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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 51

[FRL-5222-1]

Air Quality: Revision to Definition of Volatile Organic

Compounds--Exclusion of Acetone

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action revises the 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. This

action adds acetone to the list of compounds excluded from the

definition of VOC on the basis that these compounds have been

determined to have negligible photochemical reactivity.

[[Page 31634]]

EFFECTIVE DATE: This rule is effective June 16, 1995.

ADDRESSES: 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 the U.S. Environmental Protection Agency, Air and Radiation

Docket and Information Center (6102), 401 M Street SW., Washington, DC

20460. A reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: Mr. William Johnson, Office of Air

Quality Planning and Standards, Air Quality Strategies and Standards

Division (MD-15), Research Triangle Park, NC 27711, phone (919) 541-

5245.

SUPPLEMENTARY INFORMATION:

I. Background

Three petitions were 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.

The petitioners point out that 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 and would support EPA's pollution

prevention efforts. 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. 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 (CFC-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 for certain uses 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 provide a reduced overall

risk to human health and 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).

Based on a review of the scientific material submitted by the

petitioners, EPA published a notice in the Federal Register on

September 30, 1994 (59 FR 49877) which proposed to revise EPA's

definition of VOC to add acetone to the list of compounds which are

considered to be negligibly photochemically reactive. In the proposal,

EPA summarized the technical basis for its preliminary decision to add

acetone to this list. This notice asked for comments from the public on

the proposal and provided a 60-day comment period which ended November

29, 1994.

II. Comments on Proposal and EPA Responses

In accordance with section 307(d) of the Act, today's action is

accompanied by a response to the significant comments, criticisms, and

new data submitted in written or oral presentations during the public

comment period. During the comment period, written comments were

received from 52 individuals or organizations (including several

manufacturing companies, seven trade associations, two States and a

local air pollution agency) in response to EPA's September 30, 1994

proposal. Copies of these comments are located in the docket (A-94-26)

for this action. Significant comments and EPA's responses are

summarized below. In the proposal for today's action, EPA indicated

that interested persons could request that EPA hold a public hearing on

the proposed action (see section 307(d)(5)(ii) of the Act). During the

comment period, one company requested a public hearing, but later

withdrew its request. Since no one else requested a hearing, none was

held.

About 80 percent of the letters received during the comment period

were in favor of the proposal. These comments listed a variety of

benefits that would result if acetone is deregulated for industrial

use. Other substantial comments and EPA's responses are listed below.

Comment: Several commenters pointed out that removal of

restrictions on use of acetone would have a detrimental effect on

companies which have invested in research efforts to develop low

solvent processes. As an example, some companies have developed low

solvent cleaners which reduce the amount of VOC emitted into the air

when used. Another example is processes for manufacture of polyurethane

foam which do not rely on organic solvent blowing agents. Manufacturers

have developed these low polluting processes for making polyurethane

foam in order to avoid emission limitations on methylene chloride,

methyl chloroform and other regulated organic compounds. Such low

emitting polyurethane foam manufacturing processing may not be able to

compete effectively if acetone is allowed unrestricted use as a foam-

blowing agent. The companies that have developed these low-polluting

processes say that they relied on past EPA policy which restricted

emissions of acetone as a VOC when deciding to make a financial

commitment to develop the processes or products. They now face loss of

their research investments and

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future profits if acetone is no longer regarded as a VOC and,

therefore, no longer restricted in use.

Response: The EPA recognizes that some companies which have

developed low solvent products may find that their products face

increased competition when acetone is deregulated. It is true that

companies which have spent funds in developing these products may not

gain the expected financial return if these products are not able to

compete successfully against acetone. However, these products are not

prohibited by this action and may still compete in the market place.

The EPA does not think it is good public policy to continue to restrict

acetone use as an ozone precursor when current evidence indicates that

it is of negligible photochemically reactivity. Acetone is a useful

substance and a wide cross section of American industry stands to

benefit from removal of restrictions on its use.

Comment: Some commenters assert that the scientific evidence

presented in the docket for this action does not support the contention

that acetone is of comparable reactivity to ethane, which is already

regarded as negligibly photochemically reactive. One commenter, for

example, cited a paper written by Dr. William P. L. Carter, who is the

author of much of the background material in the docket. The July 1994

paper entitled ``Development of Ozone Reactivity Scales for Volatile

Organic Compounds'' was published in the Journal of the Air and Waste

Management Association. Table III in this paper gives a list of organic

compounds ranked by a maximum incremental reactivity (MIR) scale. This

scale shows that ethane has a MIR value of 0.25 while acetone has a

value of 0.56. These values are expressed in units of grams of ozone

per gram of test compound added. Since the higher value would indicate

higher ozone formation potential, the commenter concluded that this is

evidence that acetone is more reactive than ethane.

Response: The MIR values of 0.25 for ethane and 0.56 for acetone

are also given in Table 4 in ``An Experimental and Modeling Study of

the Photochemical Ozone Reactivity of Acetone'' by Dr. Carter, et al.,

which is included in the docket for this action. This journal article

explains that the MIR scale is based on a scenario derived by adjusting

the nitrogen oxide (NOX) emissions in a base case scenario to

yield the highest incremental reactivity of the base reactive organic

gas (ROG) mixture. Ozone yield for a VOC depends significantly on the

conditions within the polluted atmosphere in which it reacts, such as

VOC to NOX ratio, VOC composition, and sunlight intensity. The MIR

value presented in these studies relies on a set of conditions adjusted

for maximum ozone incremental reactivity.

In addition to calculating this value, Dr. Carter also calculated

values for conditions actually occurring in 39 cities in the United

States. His calculations showed that the reactivity of acetone,

relative to that of ethane, varied widely with conditions, ranging from

substantially higher to substantially lower than that of ethane,

although the 39-city study indicated that on average acetone is less

reactive on a weight basis that ethane for conditions found in these

cities. In the face of such variation, Dr. Carter reasonably concluded

that his results did not support a higher acetone reactivity relative

to that of ethane. After examining these data, EPA continues to believe

that, based on currently existing evidence, a ``negligibly reactive''

rating for acetone is justified.

Comment: One commenter stated that general principles of organic

photochemistry support the conclusion that acetone will be more

reactive that ethane. Two commenters point out that acetone undergoes

photolysis to form free radicals which would cause an increase in

photochemical reactivity of acetone as compared to ethane.

Response: It has been recognized that acetone, unlike ethane,

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 reactivity rate constant with

hydroxyl radicals and photolysis, was the subject of a study (Carter,

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

Photochemical Ozone Reactivity of Acetone,'' December 10, 1993) which

is included in the docket for this action. The findings of this report

take into account the potential for acetone to undergo photolysis, and

this information has been included in comparisons of acetone with

ethane. The 39-city study which is included in this report shows that

acetone reactivity is on average lower than that of ethane for the

conditions in these cities. This study indicates that situations

represented by conditions typically found in these cities do not

support the contentions made in the comments. Therefore, although

acetone may undergo photolysis, in these conditions, its reactivity is

not dissimilar to ethane's.

Comment: One commenter stated that some experimental values

reported in ``An Experimental and Modeling Study of the Photochemical

Ozone Reactivity of Acetone'' indicate that the incremental

photochemical reactivity of acetone is up to 10 times that of ethane.

Response: The referenced data are in Table 2 of that report,

``Summary of Conditions and Results of the Incremental Reactivity and

Direct Reactivity Comparison Experiments,'' in the column labeled IR

for incremental reactivity. One value of 0.059 is given for acetone and

a value of 0.006 for ethane. The units of these values are moles of

ozone per mole of test compound added. A mole of acetone weighs almost

twice as much as a mole of ethane. If the results are reported on a

basis of grams of ozone per gram of test compound added, the difference

between the two values is about half the difference indicated above.

The EPA has chosen to use the weight basis rather than a mole basis for

comparing results since emissions are regulated on a weight basis.

In addition, the report adds that it should be emphasized that

since incremental reactivities are dependent on environmental

conditions and since it is not practical to duplicate in the chamber

all the environmental factors which might affect magnitudes of

incremental reactivities, incremental reactivities measured in chamber

experiments should not be assumed to be quantitatively the same as

incremental reactivities in the atmosphere. According to the report,

the latter can only be estimated using computer airshed model

calculations. The 39-city study is such a study which predicts that

acetone will be less reactive on a weight basis than ethane for most

conditions found in these cities. Averages from this 39-city study give

a reactivity value (in grams of ozone/gram of VOC) for ethane of 0.166

and for acetone of 0.126. The value for a typical urban mix of reactive

organic gases is 1.13. These values are reported in Table 5 of the

report.

Comment: One commenter stated that the photochemical reactivity of

acetone was as much as 48 percent of the photochemical reactivity of

other VOC.

Response: The commenter reported that he derived the value based on

calculations he performed using the data in Table 2 of the report

referred to in the previous comment. He did not submit the calculation,

however. The EPA calculations using these data have not yielded as high

a value. It should be noted that, as reported before, the data in Table

2 are in moles of ozone per mole of test compound. The report also

compares acetone reactivity with the base ROG mixture on a gram of

ozone per gram of test compound basis. Page

[[Page 31636]]

71 of the report summarizes this comparison, stating that acetone is no

more than 20 percent as reactive as the base ROG mixture in terms of

peak ozone, or 15 percent as reactive in terms of integrated ozone.

Comment: A commenter noted that the report ``An Experimental and

Modeling Study of the Photochemical Ozone Reactivity of Acetone''

reports laboratory measurements of photochemical reactivities of

acetone and ethane in ``side by side'' laboratory experiments in which

it was found that the photochemical reactivity was slightly higher for

acetone. This commenter went on to complain that when this report

studied the photochemical reactivity of acetone in 39 urban areas, the

results were based on use of computer models derived from experimental

data. This commenter believed that results should be based on direct

experimental data and not on computer models which might contain

assumptions and uncertainties.

Response: The EPA agrees that direct experimental data are

desirable, provided that direct experimental comparison data exist for

a variety of ambient conditions. Existing data, however, are very

limited. Such data, for example, were obtained by Dr. H. Jeffries at

the University of North Carolina, in a study referenced in the Carter

report. Through a direct ``side by side'' experimental comparison of

the reactivities of acetone and ethane, Dr. Jeffries observed no

measurable difference in the amount of ozone formed in the acetone and

ethane sides of the chamber. These experimental data confirm that,

essentially, the difference in reactivity between ethane and acetone is

not significant. In regard to the use of computer models to predict

ozone formation, this is a common, well justified practice in

reactivity work, and EPA sees no reason to doubt the approach taken in

this analysis.

Comment: One commenter states that the Derwent and Jenkins study

shows that acetone produces 12 percent more ozone that does ethane.

Response: Dr. R.G. Derwent reported to EPA, in a January 27, 1994

letter which is contained in the docket, that a comparison of the

photochemical ozone creation potential (POCP) for ethane and acetone

gives 8.24.0 for ethane and 9.22.0 for acetone.

The commenter is apparently referring to the difference between 8.2 and

9.2, which is 12 percent. The commenter does not appear to consider the

measure of variability of the data, expressed as a standard deviation

for each number. The difference between these numbers is not considered

to be statistically significant, considering the standard deviation of

each value.

Comment: One commenter said that EPA has previously stated that ``*

* * EPA has found that almost all non-methane VOC are photochemically

reactive and that low reactivity VOC eventually form as much ozone as

highly reactive VOC,'' 40 CFR Subpart 51 (Appendix S, Section

IV(C)(4)). Another commenter said that because acetone is not

nonreactive, excluding acetone from the definition of VOC would reduce

the ability of States to attain the national ambient air quality

standard for ozone in a timely manner.

Response: The CFR section quoted above is part of a discussion of

credit for VOC substitution. The above quote is followed by the

statement that no emission credit may be allowed for replacing one VOC

with another of lesser reactivity, except for those listed in Table I

of the policy statement ``Recommended Policy on Control of Volatile

Organic Compounds'' (42 FR 35314, July 8, 1977). In that 1977 policy

statement, EPA recognized a class of organic compounds that has been

determined to have negligible photochemical reactivity and is not

required to be controlled under State implementation plans (SIP).

Ethane was one of the four compounds on the negligibly reactive list in

the 1977 policy statement. Over the years, several other compounds have

been recognized as being negligibly reactive and have been added to the

list. This list of negligibly reactive compounds was incorporated into

EPA's definition of volatile organic compounds which apears in 40 CFR

51.100(s). Today's action adds acetone to that list.

Comment: Two commenters stated that the docket materials show that

the photochemical reactivity of acetone is increased by the presence of

NOX and other VOC. If the proposal to exempt acetone from the VOC

list is accepted, the urban areas with the worst pollution would be the

areas to suffer most from that decision.

Response: Under high NOX conditions, the modeling results

predict that acetone is slightly more reactive that ethane, though the

reactivity on the MIR scale is quite low when compared to the

reactivity of the weighted average of all emitted VOC and especially

when compared to more reactive solvents such as xylene. Under the type

of NOX conditions occurring in most cities, the modeling results

indicate the reactivity of acetone is comparable to or less than that

of ethane (Table 5 in the Carter report). The 39 cities examined in the

modeling studies exhibit air quality ranging from ozone attainment to

extreme nonattainment. The modeling results as a whole do not

demonstrate an appreciable difference between acetone and ethane in

terms of their respective potential to contribute to tropospheric ozone

levels. Modeling results for those 39 cities show that acetone

reactivity is on average lower than ethane for the actual conditions

existing in them and much lower than for the typical urban mix of

reactive organic gases.

Comment: Three commenters were concerned that the proposal stated

that when this action is made final, acetone may not be used for

emission netting, offsetting, or trading with reactive VOC emissions.

Two of these commenters supported acetone being reclassified as

negligibly reactive, but were concerned that past emission reduction

credits be retained in the future. There are two aspects of concern.

First, would permits obtained in the past that are based on netting

transactions involving acetone still be valid? Secondly, could acetone

reductions that have been made in the past, with the expectation that

they would be available for future netting, still be used? The

commenters say they could suffer financial damages if they are not

allowed to use or sell emission reduction credits for past reductions

of acetone.

Response: The EPA is currently developing an open market trading

rule which will deal with issues of netting, offsetting, and trading

transactions. The EPA is deferring its decision concerning whether

credits for acetone, which were banked prior to today's action, may be

used in future netting, offsetting or trading transactions with

reactive VOC. Because of the potential impact that banked emissions

could have on attainment demonstrations and reasonable further progress

showings, EPA needs to conduct further discussions with States on this

issue.

III. Final Action

The EPA concludes that acetone is not appreciably different from

ethane in terms of photochemical reactivity. Today's final action is

based upon the material in Docket A-94-26 and EPA's review and

consideration of all comments received during the public comment

period. As proposed in EPA's September 30, 1994 notice, EPA hereby

amends its definition of VOC at 40 CFR 51.100(s) to add acetone to the

list of compounds that have been determined to have negligible

photochemical reactivity. This will have the effect of excluding

acetone as a VOC for ozone control purposes. The revised definition

will also apply in the Chicago ozone nonattainment area pursuant to the

40

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CFR 52.741(a)(3) definition of volatile organic material or VOC

compound. States are not obligated to exclude from control as a VOC

those compounds that EPA has found to be negligibly reactive. However,

after the effective date of this final action, EPA will not enforce

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

In addition, once this proposal is made final, States may 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 strategies.

This action is effective on the date of publication rather than the

more usual date 30 days after publication. There is good cause to

choose this earlier effective date; this action relieves a restriction

on users of acetone (42 U.S.C. section 553 (d)(1)).

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.).

Under sections 202, 203, and 205 of the Unfunded Mandates Reform

Act of 1995 (``Unfunded Mandates Act''), signed into law on March 22,

1995, the EPA must undertake various actions in association with

proposed or final rules that include a Federal mandate that may result

in estimated costs of $100 million or more to the private sector, or to

State, local and/or tribal government(s) in the aggregate. Since

today's action is deregulatory in nature and does not impose any

mandate upon any source, the cost of such mandates will not result in

estimated annual costs of $100 million or more.

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

Environmental protection, 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: June 7, 1995.

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 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); parachlorobenzotrifluoride

(PCBTF); cyclic, branched, or linear completely methylated siloxanes;

acetone; and perfluorocarbon compounds which fall into these classes:

* * * * *

[FR Doc. 95-14804 Filed 6-15-95; 8:45 am]

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