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> Appendix G: 1989 Air Contaminants Update Project - Exposure Limits NOT in Effect
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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 |
Adapted from: NIOSH Publication Number 2005-149
