MEMORANDUM

SUBJECT: Definition of Regulated Air Pollutant for Purposes of 

Title V 

FROM: Lydia N. Wegman, Deputy Director

Office of Air Quality Planning and Standards (MD-10)

TO: Air Division Director, Regions I-X

In response to requests for guidance on the definition of

"regulated air pollutant," this memorandum clarifies the approach

set forth by the definition in the 40 CFR part 70 regulations and

indicates the ways in which the class of regulated air pollutants

can change. The attachment provides a compilation of the lists

of pollutants which are considered "regulated air pollutants" for

purposes of the operating permits programs under title V of the

Clean Air Act (Act). This memorandum also provides guidance on

the Environmental Protection Agency's (EPA) definition of "air

pollutant," as that term is used in determining major source

status pursuant to section 302 of the Act. Finally, this

memorandum emphasizes the ability of permitting authorities to

designate certain quantities of emissions of regulated air

pollutants as "insignificant" with respect to the obligation to

report emissions of those pollutants in permit applications. The

policies set out in this memorandum and attachment are intended

solely as guidance, not final agency action, and cannot be relied

upon to create any rights enforceable by any party.

I. Regulated Air Pollutant

The definition of regulated air pollutant, found at 40 

CFR 70.2 is important because it determines which pollutants and

emissions units must be addressed in a source's title V permit

application. In addition, this definition can affect whether a

State's fee revenue is presumed adequate to fund its title V

program and in some cases, the amount of permit fees a source

must pay. Each of these roles is discussed below. 

Once a source is subject to a title V permitting program,

its emissions of all regulated air pollutants (except those which
meet the permitting authority's criteria for "insignificant"

emissions) must be described in the permit application along with

all emissions of pollutants for which the source is considered

major. Similarly, applications must describe all emissions units

which emit regulated air pollutants (except those deemed

insignificant).

In addition, the concept of regulated air pollutant plays an

important role in the area of permit fees. First, regulated air

pollutants are the starting point for determining which

pollutants must be included when relying on the $25 ton per year

(as adjusted by the consumer price index) presumptive minimum

program cost as a basis for demonstrating the adequacy of a

State's projected fee revenue. As part of this demonstration,

the State projects its revenue using a subset of regulated air

pollutants [i.e., regulated pollutant (for presumptive fee

calculation)]. Second, many States are developing fee schedules

which impose fees based on emissions of regulated air

pollutants."

The population of regulated air pollutants is composed of

the following categories of pollutants: 

(1) Nitrogen oxides (NOx) and volatile organic compounds (VOC's). 

The definition of regulated air pollutant specifically includes

these two significant precursors to ozone formation. This

approach is consistent with the Act's treatment of VOC's and NOx

pursuant to part D of title I of the Act. (These ozone

precursors are combined with the criteria pollutants for purposes

of the attached list of regulated pollutants);

(2) Any pollutant for which a national ambient air quality

standard has been promulgated [i.e., particulate matter (measured

as PM-10: particles with an aerodynamic diameter less than or

equal to a nominal 10 micrometers), sulfur dioxide, ozone,

nitrogen dioxide, carbon monoxide, and lead];

(3) Any pollutant that is subject to a new source performance

standard promulgated under section 111 of the Act [including

section 111(d)], which require new and modified sources to

satisfy emissions standards, work practice standards, and other

requirements; 

(4) Any of the ozone depleting substances specified as a Class I

(primarily chlorofluorocarbons) or Class II substance

(hydrochlorofluorocarbons) under title VI of the Act [all of

which became regulated pollutants when they became subject to 

standards and requirements for (1) servicing of motor vehicle air

conditioners and (2) restrictions on the sale of ozone-depleting

substances promulgated into 40 CFR part 82 (57 FR 31242, July 14,
3

1992)]; and

(5) Any pollutant subject to a standard promulgated under section

112 or other requirements established under section 112 of the

Act, including sections 112(g)(2), (j), and (r) of the Act. 

It is important to note that, if a pollutant is regulated

for one source category by a standard or other requirement, then

the pollutant is considered a regulated air pollutants for all

source categories. This rule is relevant to all the pollutants

listed under items (3),(4), and (5) above with one exception:

those which are the subject of case-by-case MACT determinations

under section 112(g)(2). 

The issue of when a substance regulated under section 112

becomes a regulated air pollutants merits further discussion:

! When a permitting authority makes a case-by-case MACT

determination under section 112(g)(2), then the pollutant

for which the determination is made is regulated even though

EPA has not issued a standard for that pollutant. However,

the pollutant is considered regulated only with respect to

the individual source for which the MACT determination was

made. 

! A pollutant will become regulated under section 112(j) of

the Act (the "MACT hammer") if the Administrator fails to

promulgate a standard by the date established pursuant to

section 112(e) of the Act. Pursuant to section 112(j),

permitting authorities will be required to make case-by-case

MACT equivalent determinations. The pollutants become

regulated nationwide upon the date this provision takes

effect for the pollutant (i.e., 18 months after the missed

deadline for the standard but not prior to 42 months after

the enactment of the Act Amendments of 1990). Pollutants so

regulated are considered regulated air pollutants for all

sources that emit the pollutant because the hammer provision

is a broadly applicable surrogate for the promulgation of a

MACT standard. This is in contrast to the section 112(g)(2)

determinations which are triggered only for the single

source subject to the requirement, rather than nationwide.

! The EPA's proposed rule required by section 112(r)(3), lists

substances which could cause or may reasonably be

anticipated to cause death, injury, or serious adverse

effects to human health or the environment if accidentally

released, was published in the Federal Register on January

19, 1993 (58 FR 5102). All of the listed pollutants will

become regulated air pollutants upon promulgation of the
4

list.

The attachment to this memorandum contains a list of

pollutants which are regulated as well as a list of pollutants

which are subject to regulation under section 112 in the future,

as discussed above. It is also important to note that the

attached lists are dynamic and subject to change. For example,

the EPA is required to review periodically the statutory list of

pollutants in section 112(b) and is authorized to delete and add

substances if the scientific data demonstrate that such a change

is appropriate. 

We have attempted to note the likely near-term changes in

the regulations that determine which pollutants are "regulated

air pollutants," and we will provide updates to this guidance

periodically. 

The definition of regulated air pollutants does not limit

the air pollutants which a State may choose to regulate nor does

it limit the information (such as for permit applications) which

a State may require of a source. States are free to adopt more

expansive approaches to the regulation of toxic air pollutants

than is required by part 70. 

II. Definition of "Air Pollutant" Pursuant to Section 302

Considerable interest has been expressed in a related, but

distinct, area: the definition of "air pollutant" contained in

section 302(g) of the Act. This definition governs which

pollutants are to be considered in determining whether a source

is "major" pursuant to section 302(j) of the Act. This is

important to the operating permit program because all major

sources must obtain a title V permit. Although section 302(g)

can be read quite broadly, so as to encompass virtually any

substance emitted into the atmosphere, EPA believes that it is

more consistent with the intent of Congress to interpret this

provision more narrowly. Were this not done, a variety of

sources that have no known prospect for future regulation under

the Act would nonetheless be classified as major sources and be

required to apply for title V permits. Of particular concern

would be sources of carbon dioxide or methane.

As a result, EPA is interpreting "air pollutant" for section

302(g) purposes as limited to all pollutants subject to

regulation under the Act. This would include, of course, all

regulated air pollutants plus others specified by the Act or by

EPA rulemaking. This approach results in the inclusion of the

pollutants on the list of hazardous air pollutants in section
5

112(b) that are not otherwise regulated. It should be noted that

the 1990 Amendments to the Act did include provisions with

respect to carbon dioxide (section 821) and methane (section

603), but these requirements involve actions such as reporting

and study, not actual control of emissions. Therefore, these

provisions do not preempt EPA's discretion to exclude these

pollutants in determining whether a source is major. If the

results of the studies required by the 1990 Amendments to the Act

suggest the need for regulation, these pollutants could be

reconsidered at that time for classification as pollutants

subject to regulation under the Act.

This approach to interpreting section 302(g) is similar to

the traditional practice of the prevention of significant

deterioration (PSD) program under part C of title I of the Act

[see, e.g., Implementation of North County Resource Recovery PSD

Remand, Gerald Emison, Director, OAQPS, dated September 22,

1987].

III. De Minimis Thresholds

With the 1990 Amendments, the Act expressly addresses a

significantly broader range of pollutants. The EPA believes that

this will confer real benefits to air quality management and that

the title V permit program offers the flexibility for efficient

implementation of these requirements. This function includes

providing information about emissions of these pollutants,

through the permit application process, even if the particular

pollutant is not currently required to be controlled at the

individual source. The EPA also realizes, though, that in many

cases these pollutants are emitted in amounts of no significance

to air quality management. It would be unduly burdensome to

require permit applicants to quantify all emissions of these

pollutants, especially given their considerable number and, in

some cases, difficulty in quantification.

The part 70 promulgation recognized this fact but gave only

very general guidance as to the approvable options for States in

developing their part 70 programs. Section 70.5(c) provides that

"[T]he Administrator may approve as part of a State program a

list of insignificant activities and emissions levels which need

not be included in permit applications." The regulation further

provides that "[T]he permitting authority shall require

additional information related to the emissions of air pollutants

sufficient to verify which requirements are applicable to the

source, and other information needed to collect any permit fees

owed under the fee schedule approved pursuant to §70.9(b) of this

part." §70.5(c)(3)(i).
6

The EPA understands the need for States to establish de

minimis thresholds for emissions reporting purposes in permit

applications and recognizes that the particular thresholds

selected by individual States can vary based on their air quality

management needs and professional judgement. The EPA will work

with States to develop part 70 programs that will best meet their

program needs.

For further information, call Kirt Cox at (919) 541-5399 or

Candace Carraway at (919) 541-3189. 

Attachment

cc: Air Branch Chiefs, Regions I - X

Regional Office Permit Program Contacts

OAQPS Division Directors

LIST OF REGULATED AIR POLLUTANTS

(As of April 1993)

I. Pollutants for Which an NAAQS Has Been Established

lead 

sulfur dioxide

nitrogen dioxide

carbon monoxide

particulate matter (PM10)

ozone, including precursors:

nitrogen oxides (NO, NO2, NO3, N2O, N2O3, N2O4, N2O5)

volatile organic compounds (VOC's) 

As defined in 40 CFR 51.100(s), the term VOC includes any

compound of carbon (excluding carbon monoxide, carbon dioxide,

carbonic acid, metallic carbides or carbonates, and ammonium

carbonate) which participates in atmospheric photochemical

reactions. The EPA has developed a list of substances (which is

subject to change) which are excluded from the VOC definition

because of their negligible reactivity. The EPA's proposal to

exclude perchloroethylene from the definition was published in 57

FR 48490 (October 26, 1992). 

 

The following organic compounds are excluded from the

definition of VOC because of they have been determined to have

negligible photochemical reactivity: 

methane 
7

ethane 

methylene chloride (dichloromethane) 

1,1,1-trichloroethane (methyl chloroform)

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

trichlorofluoromethane (CFC-11) 

dichlorodifluoromethane (CFC-12) 

chlorodifluoromethane (CFC-22) 

trifluoromethane (FC-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) 

perfluorocarbon compounds which fall into these classes: 

 

(i) Cyclic, branched, or linear, completely

fluorinated alkanes; 

 

 (ii) Cyclic, branched, or linear, completely

fluorinated ethers with no unsaturations;

 (iii) Cyclic, branched, or linear, completely

fluorinated tertiary amines with no unsaturations;

and

 

 (iv) Sulfur containing perfluorocarbons with no

unsaturations and with sulfur bonds only to carbon

and fluorine. 

 

II. Pollutants Regulated Under New Source Performance Standards

Criteria pollutants (including VOC's and NOx) plus:

dioxin/furan (defined in 40 CFR 60.53a to mean total tetra

through octachlorinated dibenzo-p-dioxins and dibenzofurans)*

fluorides

hydrogen chloride*

hydrogen sulfide (H2S)

sulfuric acid mist
8

total reduced sulfur

reduced sulfur compounds

total suspended particulate 

 The new source performance standard (NSPS) for municipal waste *

combustors (MWC) controls emissions of dioxin/furans and hydrogen

chloride gas (40 CFR 60.53a and 60.54a) as surrogates for

controlling emissions of organic compounds and acid gases which

are emitted in the exhaust gases from MWC units. Thus, the

indicated dioxin/furan compounds and hydrogen chloride are

regulated pollutants.

Note that the EPA has drafted a proposed revision to the

NSPS for MWC's which will regulate substances like cadmium which

are not currently regulated air pollutants. As this revised NSPS

and other standards are developed, there may be additions to the

list of regulated pollutants.

III. Class I and Class II Substances Under Title VI

Class I Substances

carbon tetrachloride 

chlorofluorocarbon-11 (CFC-11)

chlorofluorocarbon-12 (CFC-12)

chlorofluorocarbon-13 (CFC-13) 

chlorofluorocarbon-111 (CFC-111) 

chlorofluorocarbon-112 (CFC-112) 

chlorofluorocarbon-113 (CFC-113)

chlorofluorocarbon-114 (CFC-114)

chlorofluorocarbon-115 (CFC-115) 

chlorofluorocarbon-211 (CFC-211) 

chlorofluorocarbon-212 (CFC-212) 

chlorofluorocarbon-213 (CFC-213) 

chlorofluorocarbon-214 (CFC-214) 

chlorofluorocarbon-215 (CFC-215) 

chlorofluorocarbon-216 (CFC-216) 

chlorofluorocarbon-217 (CFC-217) 

halon-1211 

halon-1301 

halon-2402 

methyl chloroform 
9

Class II Substances 

hydrochlorofluorocarbon-21 (HCFC-21) 

hydrochlorofluorocarbon-22 (HCFC-22) 

hydrochlorofluorocarbon-31 (HCFC-31) 

hydrochlorofluorocarbon-121 (HCFC-121) 

hydrochlorofluorocarbon-122 (HCFC-122) 

hydrochlorofluorocarbon-123 (HCFC-123) 

hydrochlorofluorocarbon-124 (HCFC-124) 

hydrochlorofluorocarbon-131 (HCFC-131) 

hydrochlorofluorocarbon-132 (HCFC-132) 

hydrochlorofluorocarbon-133 (HCFC-133) 

hydrochlorofluorocarbon-141 (HCFC-141) 

hydrochlorofluorocarbon-142 (HCFC-142) 

hydrochlorofluorocarbon-221 (HCFC-221) 

hydrochlorofluorocarbon-222 (HCFC-222) 

hydrochlorofluorocarbon-223 (HCFC-223) 

hydrochlorofluorocarbon-224 (HCFC-224) 

hydrochlorofluorocarbon-225 (HCFC-225) 

hydrochlorofluorocarbon-226 (HCFC-226) 

hydrochlorofluorocarbon-231 (HCFC-231) 

hydrochlorofluorocarbon-232 (HCFC-232) 

hydrochlorofluorocarbon-233 (HCFC-233) 

hydrochlorofluorocarbon-234 (HCFC-234) 

hydrochlorofluorocarbon-235 (HCFC-235) 

hydrochlorofluorocarbon-241 (HCFC-241) 

hydrochlorofluorocarbon-242 (HCFC-242) 

hydrochlorofluorocarbon-243 (HCFC-243) 

hydrochlorofluorocarbon-244 (HCFC-244) 

hydrochlorofluorocarbon-251 (HCFC-251) 

hydrochlorofluorocarbon-252 (HCFC-252) 

hydrochlorofluorocarbon-253 (HCFC-253) 

hydrochlorofluorocarbon-261 (HCFC-261) 

hydrochlorofluorocarbon-262 (HCFC-262) 

hydrochlorofluorocarbon-271 (HCFC-271) 

IV. Pollutants Regulated Under Section 112

pollutants for which national emission standards for hazardous

air pollutants (NESHAP's) have been established:

arsenic

asbestos

beryllium

benzene

mercury

radionuclides
10

vinyl chloride
11

POLLUTANTS SUBJECT TO REGULATION UNDER SECTION 112

I. Pollutants listed in Section 112(b):

The 189 pollutants listed in section 112(b) are not

considered regulated air pollutants until addressed in a

requirement that it be controlled by a source. None of the

listed pollutants meets the definition except: asbestos, benzene,

and vinyl chloride (for which NESHAP's have been established);

and hydrogen chloride (gas), dibenzofurans, and 2,3,7,8-

Tetrachlorodibenzo-p-dioxin (regulated under the municipal waste

combustor NSPS). Most of the listed pollutants will become

regulated when EPA promulgates the Hazardous Organic NESHAP (HON)

which is discussed below. The remaining pollutants will become

regulated: (1) when EPA promulgates a Maximum Achievable Control

Technology (MACT) standard for the pollutant under section

112(d), (2) for a particular source, when case-by-case MACT

determinations are made under section 112(g) for the source, or

(3) the later of June 15, 1994 or 18 months after EPA fails to

issue emissions standards for categories of sources in compliance

with the timetable promulgated pursuant to section 112(e) as

mandated by Section 112(j). 

The section 112(b) list contains some technical errors which

will be corrected in subsequent rulemaking. The majority of the

technical corrections likely to be made are noted below. Also,

the pollutants from the 112(b) list which are addressed in the

proposed HON are followed by an asterisk.

CAS number Chemical name 

75070 Acetaldehyde 

*

60355 Acetamide 

*

75058 Acetonitrile 

*

98862 Acetophenone*

53963 2-Acetylaminofluorene 

*

107028 Acrolein 

*

79061 Acrylamide 

*

79107 Acrylic acid 

*

107131 Acrylonitrile 

*

107051 Allyl chloride 

*

92671 4-Aminobiphenyl 

*

62533 Aniline 

*

90040 o-Anisidine 

*

1332214 Asbestos 
12

71432 Benzene (including benzene from gasoline) 

*

92875 Benzidine 

*

98077 Benzotrichloride 

*

100447 Benzyl chloride 

*

92524 Biphenyl 

*

117817 Bis(2-ethylhexyl)phthalate (DEHP) 

*

542881 Bis(chloromethyl)ether 

*

75252 Bromoform 

*

106990 1,3-Butadiene 

*

156627 Calcium cyanamide 

105602 Caprolactam 

*

133062 Captan 

63252 Carbaryl 

75150 Carbon disulfide 

*

56235 Carbon tetrachloride 

*

463581 Carbonyl sulfide 

*

120809 Catechol 

*

133904 Chloramben 

57749 Chlordane 

7782505 Chlorine 

79118 Chloroacetic acid 

*

532274 2-Chloroacetophenone 

*

108907 Chlorobenzene 

*

510156 Chlorobenzilate 

67663 Chloroform 

*

107302 Chloromethyl methyl ether 

*

126998 Chloroprene 

*

1319773 Cresols/Cresylic acid (isomers and mixture) 

*

95487 o-Cresol 

*

108394 m-Cresol*

106445 p-Cresol*

98828 Cumene 

*

94757 2,4-D (2,4-Dichlorophenoxyacetic acid, including 

 salts and esters) 

*

 DDE [recommended technical correction: CAS number *

 72559] (1,1-dichloro-2,2-bis(p-chlorophenyl) 

 ethylene) 

334883 Diazomethane 

*

132649 Dibenzofurans [recommended technical correction: *

 Dibenzofuran] 

 96128 1,2-Dibromo-3-chloropropane 

*

 84742 Dibutylphthalate 

*

 106467 1,4-Dichlorobenzene(p)*

[recommended technical correction: 1,4-

Dichlorobenzene] 91941 

3,3-Dichlorobenzidene [recommended technical 

*

correction: 3,3'-Dichlorobenzidine] 111444 

Dichloroethyl ether (Bis(2-chloroethyl)ether) 542756 *

1,3-Dichloropropene 62737 *
13

Dichlorvos 111422 

Diethanolamine 121697 *

N,N-Diethyl aniline (N,N-Dimethylaniline) 

*

[recommended technical correction: 

 N,N-Dimethylaniline]

64675 Diethyl sulfate 

*

119904 3,3-Dimethoxybenzidine [recommended technical *

 correction: 3,3'-Dimethoxybenzidine] 

 60117 Dimethyl aminoazobenzene 

*

 119937 3,3',-Dimethyl benzidine [recommended *

technical correction: 3,3',-Dimethylbenzidine] 

 79447 Dimethyl carbamoyl chloride*

[recommended technical correction:

Dimethylcarbamoyl chloride] 68122 Dimethyl formamide*

[recommended technical correction: N,NDimethylformamide] 57147 1,1-Dimethyl

hydrazine [recommended technical correction: 1,1- *

Dimethylhydrazine] 131113 Dimethyl

phthalate 77781 *

Dimethyl sulfate 

*

4,6-Dinitro-o-cresol, and salts [recommended *

technical correction to remove CAS number]

51285 2,4-Dinitrophenol 

*

121142 2,4-Dinitrotoluene 

*

123911 1,4-Dioxane (1,4-Diethyleneoxide) 

*

122667 1,2-Diphenylhydrazine 

*

106898 Epichlorohydrin (l-Chloro-2,3-epoxypropane) 

*

106887 1,2-Epoxybutane 

*

140885 Ethyl acrylate 

*

100414 Ethyl benzene [recommended technical correction: *

 Ethylbenzene] 

 51796 Ethyl carbamate (Urethane) 

*

 75003 Ethyl chloride (Chloroethane) 

*

 106934 Ethylene dibromide

(Dibromoethane) 107062 Ethylene *

dichloride (1,2-Dichloroethane) 107211 *

Ethylene glycol 151564 *

Ethylene imine (Aziridine) [recommended technical 

correction: Ethyleneimine (Aziridine)] 75218 

Ethylene oxide 96457 *

Ethylene thiourea 75343 *

Ethylidene dichloride (1,1-Dichloroethane) 50000 *

Formaldehyde 76448 *

Heptachlor 118741 

Hexachlorobenzene 87683 *

Hexachlorobutadiene 77474 *

Hexachlorocyclopentadiene 67721 

Hexachloroethane 822060 *

Hexamethylene-1,6-diisocyanate 680319 *
14

Hexamethylphosphoramide 110543 *

Hexane 302012 *

Hydrazine 7647010 *

Hydrochloric acid [recommended technical 

correction: Hydrochloric acid (hydrogen 

chloride)(gas only)] 7664393 

Hydrogen fluoride (Hydrofluoric acid) 123319 

Hydroquinone 78591 *

Isophorone 

*

Lindane (all isomers) [Recommended technical 

correction: 1,2,3,4,5,6-Hexachlorocyclohexane (all 

stereo isomers, including lindane)] 108316 

Maleic anhydride 67561 *

Methanol 72435 *

Methoxychlor 74839 

Methyl bromide (Bromomethane) 74873 *

Methyl chloride (Chloromethane) 71556 *

Methyl chloroform (1,1,1-Trichloroethane) 78933 *

Methyl ethyl ketone (2-Butanone) 60344 *

Methyl hydrazine [recommended technical 

*

correction: Methylhydrazine] 74884 

Methyl iodide (Iodomethane) 108101 *

Methyl isobutyl ketone (Hexone) 624839 *

Methyl isocyanate 80626 *

Methyl methacrylate 1634044 *

Methyl tert butyl ether [recommended technical 

*

correction: Methyl tert-butyl ether] 101144 

4,4-Methylene bis(2-chloroaniline) [recommended 

*

technical correction: 4,4'-Methylenebis(2- 

chloroaniline] 

75092 Methylene chloride (Dichloromethane) 

*

101688 Methylene diphenyl diisocyanate (MDI) 

*

 [recommended technical correction: 

 4-4' Methylenediphenyl diisocyanate (MDI)] 

101779 4,4,-Methylenedianiline 

*

91203 Naphthalene 

*

98953 Nitrobenzene 

*

92933 4-Nitrobiphenyl 

*

100027 4-Nitrophenol 

*

79469 2-Nitropropane 

*

684935 N-Nitroso-N-methylurea 

*

62759 N-Nitrosodimethylamine*

59892 N-Nitrosomorpholine 

*

56382 Parathion 

82688 Pentachloronitrobenzene (Quintobenzene) 

87865 Pentachlorophenol 

108952 Phenol 

*

106503 p-Phenylenediamine 

*

75445 Phosgene 

*
15

7803512 Phosphine 

7723140 Phosphorus 

85449 Phthalic anhydride 

*

1336363 Polychlorinated biphenyls (Aroclors) 

*

1120714 1,3-Propane sultone 

*

57578 beta-Propiolactone 

*

123386 Propionaldehyde 

*

114261 Propoxur (Baygon) 

*

78875 Propylene dichloride (1,2-Dichloropropane) 

*

75569 Propylene oxide 

*

75558 1,2-Propylenimine (2-Methyl aziridine) 

*

91225 Quinoline 

106514 Quinone 

*

100425 Styrene*

96093 Styrene oxide 

*

1746016 2,3,7,8-Tetrachlorodibenzo-p-dioxin 

*

79345 1,1,2,2-Tetrachloroethane 

*

127184 Tetrachloroethylene (Perchloroethylene) 

*

7550450 Titanium tetrachloride 

108883 Toluene 

*

95807 2,4-Toluene diamine [recommended technical *

 correction: 2,4-Toluenediamine] 

 584849 2,4-Toluene diisocyanate 

*

 95534 o-Toluidine 

*

 8001352 Toxaphene (chlorinated camphene) 

 120821 1,2,4-Trichlorobenzene 

*

 79005 1,1,2-Trichloroethane 

*

 79016 Trichloroethylene 

*

 95954 2,4,5-Trichlorophenol 

*

 88062 2,4,6-Trichlorophenol*

 121448 Triethylamine 

*

 1582098 Trifluralin 

*

 540841 2,2,4-Trimethylpentane 

*

 108054 Vinyl acetate 

*

 593602 Vinyl bromide*

 75014 Vinyl chloride 

*

 75354 Vinylidene chloride (1,1-Dichloroethylene) 

*

 1330207 Xylenes (isomers and mixture) 

*

 95476 o-Xylenes [recommended technical *

correction: 

o-Xylene 

108383 m-Xylenes [recommended technical correction: *

m-Xylene]

106423 p-Xylenes [recommended technical correction: *

p-Xylene]

0 Antimony Compounds 

0 Arsenic Compounds (inorganic including arsine) 

0 Beryllium Compounds 

0 Cadmium Compounds 
16

0 Chromium Compounds 

0 Cobalt Compounds 

0 Coke Oven Emissions 

0 Cyanide Compounds [1] 

0 Glycol ethers [2] *

0 Lead Compounds 

0 Manganese Compounds 

0 Mercury Compounds 

0 Fine mineral fibers [3] 

0 Nickel Compounds 

0 Polycylic Organic Matter [4] [recommended *

 technical correction: Polycyclic Organic

Matter]

0 Radionuclides (including radon) [5] 

0 Selenium Compounds 

 NOTE: For all listings above which contain the word

"compounds" and for glycol ethers, the following applies: Unless

otherwise specified, these listings are defined as including any

unique chemical substance that contains the named chemical (i.e.,

antimony, arsenic, etc.) as part of that chemical's

infrastructure.

 1 X'CN where X = H' or any other group where a formal

dissociation may occur.

For example KCN or Ca(CN)2 

 

 2 Includes mono- and di- ethers of ethylene glycol, diethylene

glycol, and triethylene glycol R-(OCH2CH2)n-OR' where 

 n = 1, 2, or 3 

 

 R = alkyl or aryl groups 

 

 R' = R, H, or groups which, when removed, yield glycol ethers

with the structure: R-(OCH2CH)n-OH. [recommended technical *

correction: R-(OCH2CH2)n-OH] Polymers are excluded from the

glycol category.

 

 3 Includes mineral fiber emissions from facilities

manufacturing or processing glass, rock, or slag fibers (or other

mineral derived fibers) of average diameter 1 micrometer or less. 

 4 Includes organic compounds with more than one benzene ring,

and which have a boiling point greater than or equal to 100EC.*

[recommended technical correction: Limited to, or refers to,

products from incomplete combustion of organic compounds (or

material) and pyrolysis processes having more than one benzene

ring, and which have a boiling point greater than or equal to

100EC.]
17

 

 5 A type of atom which spontaneously undergoes radioactive

decay. 

II. Pollutants subject to the Hazardous Organic NESHAP (HON):

As part of the effort to regulate pollutants listed in

section 112(b), the EPA has developed the (HON) which will apply

to the synthetic organic chemical manufacturing industry and will

control emissions of 149 volatile hazardous air pollutants

(HAP's). All of the pollutants listed in the HON are among the

189 HAP's listed in section 112(b) and are identified (with an

asterisk) in the preceding section of this document. Pollutants

addressed by the HON will become regulated on the effective date

specified in the HON. 

III. Pollutants listed under Section 112(r):

Section 112(r)(3) requires that EPA promulgate an initial

list of at least 100 substances with threshold quantities which

would cause or may reasonably be anticipated to cause death,

injury, or serious adverse effects to human health or the

environment if accidentally released. The EPA's proposed rule to

implement 112(r)(3) was published in the Federal Register on

January 19, 1993 (58 FR 5102). The proposed list of substances

includes 100 acutely toxic substances, 62 flammable gases and

volatile flammable liquids, and commercial explosives (classified

by the Department of Transportation in Division 1.1). The listed

pollutants will become "regulated" for purposes of title V upon

final promulgation of the list.

The toxic and flammable substances listed in the proposed

rule are arranged alphabetically and by CAS number on the

attached lists. 

_________________________________________________________________

NOTICE

The policies set out in this guidance document are intended

solely as guidance and do not represent final agency action

and are not ripe for judicial review. They are not

intended, nor can they be relied upon, to create any rights

enforceable by any party in litigation with the United

States. The EPA officials may decide to follow the guidance

provided in this guidance document, or to act at variance
18

with the guidance, based on an analysis of specific

circumstances. The EPA may also change this guidance at any

time without public notice.