Regulations last checked for updates: Nov 22, 2024

Title 40 - Protection of Environment last revised: Nov 20, 2024
Appendix - Table 4 to Subpart F of Part 63—Organic Hazardous Air Pollutants Subject to Cooling Tower Monitoring Requirements in § 63.104
Chemical name CAS
Number a
Acetaldehyde75070
Acetonitrile75058
Acetophenone98862
Acrolein107028
Acrylonitrile107131
Allyl chloride107051
Aniline62533
Anisidine (o-)90040
Benzene71432
Benzyl chloride100447
Biphenyl92524
Bromoform75252
Butadiene (1,3-)106990
Carbon disulfide75150
Carbon tetrachloride56235
Chloroacetophenone (2-)532274
Chlorobenzene108907
2-Chloro-1,3-butadiene (Chloroprene)126998
Chloroform67663
Cresol and cresylic acid (o-)95487
Cresol and cresylic acid (m-)108394
Cresol and cresylic acid (p-)106445
Cumene98828
Dichlorobenzene (p-)106467
Dichlorobenzidine (3,3″-)91941
Dichloroethane (1,2-) (Ethylene dichloride) (EDC)107062
Dichloroethyl ether (Bis(2-chloroethyl)ether)111444
Dichloropropene (1,3-)542756
Diethylene glycol diethyl ether112367
Diethylene glycol dimethyl ether111966
Diethyl sulfate64675
Dimethylaniline (N,N-)121697
Dimethylhydrazine (1,1-)57147
Dimethyl phthalate131113
Dimethyl sulfate77781
Dinitrophenol (2,4-)51285
Dinitrotoluene (2,4-)121142
Dioxane (1,4-) (1,4-Diethyleneoxide)123911
Epichlorohydrin (1-Chloro-2,3-epoxypropane)106898
Ethyl acrylate140885
Ethylbenzene100414
Ethyl chloride (Chloroethane)75003
Ethylene dibromide (Dibromoethane)106934
Ethylene glycol dimethyl ether110714
Ethylene glycol monobutyl ether acetate112072
Ethylene glycol monoethyl ether acetate111159
Ethylene glycol monoethyl ether110805
Ethylene glycol monomethyl ether109864
Ethylene glycol monomethyl ether acetate110496
Ethylene glycol monopropyl ether2807309
Ethylene oxide75218
Ethylidene dichloride (1,1-Dichloroethane)75343
Formaldehyde50000
Hexachlorobenzene118741
Hexachlorobutadiene87683
Hexachloroethane67721
Hexane110543
Isophorone78591
Methanol67561
Methyl bromide (Bromomethane)74839
Methyl chloride (Chloromethane)74873
Methyl hydrazine60344
Methyl isobutyl ketone (Hexone)108101
Methyl methacrylate80626
Methyl tert-butyl ether1634044
Methylene chloride (Dichloromethane)75092
Methylenedianiline (4,4″-)101779
Naphthalene91203
Nitrobenzene98953
Nitropropane (2-)79469
Phenol108952
Phenylenediamine (p-)106503
Phosgene75445
Propionaldehyde123386
Propylene dichloride (1,2-Dichloropropane)78875
Propylene oxide75569
Quinone106514
Styrene100425
Tetrachloroethane (1,1,2,2-)79345
Tetrachloroethylene (Perchloroethylene)127184
Toluene108883
Toluidine (o-)95534
Trichlorobenzene (1,2,4-)120821
Trichloroethane (1,1,1-) (Methyl chloroform)71556
Trichloroethane (1,1,2-) (Vinyl trichloride)79005
Trichloroethylene79016
Trichlorophenol (2,4,5-)95954
Triethylamine121448
Trimethylpentane (2,2,4-)540841
Vinyl acetate108054
Vinyl chloride (chloroethylene)75014
Vinylidene chloride (1,1-Dichloroethylene)75354
Xylene (m-)108383
Xylene (o-)95476
Xylene (p-)106423

a CAS Number = Chemical Abstract Service number.

[62 FR 2740, Jan. 17, 1997, as amended at 71 FR 76614, Dec. 21, 2006; 89 FR 43175, May 16, 2024]
authority: 42 U.S.C. 7401
source: 57 FR 61992, Dec. 29, 1992, unless otherwise noted.