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6560-50-P

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[EPA-HQ-OAR-2010-0605; FRL- ]

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: 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 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 [INSERT DATE 30 DAYS 

AFTER PUBLICATION IN THE FEDERAL REGISTER]. 

Public Hearing: If anyone contacts us requesting to speak at a 

public hearing on or before [INSERT DATE 15 DAYS AFTER PUBLICATION IN 

THE FEDERAL REGISTER], we will hold a public hearing in Research 
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Triangle Park, North Carolina. Additional information about the 

hearing would be published in a subsequent Federal Register notice.

ADDRESSES: Submit your comments, identified by Docket ID No. EPAHQ-OAR-2010-0605, by one of the following methods:

 www.regulations.gov. Follow the on-line instructions for 

submitting comments.

 E-mail: a-and-r-Docket@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, D.C. 20460, Attention Docket ID No. EPA-HQOAR-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. EPA's policy is that all comments received will be included in 

the public docket without change and may be made available online at 
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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 www.regulations.gov, or e-mail. 

The www.regulations.gov website is an “anonymous access” system, 

which means EPA will not know your identity or contact information 

unless you provide it in the body of your comment. If you send an email comment directly to EPA without going through 

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, 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 EPA cannot read your comment due to 

technical difficulties and cannot contact you for clarification, 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 

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 

www.regulations.gov index. Although listed in the index, some 
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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 www.regulations.gov or in hard copy at the Docket 

ID No. EPA-HQ-OAR-2010-0605, 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 Docket ID No. EPAHQ-OAR-2010-0605 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 

not necessarily limited to, states (typically state air pollution 

control agencies) that control VOCs, and industries involved in the 
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manufacture or use of refrigerants, aerosol propellants, and blowing 

agents for insulating foams.

Industry group SICa NAICSb

Refrigerants

Aerosol propellants

Blowing agents

2869, 

358

2869

2869, 

3079

233415, 238220, 3411, 44811

3411

326140, 326150, 3411

a Standard Industrial Classification.

b North American Industry Classification System.

This proposed rule is applicable to all manufacturers, 

distributors, and users of these chemical compounds. In addition to 

this rule, the use of these compounds is subject to restrictions 

under other parts of 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 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 

determinations for trans-1,3,3,3-tetrafluoropropene (HFO-1234ze) as a 

suitable foam and refrigerant substitute (74 FR 50129, September 30, 

2009; 75 FR 34017, June 16, 2010) and a final approval for 2,3,3,3-
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tetrafluoropropene (HFO-1234yf), (76 FR 17488, March 29, 2011), as a 

substitute for use in the motor vehicle air conditioning end-use as a 

replacement for ozone depleting substances. 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 EPA?

Submitting CBI: Do not submit this information to EPA through 

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 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 C504-03, U.S. 

Environmental Protection Agency, Research Triangle Park, NC 27711, 
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telephone (919) 541-0641, facsimile number (919) 541-5509, electronic 

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 EPA?

C. How can I find information about a possible public hearing?

D. How is this preamble organized?

II. Background

A. Petition to list 2,3,3,3-tetrafluoropropene 

B. Petition to list trans-1,3,3,3-tetrafluoropropene

III. EPA Response to the Petitions

IV. Proposed Action

V. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and 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, EPA and 

state governments limit the amount of VOCs that can be released into 
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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 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. 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. 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 EPA has the authority to 

define what this term means, and hence what compounds shall be 

treated as VOCs for regulatory purposes. The policy of excluding 

negligibly reactive compounds from the VOC definition was laid out in 

the “Recommended Policy on Control of Volatile Organic Compounds” (42 

FR 35314, July 8, 1977). EPA uses the reactivity of ethane as the 
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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. 

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 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 EPA as a measure of 
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photochemical reactivity and ozone-forming activity, and they have 

been the basis for most of EPA’s previous exclusions of negligibly 

reactive compounds. 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 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, which 

compared equal molar concentrations of individual VOCs that underlie 

the original selection of ethane as the threshold compound. It is 
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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 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, trans-1,3,3,3-tetrafluoropropene and 2,3,3,3-

tetrafluoropropene, fall into this category, where the molar MIR 

value is greater than that of ethane, but the mass MIR value is less 

than that of ethane. 
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EPA has considered the choice between a molar or mass basis for 

the comparison to ethane in past rulemakings and guidance. Most 

recently, in “Interim Guidance on Control of Volatile Organic 

Compounds in Ozone State Implementation Plans” published on September 

13, 2005 (70 FR 54046), 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 VOCexempt 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, 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 EPA believes that this 

comparison is appropriate.

EPA’s 2005 Interim Guidance also notes that, although VOC 

exemption decisions should be based on the contribution of a compound

to tropospheric ozone formation, the EPA may consider whether 

granting a VOC exemption may lead to other significant risks to human 

health and the environment that would not be addressed adequately by 

existing programs or policies. Such considerations with respect to 

the two compounds considered here are discussed further in Section 

III.

A. Petition to list 2,3,3,3-tetrafluoropropene (HFO-1234yf)
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Honeywell, Inc. submitted a petition to EPA on June 29, 2009, 

requesting that 2,3,3,3-tetrafluoropropene be exempted from VOC 

control based on its low reactivity relative to ethane. The 

petitioner indicated that 2,3,3,3-tetrafluoropropene may be used as a 

refrigerant for refrigeration and air-conditioning. Honeywell also 

indicated that it expects 2,3,3,3-tetrafluoropropene to be widely 

used as a replacement for HFC-134a in motor vehicle air-conditioners

(MVAC), and that 2,3,3,3-tetrafluoropropene 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 

2,3,3,3-tetrafluoropropene is 4, which is substantially lower than 

the GWP for HFC-134a (100-year GWP = 1430) which 2,3,3,3-

tetrafluoropropene is designed to replace. Honeywell submitted 

several documents, including several peer-reviewed journal articles, 

to support this petition which have been added to the docket for this 

action.

B. Petition to list trans-1,3,3,3-tetrafluoropropene (HFO-1234ze) 

Honeywell, Inc. also submitted a petition to EPA on December 2, 

2009, requesting that trans-1,3,3,3-tetrafluoropropene be exempted 

from VOC control based on its low reactivity relative to ethane. The 

petitioner indicated that trans-1,3,3,3-tetrafluoropropene may be 

used in a variety of applications including as a refrigerant, an 
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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. EPA Response to the Petitions

EPA’s response to the petitions is based on a consideration of 

a) the contribution that the chemicals make to tropospheric ozone 

formation based on a comparison of reactivity metrics, and b) the 

potential for other significant health and environmental risks that 

may not be adequately addressed by other programs or policies.

Table 1 presents three reactivity metrics for ethane and for 

2,3,3,3-tetrafluoropropene (CAS 754-12-1) and trans-1,3,3,3-

tetrafluoropropene (CAS 29118-24-9) which are discussed in this 

proposed rule. 

Table 1 - Reactivities of ethane, trans-1,3,3,3-

tetrafluoropropene and 

2,3,3,3-tetrafluoropropene

Compound kOH

(cm3/moleculesec)

MIR 

(g O3/mole 

VOC)

MIR 

(g O3/gram

VOC)

Ethane 2.4 x 10-13 8.4 0.28

2,3,3,3- 10.5 x 10-13 31.92 0.28
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tetrafluoropropene

(HFO-1234yf)

trans-1,3,3,3-

tetrafluoropropene

(HFO-1234ze)

9.25 x 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 trans-1,3,3,3-tetrafluoropropene 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 2,3,3,3-tetrafluoropropene 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, trans-1,3,3,3-tetrafluoropropene and 2,3,3,3-

tetrafluoropropene 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 also be seen that 2,3,3,3-

tetrafluoropropene has a higher kOH value than ethane, meaning that it 

initially reacts more quickly in the atmosphere than ethane. A 

molecule of 2,3,3,3-tetrafluoropropene is also more reactive than a 
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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 2,3,3,3-tetrafluoropropene is less reactive, or 

creates less ozone on the day of its emission to the atmosphere, than 

a gram of ethane. This is because 2,3,3,3-tetrafluoropropene has a 

molecular weight (114) that is more than three times that of ethane 

(molecular weight 30), thus requiring less than a third the number of 

molecules of 2,3,3,3-tetrafluoropropene per gram than the number of 

molecules of ethane per gram.

From the data in Table 1, it can be seen that trans-1,3,3,3-

tetrafluoropropene has a higher kOH value than ethane, meaning that it 

initially reacts more quickly in the atmosphere than ethane. A 

molecule of trans-1,3,3,3-tetrafluoropropene 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 trans-1,3,3,3-tetrafluoropropene is less reactive, 

or creates less ozone on the day of its emission to the atmosphere, 

than a gram of ethane. This is because trans-1,3,3,3-

tetrafluoropropene has a molecular weight (114) that is more than 

three times that of ethane (molecular weight 30), thus requiring less 

than a third the number of molecules of trans-1,3,3,3-

tetrafluoropropene per gram than the number of molecules of ethane 

needed per gram. 
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For the petitions submitted by Honeywell, the data supports the 

contention that the reactivity of the compounds in the petitions are 

equal to or lower than that of ethane on a mass MIR basis.

EPA also considered the results of a peer-reviewed study1, in 

which, among other things, potential air quality impacts from 

generation of ground-level ozone were modeled using a regional-scale 

3-dimensional atmospheric model. This study found that, if 2,3,3,3-

tetrafluoropropene was used in all automobiles and was only emitted 

from automobiles, the incremental amount of ozone formed from its 

degradation in the atmosphere was only 0.01% of total ozone formed 

during the simulation. The baseline for this analysis was that if 

2,3,3,3-tetrafluoropropene were not used in automobiles, the 

refrigerant that auto manufacturers would continue to use is HCF-134a 

which, because of its slower reaction time, would produce a smaller

incremental amount of ozone. However, the study also noted that if 

2,3,3,3-tetrafluoropropene were used in additional applications, 

e.g., non-vehicle refrigerant applications, its contribution to ozone 

formation would be greater. Thus, the additional information from 

this study shows that 2,3,3,3-tetrafluoropropene does produce ozone, 

but the amount is unlikely to have a significant impact on local air 

 

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.
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quality under current conditions. The study authors also considered 

the potential for the use of 2,3,3,3-tetrafluoropropene to increase 

the deposition of trifluoroacetic acid, a product of atmospheric 

degradation, into water bodies. The authors concluded that the 

modeled concentrations of deposited trifluoroacetic acid from the use 

of 2,3,3,3-tetrafluoropropene in automobiles were well below levels 

of concern for aquatic toxicity; however, the potential for longterm accumulation of trifluoroacetic acid in water bodies is still 

somewhat uncertain. 

The definition of VOC, and thus the exclusion from that 

definition, applies to all uses of a chemical. The currently known 

uses for the chemicals being considered here are regulated as 

substitutes for stratospheric ozone-depleting substances (ODS) under 

the SNAP program. Under SNAP, 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. 

EPA’s SNAP program has issued determinations of acceptability 

for trans-1,3,3,3-tetrafluoropropene (HFO-1234ze) as an acceptable 

substitute for certain ODS in a number of foam blowing end uses and 

as a refrigerant in non-mechanical heat transfer as stated in Section 

I.
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EPA proposed an approval (74 FR 53445, October 19, 2009) for

2,3,3,3-tetrafluoropropene (HFO-1234yf) as an acceptable ODS 

substitute for use in MVAC, subject to specific use conditions, in 

place of CFC-12 and HFC-134a and issued final approval in March 2011 

as stated in Section I. HFC-134a, which is not an ozone depleting 

substance but has a high global warming potential (100 year GWP = 

1430), has largely replaced CFC-12 in motor vehicle air conditioners. 

Substituting 2,3,3,3-tetrafluoropropene (HFO-1234yf) for HFC-134a is 

environmentally beneficial as the global warming potential of HFO1234yf is much lower (100 year GWP = 4). 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 EPA to remove HFC-134a from 

the list of acceptable substitutes under the SNAP program for use in 

motor vehicle air conditioners. 

Under TSCA, EPA has performed a pre-manufacture review for 

2,3,3,3-tetrafluoropropene (HFO-1234yf) (75 FR 65987, Oct. 27, 2010). 

Based on toxicity testing data submitted as part of the premanufacture notice for HFO-1234yf, EPA identified health concerns for 

developmental toxicity and lethality to workers and consumers if they 

were exposed to a significant amount of HFO-1234yf via inhalation. As 

a result, EPA has requested additional toxicity testing and issued a 
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SNUR for 2,3,3,3-tetrafluoropropene (HFO-1234yf). The SNUR requires 

manufacturers or other affected parties to submit a notice (a 

Significant New Use Notice, or SNUN) to EPA at least 90 days before 

the manufacture, import, or processing of HFO-1234yf for the 

following uses: a) use other than as a refrigerant in MVAC systems in 

new passenger cars and vehicles; b) commercial use other than in new 

passenger cars and vehicles in which the charging of MVAC systems 

with HFO-1234yf was done by the motor vehicle original equipment 

manufacturer (OEM); and c) distribution in commerce of products 

intended for use by a consumer for the purpose of servicing, 

maintenance and disposal involving HFO-1234yf. By issuing this SNUR, 

the Agency will: a) receive a SNUN of any person's intent to 

manufacture, import, or process the chemical substance for the 

described significant new use before that activity begins; b) have an 

opportunity to review and evaluate data submitted with a SNUN before 

the notice submitter begins manufacturing, importing, or processing a 

listed chemical substance for the described significant new use; and 

c) be able to regulate prospective manufacture, import, or processing 

of a listed chemical substance before the described significant new 

use of that chemical substance occurs, if warranted. 

In issuing the SNUR, EPA did not raise concerns about potential 

exposures due to the use of HFO-1234yf in MVAC as approved under the 

SNAP program, as the use restrictions under SNAP are expected to 
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minimize environmental release and exposures. Other potential 

applications that may lead to significant exposures would trigger a 

SNUN and would likely trigger further review under SNAP. EPA believes 

these processes will provide adequate opportunity to address any 

health effects issues associated with possible increased use of HFO1234yf which might result from a VOC exemption. 

In summary, for both trans-1,3,3,3-tetrafluoropropene (HFO1234ze) and 2,3,3,3-tetrafluoropropene (HFO-1234yf), 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 invite the public to submit comments and additional 

information relevant to the issue of these compounds’ overall risks 

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

EPA is responding to the petitions by proposing to revise its 

definition of VOC at 40 CFR 51.100(s) to add trans-1,3,3,3-

tetrafluoropropene and 2,3,3,3-tetrafluoropropene to the list of 

compounds that are exempt from the regulatory definition of VOC 
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because they are negligibly reactive on the basis that they are less 

reactive than ethane on a mass MIR basis. 

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, 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 
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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-for-profit 

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. 
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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 EPA 

policy to promote communications between EPA and state and local 

governments, 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 
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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, EPA specifically solicits additional comment on this proposed 

rule from tribal officials.

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, EPA has reason to believe that ozone has a disproportionate 

effect on active children who play outdoors (62 FR 38856; 38859, July 

18, 1997). EPA has not identified any specific studies on whether or 

to what extent these chemical compounds may affect children's health. 

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 peerreviewed studies and data, of which EPA may not be aware, that assess 

results of early life exposure to the chemical compounds herein.
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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 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 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 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 
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standards. Therefore, 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. 

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.
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Page 28 of 29 - Air Quality: Revision to Definition of Volatile 

Organic Compounds – Exclusion of trans-1,3,3,3-tetrafluoropropene and 

2,3,3,3-tetrafluoropropene

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: 

_________________________

Lisa P. Jackson,

Administrator.
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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:”.