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['Air Programs']
['Air Emissions', 'Air Permitting', 'Air Programs', 'Air Quality', 'Hazardous Air Pollutants']
02/24/2026
Copyright 2026 J. J. Keller & Associate, Inc. For re-use options please contact copyright@jjkeller.com or call 800-558-5011.
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HAP list
['Air Programs']
- There are 187 HAPs that the EPA is required to regulate under the CAA.
The current list of hazardous air pollutants (HAPs) that the Environmental Protection Agency (EPA) is required to regulate under the Clean Air Act (CAA) includes 187 chemicals, enumerated in the table below by their Chemical Abstracts Service (CAS) numbers and chemical names.
NOTE: For all listings below 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.
| 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 |
| 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, salts and esters |
| 3547044 | DDE |
| 334883 | Diazomethane |
| 132649 | Dibenzofurans |
| 96128 | 1,2-Dibromo-3-chloropropane |
| 84742 | Dibutylphthalate |
| 106467 | 1,4-Dichlorobenzene(p) |
| 91941 | 3,3-Dichlorobenzidene |
| 111444 | Dichloroethyl ether (Bis(2-chloroethyl)ether) |
| 542756 | 1,3-Dichloropropene |
| 62737 | Dichlorvos |
| 111422 | Diethanolamine |
| 121697 | N,N-Dimethylaniline |
| 64675 | Diethyl sulfate |
| 119904 | 3,3-Dimethoxybenzidine |
| 60117 | Dimethyl aminoazobenzene |
| 119937 | 3,3’-Dimethyl benzidine |
| 79447 | Dimethyl carbamoyl chloride |
| 68122 | Dimethyl formamide |
| 57147 | 1,1-Dimethyl hydrazine |
| 131113 | Dimethyl phthalate |
| 77781 | Dimethyl sulfate |
| 534521 | 4,6-Dinitro-o-cresol, and salts |
| 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 |
| 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) |
| 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 | Hexamethylphosphoramide |
| 110543 | Hexane |
| 302012 | Hydrazine |
| 7647010 | Hydrochloric acid |
| 7664393 | Hydrogen fluoride (Hydrofluoric acid) |
| 7783064 | Hydrogen sulfide |
| 123319 | Hydroquinone |
| 78591 | Isophorone |
| 58899 | Lindane (all isomers) |
| 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 |
| 74884 | Methyl iodide (Iodomethane) |
| 108101 | Methyl isobutyl ketone (Hexone) |
| 624839 | Methyl isocyanate |
| 80626 | Methyl methacrylate |
| 1634044 | Methyl tert butyl ether |
| 101144 | 4,4-Methylene bis(2-chloroaniline) |
| 75092 | Methylene chloride (Dichloromethane) |
| 101688 | Methylene diphenyl 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 |
| 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 |
| 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 |
| 108383 | m-Xylenes |
| 106423 | p-Xylenes |
| 0 | Antimony compounds |
| Arsenic compounds (inorganic including arsine) | |
| Beryllium compounds | |
| Cadmium compounds | |
| Chromium compounds | |
| Cobalt compounds | |
| Coke oven emissions | |
| Cyanide compounds | |
| Glycol ethers | |
| Lead compounds | |
| Manganese compounds | |
| Mercury compounds | |
| Fine mineral fibers | |
| Nickel compounds | |
| Polycyclic organic matter | |
| Radionuclides (including radon) | |
| Selenium compounds |
:
air-programs
air-programs
FOUNDATIONAL LEARNING
- There are 187 HAPs that the EPA is required to regulate under the CAA.
The current list of hazardous air pollutants (HAPs) that the Environmental Protection Agency (EPA) is required to regulate under the Clean Air Act (CAA) includes 187 chemicals, enumerated in the table below by their Chemical Abstracts Service (CAS) numbers and chemical names.
NOTE: For all listings below 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.
| 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 |
| 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, salts and esters |
| 3547044 | DDE |
| 334883 | Diazomethane |
| 132649 | Dibenzofurans |
| 96128 | 1,2-Dibromo-3-chloropropane |
| 84742 | Dibutylphthalate |
| 106467 | 1,4-Dichlorobenzene(p) |
| 91941 | 3,3-Dichlorobenzidene |
| 111444 | Dichloroethyl ether (Bis(2-chloroethyl)ether) |
| 542756 | 1,3-Dichloropropene |
| 62737 | Dichlorvos |
| 111422 | Diethanolamine |
| 121697 | N,N-Dimethylaniline |
| 64675 | Diethyl sulfate |
| 119904 | 3,3-Dimethoxybenzidine |
| 60117 | Dimethyl aminoazobenzene |
| 119937 | 3,3’-Dimethyl benzidine |
| 79447 | Dimethyl carbamoyl chloride |
| 68122 | Dimethyl formamide |
| 57147 | 1,1-Dimethyl hydrazine |
| 131113 | Dimethyl phthalate |
| 77781 | Dimethyl sulfate |
| 534521 | 4,6-Dinitro-o-cresol, and salts |
| 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 |
| 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) |
| 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 | Hexamethylphosphoramide |
| 110543 | Hexane |
| 302012 | Hydrazine |
| 7647010 | Hydrochloric acid |
| 7664393 | Hydrogen fluoride (Hydrofluoric acid) |
| 7783064 | Hydrogen sulfide |
| 123319 | Hydroquinone |
| 78591 | Isophorone |
| 58899 | Lindane (all isomers) |
| 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 |
| 74884 | Methyl iodide (Iodomethane) |
| 108101 | Methyl isobutyl ketone (Hexone) |
| 624839 | Methyl isocyanate |
| 80626 | Methyl methacrylate |
| 1634044 | Methyl tert butyl ether |
| 101144 | 4,4-Methylene bis(2-chloroaniline) |
| 75092 | Methylene chloride (Dichloromethane) |
| 101688 | Methylene diphenyl 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 |
| 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 |
| 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 |
| 108383 | m-Xylenes |
| 106423 | p-Xylenes |
| 0 | Antimony compounds |
| Arsenic compounds (inorganic including arsine) | |
| Beryllium compounds | |
| Cadmium compounds | |
| Chromium compounds | |
| Cobalt compounds | |
| Coke oven emissions | |
| Cyanide compounds | |
| Glycol ethers | |
| Lead compounds | |
| Manganese compounds | |
| Mercury compounds | |
| Fine mineral fibers | |
| Nickel compounds | |
| Polycyclic organic matter | |
| Radionuclides (including radon) | |
| Selenium compounds |
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Copyright 2026 J. J. Keller & Associate, Inc. For re-use options please contact copyright@jjkeller.com or call 800-558-5011.