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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 of Volatile

Organic Compounds

PuPosE

The purpose of this notice is to rec- ommend a policy for States to follow on the control of volatile organic compounds

(VOC), which are i-constituent in the

formatioln of photochemical oxidants

(smog). This notice does not place any requirements on States; State Implemen- tation Plan (SIP) provisions which offer

reasonable alternatives to this policy-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 their nature, start to form

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 the preparation, adoption, and submittal of State

Implementation Plans published in 1971,

the Environmental Protection Agency

emphasized reduction of total organic compound emissions, rather than substitution. (See-40 CFR Part 51, Appendix

B.) However, in Appendix B, EPA stated

that substitution of one compound for

another might be useful where it would

result in a clearly evident decrease in

reactivity and thus tend to reduce photochemical oxidant forniation. Subsequently, many State Implementation

Plans were promulgated with solventsubstitution provisions similar to Rule

66 of the Los 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 on Use of the Concept 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 (4i FR 5350).

The 1976 policy statement emphasized

that the reactivity concept was useful as an interim measure only, and would

not be considered a reduction in organic

emissions for purposes of estimating attainment of the ambient air quality

standard for oxidants. The document

also included the following statement:

Although the substitution portion] of Rule

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 rule for national use.

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 i recommended

policy reiterates the need for positive reduction techniques (such as the reduction 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 as having 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 been identified or implicated as being carcinogenic, mu- tagenic, or teratogenic. An additional

compound, benzaldehyde, while producing no appreciable ozone, nevertheless, forms a strong eye irritant under 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 SIP regulations 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 in the base line nor thould reductions in their emission be credited toward

achievement of the NAAQS.

It is recognized that the two halojenated compounds listed in Table 1

(methyl chloroform and Freon 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 on the effects of only '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 as aero- sol propellants. The restrictions 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 Is planning to investigate control

systems and substitutes for nonpropellant uses under TSCA, as announced on May 13. Methyl chloroform Is not a fully

halogenated chorofluoroalkane. Rather,

'it is among the chlorne=:cntainlng com- pounds for which the Agency has not

completed its analysis; EPA has not yet concluded whether it Is or Is not a threat

to the stratospheric ozone. Therefore, It

has been placed on 'this list as an accept- ,able exempt compound. As new information: becomes available on these com- pounds, EPA will reconsider the recom- mendation.

.The volatile organic compounds, listed

in Table 2, while more photochemicaily

reactive than. those in Table 1, never- theless do not contribute large quantities of oxidant under many atmospheric con- ditions.

TABLE J.-Volatfle Organic Compounds of

Negligible Photochemical Reactivity That

Should Be Exempt From Regulation Undcr

State Implementation Planm

Methane

Ethane

1,1,l-Trichloroethano (Methyl Chloroform)1 TrIchlorotrfluoroothane (Freon 113)1

2 These 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 Photochemical Reactivity

Propane

Acetone

Methyl ELthyl Ketono

Methanol

Isopropanbl

Methyl Benzoate

Tertlary-Alkyl Alcohols

Methyl Acetate

Phenyl Acetate

Ethyl Amines

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 significant sources of Table 2 VOC where neces- sary to attain the NAA(OS for oxidants.

New sources of these compounds will also

be subject to new source review requirements.

Perchloroethylene, the principal solvent employed in the dry cleaning Industry, Is also of low reactivity, comparable

to VOC listed in Table 2. It was not Included in Table 2 because of reported 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 control reg- ulations for perchoroethylene sources,

particularly dry cleaners, consideration

should be given to these findings as well as industry requirements aid the cast of

applying controls. Available control technology 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.

- As part of its continuing program, EPA.

will review new information relative to

the photochemical reactivity, toxicity, or effects on stratospheric ozone of volatile

organic compounds. Where appropriate,

additions or deletions will be made to the

lists of VOC in Tabels 1 and'2.

DISCUSSION

-Most air pollution control regulations, applicable to stationary sources of VOC n the United States are patterned after

Rule 66 of the Los Angeles County Air

Pollution Control District (presently Regulation 442 of the Southern California Air 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

based on photochemical reactivity. Positive reduction schemes such as incineration, absorption, and the use of low-solvent coatings are acknowledged means of

reducing ambient _oxidant levels; they should be retained In future VOC control

prbgrams. In contrast, the utility of 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 1976 policy statement (41 FR 5350). Findings were cited

which indicated that almost all VOC

eventually react in the atmosphere to

form some oxidant., Concurrently, EPA

initiated an investigation to considerimplications of revising the solvent substituton aspects of Rule 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, the reduction Is small compared to

that which can be accomplished with

positive reduction techniques. Revision

of Rule 66 consistent with current knowledge of reactivity would eliminate the

solvent substitution option for most sources in which substitution is new em- ployed. Many of the organic solvents

which have been categorized as having low photochemical reactivity are, In fact,

moderathly or highly reactive; they yield

significant Dxidant when subjected to

Irradiation In smog chambers designed to

simulate the urban atmosphere. 2. A few VOC yield only negligible ozone when irradiated In smog chambers

under both urban and rural conditions.

-Experiments conducted to date indicate

that only methane and ethane, a group

of halogenated 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 their release to the atmosphere. Available data suggest that none of the

listed compounds contribute significant oxidant even during extended irradiation

under multiday stagnation conditions. - The broad group "halogenated paraffins" includes important industrial

solvents, most of which are chlorinated

methanes and ethanes and chlorofluoroethanes. They find use as metal cleaning

and dry .cleaning solvents and as paint removers. Halogenated paraffins also serve as building blocks In the manufacture of other halogenated organics; these processes do not necessarily release

significant VOC to the atmosphere.

3. Besides focusing on VOC of

negligible reactivity, smog chamber

studies show that a few additional VOC

generate oxidant at a relatively slow rate.

Under favorable atmospheric conditions,

these VOC releases may not form oxidant

until they have been transported substantial distances and become greatly

diluted. However, under multiday stagnation conditions such as occur during summer In many areas of the middle and

eastern United States, there is the

potential for these organics to undergo appreciable conversion to oxidant. The more important VOC In this category are acetone, methyl ethyl ketone, 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. The vast number 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 ozone formation, 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. Low photochemical reactivity is not

synonymous with low biological activity.

Some of the 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

oxidant levels, it would be unwise to en- courage their uncontrolled release. Additional halogenated organics are being investigated for possible toxicity. - Most of the related health information available at this time concerns acute

toxicity. Threshold limit values (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- Hazards represented by chronic and subchronic exposure are much more difficultbto quantify than acute toxicity. Ad- verse health effects of the VOC cited

above are generally recognized 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 where they are suspected of reacting and

destroying ozone. Since stratospheric ozone is the principal absorber of ultraviolet (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 of this potential problem has focused on the chlorofluoromethanes (CFM), Freon

11 and Freon 12, because of their 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

and releases Is almost certain to be necessary

at some time and to some extent of completeness.

In response to the report of the National

Academy of Sciences and other studies,

EPA on May 13, 1977 (42 FR 24542), proposed rules to prohibit nonessential use- age of fully halogenated chlorofluoroalkanes as areosol propellants. The re- strictions were applied to all members

of this class including Freon 113 since

they are potential substitutes for Freon

11, Freon 12, Freon 114, and Freon 115

which are currently used as aerosol

prbpellants.

Other stable halogenated solvents

which are released 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 of methyl 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 or banning it altogether would significantly increase emissions of trichloroethylene even if degreasers were controlled to the limits of

available technology. Presently, tectihiology is only able 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 which Is neither 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 a carcinogen and also reacts slowly in the atmosphere to form oxidant.

7. Organic solvents of low or 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't possibly satisfy all the myriad

needs of the paint, plastics, pharmaceutical, or many other industries. While' users of reactive VOC usually can employ effective control equipment to recover or

destroy VOC emissions, they seldom havo

the option of applying reactivity con- siderations In choosing solvents. Applying

reactivity restrictions to the surface coating Industry would be especially disadvantageous since It would greatly inhibit

the development of low-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. (30:1 and greater), comparable to rural conditions. Any policy on photochemical reactivity necessarily has

to be open to revision as new 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.Assistant Administrator

for Air and Waste Management.

(FR floo.77-193085 lied 7-7-778:45 null

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