Regulations last checked for updates: Feb 22, 2025

Title 40 - Protection of Environment last revised: Nov 22, 2025
Appendix - Table 2A to Subpart E of Part 59—Reactivity Factors
Compound CAS No. Reactivity factor
(g O3/g VOC)
Formaldehyde50-00-09.46
Glycerol (1,2,3-Propanetriol)56-81-53.15
Propylene Glycol57-55-62.58
Ethanol64-17-51.53
Formic Acid64-18-60.06
Acetic Acid64-19-70.68
Methanol67-56-10.67
Isopropyl Alcohol (2-Propanol)67-63-00.61
Acetone (Propanone)67-64-10.36
n-Propanol (n-Propyl Alcohol)71-23-82.50
n-Butyl Alcohol (Butanol)71-36-32.88
n-Pentanol (Amyl Alcohol)71-41-02.83
Benzene71-43-20.72
1,1,1-Trichloroethane71-55-60.01
Propane74-98-60.49
Vinyl Chloride75-01-42.83
Acetaldehyde75-07-06.54
Methylene Chloride (Dichloromethane)75-09-20.04
Ethylene Oxide75-21-80.03
Isobutane75-28-51.23
HFC-152A (1,1-Difluoroethane)75-37-60.02
Propylene Oxide75-56-90.29
t-Butyl Alcohol75-65-00.41
Methyl t-Butyl Ketone75-97-80.65
Isophorone (3,5,5-Trimethyl-2-Cyclohexenone)78-59-14.63
Isopentane78-78-41.45
Isobutanol78-83-12.51
2-Butanol (s-butyl alcohol)78-92-21.36
Methyl Ethyl Ketone (2-Butanone)78-93-31.48
Monoisopropanol Amine (1-Amino-2-Propanol)78-96-65.42
Trichloroethylene79-01-60.64
Propionic Acid79-09-41.22
Acrylic Acid79-10-711.38
Methyl Acetate79-20-90.07
Nitroethane79-24-30.06
Methacrylic Acid79-41-418.50
2-Nitropropane79-46-90.11
a-Pinene (Pine Oil)80-56-84.51
Methyl Methacrylate80-62-615.61
Diethyl Phthalate84-66-21.62
Dibutyl Phthalate84-74-21.25
Naphthalene91-20-33.34
2-Ethyl-1,3-hexanediol94-96-22.05
Xylene, ortho-95-47-67.64
o-Cresol95-48-72.40
1,2,4-Trimethylbenzene95-63-68.87
3-Pentanone96-22-01.24
Methyl Ethyl Ketoxime (Ethyl Methyl Ketone Oxime)96-29-71.58
gamma-Butyrolactone96-48-00.96
Ethyl Lactate97-64-32.48
Isobutyl Isobutyrate97-85-80.60
Isobutyl Methacrylate97-86-98.62
Butyl Methacrylate97-88-18.70
Tert-butyl benzene98-06-61.95
Benzotrifluoride98-08-80.29
PCBTF (p-Trifluoromethyl-Cl-Benzene)98-56-60.13
Cumene (Isopropyl Benzene)98-82-82.52
a-Methyl Styrene98-83-91.53
Ethyl Benzene100-41-43.04
Styrene100-42-51.73
Benzyl Alcohol100-51-65.11
Benzaldehyde100-52-70.00
Triethanolamine102-71-64.21
2-Ethyl-Hexyl Acetate103-09-30.66
2-Ethyl-Hexyl Acrylate103-11-72.52
2-Ethyl-1-Hexanol (Ethyl Hexyl Alcohol)104-76-72.00
Ethyl Propionate105-37-30.77
s-Butyl Acetate105-46-41.32
Diethyl Carbonate105-58-80.71
n-Propyl Propionate106-36-50.84
Xylene, para-106-42-35.84
p-Dichlorobenzene106-46-70.18
Dimethyl Succinate106-65-00.23
1,2-Epoxybutane (Ethyl Oxirane)106-88-70.91
n-Propyl Bromide106-94-50.42
Butane106-97-81.15
1,3-Butadiene106-99-012.61
Ethylene Glycol107-21-13.13
2-Methyl-2,4-Pentanediol107-41-51.45
Hexamethyldisiloxane107-46-00.00
Isohexane Isomers107-83-51.50
Methyl n-Propyl Ketone (2-Pentanone)107-87-92.81
Propylene Glycol Monomethyl Ether (1-Methoxy-2-Propanol)107-98-22.44
n,n-Dimethylethanolamine108-01-05.62
1-Nitropropane108-03-20.22
Vinyl Acetate108-05-43.20
Methyl Isobutyl Ketone108-10-13.88
Isopropyl Acetate108-21-41.07
Propylene Carbonate (4-Methyl-1,3-Dioxolan-2one)108-32-70.28
Xylene, meta-108-38-39.75
Propylene Glycol Monomethyl Ether Acetate (1-Methoxy-2-Propyl Acetate)108-65-61.70
1,3,5-Trimethyl Benzene108-67-811.76
Di-Isobutyl Ketone (2,6-Dimethyl-4-Heptanone)108-83-82.68
Methylcyclohexane108-87-21.70
Toluene108-88-34.00
Monochlorobenzene108-90-70.32
Cyclohexanol108-93-01.95
Cyclohexanone108-94-11.35
n-Butyl Butyrate109-21-71.08
Propyl Acetate109-60-40.78
Pentane109-66-01.31
Ethylene Glycol Monomethyl Ether (2-Methoxyethanol)109-86-42.93
Dimethoxy Methane109-87-50.94
Tetrahydrofuran109-99-94.31
Methyl Isoamyl Ketone (5-Methyl-2-Hexanone)110-12-32.41
Isobutyl Acetate110-19-00.62
Methyl Amyl Ketone110-43-02.36
Hexane110-54-31.24
n-Propyl Formate110-74-70.78
2-Ethoxyethanol110-80-53.71
Cyclohexane110-82-71.25
Morpholine110-91-81.98
Dipropylene Glycol110-98-52.31
Ethylene Glycol Monoethyl Ether Acetate (2-Ethoxyethyl Acetate)111-15-91.84
Diethylenetriamine111-40-015.53
Diethanolamine111-42-22.47
Diethylene Glycol111-46-63.35
n-Octane111-65-90.90
2-Butoxy-1-Ethanol (Ethylene Glycol Monobutyl Ether)111-76-22.90
Diethylene Glycol Methyl Ether (2-(2-Methoxyethoxy) Ethanol)111-77-32.66
n-Nonane111-84-20.78
2-(2-Ethoxyethoxy) Ethanol111-90-03.26
Ethylene Glycol Monobutyl Ether Acetate (2-Butoxyethyl Acetate)112-07-21.62
2-(2-Ethoxyethoxy) Ethyl Acetate112-15-21.48
2-(2-Butoxyethoxy)-Ethanol112-34-52.39
Dimethyl Ether115-10-60.81
Triethylamine121-44-83.84
2-Phenoxyethanol; Ethylene Glycol Phenyl Ether122-99-64.49
Diacetone Alcohol123-42-20.60
2,4-Pentanedione123-54-61.01
Butanal123-72-85.97
Butyl Acetate, n123-86-40.83
3-Methyl-Butyl Acetate123-92-21.09
2-(2-Butoxyethoxy) Ethyl Acetate124-17-41.38
2-Amino-2-Methyl-1-Propanol124-68-50.25
Perchloroethylene127-18-40.03
Ethanolamine141-43-56.81
Ethyl acetate141-78-60.63
Heptane142-82-51.07
n-Hexyl Acetate (Hexyl Acetate)142-92-70.69
2-Ethyl Hexanoic Acid149-57-53.32
trans-1,2-Dichloroethene156-60-51.70
1,2,3-Trimethyl Benzene526-73-811.97
t-Butyl Acetate540-88-50.18
Methyl Isobutyrate547-63-70.61
Methyl Lactate547-64-82.67
Methyl Propionate554-12-10.66
1,2-Butanediol584-03-22.52
n-Butyl Propionate590-01-20.84
Methyl n-Butyl Ketone (2-Hexanone)591-78-63.14
Dimethyl carbonate616-38-60.06
2-Methyl-1-Butyl Acetate624-41-91.08
n-Pentyl Propionate624-54-40.71
Ethyl Isopropyl Ether625-54-73.74
Dimethyl Adipate627-93-01.80
Methyl n-Butyl Ether628-28-43.15
Amyl Acetate (Pentyl Ethanoate, Pentyl Acetate)628-63-70.84
Ethyl n-Butyl Ether628-81-93.48
Ethyl t-Butyl Ether637-92-32.01
1,3-Dioxolane646-06-04.96
Ethyl-3-Ethoxypropionate763-69-93.58
Methyl Pyrrolidone (n-Methyl-2-Pyrrolidone)872-50-42.41
Dimethyl Gluterate1119-40-00.42
C8 Disubstituted Benzenes1330-20-77.76
Ethylene Glycol 2-Ethylhexyl Ether [2-(2-Ethylhexyloxy) Ethanol]1559-35-91.55
Propylene Glycol Monopropyl Ether (1-Propoxy-2-Propanol)1569-01-32.68
Propylene Glycol Monoethyl Ether (1-Ethoxy-2-Propanol)1569-02-43.09
2-Methoxy-1-Propanol1589-47-53.01
Methyl t-Butyl Ether1634-04-40.73
trans-1,3,3,3-tetrafluoropropene (HFO-1234ze)1645-83-60.10
Ethylcyclohexane1678-91-71.47
Isoamyl Isobutyrate2050-01-30.82
2-Propoxy-ethanol (Ethylene Glycol Monopropyl Ether)2807-30-93.30
n-Butoxy-2-Propanol5131-66-82.72
d-Limonene (Dipentene or Orange Terpene)5989-27-54.55
2,2,4-trimethyl-1,3-pentanediol diisobutyrate6846-50-00.38
Dipropylene Glycol Methyl Ether Isomer (2-[2Methoxypropoxy]-1-Propanol)13588-28-82.58
C9 Styrenes25013-15-41.53
Texanol (1,3 Pentanediol, 2,2,4-Trimethyl, 1-Isobutyrate)25265-77-40.81
Isodecyl Alcohol (8-Methyl-1-Nonanol)25339-17-71.06
Tripropylene Glycol Monomethyl Ether25498-49-11.92
Glycol Ether DPNB (1-(2-Butoxy-1-Methylethoxy) 2-Propanol)29911-28-21.83
Dipropylene Glycol Monomethyl Ether (mixture of isomers)34590-94-82.58
Propylene Glycol t-Butyl Ether (1-tert-Butoxy-2-Propanol)57018-52-71.61
2-Methoxy-1-Propyl Acetate70657-70-41.12
Dipropylene Glycol Methyl Ether Acetate Isomers88917-22-01.45
Oxo-Heptyl Acetate90438-79-20.83
2-tert-Butoxy-1-Propanol94023-15-11.81
trans-1-chloro-3,3,3-trifluoropropene (HFO-1233zdE)102687-65-00.04
Oxo-Octyl Acetate108419-32-50.81
[77 FR 14284, Mar. 9, 2012, as amended at 90 FR 5710, Jan. 17, 2025]
authority: 42 U.S.C. 7414 and 7511b(e)
source: 64 FR 48815, Sept. 11, 1998, unless otherwise noted.