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Citation: 42 Fed. Reg. 35314 1977

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### NOTICES



### ENVIRONMENTAL PROTECTION AGENCY
[FEML 729-51

AIR QUALITY
Recommended Policy on Control ofVolatile Organic Compounds
PuPosE
The purpose of this notice is to rec- ommend apolicy for States tofollow on thecontrol ofvolatile organic compounds (VOC), which are i-constituent in 

### the formatioln of photochemical oxidants (smog). This notice does not place any requirements onStates; StateImplemen- tation Plan (SIP) provisions which offer reasonable alternatives tothispolicy-will be app'rovable. However, this policy will be followed by EPA whenever it is re- quired to draft State Implementation Plans for the control of photochemicaloxidants.'
BACKGROUND

Photochemical oxidants result from sunlight acting on volatile organic com- pounds (VOC) and oxides of nitrogen. Some VOC, by theirnature, start toform oxidant after only a short period Of irradiation in the atmosphere. Other VOC may undergo irradiation for a longer period before they -yield measurable oxidant.

In its guidance to States for thepreparation, adoption, and submittal ofState Implementation Plans published in 1971, the Environmental Protection Agency emphasized reduction of total organic compound emissions, rather than substitution. (See-40 CFRPart 51, Appendix B.) However, inAppendix B, EPA stated that substitution of one compound for another might be useful where it would result in a clearly evident decrease in reactivity andthustend toreducephotochemical oxidant forniation. Subsequently, many State Implementation Plans were promulgated with solventsubstitution provisions similar to Rule 66 of theLos Angeles County Air Pollution Control District. These regulations allowed exemptions for many organic solvents which have now been shown to generate- significant photochemical oxidant.

On January 29, 1976, EPA published Its "Policy Statement onUse of theConcept of Photochemical Reactivity of Organic Compounds in State Implementation Plans for Oxidant Control." The notice of availability of.this document appeared in the FEDERAL REGISTER on February 5, 1976 (4iFR 5350).

The 1976 policy statement emphasized that the reactivity concept was useful

as an interim measure only, and would
notbe considered areduction in organic emissions for purposes of estimating attainment of the ambient air quality standard for oxidants. The document also included thefollowingstatement:

Although the substitution portion] ofRule 66 and similar rules represent a workable and acceptable program at the present time, better substitution regulations -can be developed, based on current knowledge of reactivity and Industrial capability. EPA in collaboratlon with State and industry repre sentatives 

### Will formulate 

### in 1976 an improved rulefor nationaluse. SUMMARY Analysis of available data and information show that very few volatile or- ganic compounds are of such low photochemical reactivity thdt they can be ignored in oxidant control programs. For. this reason, EPA's irecommended policy reiterates the need for positive reduction techniques (such as thereduction of vo atile organic compounds in surface coatings, process changes, and the use of control equipment) rather than the substitution of compounds of low (slow) reactivity in the place' of

more highly (fatt) reactive compounds. There are three reasons for this. First, many of the VOC that previously have been designated ashaving low reactivity

are now known to be moderately or highly reactive in urban atmospheres. Second, even compounds that are pres- ently known to have low reactivity can form appreciable amounts of 'oxidant under multiday stagnation conditions such as occur during summer in many
areas. Third, some compounds of low

or negligible reactivity may have other deleterious effects.

Of the small number of VOC which haveonly negligible photochemical re- activity, several (benzene, .acetonitrile, -chloroform, carbon tetrachloride, ethyl-

ene dichloride, ethylene dibromide, and methylene chloride).have beenidentified

or implicated as being carcinogenic, mu- tagenic, or teratogenic. An additional compound, benzaldehyde, while producing no appreciable ozone, nevertheless, forms a strong eyeirritantunder irradiation. In view of these circumstances, it would-be inappropriate for EPA to en- courage or support increased utilization of these compounds. Therefore, they are not recommended for exclusion from control. Only the four compounds listed in Table 1 are recommended for exclusion from SIPregulations and, therefore, it is not necessary that they be inventoried or cQntrolled. In determining re- ductions required to meet oxidant NAAQS, these VOC should not be included inthe base linenorthould reductions intheir emissionbecredited toward achievement of theNAAQS.

It is recognized that the two halojenated compounds listed in Table 1 (methyl chloroform andFreon 113) may-
cause deterioration of the earth's ultraviolet radiation shield since they are nearly unreactie in. the lower atmosphere and all contain appreciable fractions of ,chlorine. The Agency has reached conclusions ontheeffects ofonly 'the fully halogenated chlorofluoroalkanes. The Agency on May 13, 1977 (42 FR 24542), proposed rules under the, Toxic Substances Control Act (TSCA) to prohibit the nonessential use of fully halogenated chlorofluoroalkanes asaero- sol propellants. Therestrictions were ap- plied to all members of this class, including Freon 113, since they are potential substitutes for Freon 11, Freon 12, Freon 114, andFreon 115, which are cur- rently used as aerosol propellants. The Agency Isplanning toinvestigate control systems and substitutes for nonpropellantuses under TSCA, as announced on May 13. Methyl chloroform Is not a fully halogenated chorofluoroalkane. Rather, 'it isamong the chlorne=:cntainlng com- pounds for which the Agency has not completed its analysis; EPA has not yet concluded whether it Is orIs not athreat to the stratospheric ozone. Therefore, It hasbeenplaced on'thislistas an accept- ,ableexemptcompound. Asnewinformation: becomes available on these com- pounds, EPA will reconsider the recom- mendation.

.Thevolatile organic compounds, listed in Table 2, while more photochemicaily reactive than. those in Table 1, never- theless do notcontribute large quantities ofoxidant undermany atmospheric con- ditions.

TABLE J.-Volatfle Organic Compounds of

Negligible PhotochemicalReactivity That ShouldBeExemptFrom RegulationUndcr StateImplementationPlanm Methane Ethane 1,1,l-Trichloroethano (MethylChloroform)1 TrIchlorotrfluoroothane (Freon113)1

2These compounds have been Implicatod

as having deleterious effects on stratospheric

ozone and, therefore, may be subject to future controls.

TABLE 2-Volatile Organic Contpoinds 

### of

Low PhotochemicalReactivity
Propane Acetone Methyl ELthylKetono Methanol Isopropanbl Methyl Benzoate Tertlary-Alkyl Alcohols MethylAcetate PhenylAcetate EthylAmines Acetylene N,*N-dimethyl formamildo

Only during multiday stagnatlons do Table 2 VOC yield significant oxidants, Therefore, If resources are limited or If the sources are located in areas where prolonged atmospheric stagnations are uncommon, priority should be given to controlling more reactive VOC first and Table 2 organics later. Table 2 VOC are to be included in base line emission Inventories and reductions in them will be credited toward achievement of the NAAQS. Reasonably available control technology should be applied to significantsources ofTable2 VOCwhere neces- sary to attain the NAA(OS for oxidants. New sources ofthese compounds will also be subject to new source review requirements.

Perchloroethylene, the principal solvent employed in thedry cleaningIndustry, Is also of low reactivity, comparable to VOC listed in Table 2. It was not Includedin Table 2because ofreported ad-

verse health-effects. Uses, environmental distribution, and effects of perchloro- ethylene currently are being studied n- tensively by occupational health authorethylene currently are being studied investigations may have major Impact on

FEDERAL REGISTER, VOL.-42, NO. 131-FRIDAY, JULY 8, 1977 

### 35314

### NOTICES

Industrial users.In designing controlreg- ulations for perchoroethylene sources, particularly dry cleaners, consideration should be given to these findings as well

as industry requirements aid the cast of applyingcontrols. Available controltechnology is highly cost effective for large .perchloroethylene dry cleaning operations. However, for coin-operated and small dry cleaners, the same equipment would represent a heavy economic burden.

- Aspartofits continuingprogram,EPA. will review new information relative to the photochemical reactivity, toxicity, or effects onstratospheric ozone of volatile organic compounds. Where appropriate, additions or deletions willbemade tothe lists ofVOC in Tabels 1 and'2.

DISCUSSION
-Mostair pollution control regulations, applicable to stationary sources of VOC

n the United States arepatterned after Rule 66 of the Los Angeles County Air Pollution Control District (presently Regulation 442 of the Southern CaliforniaAir Pollution Control District). Rule" 66 and similar regulations incorporate two basic strategies to reduce ambient oxidant levels, I.e., positive VOC reduction and selective solvent substitution basedon photochemical reactivity. Positivereduction schemes suchas incineration, absorption, and the use of low-solventcoatings are acknowledged meansof reducing ambient _oxidant levels; they should beretainedInfuture VOC control prbgrams. In contrast, the utilityof solvent substitution strtegies has been questioned as moms information on photo chemical reactivity has emerged.

EPA acknowledged the shortcomings of solvent substitution based on Rule 66 reactivity criteria In a 1976policy statement (41 FR 5350). Findings were cited which indicated that almost all VOC eventually react in the atmosphere to form some oxidant., Concurrently, EPA initiatedaninvestigation toconsiderimplications ofrevising the solvent substituton aspects ofRule 66. Three separate forms were conducted with representatives of State and local air pollution control agencies, university-professors, and ndustrial representatives * with knowledge and expertise in the fields of Mtmo pheric chemistry and industrial 

### Volvent applications. In addition, nu-

onerous discussions were held with acknowledged experts In the field. Topics 

### of-particular concern were:

Whether Rule 66 substitution criteiia could be revised consistent with available reactivity data and yet be compatible with Industrial processes and with product requirements.

Whether some compounds are of sumfficdently low reactivity that they are not oxidant precursors and can be exempted from *control under-State Implementation Plans. Whether the Imposition of reactivity restrictions in'addition to positive emission reductons win delay the development or implementation of promising technologies, particularly the use of -water-borne and blgh-8olids surface coatings. Investigation 

### showed tbat: 1.Solvent substlution based on Rule 66 has been directionally correct in the aggregate and probably effect5 some re- ductions In peak oxidant levels. However, because of the relatively high re- activity of most of the substituted solvents, thereduction Issmall compared to that which can be accomplished with positive reduction techniques. Revision ofRule 66consistentwithcurrent knowledge of reactivity would eliminate the solvent substitution option for most

sources inwhich substitution isnewem- ployed. Many of the organic solvents which have been categorized as having lowphotochemical reactivity are, Infact, moderathly orhighlyreactive; theyyield significant Dxidant when subjected to Irradiation Insmogchambers designedto simulate the urban atmosphere.

2. A few VOC yield only negligible

ozone when irradiated In smogchambers under both urban and rural conditions. -Experiments conducted to date indicate that only methane and ethane, a group ofhalogenated paraflins, and three other organics-benzene, benzaldehyde, and acetonitrile--can be so classified. These compounds react very slowly yielding little ozone during the first few days following theirreleasetotheatmosphere. Available data suggest that none ofthe listed compounds contribute significant oxidanteven duringextended irradiation undermultiday stagnation conditions.

- The broad group "halogenated paraffins" includes important industrial solvents, most of which are chlorinated methanes and ethanes and chlorofluoroethanes. They finduse asmetal cleaning and dry.cleaning solvents and as paint

removers. Halogenated paraffins also

serve asbuildingblocks Inthemanufacture of other halogenated organics; these processes donotnecessarily release significant VOC to the atmosphere.

3. Besides focusing on VOC of negligible reactivity, smog chamber studies show that a few additional VOC generate oxidantatarelatively slowrate. Under favorable atmospheric conditions, theseVOCreleases maynotform oxidant until they have been transported substantial distances and become greatly diluted. However, under multiday stagnation conditions such as occur during

summerInmany areas ofthemiddle and eastern United States, there is the potential for these organics to undergo appreciable conversion to oxidant. The

moreimportantVOC In thiscategory are acetone, methyl ethylketone,parchloro- ethylene, methanol, isopropanol, and propane. All except propane are industrial solvents. The latter, a gas under normal conditions, is associated prin- cipally with crude oil and liquefied petroleum gas operations.

4. Thevastnumber of volatile organic compounds-particularly nonhalogenat- ed VOC-yield appreciable ozone when irradiated In the presence of oxides of nitrogen. While there are measurable variations In their rates of ozoneformation,all are significantly more reactive than VOC listed In T4ble 2. Quickly re- active VOC include almost all allphatlc and aromatic solyents, alcohols, ketones, glycols, and ethers.

5. Lowphotochemical reactivity is not synonymous with low biological activity. Some ofthe negligible or slowly reactive compounds have adverse effects off hu-

man health. Benzene, acetonltrile, car- bon tetrachloride, chloroform, perchloroethyene%ethylene dichlorlde, ethylene dibromIde, and methylene chloride have been implicated as being carcinogens, teratogens, or mutagens. In addition. benzaldehyde, which produces no ap- preclable ozone, nevertheless forms a strong eye Irritant under IrradiationWhile their use might reduce ambient oxidantlevels, it would be unwise to en- courage their uncontrolled release. Additional halogenated organics are being investigated forpossibletoxicity.

-

Most of the related health informationavailable atthistimeconcerns acute toxicity. Threshold limitvalues (TLV's) have been developed for many VOC. They are appropriate for the healthy adult work force exposed eight hours a day, five days a week. Experts suggest that more stringent levels should be established for the general population- Hazardsrepresented bychronic andsubchronic exposure are much more difficultbto quantify than acute toxicity.Ad-

verse health effects of the VOC cited above are generallyrecognized although not completely quantified. Chlorinated solvents currently are under intensive study.

6. Some VOC are of such low photo- chemical reactivity that they persist in the atmosphere for several years, even- tually migrating to the stratosphere wherethey are suspectedofreacting and destroying ozone. Since stratospheric

ozone is the principal absorber ofultraviolet (UV) light, the depletion could lead to an increase in UV penetration with a resultant worldwide increase in skin cancer. The only In-depth analysis ofthispotential problem has focused on the chlorofluoromethanes (CFM), Freon 11 and Freon 12,because oftheir known stability and widespread use In aerosol containers. A report of the National Academy of Sciences concerning environmental effects of CF"'s concluded that:

e e

- seletclve regulation of Cr7ar uses andreleases Is almost certain tobe necessary at some time and to some extent of completeness.
In response tothe reportofthe National Academy of Sciences and other studies, EPAonMay 13, 1977 (42FR 24542), proposed rules toprohibit nonessential use- age offully halogenated chlorofluoroalkanes as areosol propellants. The re- strictions were applied to all members of this class including Freon 113 since they arepotential substitutes for Freon 11, Freon 12, Freon 114, and Freon 115 which are currently used as aerosol prbpellants.

Other stable halogenated solvents which arereleased In volumes compara- ble to the chlorofluoroalkanes also are suspected of depleting the earth's UV ahled. Of major concern is the wideFEDERAl REGISTER, VOL 42, NO. 131-FRIDAY, JULY 8, 1977 

### 35315

### 35316

spread substitution ofmethyl chloroform (1,1,1 trichloroethane)-'for the photochemically reactive degreasing solvent trichloroethylene. Such substitution un- der Rule. 66 generation regulations has already influenced industrial degreasing. operations to the extent that methyl chloroform production has surpassed .that of, trichoroethylene in the United States: Any regulation in the area will have a marked effect on the production and atmospheric emissions of both solvents.Endorsing methyl chloroform substitution would increase emissions, particularly in industrial States that have not,heretofore,implemented Rule 66.On the other hand, disallowing methyl-chloreform as a substitute orbanningit altogether would significantly increase emissions of trichloroethylene even if degreasers were controlled to the limits of available technology. Presently, tectihiology is onlyable to-reduce emissions by approximately 50 percent. In metropolitan areas which have already implemented Rule 66, a return to trichloroethylene would have an adverse effect

on ambient oxidant levels. In addition to being highly reactive, trichloroethylene has been implicated as a carcinogen.

Alternatives to the above-cited choices would be (1) development and applica- tion of highly efficient degreaser control systems and (2) replacement with an 

### NOTICES

Intermediate solvent whichIsneither re- active nor detrimental to the upper atmosphe7e. Major revisions would be needed to degreaser designs to improve
vapor capture above the current best level Anticipated design changes could add materially to degreaser costs. No alternative solvent Is clearly acceptable from the standpoints of photochemical oxidant and stratospheric ozone depletion. Neither methylene chloride nor trichlorotrfluoroethane'are reactive,but, like methyl chloroform, are suspected of causing damage .to the stratospheric

ozone layer.In addition, methylene chloride-is a suspect mutagen. Perchloroethylene, the principal dry cleaning solvent, does not piresent a hazard to the stratosphere but has been implicated as being acarcinogen and also reacts slowly in the atmosphere to form oxidant.

7. Organic solvents of lowor negligible photochemical reactivity have only limited use in many industries. Most are chlorinated organics that find principal applications- as cleaners for metals and' fabrics. A few nonhalogenated VOC such

as -acetone, methyl ethyl ketone, and isopropanol are of low reactivity but these o'can'tpossibly satisfy all themyriad needs ofthe paint, plastics, pharmaceutical, or many other industries. While'

users ofreactive VOC usually canemploy effective control equipment to recover or destroy VOC emissions, they seldom havo the option of applying reactivity con- siderationsIn choosingsolvents. Applying reactivity restrictions tothe surface coating Industry would be especially disadvantageous sinceIt would greatly inhibit the development oflow-solvent coatings; essentially all of the organic solvents used to constitute high-solids coatings and water-borne coatings are, in fact, highly reactive. 8. It is recognized that smog chqmbor studies conducted to date are incomplete because many organic compounds have not been examined and It has been Impossible to duplicate all-atmospheric situations. For example, there has been only limited examination of oxidant foxmation under relatively high ratios of VOC to NO. (30:1and greater), comparable to rural conditions. Any policy on photochemical reactivity necessarily has
tobe opentorevision asnew Information is developed which may show specific organic compounds to be more or less photochemically reactive than Indicated by current data.

Dated: June 29, 1977.

EDWRD F. TUEuIC, Acting.AssistantAdministrator

forAir andWasteManagement.
(FRfloo.77-193085 lied 7-7-778:45 null

SFED RGISTER, VOL 42, NO. 131-FRIDAY, JULY 8, 1977