[Federal Register Volume 60, Number 116 (Friday, June 16, 1995)]
[Rules and Regulations]
[Pages 31633-31637]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-14804]



=======================================================================
-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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 

[[Page 31635]]
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 

[[Page 31637]]
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]
BILLING CODE 6560-50-P