Air Quality: Revision to Definition of Volatile Organic CompoundsExclusion of Acetone

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[FRL-4895-4]

Air Quality: Revision to Definition of Volatile Organic

Compounds--Exclusion of Acetone

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The EPA is proposing to revise its definition of volatile

organic compounds (VOC) for purposes of preparing State implementation

plans (SIP's) to attain the national ambient air quality standards

(NAAQS) for ozone under title I of the Clean Air Act (Act) and for the

Federal implementation plan for the Chicago ozone nonattainment area.

The proposed revision would add acetone to the list of compounds

excluded from the definition of VOC on the basis that these compounds

have negligible contribution to tropospheric ozone formation.

DATES: Comments on this proposal must be received by November 29, 1994.

ADDRESSES: Comments should be submitted in duplicate (if possible) to:

Air and Radiation Docket and Information Center (6102), Attention:

Docket No. A-94-26, U.S. Environmental Protection Agency, 401 M Street,

SW., Washington, DC 20460. Comments should be strictly limited to the

subject matter of this proposal, the scope of which is discussed below.

Public Hearing: If anyone contacts EPA requesting a public hearing,

it will be held at Research Triangle Park, North Carolina. Persons

wishing to request a public hearing, wanting to attend the hearing or

wishing to present oral testimony should notify Mr. William Johnson,

Air Quality Management Division (MD-15), U.S. Environmental Protection

Agency, Research Triangle Park, North Carolina 27711, telephone (919)

541-5245. The EPA will publish notice of a hearing, if a hearing is

requested, in the Federal Register. Any hearing will be strictly

limited to the subject matter of the proposal, the scope of which is

discussed below.

This action is subject to the procedural requirements of section

307(d)(1) (B), (J), and (U) of the Act, and 42 U.S.C. 7607(d)(1) (B),

(J), and (U). Therefore, EPA has established a public docket for this

action, A-94-26, which is available for public inspection and copying

between 8 a.m. and 4 p.m., Monday through Friday, at EPA's Central

Docket Section, room M-1500, 401 M Street, SW., Washington, DC 20460. A

reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: William Johnson, Office of Air Quality

Planning and Standards, Air Quality Management Division (MD-15),

Research Triangle Park, NC 27711, phone (919) 541-5245.

SUPPLEMENTARY INFORMATION:

I. Background

Three petitions have been received by the EPA asking that acetone

be added to the list of negligibly-reactive compounds in the definition

of VOC at 40 CFR 51.100(s). These petitions were submitted by Eastman

Chemical Company and Hoechst Celanese Corporation on April 26, 1993,

Hickory Springs Manufacturing Company on May 6, 1993, and the Chemical

Manufacturers Association on May 14, 1993. Along with their petitions

and in supplemental submissions, these organizations submitted a

variety of scientific materials which support the assertion that

acetone is of negligible photochemical reactivity. These materials have

been added to the docket for this rulemaking.

The petitioners based their request for the exclusion of acetone on

a demonstration that the photochemical reactivity of acetone is not

appreciably different from that of ethane, which is the most reactive

compound on the current list of compounds which are named in the

definition of VOC as being of negligible reactivity. Acetone's

photochemical reactivity arises through two chemical pathways: through

reaction with hydroxyl (OH) radicals (kOH reactivity) and through

photolysis. Data on the reaction of OH radicals with various organic

compounds are reported in a review article (Atkinson, R. (1990),

``Gas--Phase Tropospheric Chemistry of Organic Compounds: A Review.''

Atmospheric Environment, 24 A:1-41) which gives the following rate

constants for reactions of ethane and acetone with OH:

Ethane: 2.68 x 10-13 cc/molecule/sec.

Acetone: 2.26 x 10-13 cc/molecule/sec.

Thus, if the kOH reactivities alone are considered, acetone is

less reactive than ethane. Unlike ethane, however, acetone undergoes

photodecomposition, or photolysis, in the atmosphere to form radicals,

which tend to cause increased rates of ozone formation. Total

reactivity of acetone, considering both kOH reactivity and

photolysis, was the subject of a special study reported recently

(Carter, W. P. L. et al., ``An Experimental and Modeling Study of the

Photochemical Ozone Reactivity of Acetone,'' University of California/

Riverside, December 10, 1993).

The Carter report describes a series of environmental chamber

experiments and computer model simulations carried out to assess the

tendency of acetone to promote ozone formation under atmospheric

conditions, relative to that of ethane. This was done by calculating

and comparing the ``incremental reactivities'' of acetone and ethane

for a variety of atmospheric conditions representing ozone episodes in

39 urban areas throughout the United States.

``Incremental reactivity'' is the most recently proposed

quantitative measure of the degree to which a VOC contributes to ozone

formation in a photochemical air pollution episode. It is defined as

the amount of additional ozone formation resulting from the addition of

a small amount of VOC to the urban emissions, divided by the amount of

compound added. This measure of reactivity takes into account all of

the factors by which a VOC affects ozone formation, including the

effect of the environment where the VOC reacts. The latter is important

because the amount of ozone formation caused by the reactions of a VOC

depends significantly on the conditions within the polluted atmosphere,

such as VOC to nitrogen oxide (NOX) ratio, VOC composition, and

sunlight intensity. Figure 1 shows distribution plots of the reactivity

of acetone relative to that of ethane for the 39 urban scenarios used,

where reactivity is defined in terms of grams of ozone formed per gram

of VOC emitted. (Use of the unit grams of ozone formed per gram of VOC

emitted is significant. Another way of defining reactivity is in terms

of grams of ozone formed per mole of VOC emitted, which would give

different results. For practicality, the EPA has elected to adopt the

grams ozone per gram VOC basis, since grams (or tons), rather than

moles, is the mass unit used in regulations dealing with VOC

emissions.) In Figure 1, acetone/ethane reactivity ratios less than 1.0

indicate scenarios where acetone is less reactive than ethane. The

acetone/ethane reactivity ratio, as reported by Carter, appears to have

widely varying values among the 39 urban scenarios and to reflect, with

a few exceptions, slightly lower reactivity for acetone. For one

scenario, which represents unusually high NOX conditions, acetone

was calculated to be over two times more reactive than ethane. This is

due to the unusually low reactivity of ethane for that particular

scenario, rather than to higher acetone reactivity. Figure 2 shows the

variability of ethane reactivity relative to that of a ``typical''

urban VOC mix. Figure 2 also shows that the reactivity range of acetone

falls entirely within the range for ethane.

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Although there are uncertainties in acetone's atmospheric photo-

oxidation mechanism and in the other aspects of ozone-related

atmospheric photochemistry, one can reasonably deduce, based on the

Carter report, that acetone and ethane probably have nearly the same

reactivity for most sets of environmental conditions.

Additional studies have been conducted on the relative reactivity

of acetone in Europe. For example, R. G. Derwent and M. E. Jenkins

(Hydrocarbons and the Long-range Transport of Ozone and PAN Across

Europe, Atmospheric Environment, vol 24A, pp 1661-1678, 1991) used a

chemical mechanism to calculate ozone impacts of acetone, ethane, and

other VOC for three trajectories across Europe. The photochemical

trajectory model the authors employed was developed at Harwell

Laboratory (United Kingdom) and was used to calculate the photochemical

ozone creation potential (POCP) values for 69 organic compounds,

including acetone. The POCP values were assigned to VOC species

according to a relative scale, with ethylene having a value of 100. Dr.

Derwent reported in a letter (January 27, 1994) to EPA that: ``A

comparison of POCP's for ethane and acetone in the work of my

colleagues at Harwell Laboratory, which incidentally updates the

acetone entries in the VOC Protocol Annex, gives 8.2 4.0

and 9.2 2.0, respectively.'' The difference between these

numbers is not considered to be statistically significant.

If acetone is accepted as having negligible photochemical

reactivity, exempting acetone from regulation as an ozone precursor

could contribute to the achievement of several important environmental

goals. For example, acetone can be used as a substitute for several

compounds that are listed as hazardous air pollutants (HAP) under

section 112 of the Act. Methylene chloride and methyl chloroform are

HAP that are used for metal cleaning and for flexible polyurethane foam

blowing. Other HAP, such as toluene, are often used as solvents in

paints and coatings. Acetone can substitute for these substances in

some circumstances.

Acetone can also be used as a substitute for ozone depleting

substances (ODS) which are active in depleting the stratospheric ozone

layer. Under the London Amendments to the Montreal Protocol on

substances that deplete the ozone layer (``Montreal Protocol''), the

United States agreed to phase out production and consumption of certain

chlorofluorocarbons (CFC) by the year 2000 and methyl chloroform by

2005 (see 58 FR 15016 (March 18, 1993)). In 1990, Congress added title

VI to the Act in part to provide for the implementation of this

phaseout (see 42 U.S.C. 7671 et seq.). The 1990 Amendments specified an

initial list of Class I and Class II ODS, authorizing EPA to add

compounds to both lists depending on a given compound's potential to

contribute to stratospheric ozone depletion, (Id. Sec. 7671a.) The 1990

Amendments further required phaseout of the production and consumption

of Class I ODS by 2000, methyl chloroform by 2002, and Class II ODS by

2030 (see 42 U.S.C. 7671c, 7671d). At the fourth meeting, in 1992, of

the parties to the Montreal Protocol in Copenhagen, Denmark, the

parties adjusted the phaseout schedules for Class I substances under

the Montreal Protocol to phase out Class I CFC and methyl chloroform by

1996. In 1993, EPA proposed to accelerate the phaseout of Class I CFC

and methyl chloroform in order to discontinue use of these compounds

after January 1, 1996 (see 58 FR 15022).

As a result of these phaseout deadlines, there is a need to develop

substitutes for ODS. Allowing wider use of acetone will facilitate the

transition away from ODS without adversely affecting efforts to control

ground level ozone concentrations. For example, chlorofluorocarbon-11

and methyl chloroform have been used as foam-blowing agents in the

manufacture of polyurethane foam. These compounds are also used in

metal cleaning in the aircraft manufacturing industry. Both CFC-11 and

methyl chloroform are listed as Class I substances under title VI of

the Act, i.e., as substances that have the highest stratospheric ozone-

depleting potential. Acetone may be able to be used as a foam-blowing

agent and cleaning agent in place of these chemicals.

The EPA has already listed acetone as an acceptable ozone-depleting

substance substitute under the program known as the ``Significant New

Alternatives Policy'' (SNAP) program, (59 FR 13044, March 18, 1994).

Within the context of the SNAP rule, substitutes are ``acceptable'' if

they are technically feasible to be used as an alternative to an ODS

for particular uses and give reduced overall risk to human health and

the the environment compared to the ODS they replace. In the SNAP rule,

EPA listed acetone as an acceptable substitute for flexible

polyurethane foam blowing (59 FR 13132). The SNAP rule lists ketones

(which include acetone) as an acceptable substitute for solvent

cleaning in metal cleaning, electronics cleaning, and precision

cleaning (59 FR 13134). Ketones are also listed in the SNAP rule as an

acceptable substitute solvent for aerosols and for adhesives, coatings,

and inks (59 FR 13145).

In each of these areas of concern, toxic air emissions and

depletion of stratospheric ozone, adding acetone to the list of

negligibly-reactive VOC will support the EPA's pollution prevention

efforts. By enacting the Pollution Prevention Act of 1990, Congress

established as a national policy that ``pollution should be prevented

or reduced at the source whenever feasible'' (42 U.S.C. 13). An

important part of EPA's pollution prevention strategy is encouraging

companies to use substitutes in their production processes that are

more environmentally benign than the substances they currently use. For

example, in its blueprint for a comprehensive national pollution

prevention strategy, (56 FR 7849 (February 26, 1991)), the EPA

recognized that the definition of pollution prevention includes a

``switch to non-toxic or less toxic substitutes'' (Id. at 7854).

National air emissions of acetone from industrial sources were

estimated to be 80,000 tons per year in 1991. It should be noted that

due to the high volatility of acetone, increased use of acetone for

metal cleaning will most likely increase emissions of the compound to

the air.

II. The EPA Response to the Petition

Based on the scientific data presented in the material submitted by

the petitioners, EPA accepts the conclusion that acetone is not

appreciably different from ethane in terms of photochemical reactivity.

The EPA is responding to the petitions by proposing in this notice to

add acetone to the list of compounds appearing in 40 CFR 51.100(s) that

are considered to be negligibly reactive and are thus excluded from the

definition of VOC for ozone SIP and ozone control purposes. The revised

definition will apply in the Chicago ozone nonattainment area pursuant

to the 40 CFR 52.741(a)(3) definition of volatile organic material or

volatile organic compound. States are not obligated to exclude from

control as a VOC those compounds that EPA has found to be negligibly

reactive. However, if this proposal is made final, EPA will not enforce

measures controlling acetone as part of a federally-approved ozone SIP.

In addition, once this proposal is made final, States should not

include acetone in their VOC emissions inventories for determining

reasonable further progress under the Act (e.g., section 182(b)(1)) and

may not take credit for controlling acetone in their ozone control

strategy. Further, after this proposal is made final, acetone may not

be used for emissions netting (e.g., 40 CFR 51.166(b)(2)(c)),

offsetting (40 CFR appendix S), or trading with reactive VOC (Emissions

Trading Policy Statement, 51 FR 43814, December 4, 1986 and Economic

Incentive Program Rules, 59 FR 16690, April 7, 1994).

Since acetone will no longer be treated as a VOC, a State should

revise its base year inventory and plans that rely on that inventory

(e.g., the 15 percent plan) to remove acetone and the VOC emissions

reduction credit taken from controlling acetone. To avoid unnecessary

work, however, States may account for the fraction of the VOC inventory

that acetone comprises or the amount of reduction claimed for

controlling acetone. If the acetone fraction in the inventory or the

amount of control claimed is not significant for a particular area, EPA

would not expect a State to revise its emissions inventory or a plan

based on that inventory to account for the revised VOC definition.

In addition, corrections are made to the names of three compounds

which have previously been exempted from the definition of VOC; 1,1,1-

trichloro-2,2,2-trifluoroethane (CFC-113) is changed to 1,1,2-

trichloro-1,2,2-trifluoroethane (CFC-113); chlorodifluoromethane (CFC-

22) is changed to chlorodifluoromethane (HCFC-22); and trifluoromethane

(FC-23) is changed to trifluoromethane (HFC-23). These changes are

corrections to nomenclature only and are not substantive.

Pursuant to 5 U.S.C. 605(b), I hereby certify that this action will

not have a significant economic impact on a substantial number of small

entities because it relaxes current regulatory requirements rather than

imposing new ones. The EPA has determined that this rule is not

``significant'' under the terms of Executive Order 12866 and is,

therefore, not subject to Office of Management and Budget (OMB) review.

This action does not contain any information collection requirements

subject to OMB review under the Paperwork Reduction Act of 1980 (44

U.S.C. 3501 et seq.).

Assuming this rulemaking is subject to section 317 of the Act, the

Administrator concludes, weighing the Agency's limited resources and

other duties, that it is not practicable to conduct an extensive

economic impact assessment of today's action since this rule will relax

current regulatory requirements. Accordingly, the Administrator simply

notes that any costs of complying with today's action, any inflationary

or recessionary effects of the regulation, and any impact on the

competitive standing of small businesses, on consumer costs, or on

energy use, will be less than or at least not more than the impact that

existed before today's action.

List of Subjects in 40 CFR Part 51

Administrative practice and procedure, Air pollution control,

Carbon monoxide, Intergovernmental relations, Lead, Nitrogen dioxide,

Ozone, Particulate matter, Reporting and recordkeeping requirements,

Sulfur oxides, Volatile organic compounds.

Dated: September 23, 1994.

Carol M. Browner,

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 continues to read as follows:

Authority: 42 U.S.C. 7410(a)(2), 7475(e), 7502(a) and (b), 7503,

7601(a)(1), and 7620.

2. Section 51.100 is amended by revising paragraph (s)(1)

introductory text to read as follows:

Sec. 51.100 Definitions.

* * * * *

(s) * * *

(1) This includes any such organic compound other than the

following, which have been determined to have negligible photochemical

reactivity: methane; ethane; methylene chloride (dichloromethane);

1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-

trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11);

dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22);

trifluoromethane (HFC-23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC-

114); chloropentafluoroethane (CFC-115); 1,1,1-trifluoro 2,2-

dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1-

dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-difluoroethane (HCFC

142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); pentafluoroethane

(HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1-trifluoroethane

(HFC-143a); 1,1-difluoroethane (HFC-152a); acetone; and perfluorocarbon

compounds which fall into these classes:

* * * * *

[FR Doc. 94-24251 Filed 9-29-94; 8:45 am]

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