’s 

SNAP review reached the following 

conclusions in support of this finding. 

• Substituting HFO–1234yf for HFC– 

134a is environmentally beneficial from 

a climate change perspective as the 

global warming potential of HFO– 

1234yf is much lower (100 year GWP of 

4 for HFO–1234yf vs. 100 year GWP of 

1430 for HFC–134a). The EPA received 

a petition on May 7, 2010, (with a 

follow up petition on November 16, 

2010) from the Natural Resources 

Defense Council, the Institute for 

Governance & Sustainable Development, 

and the Environmental Investigation 

Agency (a non-governmental 

organization) asking the EPA to remove 

HFC–134a from the list of acceptable 

substitutes under the SNAP program for 

use in motor vehicle air conditioners. 

The petitioners cited this difference in 

GWP as a reason for the EPA to approve 

their request. 

• The use conditions of the final 

SNAP approval for HFO–1234yf provide 

protection against potential safety 

hazards related to the flammability of 

the compound, including potential 

exposure to hydrogen fluoride arising 

from thermal decomposition during a 

fire. 

• Like HFC–134a, HFO–1234yf is not 

an ODS, so the substitution of the latter 

for the former will not affect 

stratospheric ozone concentrations. 

• HFO–1234yf will not create 

significant impacts on ground level 

ozone or on local air quality.7

• The production of triflouroacetic 

acid from the atmospheric degradation 

of HFO–1234yf does not pose a 

significant risk of aquatic toxicity or 

ecosystem impacts. 

• When used in accordance with the 

SNAP use restrictions, HFO–1234yf 

does not result in significantly greater 

risks to human health than the use of 

other available or potentially available 

substitutes. 

The EPA conclusion in the final 

SNAP action regarding human health 

risks of HFO–1234yf was based on an 

extensive risk assessment and review of 

public comments. The EPA also noted 

that under the TSCA, the EPA had 

recently performed a pre-manufacture 

review for HFO–1234yf and adopted the 

SNUR (75 FR 65987, Oct. 27, 2010). The 

SNUR for HFO–1234yf requires 

reporting of additional information to 

the EPA before sale may begin for uses 

beyond air conditioning in new 

automobiles or commercial servicing of 

new automobiles built using HFO– 

1234yf, i.e., the EPA must be given 90- 

days notice before HFO–1234yf 

products can be sold directly to 

consumers for the purpose of servicing, 

maintenance, and disposal. During these 

90 days, the EPA can take further action 

to stop that marketing. This 

precautionary step was taken because of 

certain animal data indicating toxicity, 

and the possibility that home mechanics 

might accidentally expose themselves. 

Auto plant workers and repair shop 

professionals were expected to avoid 

exposure through work practices.8

Under the SNUR, the agency will: (a) 

Receive a Significant New Use Notice, 

or SNUN, of any person’s intent to 

manufacture, import, or process HFO– 

1234yf for sale directly to consumers; 

(b) have an opportunity to review and 

evaluate data submitted with the SNUN; 

and (c) be able to regulate HFO–1234yf 

consumer products, if warranted. Any 

other potential applications beyond air 

conditioning in new automobiles or 

commercial servicing of new 

automobiles built using HFO–1234yf 

that may lead to significant exposures 

will also trigger the requirement for a 

SNUN, and would likely trigger further 

review under SNAP. The EPA believes 

these processes will provide adequate 

opportunity to address any health 

effects issues associated with possible 

increased use of HFO–1234yf. 

The EPA’s SNAP program has also 

issued determinations of acceptability 

for HFO–1234ze as an acceptable 

substitute for certain ODS in a number 

of foam blowing end uses, as a 

refrigerant in non-mechanical heat 

transfer, and as a propellant as stated in 

Section I. In this action, the EPA noted 

that HFO–1234ze is not ozone 


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64064 Federal Register / Vol. 76, No. 200 / Monday, October 17, 2011 / Proposed Rules 

depleting, the GWP for HFO–1234ze is 

significantly lower than the GWPs for 

the ozone-depleting substances it will 

replace, HFO–1234ze is not flammable, 

and the toxicity risks of HFO–1234ze 

are low. For these reasons, the EPA 

found that HFO–1234ze will not pose a 

greater overall risk to human health and 

the environment than the other 

substitutes acceptable in these end uses. 

C. Conclusions 

In summary, for both HFO–1234yf 

and HFO–1234ze, the EPA believes that 

(a) these chemicals qualify as negligibly 

reactive with respect to their 

contribution to tropospheric ozone 

formation, and (b) any non-tropospheric 

ozone related risks associated with 

potential increased use are adequately 

addressed by other existing programs 

and policies. We also believe that the 

much lower global warming potential of 

HFO–1234yf compared to the 

compound HFC–134a for which it will 

substitute, as described in Section III.B, 

is an additional reason to approve the 

HFO–1234yf petition in particular, 

given that applying the Interim 

Guidance itself supports such approval. 

We invite the public to submit 

comments and additional information 

relevant to the issue of these 

compounds’ overall risks and benefits to 

human health and the environment, and 

on whether such information should be 

considered in connection with the 

decision to grant an exemption from the 

regulatory definition of VOC. 

IV. Proposed Action 

The EPA is responding to the 

petitions by proposing to revise its 

definition of VOC at 40 CFR 51.100(s) to 

add HFO–1234yf and HFO–1234ze to 

the list of compounds that are exempt 

from the regulatory definition of VOC 

because they are negligibly reactive on 

the basis that they are less reactive than 

ethane on a mass MIR basis. If an entity 

uses or produces any of these two 

compounds 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 ozone NAAQS, then these 

two compounds will not be counted as 

a VOC in determining whether these 

regulatory obligations have been met. 

This action may also affect whether any 

of these two compounds are considered 

as VOCs for state regulatory purposes to 

reduce ozone formation, if a state relies 

on the EPA’s 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, if this action is made 

final, states may not take credit for 

controlling these compounds in their 

ozone control strategies. 

V. Statutory and Executive Order 

Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review and Executive 

Order 13563: Improving Regulation and 

Regulatory Review 

Under Executive Order (EO) 12866 

(58 FR 51735, October 4, 1993), this 

action is treated as a significant 

regulatory action because some may 

view it as raising novel legal or policy 

issues arising out of legal mandates. 

Accordingly, the EPA submitted this 

action to the Office of Management and 

Budget (OMB) for review under EO 

12866 and 13563 (76 FR 3821, January 

21, 2011) and any changes made in 

response to OMB recommendations 

have been documented in the docket for 

this action. 

B. Paperwork Reduction Act 

This action does not impose an 

information collection burden under the 

provisions of the Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. Burden is 

defined at 5 CFR 1320.3(b). It does not 

contain any recordkeeping or reporting 

requirement. 

C. Regulatory Flexibility Act 

The Regulatory Flexibility Act (RFA) 

generally requires an agency to prepare 

a regulatory flexibility analysis of any 

rule subject to notice and comment 

rulemaking requirements under the 

Administrative Procedure Act or any 

other statute unless the agency certifies 

that the proposed rule will not have a 

significant economic impact on a 

substantial number of small entities. 

Small entities include small businesses, 

small organizations, and small 

governmental jurisdictions. For 

purposes of assessing the impacts of this 

notice on small entities, small entity is 

defined as: (1) A small business that is 

a small industrial entity as defined in 

the U.S. Small Business Administration 

(SBA) size standards. (See 13 CFR 121.); 

(2) A governmental jurisdiction that is a 

government of a city, county, town, 

school district or special district with a 

population of less than 50,000; and (3) 

A small organization that is any not-forprofit enterprise which is independently 

owned and operated and is not 

dominant in its field. 

After considering the economic 

impacts of this proposed rule on small 

entities, I certify that this action will not 

have a significant economic impact on 

a substantial number of small entities. 

This proposed rule will not impose any 

requirements on small entities. 

We continue to be interested in the 

potential impacts of the proposed rule 

on small entities and welcome 

comments on issues related to such 

impacts. 

D. Unfunded Mandates Reform Act 

This action contains no Federal 

mandates under the provisions of Title 

II of the Unfunded Mandates Reform 

Act of 1995 (UMRA), 2 U.S.C. 1531– 

1538 for state, local, or Tribal 

governments or the private sector. The 

action imposes no enforceable duty on 

any state, local or Tribal governments, 

or the private sector. Therefore, this 

action is not subject to the requirements 

of sections 202 and 205 of the UMRA. 

This action is also not subject to the 

requirements of section 203 of UMRA 

because it contains no regulatory 

requirements that might significantly or 

uniquely affect small governments. 

E. Executive Order 13132—Federalism 

This action does not have federalism 

implications. It will not have substantial 

direct effects on the states, on the 

relationship between the national 

government and the states, or on the 

distribution of power and 

responsibilities among the various 

levels of government, as specified in 

Executive Order 13132. This action 

addresses the exemption of a set of 

chemical compounds from the VOC 

definition. Thus, Executive Order 13132 

does not apply to this rule. In the spirit 

of Executive Order 13132, and 

consistent with the EPA policy to 

promote communications between the 

EPA and state and local governments, 

the EPA specifically solicits comment 

on this proposed rule from state and 

local officials. 

F. Executive Order 13175: Consultation 

and Coordination With Indian Tribal 

Governments 

This action does not have Tribal 

implications, as specified in Executive 

Order 13175 (65 FR 67249, November 9, 

2000). It will not have substantial direct 

effects on Tribal governments, on the 

relationship between the Federal 

government and Indian Tribes, or on the 

distribution of power and 

responsibilities between the Federal 

government and Indian Tribes, as 

specified in Executive Order 13175. 

Thus, Executive Order 13175 does not 

apply to this rule. 

Although Executive Order 13175 does 

not apply to this proposed rule, the EPA 

specifically solicits additional comment 

on this proposed rule from Tribal 

officials. 


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Federal Register / Vol. 76, No. 200 / Monday, October 17, 2011 / Proposed Rules 64065 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

and Safety Risks 

This action is not subject to EO 13045 

(62 FR 19885, April 23, 1997) because 

it is not economically significant as 

defined in EO 12866. While this 

proposed rule is not subject to the 

Executive Order, the EPA has reason to 

believe that ozone has a 

disproportionate effect on active 

children who play outdoors (62 FR 

38856; 38859, July 18, 1997). The EPA 

has not identified any specific studies 

on whether or to what extent these 

chemical compounds may affect 

children’s health. The EPA has placed 

the available data regarding the health 

effects of HFO–1234yf in Docket No. 

EPA–HQ–OAR–2003–0032 which is the 

docket for the SNUR for this compound. 

The public is invited to submit 

comments or identify peer-reviewed 

studies and data, of which the EPA may 

not be aware, that assess results of early 

life exposure to the chemical 

compounds herein. 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not a ‘‘significant 

energy action’’ as defined in Executive 

Order 13211, ‘‘Actions Concerning 

Regulations That Significantly Affect 

Energy Supply, Distribution, or Use’’ (66 

FR 28355, May 22, 2001) because it is 

not likely to have a significant adverse 

effect on the supply, distribution, or use 

of energy. This action proposes to revise 

the EPA’s definition of VOCs for 

purposes of preparing SIPs to attain the 

NAAQS for ozone under title I of the 

CAA. 

I. National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (‘‘NTTAA’’), Public Law 

104–113, section 12(d), (15 U.S.C. 272 

note) directs the EPA to use voluntary 

consensus standards in its regulatory 

activities unless to do so would be 

inconsistent with applicable law or 

otherwise impractical. Voluntary 

consensus standards are technical 

standards (e.g., materials specifications, 

test methods, sampling procedures, and 

business practices) that are developed or 

adopted by voluntary consensus 

standards bodies. The NTTAA directs 

the EPA to provide Congress, through 

OMB, explanations when the agency 

decides not to use available and 

applicable voluntary consensus 

standards. This rulemaking does not 

involve technical standards. Therefore, 

the EPA is not considering the use of 

any voluntary consensus standards. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations 

Executive Order (EO) 12898 (59 FR 

7629, Feb. 16, 1994) establishes Federal 

executive policy on environmental 

justice. Its main provision directs 

Federal agencies, to the greatest extent 

practicable and permitted by law, to 

make environmental justice part of their 

mission by identifying and addressing, 

as appropriate, disproportionately high 

and adverse human health or 

environmental effects of their programs, 

policies, and activities on minority 

populations and low-income 

populations in the United States. 

The EPA has determined that this 

proposed rule will not have 

disproportionately high and adverse 

human health or environmental effects 

on minority or low-income populations 

because it will not affect the level of 

protection provided to human health or 

the environment. 

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: October 11, 2011. 

Lisa P. Jackson, 

Administrator. 

For reasons set forth in the preamble, 

part 51 of chapter I of title 40 of the 

Code of Federal Regulations is proposed 

to be amended as follows: 

PART 51—REQUIREMENTS FOR 

PREPARATION, ADOPTION, AND 

SUBMITTAL OF IMPLEMENTATION 

PLANS 

1. The authority citation for Part 51, 

Subpart F, continues to read as follows: 

Authority: 42 U.S.C. 7401, 7411, 7412, 

7413, 7414, 7470–7479, 7501–7508, 7601, 

and 7602. 

§ 51.100 [Amended] 

2. Section 51.100 is amended at the 

end of paragraph (s)(1) introductory text 

by removing the words ‘‘and 

perfluorocarbon compounds which fall 

into these classes:’’ and adding in their 

place a semi-colon and the words 

‘‘trans-1,3,3,3-tetrafluoropropene; 

2,3,3,3-tetrafluoropropene and 

perfluorocarbon compounds which fall 

into these classes:’’. 

[FR Doc. 2011–26768 Filed 10–14–11; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R06–OAR–2007–0314; FRL–9479–9] 

Approval and Promulgation of 

Implementation Plans; Oklahoma; 

Interstate Transport of Pollution 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: EPA is proposing to take 

action on portions of State 

Implementation Plan (SIP) revisions 

submitted by the State of Oklahoma to 

address Clean Air Act requirements that 

prohibit air emissions which will 

contribute significantly to 

nonattainment in, or interfere with 

maintenance by, any other State for the 

1997 8-hour ozone National Ambient 

Air Quality Standards (NAAQS or 

standards), the 1997 fine particulate 

matter (PM2.5) NAAQS and the 2006 24- 

hour PM2.5 NAAQS. EPA is basing these 

proposed actions on the final 

determinations concluded within the 

Cross State Air Pollution Rule (CSAPR 

or Transport Rule) and proposed 

determination within the Supplemental 

Notice of Proposed Rulemaking (SNPR). 

EPA is proposing to disapprove, or in 

the alternative, approve the portion of 

the submittal demonstrating Oklahoma 

does not interfere with maintenance of 

the ozone NAAQS in other states. EPA 

intends to finalize approval or 

disapproval based on its final 

determination for the SNPR regarding 

Oklahoma for the ozone NAAQS. EPA is 

also proposing to approve the portion of 

the submittal demonstrating Oklahoma 

does not contribute significantly to 

nonattainment of the ozone NAAQS in 

other states. Finally, EPA is proposing 

to approve the portions of the submittals 

addressing Oklahoma’s impacts for the 

PM2.5 NAAQS in other states. This 

action is being taken under section 110 

of the CAA. 

DATES: Written comments must be 

received on or before November 16, 

2011. 

ADDRESSES: Submit your comments, 

identified by Docket No. EPA–R06– 

OAR–2007–0314, by one of the 

following methods: 

• Federal e-Rulemaking Portal: 

http://www.regulations.gov. 

• Follow the online instructions for 

submitting comments. 

• E-mail: Mr. Guy Donaldson at 

donaldson.guy@epa.gov. Please also 

send a copy by e-mail to the person 

listed in the FOR FURTHER INFORMATION

CONTACT section below. 


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