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Appendix G: 1989 Air Contaminants Update Project - Exposure Limits NOT in Effect

The OSHA permissible exposure limits (PELs), as found in Tables Z-1, Z-2, and Z-3 of the OSHA General Industry Air Contaminants Standard (29 CFR 1910.1000), that were effective on July 1, 1993* and which are currently enforced by OSHA are listed on the page for each chemical in the Pocket Guide.

*In July 1992, the 11th Circuit Court of Appeals in its decision in AFL-CIO v. OSHA, 965 F.2d 962 (11th Cir., 1992) vacated more protective PELs set by OSHA in 1989 for 212 substances, moving them back to PELs established in 1971. The appeals court also vacated new PELs for 164 substances that were not previously regulated. Enforcement of the court decision began on June 30, 1993. Although OSHA is currently enforcing exposure limits in Tables Z-1, Z-2, and Z-3 of 29 CFR 1910.1000 which were in effect before 1989, violations of the "general duty clause" as contained in Section 5(a) (1) of the Occupational Safety and Health Act may be considered when worker exposures exceed the 1989 PELs for the 164 substances that were not previously regulated. The substances for which OSHA PELs were vacated on June 30, 1993 are indicated by the symbol "†" following OSHA in the Exposure Limit section on the page for each chemical in the Pocket Guide. Appendix G lists the previous values (the PELs that were vacated).

Acetaldehyde TWA 100 ppm (180 mg/m3)
ST 150 ppm (270 mg/m3)
Acetic anhydride C 5 ppm (20 mg/m3)
Acetone TWA 750 ppm (1800 mg/m3)
ST 1000 ppm (2400 mg/m3)
Acetonitrile TWA 40 ppm (70 mg/m3)
ST 60 ppm (105 mg/m3)
Acetylsalicyclic acid TWA 5 mg/m3
Acrolein TWA 0.1 ppm (0.25 mg/m3)
ST 0.3 ppm (0.8 mg/m3)
Acrylamide TWA 0.03 mg/m3 [skin]
Acrylic acid TWA 10 ppm (30 mg/m3) [skin]
Allyl alcohol TWA 2 ppm (5 mg/m3)
ST 4 ppm (10 mg/m3) [skin]
Allyl chloride TWA 1 ppm (3 mg/m3)
ST 2 ppm (6 mg/m3)
Allyl glycidyl ether TWA 5 ppm (22 mg/m3)
ST 10 ppm (44 mg/m3)
Allyl propyl disulfide TWA 2 ppm (12 mg/m3)
ST 3 ppm (18 mg/m3)
alpha-Alumina TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Aluminum (pyro powders & welding fumes, as Al) TWA 5 mg/m3
Aluminum (soluble salts & alkyls, as Al) TWA 2 mg/m3
Amitrole TWA 0.2 mg/m3
Ammonia ST 35 ppm (27 mg/m3)
Ammonium chloride fume TWA 10 mg/m3
ST 20 mg/m3
Ammonium sulfamate TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Aniline (and homologs) TWA 2 ppm (8 mg/m3) [skin]
Atrazine TWA 5 mg/m3
Barium sulfate TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Benomyl TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Benzenethiol TWA 0.5 ppm (2 mg/m3)
Bismuth telluride (doped with selenium sulfide, as Bi2Te3) TWA 5 mg/m3
Borates, tetra, sodium salts (Anhydrous) TWA 10 mg/m3
Borates, tetra, sodium salts (Decahydrate) TWA 10 mg/m3
Borates, tetra, sodium salts (Pentahydrate) TWA 10 mg/m3
Boron oxide TWA 10 mg/m3
Boron tribromide C 1 ppm (10 mg/m3)
Bromacil TWA 1 ppm (10 mg/m3)
Bromine TWA 0.1 ppm (0.7 mg/m3)
ST 0.3 ppm (2 mg/m3)
Bromine pentafluoride TWA 0.1 ppm (0.7 mg/m3)
n-Butane TWA 800 ppm (1900 mg/m3)
2-Butanone TWA 200 ppm (590 mg/m3)
ST 300 ppm (885 mg/m3)
2-Butoxyethanol TWA 25 ppm (120 mg/m3) [skin]
n-Butyl acetate TWA 150 ppm (710 mg/m3)
ST 200 ppm (950 mg/m3)
Butyl acrylate TWA 10 ppm (55 mg/m3)
n-Butyl alcohol C 50 ppm (150 mg/m3) [skin]
sec-Butyl alcohol TWA 100 ppm (305 mg/m3)
tert-Butyl alcohol TWA 100 ppm (300 mg/m3)
ST 150 ppm (450 mg/m3)
n-Butyl glycidyl ether TWA 25 ppm (135 mg/m3)
n-Butyl lactate TWA 5 ppm (25 mg/m3)
n-Butyl mercaptan TWA 0.5 ppm (1.5 mg/m3)
o-sec-Butylphenol TWA 5 ppm (30 mg/m3) [skin]
p-tert-Butyltoluene TWA 10 ppm (60 mg/m3)
ST 20 ppm (120 mg/m3)
Calcium cyanamide TWA 0.5 mg/m3
Caprolactam Dust:
TWA 1 mg/m3
ST 3 mg/m3

Vapor:
TWA 5 ppm (20 mg/m3)
ST 10 ppm (40 mg/m3)
Captafol TWA 0.1 mg/m3
Captan TWA 5 mg/m3
Carbofuran TWA 0.1 mg/m3
Carbon dioxide TWA 10,000 ppm (18,000 mg/m3)
ST 30,000 ppm (54,000 mg/m3)
Carbon disulfide TWA 4 ppm (12 mg/m3)
ST 12 ppm (36 mg/m3) [skin]
Carbon monoxide TWA 35 ppm (40 mg/m3)
C 200 ppm (229 mg/m3)
Carbon tetrabromide TWA 0.1 ppm (1.4 mg/m3)
ST 0.3 ppm (4 mg/m3)
Carbon tetrachloride TWA 2 ppm (12.6 mg/m3)
Carbonyl fluoride TWA 2 ppm (5 mg/m3)
ST 5 ppm (15 mg/m3)
Catechol TWA 5 ppm (20 mg/m3) [skin]
Cesium hydroxide TWA 2 mg/m3
Chlorinated camphene TWA 0.5 mg/m3
ST 1 mg/m3 [skin]
Chlorine TWA 0.5 ppm (1.5 mg/m3)
ST 1 ppm (3 mg/m3)
Chlorine dioxide TWA 0.1 ppm (0.3 mg/m3)
ST 0.3 ppm (0.9 mg/m3)
Chloroacetyl chloride TWA 0.05 ppm (0.2 mg/m3)
o-Chlorobenzylidene malononitrile C 0.05 ppm (0.4 mg/m3) [skin]
Chlorodifluoromethane TWA 1000 ppm (3500 mg/m3)
Chloroform TWA 2 ppm (9.78 mg/m3)
1-Chloro-1-nitropropane TWA 2 ppm (10 mg/m3)
Chloropentafluoroethane TWA 1000 ppm (6320 mg/m3)
beta-Chloroprene TWA 10 ppm (35 mg/m3) [skin]
o-Chlorostyrene TWA 50 ppm (285 mg/m3)
ST 75 ppm (428 mg/m3)
o-Chlorotoluene TWA 50 ppm (250 mg/m3)
Chlorpyrifos TWA 0.2 mg/m3 [skin]
Coal dust TWA 2 mg/m3 (<5% SiO2)(resp dust)
TWA 0.1 mg/m3 (> or = 5% SiO2) (resp quartz)
Cobalt metal dust & fume, as Co) TWA 0.05 mg/m3
Cobalt carbonyl (as Co) TWA 0.1 mg/m3
Cobalt hydrocarbonyl (as Co) TWA 0.1 mg/m3
Crag® herbicide TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Crufomate TWA 5 mg/m3
Cyanamide TWA 2 mg/m3
Cyanogen TWA 10 ppm (20 mg/m3)
Cyanogen chloride C 0.3 ppm (0.6 mg/m3)
Cyclohexanol TWA 50 ppm (200 mg/m3) [skin]
Cyclohexanone TWA 25 ppm (100 mg/m3) [skin]
Cyclohexylamine TWA 10 ppm (40 mg/m3)
Cyclonite TWA 1.5 mg/m3 [skin]
Cyclopentane TWA 600 ppm (1720 mg/m3)
Cyhexatin TWA 5 mg/m3
Decaborane TWA 0.3 mg/m3 (0.05 ppm)
ST 0.9 mg/m3 (0.15 ppm) [skin]
Diazinon TWA 0.1 mg/m3 [skin]
2-N-Dibutylaminoethanol TWA 2 ppm (14 mg/m3)
Dibutyl phosphate TWA 1 ppm (5 mg/m3)
ST 2 ppm (10 mg/m3)
Dichloroacetylene C 0.1 ppm (0.4 mg/m3)
p-Dichlorobenzene TWA 75 ppm (450 mg/m3)
ST 110 ppm (675 mg/m3)
1,3-Dichloro-5,5-dimethylhydantoin TWA 0.2 mg/m3
ST 0.4 mg/m3
Dichloroethyl ether TWA 5 ppm (30 mg/m3)
ST 10 ppm (60 mg/m3) [skin]
Dichloromonofluoromethane TWA 10 ppm (40 mg/m3)
1,1-Dichloro-1-nitroethane TWA 2 ppm (10 mg/m3)
1,3-Dichloropropene TWA 1 ppm (5 mg/m3) [skin]
2,2-Dichloropropionic acid TWA 1 ppm (6 mg/m3)
Dicrotophos TWA 0.25 mg/m3 [skin]
Dicyclopentadiene TWA 5 ppm (30 mg/m3)
Dicyclopentadienyl iron TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Diethanolamine TWA 3 ppm (15 mg/m3)
Diethylamine TWA 10 ppm (30 mg/m3)
ST 25 ppm (75 mg/m3)
Diethylenetriamine TWA 1 ppm (4 mg/m3)
Diethyl ketone TWA 200 ppm (705 mg/m3)
Diethyl phthalate TWA 5 mg/m3
Diglycidyl ether TWA 0.1 ppm (0.5 mg/m3)
Diisobutyl ketone TWA 25 ppm (150 mg/m3)
N,N-Dimethylaniline TWA 5 ppm (25 mg/m3)
ST 10 ppm (50 mg/m3) [skin]
Dimethyl-1,2-dibromo-2,2-dichlorethyl phosphate TWA 3 mg/m3 [skin]
Dimethyl sulfate TWA 0.1 ppm (0.5 mg/m3) [skin]
Dinitolmide TWA 5 mg/m3
Di-sec octyl phthalate TWA 5 mg/m3
ST 10 mg/m3
Dioxane TWA 25 ppm (90 mg/m3) [skin]
Dioxathion TWA 0.2 mg/m3 [skin]
Diphenylamine TWA 10 mg/m3
Dipropylene glycol methyl ether TWA 100 ppm (600 mg/m3)
ST 150 ppm (900 mg/m3) [skin]
Dipropyl ketone TWA 50 ppm (235 mg/m3)
Diquat (Diquat dibromide) TWA 0.5 mg/m3
Disulfiram TWA 2 mg/m3
Disulfoton TWA 0.1 mg/m3 [skin]
2,6-Di-tert-butyl-p-cresol TWA 10 mg/m3
Diuron TWA 10 mg/m3
Divinyl benzene TWA 10 ppm (50 mg/m3)
Emery TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Endosulfan TWA 0.1 mg/m3 [skin]
Epichlorohydrin TWA 2 ppm (8 mg/m3) [skin]
Ethanolamine TWA 3 ppm (8 mg/m3)
ST 6 ppm (15 mg/m3)
Ethion TWA 0.4 mg/m3 [skin]
Ethyl acrylate TWA 5 ppm (20 mg/m3)
ST 25 ppm (100 mg/m3) [skin]
Ethyl benzene TWA 100 ppm (435 mg/m3)
ST 125 ppm (545 mg/m3)
Ethyl bromide TWA 200 ppm (890 mg/m3)
ST 250 ppm (1110 mg/m3)
Ethylene chlorohydrin C 1 ppm (3 mg/m3) [skin]
Ethylene dichloride TWA 1 ppm (4 mg/m3)
ST 2 ppm (8 mg/m3)
Ethylene glycol C 50 ppm (125 mg/m3)
Ethylene glycol dinitrate ST 0.1 mg/m3 [skin]
Ethyl ether TWA 400 ppm (1200 mg/m3)
ST 500 ppm (1500 mg/m3)
Ethylidene norbornene C 5 ppm (25 mg/m3)
Ethyl mercaptan TWA 0.5 ppm (1 mg/m3)
N-Ethylmorpholine TWA 5 ppm (23 mg/m3) [skin]
Ethyl silicate TWA 10 ppm (85 mg/m3)
Fenamiphos TWA 0.1 mg/m3 [skin]
Fensulfothion TWA 0.1 mg/m3
Fenthion TWA 0.2 mg/m3 [skin]
Ferbam TWA 10 mg/m3
Ferrovanadium dust TWA 1 mg/m3
ST 3 mg/m3
Fluorotrichloromethane C 1000 ppm (5600 mg/m3)
Fonofos TWA 0.1 mg/m3 [skin]
Formamide TWA 20 ppm (30 mg/m3)
ST 30 ppm (45 mg/m3)
Furfural TWA 2 ppm (8 mg/m3) [skin]
Furfuryl alcohol TWA 10 ppm (40 mg/m3)
ST 15 ppm (60 mg/m3) [skin]
Gasoline TWA 300 ppm (900 mg/m3)
ST 500 ppm (1500 mg/m3)
Germanium tetrahydride TWA 0.2 ppm (0.6 mg/m3)
Glutaraldehyde C 0.2 ppm (0.8 mg/m3)
Glycerin (mist) TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Glycidol TWA 25 ppm (75 mg/m3)
Graphite (natural) TWA 2.5 mg/m3 (resp)
Graphite (synthetic) TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
n-Heptane TWA 400 ppm (1600 mg/m3)
ST 500 ppm (2000 mg/m3)
Hexachlorobutadiene TWA 0.02 ppm (0.24 mg/m3)
Hexachlorocyclopentadiene TWA 0.01 ppm (0.1 mg/m3)
Hexafluoroacetone TWA 0.1 ppm (0.7 mg/m3) [skin]
n-Hexane TWA 50 ppm (180 mg/m3)
Hexane isomers (except n-Hexane) TWA 500 ppm (1800 mg/m3)
ST 1000 ppm (3600 mg/m3)
2-Hexanone TWA 5 ppm (20 mg/m3)
Hexone TWA 50 ppm (205 mg/m3)
ST 75 ppm (300 mg/m3)
Hexylene glycol C 25 ppm (125 mg/m3)
Hydrazine TWA 0.1 ppm (0.1 mg/m3) [skin]
Hydrogenated terphenyls TWA 0.5 ppm (5 mg/m3)
Hydrogen bromide C 3 ppm (10 mg/m3)
Hydrogen cyanide ST 4.7 ppm (5 mg/m3) [skin]
Hydrogen fluoride (as F) TWA 3 ppm
ST 6 ppm
Hydrogen sulfide TWA 10 ppm (14 mg/m3)
ST 15 ppm (21 mg/m3)
2-Hydroxypropyl acrylate TWA 0.5 ppm (3 mg/m3) [skin]
Indene TWA 10 ppm (45 mg/m3)
Indium TWA 0.1 mg/m3
Iodoform TWA 0.6 ppm (10 mg/m3)
Iron pentacarbonyl (as Fe) TWA 0.1 ppm (0.8 mg/m3)
ST 0.2 ppm (1.6 mg/m3)
Iron salts (soluble, as Fe) TWA 1 mg/m3
Isoamyl alcohol (primary & secondary) TWA 100 ppm (360 mg/m3)
ST 125 ppm (450 mg/m3)
Isobutane TWA 800 ppm (1900 mg/m3)
Isobutyl alcohol TWA 50 ppm (150 mg/m3)
Isooctyl alcohol TWA 50 ppm (270 mg/m3) [skin]
Isophorone TWA 4 ppm (23 mg/m3)
Isophorone diisocyanate TWA 0.005 ppm
ST 0.02 ppm [skin]
2-Isopropoxyethanol TWA 25 ppm (105 mg/m3)
Isopropyl acetate TWA 250 ppm (950 mg/m3)
ST 310 ppm (1185 mg/m3)
Isopropyl alcohol TWA 400 ppm (980 mg/m3)
ST 500 ppm (1225 mg/m3)
Isopropylamine TWA 5 ppm (12 mg/m3)
ST 10 ppm (24 mg/m3)
N-Isopropylaniline TWA 2 ppm (10 mg/m3) [skin]
Isopropyl glycidyl ether TWA 50 ppm (240 mg/m3)
ST 75 ppm (360 mg/m3)
Kaolin TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Ketene TWA 0.5 ppm (0.9 mg/m3)
ST 1.5 ppm (3 mg/m3)
Magnesium oxide fume TWA 10 mg/m3
Malathion TWA 10 mg/m3 [skin]
Manganese compounds and fume (as Mn) Compounds:
C 5 mg/m3

Fume:
TWA 1 mg/m3
ST 3 mg/m3
Manganese cyclopentadienyl tricarbonyl (as Mn) TWA 0.1 mg/m3 [skin]
Manganese tetroxide (as Mn) TWA 1 mg/m3
Mercury compounds, as Hg [except(organo) alkyls]
Hg Vapor TWA 0.05 mg/m3 [skin]
Non-alkyl compounds C 0.1 mg/m3 [skin]
Mercury (organo) alkyl compounds (as Hg) TWA 0.01 mg/m3
ST 0.03 mg/m3 [skin]
Mesityl oxide TWA 15 ppm (60 mg/m3)
ST 25 ppm (100 mg/m3)
Methacrylic acid TWA 20 ppm (70 mg/m3) [skin]
Methomyl TWA 2.5 mg/m3
Methoxychlor TWA 10 mg/m3
4-Methoxyphenol TWA 5 mg/m3
Methyl acetate TWA 200 ppm (610 mg/m3)
ST 250 ppm (760 mg/m3)
Methyl acetylene-propadiene mixture TWA 1000 ppm (1800 mg/m3)
ST 1250 ppm (2250 mg/m3)
Methylacrylonitrile TWA 1 ppm (3 mg/m3) [skin]
Methyl alcohol TWA 200 ppm (260 mg/m3)
ST 250 ppm (325 mg/m3) [skin]
Methyl bromide TWA 5 ppm (20 mg/m3) [skin]
Methyl chloride TWA 50 ppm (105 mg/m3)
ST 100 ppm (210 mg/m3)
Methyl chloroform TWA 350 ppm (1900 mg/m3)
ST 450 ppm (2450 mg/m3)
Methyl-2-cyanoacrylate TWA 2 ppm (8 mg/m3)
ST 4 ppm (16 mg/m3)
Methylcyclohexane TWA 400 ppm (1600 mg/m3)
Methylcyclohexanol TWA 50 ppm (235 mg/m3)
o-Methylcyclohexanone TWA 50 ppm (230 mg/m3)
ST 75 ppm (345 mg/m3) [skin]
Methyl cyclopentadienyl manganese tricarbonyl (as Mn) TWA 0.2 mg/m3 [skin]
Methyl demeton TWA 0.5 mg/m3 [skin]
4,4'-Methylenebis(2-chloroaniline) TWA 0.02 ppm (0.22 mg/m3) [skin]
Methylene bis(4-cyclo-hexylisocyanate) C 0.01 ppm (0.11 mg/m3) [skin]
Methyl ethyl ketone peroxide C 0.7 ppm (5 mg/m3)
Methyl formate TWA 100 ppm (250 mg/m3)
ST 150 ppm (375 mg/m3)
Methyl iodide TWA 2 ppm (10 mg/m3) [skin]
Methyl isoamyl ketone TWA 50 ppm (240 mg/m3)
Methyl isobutyl carbinol TWA 25 ppm (100 mg/m3)
ST 40 ppm (165 mg/m3) [skin]
Methyl isopropyl ketone TWA 200 ppm (705 mg/m3)
Methyl mercaptan TWA 0.5 ppm (1 mg/m3)
Methyl parathion TWA 0.2 mg/m3 [skin]
Methyl silicate TWA 1 ppm (6 mg/m3)
alpha-Methyl styrene TWA 50 ppm (240 mg/m3)
ST 100 ppm (485 mg/m3)
Metribuzin TWA 5 mg/m3
Mica TWA 3 mg/m3 (resp)
Molybdenum (insoluble compounds, as Mo) TWA 10 mg/m3
Monocrotophos TWA 0.25 mg/m3
Monomethyl aniline TWA 0.5 ppm (2 mg/m3) [skin]
Morpholine TWA 20 ppm (70 mg/m3)
ST 30 ppm (105 mg/m3) [skin]
Naphthalene TWA 10 ppm (50 mg/m3)
ST 15 ppm (75 mg/m3)
Nickel metal & other compounds (as Ni)
Metal & insoluble compounds TWA 1 mg/m3
Soluble compounds TWA 0.1 mg/m3
Nitric acid TWA 2 ppm (5 mg/m3)
ST 4 ppm (10 mg/m3)
p-Nitroaniline TWA 3 mg/m3 [skin]
Nitrogen dioxide ST 1 ppm (1.8 mg/m3)
Nitroglycerine ST 0.1 mg/m3 [skin]
2-Nitropropane TWA 10 ppm (35 mg/m3)
Nitrotoluene (o-, m-, p-isomers) TWA 2 ppm (11 mg/m3) [skin]
Nonane TWA 200 ppm (1050 mg/m3)
Octachloronaphthalene TWA 0.1 mg/m3
ST 0.3 mg/m3 [skin]
Octane TWA 300 ppm (1450 mg/m3)
ST 375 ppm (1800 mg/m3)
Osmium tetroxide (as Os) TWA 0.002 mg/m3 (0.0002 ppm)
ST 0.006 mg/m3 (0.0006 ppm)
Oxalic acid TWA 1 mg/m3
ST 2 mg/m3
Oxygen difluoride C 0.05 ppm (0.1 mg/m3)
Ozone TWA 0.1 ppm (0.2 mg/m3)
ST 0.3 ppm (0.6 mg/m3)
Paraffin wax fume TWA 2 mg/m3
Paraquat TWA 0.1 mg/m3 (resp) [skin]
Pentaborane TWA 0.005 ppm (0.01 mg/m3)
ST 0.015 ppm (0.03 mg/m3)
Pentaerythritol TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
n-Pentane TWA 600 ppm (1800 mg/m3)
ST 750 ppm (2250 mg/m3)
2-Pentanone TWA 200 ppm (700 mg/m3)
ST 250 ppm (875 mg/m3)
Perchloryl fluoride TWA 3 ppm (14 mg/m3)
ST 6 ppm (28 mg/m3)
Petroleum distillates (naphtha) TWA 400 ppm (1600 mg/m3)
Phenothiazine TWA 5 mg/m3 [skin]
Phenyl glycidyl ether TWA 1 ppm (6 mg/m3)
Phenylhydrazine TWA 5 ppm (20 mg/m3)
ST 10 ppm (45 mg/m3) [skin]
Phenylphosphine C 0.05 ppm (0.25 mg/m3)
Phorate TWA 0.05 mg/m3
ST 0.2 mg/m3 [skin]
Phosdrin TWA 0.01 ppm (0.1 mg/m3)
ST 0.03 ppm (0.3 mg/m3) [skin]
Phosphine TWA 0.3 ppm (0.4 mg/m3)
ST 1 ppm (1 mg/m3)
Phosphoric acid TWA 1 mg/m3
ST 3 mg/m3
Phosphorus oxychloride TWA 0.1 ppm (0.6 mg/m3)
Phosphorus pentasulfide TWA 1 mg/m3
ST 3 mg/m3
Phosphorus trichloride TWA 0.2 ppm (1.5 mg/m3)
ST 0.5 ppm (3 mg/m3)
Phthalic anhydride TWA 6 mg/m3 (1 ppm)
m-Phthalodinitrile TWA 5 mg/m3
Picloram TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Piperazine dihydrochloride TWA 5 mg/m3
Platinum metal (as Pt) TWA 1 mg/m3
Portland cement TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Potassium hydroxide TWA 2 mg/m3
Propargyl alcohol TWA 1 ppm (2 mg/m3) [skin]
Propionic acid TWA 10 ppm (30 mg/m3)
Propoxur TWA 0.5 mg/m3
n-Propyl acetate TWA 200 ppm (840 mg/m3)
ST 250 ppm (1050 mg/m3)
n-Propyl alcohol TWA 200 ppm (500 mg/m3)
ST 250 ppm (625 mg/m3)
Propylene dichloride TWA 75 ppm (350 mg/m3)
ST 110 ppm (510 mg/m3)
Propylene glycol dinitrate TWA 0.05 ppm (0.3 mg/m3)
Propylene glycol monomethyl ether TWA 100 ppm (360 mg/m3)
ST 150 ppm (540 mg/m3)
Propylene oxide TWA 20 ppm (50 mg/m3)
n-Propyl nitrate TWA 25 ppm (105 mg/m3)
ST 40 ppm (170 mg/m3)
Resorcinol TWA 10 ppm (45 mg/m3)
ST 20 ppm (90 mg/m3)
Ronnel TWA 10 mg/m3
Rosin core solder, pyrolysis products (as formaldehyde) TWA 0.1 mg/m3
Rouge TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Silica, amorphous TWA 6 mg/m3
TWA 0.1 mg/m3 (fused)
Silica, crystalline (as respirable dust) TWA 0.05 mg/m3 (cristobalite)
TWA 0.05 mg/m3 (tridymite)
TWA 0.1 mg/m3 (quartz)
TWA 0.1 mg/m3 (tripoli)
Silicon TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Silicon carbide TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Silicon tetrahydride TWA 5 ppm (7 mg/m3)
Soapstone TWA 6 mg/m3 (total)
TWA 3 mg/m3 (resp)
Sodium azide C 0.1 ppm (as HN3) [skin]
C 0.3 mg/m3 (as NaN3) [skin]
Sodium bisulfite TWA 5 mg/m3
Sodium fluoroacetate TWA 0.05 mg/m3
ST 0.15 mg/m3 [skin]
Sodium hydroxide C 2 mg/m3
Sodium metabisulfite TWA 5 mg/m3
Stoddard solvent TWA 525 mg/m3 (100 ppm)
Styrene TWA 50 ppm (215 mg/m3)
ST 100 ppm (425 mg/m3)
Subtilisins ST 0.00006 mg/m3 [60-minute]
Sulfur dioxide TWA 2 ppm (5 mg/m3)
ST 5 ppm (13 mg/m3)
Sulfur monochloride C 1 ppm (6 mg/m3)
Sulfur pentafluoride C 0.01 ppm (0.1 mg/m3)
Sulfur tetrafluoride C 0.1 ppm (0.4 mg/m3)
Sulfuryl fluoride TWA 5 ppm (20 mg/m3)
ST 10 ppm (40 mg/m3)
Sulprofos TWA 1 mg/m3
Talc TWA 2 mg/m3 (resp)
Temephos TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Terphenyl (o-, m-, p-isomers) C 5 mg/m3 (0.5 ppm)
1,1,2,2-Tetrachloroethane TWA 1 ppm (7 mg/m3) [skin]
Tetrachloroethylene TWA 25 ppm (170 mg/m3)
Tetrahydrofuran TWA 200 ppm (590 mg/m3)
ST 250 ppm (735 mg/m3)
Tetrasodium pyrophosphate TWA 5 mg/m3
4,4'-Thiobis(6-tert-butyl-m-cresol) TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Thioglycolic acid TWA 1 ppm (4 mg/m3) [skin]
Thionyl chloride C 1 ppm (5 mg/m3)
Tin (organic compounds, as Sn) TWA 0.1 mg/m3 [skin]
Tin(II) oxide (as Sn) TWA 2 mg/m3
Tin(IV) oxide (as Sn) TWA 2 mg/m3
Titanium dioxide TWA 10 mg/m3
Toluene TWA 100 ppm (375 mg/m3)
ST 150 ppm (560 mg/m3)
Toluene-2,4-diisocyanate TWA 0.005 ppm (0.04 mg/m3)
ST 0.02 ppm (0.15 mg/m3)
m-Toluidine TWA 2 ppm (9 mg/m3) [skin]
p-Toluidine TWA 2 ppm (9 mg/m3) [skin]
Tributyl phosphate TWA 0.2 ppm (2.5 mg/m3)
Trichloroacetic acid TWA 1 ppm (7 mg/m3)
1,2,4-Trichlorobenzene C 5 ppm (40 mg/m3)
Trichloroethylene TWA 50 ppm (270 mg/m3)
ST 200 ppm (1080 mg/m3)
1,2,3-Trichloropropane TWA 10 ppm (60 mg/m3)
1,1,2-Trichloro-1,2,2-trifluoroethane TWA 1000 ppm (7600 mg/m3)
ST 1250 ppm (9500 mg/m3)
Triethylamine TWA 10 ppm (40 mg/m3)
ST 15 ppm (60 mg/m3)
Trimellitic anhydride TWA 0.005 ppm (0.04 mg/m3)
Trimethylamine TWA 10 ppm (24 mg/m3)
ST 15 ppm (36 mg/m3)
1,2,3-Trimethylbenzene TWA 25 ppm (125 mg/m3)
1,2,4-Trimethylbenzene TWA 25 ppm (125 mg/m3)
1,3,5-Trimethylbenzene TWA 25 ppm (125 mg/m3)
Trimethyl phosphite TWA 2 ppm (10 mg/m3)
2,4,6-Trinitrotoluene TWA 0.5 mg/m3 [skin]
Triorthocresyl phosphate TWA 0.1 mg/m3 [skin]
Triphenylamine TWA 5 mg/m3
Tungsten (insoluble compounds, as W) TWA 5 mg/m3
ST 10 mg/m3
Tungsten (soluble compounds, as W) TWA 1 mg/m3
ST 3 mg/m3
Tungsten carbide (cemented) TWA 5 mg/m3 (as W)
ST 10 mg/m3 (as W)
TWA 0.05 mg/m3 (as Co)
TWA 1 mg/m3 (as Ni)
Uranium (insoluble compounds, as U) TWA 0.2 mg/m3
ST 0.6 mg/m3
n-Valeraldehyde TWA 50 ppm (175 mg/m3)
Vanadium dust TWA 0.05 mg V2O5/m3 (resp)
Vanadium fume C 0.05 mg V2O5/m3
Vinyl acetate TWA 10 ppm (30 mg/m3)
ST 20 ppm (60 mg/m3)
Vinyl bromide TWA 5 ppm (20 mg/m3)
Vinyl cyclohexene dioxide TWA 10 ppm (60 mg/m3) [skin]
Vinylidene chloride TWA 1 ppm (4 mg/m3)
VM & P Naphtha TWA 1350 mg/m3 (300 ppm)
ST 1800 mg/m3 (400 ppm)
Welding fumes TWA 5 mg/m3
Wood dust (all wood dusts except Western red cedar) TWA 5 mg/m3
ST 10 mg/m3
Wood dust (Western red cedar) TWA 2.5 mg/m3
Xylene (o-, m-, p-isomers) TWA 100 ppm (435 mg/m3)
ST 150 ppm (655 mg/m3)
m-Xylene alpha, alpha'-diamine C 0.1 mg/m3 [skin]
Xylidine TWA 2 ppm (10 mg/m3) [skin]
Zinc chloride fume TWA 1 mg/m3
ST 2 mg/m3
Zinc oxide TWA 5 mg/m3 (fume)
ST 10 mg/m3 (fume)
TWA 10 mg/m3 (total dust)
TWA 5 mg/m3 (resp dust)
Zinc stearate TWA 10 mg/m3 (total)
TWA 5 mg/m3 (resp)
Zirconium compounds (as Zr) TWA 5 mg/m3
ST 10 mg/m3

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