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  2. OSHA Annotated Table Z-1

Note: This table only includes occupational exposure limits (OELs) for substances listed in the OSHA Z-1 Table. OELs for hundreds of additional substances have been adopted by Cal/OSHA, NIOSH, and ACGIH. These organizations periodically make revisions to their OELs and so they should be consulted directly for their most current values and substances, as well as special notations such as for skin absorption. The TLVs® and BEIs® are copyrighted by ACGIH® and are not publicly available. However, they can be purchased in their entirety on the ACGIH® website. Permission must be requested from ACGIH® to reproduce the TLVs® and BEIs®. Click here for permission request form.

OSHA Annotated Table Z-1(a)

*Go to list of all footnotes
Substance CAS No.(c) Regulatory Limits Recommended Limits
OSHA PEL(b) Cal/OSHA PEL(f)
(as of 10/2/2019)		 NIOSH REL(g)
(as of 10/18/2019)		 ACGIH® 2019 TLV® (h)
ppm(d) mg/m3(e) 8-hour TWA
(ST) STEL
(C) Ceiling		 Up to 10-hour TWA
(ST) STEL
(C) Ceiling		 8-hour TWA
(ST) STEL
(C) Ceiling
Acetaldehyde 75-07-0 200 360 (C) 25 ppm Ca
See Appendix A
See Appendix C		 (C) 25 ppm
Acetic acid 64-19-7 10 25 10 ppm
(ST) 15 ppm
(C) 40 ppm		 10 ppm
(ST) 15 ppm		 10 ppm
(ST) 15 ppm
Acetic anhydride 108-24-7 5 20 (C) 5 ppm (C) 5 ppm 1 ppm
(ST) 3 ppm
Acetone 67-64-1 1000 2400 500 ppm
(ST) 750 ppm
(C) 3000 ppm		 250 ppm 250 ppm
(ST) 500 ppm
Acetonitrile 75-05-8 40 70 40 ppm
(ST) 60 ppm		 20 ppm 20 ppm
2-Acetylaminofluorene; see 1910.1014 53-96-3     See Section 5209 Ca
See Appendix A		  
Acetylene dichloride; see 1,2-Dichloroethylene            
Acetylene tetrabromide 79-27-6 1 14 1 ppm See Appendix D 0.1 ppm
Acrolein 107-02-8 0.1 0.25 (C) 0.1 ppm 0.1 ppm
(ST) 0.3 ppm See Appendix C (Aldehydes)		 (C) 0.1 ppm
Acrylamide 79-06-1   0.3 0.03 mg/m3 Ca
0.03 mg/m3
See Appendix A		 0.03 mg/m3 (IFV)
Acrylonitrile; see 1910.1045 107-13-1     2 ppm
Section 5213		 Ca
1 ppm
(C) 10 ppm [15-min]
See Appendix A		 2 ppm
Aldrin 309-00-2   0.25 0.25 mg/m3 Ca
0.25 mg/m3
See Appendix A		 0.05 mg/m3 (IFV)
Allyl alcohol 107-18-6 2 5 0.5 ppm
(ST) 4 ppm		 2 ppm
(ST) 4 ppm		 0.5 ppm
Allyl chloride 107-05-1 1 3 1 ppm
(ST) 2 ppm		 1 ppm
(ST) 2 ppm		 1 ppm
(ST) 2 ppm
Allyl glycidyl ether (AGE) 106-92-3 (C) 10 (C) 45 0.2 ppm 5 ppm
(ST) 10 ppm		 1 ppm
Allyl propyl disulfide 2179-59-1 2 12 2 ppm
(ST) 3 ppm		 2 ppm
(ST) 3 ppm		 0.5 ppm
alpha-Alumina 1344-28-1     see PNOR See Appendix D See TLV® for Aluminum, metal and insoluble compounds
Total dust     15 10 mg/m3    
Respirable fraction     5 5 mg/m3    
Aluminum Metal (as Al) 7429-90-5          
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction;     5 5 mg/m3 5 mg/m3 1 mg/m3
4-Aminodiphenyl see 1910.1011 92-67-1     See Section 5209 Ca
See Appendix A		 Exposure by all routes should be carefully controlled to levels as low as possible
2-Aminoethanol; see Ethanolamine            
2-Aminopyridine 504-29-0 0.5 2 0.5 ppm 0.5 ppm 0.5 ppm
Ammonia 7664-41-7 50 35 25 ppm
(ST) 35 ppm		 25 ppm
(ST) 35 ppm		 25 ppm
(ST) 35 ppm
Ammonium sulfamate 7773-06-0          
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
n-Amyl acetate 628-63-7 100 525 50 ppm
(ST) 100 ppm		 100 ppm 50 ppm
(ST) 100 ppm
sec-Amyl acetate 626-38-0 125 650 50 ppm
(ST) 100 ppm		 125 ppm 50 ppm
(ST) 100 ppm
Aniline and homologs 62-53-3 5 19 2 ppm
(aniline only)		 Ca
See Appendix A		 2 ppm
(aniline only)
Anisidine (o-,p-isomers) 29191-52-4   0.5 0.5 mg/m3 Ca
0.5 mg/m3
See Appendix A		 0.5 mg/m3
Antimony and compounds (as Sb) 7440-36-0   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3
ANTU (alpha Naphthylthiourea) 86-88-4   0.3 0.3 mg/m3 0.3 mg/m3 0.3 mg/m3
Arsenic, inorganic compounds (as As) see 1910.1018 7440-38-2     0.01 mg/m3
See Section 5214		 Ca
(C) 0.002 mg/m3 [15-min]
See Appendix A		 0.01 mg/m3
Arsenic, organic compounds (as As) 7440-38-2   0.5 0.2 mg/m3 None  
Arsine 7784-42-1 0.05 0.2 0.05 ppm Ca
(C) 0.002 mg/m3 [15-min]
See Appendix A		 0.005 ppm
Asbestos; see 1910.1001 Varies with compound     See Section 5208 Ca
0.1 f/cm3
See Appendix A
See Appendix C		 0.1 f/cc (resp. fiber)
Azinphos-methyl 86-50-0   0.2 0.2 mg/m3 0.2 mg/m3 0.2 mg/m3 (IFV)
Barium, soluble compounds (as Ba) 7440-39-3   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3
Barium sulfate 7727-43-7     see PNOR    
Total dust     15 10 mg/m3 10 mg/m3 5 mg/m3 (IHL, no asbestos and < 1% crystalline silica)
Respirable fraction     5 5 mg/m3 5 mg/m3  
Benomyl 17804-35-2       See Appendix D 1 mg/m3 (IHL)
Total dust     15 10 mg/m3    
Respirable fraction     5 5 mg/m3    
Benzene; See 1910.1028; See Table Z-2 for the limits applicable in the operations or sectors excluded in 1910.1028(j) 71-43-2     1 ppm
(ST) 5 ppm
See Section 5218		 Ca
0.1 ppm
(ST) 1 ppm
See Appendix A		 0.5 ppm
(ST) 2.5 ppm
Benzidine; See 1910.1010 92-87-5     See Section 5209 Ca
See Appendix A
See Appendix C		 Exposure by all routes should be carefully controlled to levels as low as possible
p-Benzoquinone; see Quinone            
Benzo(a)pyrene; see Coal tar pitch volatiles            
Benzoyl peroxide 94-36-0   5 5 mg/m3 5 mg/m3 5 mg/m3
Benzyl chloride 100-44-7 1 5 0.03 ppm (C) 1 ppm [15 min] 1 ppm
Beryllium and beryllium compounds (as Be); see 1910.1024(o) 7440-41-7    
Biphenyl; see Diphenyl            
Bismuth telluride, Undoped 1304-82-1          
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
Boron oxide 1303-86-2          
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Boron trifluoride 7637-07-2 (C) 1 (C) 3 (C) 1 ppm (C) 1 ppm 0.1 ppm
(C) 0.7 ppm
Bromine 7726-95-6 0.1 0.7 (C) 0.1 ppm 0.1 ppm
(ST) 0.3 ppm		 0.1 ppm
(ST) 0.2 ppm
Bromoform 75-25-2 0.5 5 0.5 ppm 0.5 ppm 0.5 ppm
Butadiene (1,3-Butadiene); See 29 CFR 1910.1051; 29 CFR 1910.19(l) 106-99-0 1 ppm / 5 ppm STEL   1 ppm
(ST) 5 ppm
See Section 5201		 Ca
See Appendix A		 2 ppm
Butanethiol; see Butyl mercaptan            
2-Butanone (Methyl ethyl ketone) 78-93-3 200 590 200 ppm
(ST) 300 ppm		 200 ppm
(ST) 300 ppm		 200 ppm
(ST) 300 ppm
2-Butoxyethanol 111-76-2 50 240 20 ppm 5 ppm 20 ppm
n-Butyl-acetate 123-86-4 150 710 150 ppm
(ST) 200 ppm		 150 ppm
(ST) 200 ppm		 (n)
sec-Butyl acetate 105-46-4 200 950 200 ppm 200 ppm (n)
tert-Butyl-acetate 540-88-5 200 950 200 ppm 200 ppm (n)
n-Butyl alcohol 71-36-3 100 300 (C) 50 ppm (C) 50 ppm 20 ppm
sec-Butyl alcohol 78-92-2 150 450 100 ppm 100 ppm
(ST) 150 ppm		 100 ppm
tert-Butyl alcohol 75-65-0 100 300 100 ppm
(ST) 150 ppm		 100 ppm
(ST) 150 ppm		 100 ppm
Butylamine 109-73-9 (C) 5 (C) 15 (C) 5 ppm (C) 5 ppm (C) 5 ppm
tert-Butyl chromate (as CrO3)(m); see 1910.1026 1189-85-1     (C) 0.1 mg/m3 Ca
0.001 mg/m3 CR (VI)
See Appendix A
See Appendix C		 (C) 0.1 mg/m3
n-Butyl glycidyl ether (BGE) 2426-08-6 50 270 25 ppm (C) 5.6 ppm [15-min] 3 ppm
Butyl mercaptan 109-79-5 10 35 0.5 ppm (C) 0.5 ppm [15-min] 0.5 ppm
p-tert-Butyltoluene 98-51-1 10 60 1 ppm
(ST) 20 ppm		 10 ppm
(ST) 20 ppm		 1 ppm
Cadmium (as Cd); see 1910.1027 7440-43-9     0.005 mg/m3
see Sections 1532 & 5207		 Ca
See Appendix A		 0.01 mg/m3
(total)
0.002 mg/m3
(resp.)
Calcium Carbonate 1317-65-3     see PNOR    
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Calcium hydroxide 1305-62-0          
Total dust     15 5 mg/m3 5 mg/m3 5 mg/m3
Respirable fraction     5      
Calcium oxide 1305-78-8   5 2 mg/m3 2 mg/m3 2 mg/m3
Calcium silicate 1344-95-2     see PNOR   1 mg/m3, natural as Wollastonite (IHL, no asbestos and < 1% crystalline silica)
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Calcium sulfate 7778-18-9     see PNOR   10 mg/m3 (IHL)
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Camphor, synthetic 76-22-2   2 2 mg/m3 2 mg/m3 2 ppm
(ST) 3 ppm
Carbaryl (Sevin) 63-25-2   5 5 mg/m3 5 mg/m3 0.5 mg/m3 (IFV)
Carbon black 1333-86-4   3.5 3.5 mg/m3 3.5 mg/m3 (without PAHs); when PAHs are present, NIOSH considers carbon black to be a potential occupational carcinogen.
See Appendix A, See Appendix C		 3 mg/m3 (IHL)
Carbon dioxide 124-38-9 5000 9000 5000 ppm
(ST) 30,000 ppm		 5000 ppm
(ST) 30,000 ppm		 5000 ppm
(ST) 30,000 ppm
Carbon disulfide 75-15-0 See Annotated Z-2 See Annotated Z-2
Carbon monoxide 630-08-0 50 55 25 ppm
(C) 200 ppm		 35 ppm
(C) 200 ppm		 25 ppm
Carbon tetrachloride 56-23-5 See Annotated Z-2 See Annotated Z-2
Cellulose 9004-34-6     see PNOR    
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
Chlordane 57-74-9   0.5 0.5 mg/m3 Ca
0.5 mg/m3
See Appendix A		 0.5 mg/m3 (IFV)
Chlorinated camphene 8001-35-2   0.5 0.5 mg/m3
(ST) 1 mg/m3		 Ca
See Appendix A		 0.5 mg/m3
(ST) 1 mg/m3
Chlorinated diphenyl oxide 55720-99-5   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3 (ortho isomer)
Chlorine 7782-50-5 (C) 1 (C) 3 0.5 ppm
(ST) 1 ppm		 (C) 0.5 ppm [15-min] 0.1 ppm
(ST) 0.4 ppm
Chlorine dioxide 10049-04-4 0.1 0.3 0.1 ppm
(ST) 0.3 ppm		 0.1 ppm
(ST) 0.3 ppm		 (C) 0.1 ppm
Chlorine trifluoride 7790-91-2 (C) 0.1 (C) 0.4 (C) 0.1 ppm (C) 0.1 ppm (C) 0.1 ppm
Chloroacetaldehyde 107-20-0 (C) 1 (C) 3 (C) 1 ppm (C) 1 ppm (C) 1 ppm
a-Chloroacetophenone (Phenacyl chloride) 532-27-4 0.05 0.3 0.05 ppm 0.05 ppm 0.05 ppm
Chlorobenzene 108-90-7 75 350 10 ppm See Appendix D 10 ppm
o-Chlorobenzylidene malononitrile 2698-41-1 0.05 0.4 (C) 0.05 ppm (C) 0.05 ppm (C) 0.05 ppm (IFV)
Chlorobromomethane 74-97-5 200 1050 200 ppm 200 ppm 200 ppm
2-Chloro-1,3-butadiene; See beta-Chloroprene            
Chlorodiphenyl (42% Chlorine) (PCB) 53469-21-9   1 1 mg/m3 Ca
0.001 mg/m3
See Appendix A		 1 mg/m3
Chlorodiphenyl (54% Chlorine) (PCB) 11097-69-1   0.5 0.5 mg/m3 Ca
0.001 mg/m3
See Appendix A		 0.5 mg/m3
1-Chloro-2,3-epoxypropane; See Epichlorohydrin            
2-Chloroethanol; See Ethylene chlorohydrin            
Chloroethylene; see Vinyl chloride            
Chloroform (Trichloromethane) 67-66-3 (C) 50 (C) 240 2 ppm Ca
(ST) 2 ppm [60-min]
See Appendix A		 10 ppm
bis(Chloromethyl) ether; see 1910.1008 542-88-1     0.001 ppm
See Section 5209		 Ca
See Appendix A		 0.001 ppm
Chloromethyl methyl ether
see 1910.1006		 107-30-2     See Section 5209 Ca
See Appendix A		 Exposure by all routes should be carefully controlled to levels as low as possible.
1-Chloro-1-nitropropane 600-25-9 20 100 2 ppm 2 ppm 2 ppm
Chloropicrin 76-06-2 0.1 0.7 0.1 ppm 0.1 ppm 0.1 ppm
beta-Chloroprene 126-99-8 25 90 10 ppm Ca
(C) 1 ppm [15-min]
See Appendix A		 1 ppm
2-Chloro-6-(trichloromethyl)pyridine 1929-82-4         10 mg/m3 (IFV)
(ST) 20 mg/m3 (IFV)
Total dust     15 10 mg/m3 10 mg/m3
(ST) 20 mg/m3		  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Chromium (II) compounds (as Cr) 7440-47-3   0.5 0.5 mg/m3 0.5 mg/m3
See Appendix C		  
Chromium (III) compounds (as Cr) 7440-47-3   0.5 0.5 mg/m3 0.5 mg/m3
See Appendix C		 0.003 mg/m3-(IHL),
water soluble
Chromium (VI) compounds See 1910.1026(k)       0.005 mg/m3 as Cr
(C) 0.1 mg/m3
See Sections 1532.2, 5206, and 8359

Ca
0.0002 mg/m3 (8-hr-TWA)
See Appendix A
See Appendix C

 0.0002 mg/m3 (IHL) (ST) 0.0005 mg/m3(IHL), water soluble
(includes chromic acid and chromates)
Chromium metal and insol. salts (as Cr) 7440-47-3   1 0.5 mg/m3 0.5 mg/m3
See Appendix C		 0.5 mg/m3(IHL)(metallic chromium)
Chrysene; see Coal tarpitch volatiles           Exposure by all routes should be carefully controlled to levels as low as possible.
Clopidol 2971-90-6         3 mg/m3 (IFV)
Total dust     15 10 mg/m3 10 mg/m3
(ST) 20 mg/m3		  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Coal dust (less than 5% SiO2, respirable fraction)   See Annotated Z-3 See Annotated Z-3
Coal dust (greater than or equal to 5% SiO2 respirable fraction)   See Annotated Z-3 See Annotated Z-3
Coal tar pitch volatiles (benzene soluble fraction), anthracene, BaP, phenanthrene, acridine, chrysene, pyrene) 65966-93-2   0.2 0.2 mg/m3 Ca
0.1 mg/m3 (cyclohexane-extractable fraction)
See Appendix A
See Appendix C		 0.2 mg/m3(as benzene soluble aerosol)
Cobalt metal, dust, and fume (as Co) 7440-48-4   0.1 0.02 mg/m3 0.05 mg/m3 0.02 mg/m3 (IHL)
Coke oven emissions; see 1910.1029       0.15 mg/m3
See Section 5211		 Ca
0.2 mg/m3(benzene-soluble fraction)
See Appendix A
See Appendix C		  
Copper 7440-50-8          
Fume (as Cu)     0.1 0.1 mg/m3 0.1 mg/m3 0.2 mg/m3
Dusts and mists (as Cu)     1 1 mg/m3 1 mg/m3 1 mg/m3
Cotton dust(l), see 1910.1043     1 1 mg/m3 (in waste processing)
See Section 5190		 < 0.200 mg/m3
See Appendix C		 0.1 mg/m3 (Thor.) (raw untreated)
Crag herbicide (Sesone) 136-78-7          
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
Cresol, all isomers 1319-77-3 5 22 5 ppm 2.3 ppm 20 mg/m3 (IFV)
Crotonaldehyde 123-73-9 /
4170-30-3		 2 6 (C) 0.3 ppm 2 ppm
See Appendix C
(Aldehydes)		 (C) 0.3 ppm
Cumene 98-82-8 50 245 50 ppm 50 ppm 50 ppm
Cyanides (as CN) Varies with compound   5 5 mg/m3 (C) 5 mg/m3 [10-min] (C) 5 mg/m3, salts
Cyclohexane 110-82-7 300 1050 300 ppm 300 ppm 100 ppm
Cyclohexanol 108-93-0 50 200 50 ppm 50 ppm 50 ppm
Cyclohexanone 108-94-1 50 200 25 ppm 25 ppm 20 ppm
(ST) 50 ppm
Cyclohexene 110-83-8 300 1015 300 ppm 300 ppm 300 ppm
Cyclopentadiene 542-92-7 75 200 75 ppm 75 ppm (q)
2,4-D (Dichlorophen-oxyacetic acid) 94-75-7   10 10 mg/m3 10 mg/m3 10 mg/m3 (IHL)
Decaborane 17702-41-9 0.05 0.3 0.05 ppm
(ST) 0.15 ppm		 0.05 ppm
(ST) 0.15 ppm		 0.05 ppm
(ST) 0.15 ppm
Demeton (Systox) 8065-48-3   0.1 0.1 mg/m3 0.1 mg/m3 0.05 mg/m3 (IFV)
Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone) 123-42-2 50 240 50 ppm 50 ppm 50 ppm
1,2-Diaminoethane; see Ethylenediamine            
Diazomethane 334-88-3 0.2 0.4 0.2 ppm 0.2 ppm 0.2 ppm
Diborane 19287-45-7 0.1 0.1 0.1 ppm 0.1 ppm 0.1 ppm
1,2-Dibromo-3-chloropropane (DBCP); see 1910.1044 96-12-8     0.001 ppm
See Section 5212		 Ca
See Appendix A		  
1,2-Dibromoethane; see Ethylene dibromide            
Dibutyl phosphate 107-66-4 1 5 1 ppm
(ST) 2 ppm		 1 ppm
(ST) 2 ppm		 5 mg/m3 (IFV)
Dibutyl phthalate 84-74-2   5 5 mg/m3 5 mg/m3 5 mg/m3
o-Dichlorobenzene 95-50-1 (C) 50 (C) 300 25 ppm
(C) 50 ppm		 (C) 50 ppm 25 ppm
(C) 50 ppm
p-Dichlorobenzene 106-46-7 75 450 10 ppm
(ST) 110 ppm
(C) 200 ppm		 Ca
See Appendix A		 10 ppm
3,3'-Dichlorobenzidine;
see 1910.1007		 91-94-1     See Section 5209 Ca
See Appendix A		 Exposure by all routes should be carefully controlled to levels as low as possible.
Dichlorodifluoromethane 75-71-8 1000 4950 1000 ppm
(C) 6200 ppm		 1000 ppm 1000 ppm
1,3-Dichloro-5,5-dimethyl hydantoin 118-52-5   0.2 0.2 mg/m3
(ST) 0.4 mg/m3		 0.2 mg/m3
(ST) 0.4 mg/m3		 0.2 mg/m3
(ST) 0.4 mg/m3
Dichlorodiphenyltrichloroethane (DDT) 50-29-3   1 1 mg/m3 Ca
0.5 mg/m3
See Appendix A		 1 mg/m3
1,1-Dichloroethane 75-34-3 100 400 100 ppm 100 ppm
See Appendix C
(Chloroethanes)		 100 ppm
1,2-Dichloroethane; see Ethylene dichloride            
1,2-Dichloroethylene 540-59-0 200 790 200 ppm 200 ppm 200 ppm
Dichloroethyl ether 111-44-4 (C) 15 (C) 90 5 ppm
(ST) 10 ppm		 Ca
5 ppm
(ST) 10 ppm
See Appendix A		 5 ppm
(ST) 10 ppm
Dichloromethane; see Methylene chloride            
Dichloromonofluoromethane 75-43-4 1000 4200 10 ppm 10 ppm 10 ppm
1,1-Dichloro-1-nitroethane 594-72-9 (C) 10 (C) 60 2 ppm 2 ppm 2 ppm
1,2-Dichloropropane; see Propylene dichloride            
Dichlorotetrafluoroethane 76-14-2 1000 7000 1000 ppm 1000 ppm 1000 ppm
Dichlorvos (DDVP) 62-73-7   1 1 mg/m3 1 mg/m3 0.1 mg/m3 (IFV)
Dicyclopentadienyl iron 102-54-5          
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3 as Fe
Respirable fraction     5 5 mg/m3 5 mg/m3  
Dieldrin 60-57-1   0.25 0.25 mg/m3 Ca
0.25 mg/m3
See Appendix A		 0.1 mg/m3 (IFV)
Diethylamine 109-89-7 25 75 (C) 5 ppm 10 ppm
(ST) 25 ppm		 5 ppm
(ST) 15 ppm
2-Diethylaminoethanol 100-37-8 10 50 2 ppm 10 ppm 2 ppm
Diethyl ether; see Ethyl ether            
Difluorodibromomethane 75-61-6 100 860 100 ppm 100 ppm 100 ppm
Diglycidyl ether (DGE) 2238-07-5 (C) 0.5 (C) 2.8 0.1 ppm Ca
0.1 ppm
See Appendix A		 0.01 ppm
Dihydroxybenzene; see Hydroquinone            
Diisobutyl ketone 108-83-8 50 290 25 ppm 25 ppm 25 ppm
Diisopropylamine 108-18-9 5 20 5 ppm 5 ppm 5 ppm
4-Dimethylaminoazo-benzene; see 1910.1015 60-11-7     See Section 5209 Ca
See Appendix A		  
Dimethoxymethane; see Methylal            
Dimethyl acetamide 127-19-5 10 35 10 ppm 10 ppm 10 ppm
Dimethylamine 124-40-3 10 18 5 ppm
(ST) 15 ppm		 10 ppm 5 ppm
(ST) 15 ppm
Dimethylaminobenzene; see Xylidine            
Dimethylaniline (N,N-Dimethylaniline) 121-69-7 5 25 5 ppm
(ST) 10 ppm		 5 ppm
(ST) 10 ppm		 5 ppm
(ST) 10 ppm
Dimethylbenzene; see Xylene            
Dimethyl-1,2-dibromo-2,2-dichloroethylphosphate 300-76-5   3 3 mg/m3 3 mg/m3 0.1 mg/m3 (IFV)
Dimethylformamide 68-12-2 10 30 10 ppm 10 ppm 5 ppm
2,6-Dimethyl-4-heptanone; see Diisobutyl ketone            
1,1-Dimethylhydrazine 57-14-7 0.5 1 0.01 ppm Ca
(C) 0.06 ppm [2-hr]
See Appendix A		 0.01 ppm
Dimethylphthalate 131-11-3   5 5 mg/m3 5 mg/m3 5 mg/m3
Dimethyl sulfate 77-78-1 1 5 0.1 ppm Ca
0.1 ppm
See Appendix A		 0.1 ppm
Dinitrobenzene (all isomers)     1 0.15 ppm 1 mg/m3 0.15 ppm (IFV)
(ortho) 528-29-0          
(meta) 99-65-0          
(para) 100-25-4          
Dinitro-o-cresol 534-52-1   0.2 0.2 mg/m3 0.2 mg/m3 0.2 mg/m3 (IFV)
Dinitrotoluene 25321-14-6   1.5 0.15 mg/m3 Ca
1.5 mg/m3
See Appendix A		 0.2 mg/m3
Dioxane (Diethylene dioxide) 123-91-1 100 360 0.28 ppm Ca
(C) 1 ppm [30-min]
See Appendix A		 20 ppm
Diphenyl (Biphenyl) 92-52-4 0.2 1 0.2 ppm 0.2 ppm 0.2 ppm
Diphenylmethane diisocyanate; see Methylene bisphenylisocyanate            
Dipropylene glycol methyl ether 34590-94-8 100 600 100 ppm
(ST) 150 ppm		 100 ppm
(ST) 150 ppm		 100 ppm
(ST) 150 ppm
Di-sec octyl phthalate (Di-(2-ethylhexyl) phthalate) 117-81-7   5 5 mg/m3 Ca
5 mg/m3
(ST) 10 mg/m3
See Appendix A		 5 mg/m3
Emery 12415-34-8     see PNOR See Appendix D See TLV® for Aluminum metal and insoluble compounds
Total dust     15 10 mg/m3    
Respirable fraction     5 5 mg/m3    
Endrin 72-20-8   0.1 0.1 mg/m3 0.1 mg/m3 0.1 mg/m3
Epichlorohydrin 106-89-8 5 19 0.05 ppm Ca
See Appendix A		 0.5 ppm
EPN 2104-64-5   0.5 0.1 mg/m3 0.5 mg/m3 0.1 mg/m3 (IFV)
1,2-Epoxypropane; see Propylene oxide            
2,3-Epoxy-1-propanol; see Glycidol            
Ethanethiol; see Ethyl mercaptan            
Ethanolamine 141-43-5 3 6 3 ppm
(ST) 6 ppm		 3 ppm
(ST) 6 ppm		 3 ppm
(ST) 6 ppm
2-Ethoxyethanol (Cellosolve) 110-80-5 200 740 5 ppm 0.5 ppm 5 ppm
2-Ethoxyethyl acetate (Cellosolve acetate) 111-15-9 100 540 5 ppm 0.5 ppm 5 ppm
Ethyl acetate 141-78-6 400 1400 400 ppm 400 ppm 400 ppm
Ethyl acrylate 140-88-5 25 100 5 ppm
(ST) 25 ppm		 Ca
See Appendix A		 5 ppm
(ST) 15 ppm
Ethyl alcohol (Ethanol) 64-17-5 1000 1900 1000 ppm 1000 ppm (ST) 1000 ppm
Ethylamine 75-04-7 10 18 (C) 5 ppm 10 ppm 5 ppm
(ST) 15 ppm
Ethyl amyl ketone (5-Methyl-3-heptanone) 541-85-5 25 130 25 ppm 25 ppm 10 ppm
Ethyl benzene 100-41-4 100 435 5 ppm
(ST) 30 ppm		 100 ppm
(ST) 125 ppm		 20 ppm
Ethyl bromide 74-96-4 200 890 5 ppm See Appendix D 5 ppm
Ethyl butyl ketone (3-Heptanone) 106-35-4 50 230 50 ppm
(ST) 75 ppm		 50 ppm 50 ppm
(ST) 75 ppm
Ethyl chloride 75-00-3 1000 2600 100 ppm See Appendix C (Chloroethanes) 100 ppm
Ethyl ether 60-29-7 400 1200 400 ppm
(ST) 500 ppm		 See Appendix D 400 ppm
(ST) 500 ppm
Ethyl formate 109-94-4 100 300 100 ppm 100 ppm (ST) 100 ppm
Ethyl mercaptan 75-08-1 (C) 10 (C) 25 0.5 ppm (C) 0.5 ppm [15-min] 0.5 ppm
Ethyl silicate 78-10-4 100 850 10 ppm 10 ppm 10 ppm
Ethylene chlorohydrin 107-07-3 5 16 (C) 1 ppm (C) 1 ppm (C) 1 ppm
Ethylenediamine 107-15-3 10 25 10 ppm 10 ppm 10 ppm
Ethylene dibromide 106-93-4 See Annotated Z-2 See Annotated Z-2
Ethylene dichloride (1,2-Dichloroethane) 107-06-2 See Annotated Z-2 See Annotated Z-2
Ethylene glycol dinitrate 628-96-6 (C) 0.2 (C) 1 0.05 ppm for exposures to mixture of ethylene glycol dinitrate and nitroglycerin
(ST) 0.1 mg/m3		 (ST) 0.1 mg/m3 0.05 ppm
Ethylene glycol methylacetate; see Methylcellosolve acetate            
Ethyleneimine; see 1910.1012 151-56-4     0.5 ppm
See Section 5209		 Ca
See Appendix A		 0.05 ppm
(ST) 0.1 ppm
Ethylene oxide; see 1910.1047 75-21-8     1 ppm
(ST) 5 ppm
See Section 5220		 Ca
< 0.1 ppm
(C) 5 ppm [10-min/day]
See Appendix A		 1 ppm
Ethylidene chloride; see 1,1-Dichlorethane            
N-Ethylmorpholine 100-74-3 20 94 5 ppm 5 ppm 5 ppm
Ferbam 14484-64-1          
Total dust   ........ 15 10 mg/m3 10 mg/m3 5 mg/m3 (IHL)
Ferrovanadium dust 12604-58-9 ........ 1 1 mg/m3
(ST) 3 mg/m3		 1 mg/m3
(ST) 3 mg/m3		 1 mg/m3
(ST) 3 mg/m3
Fluorides (as F) Varies with compound ........ 2.5 2.5 mg/m3 2.5 mg/m3 2.5 mg/m3
Fluorine 7782-41-4 0.1 0.2 0.1 ppm 0.1 ppm 0.1 ppm
(C) 0.5 ppm
Fluorotrichloromethane (Trichlorofluoromethane) 75-69-4 1000 5600 (C) 1000 ppm (C) 1000 ppm (C) 1000 ppm
Formaldehyde; see 1910.1048 50-00-0     0.75 ppm
(ST) 2 ppm
See Section 5217		 Ca
0.016 ppm
(C) 0.1 ppm [15-min]
See Appendix A		 0.1 ppm
(ST) 0.3 ppm
Formic acid 64-18-6 5 9 5 ppm
(ST) 10 ppm		 5 ppm 5 ppm
(ST) 10 ppm
Furfural 98-01-1 5 20 2 ppm See Appendix D 0.2 ppm
Furfuryl alcohol 98-00-0 50 200 10 ppm
(ST) 15 ppm		 10 ppm
(ST) 15 ppm		 0.2 ppm
Grain dust (oat, wheat barley)     10 10 mg/m3 4 mg/m3 4 mg/m3
Glycerin (mist) 56-81-5     PNOR See Appendix D  
Total dust     15 10 mg/m3    
Respirable fraction     5 5 mg/m3    
Glycidol 556-52-5 50 150 2 ppm 25 ppm 2 ppm
Glycol monoethyl ether; see 2-Ethoxyethanol            
Graphite, natural respirable dust 7782-42-5 See Annotated Z-3 See Annotated Z-3
Graphite, synthetic            
Total dust     15 10 mg/m3 See Appendix D  
Respirable Fraction     5 5 mg/m3   2 mg/m3 (all forms except fibers)
Guthion; see Azinphos methyl            
Gypsum 13397-24-5     PNOR   See calcium sulfate
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Hafnium 7440-58-6   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3
Heptachlor 76-44-8   0.5 0.05 mg/m3 Ca
0.5 mg/m3
See Appendix A		 0.05 mg/m3
Heptane (n-Heptane) 142-82-5 500 2000 400 ppm
(ST) 500 ppm		 85 ppm
(ST) 440 ppm [15-min]		 400 ppm
(ST) 500 ppm
Hexachloroethane 67-72-1 1 10 1 ppm Ca
1 ppm
See Appendix A
See Appendix C
(Chloroethanes)		 1 ppm
Hexachloronaphthalene 1335-87-1   0.2 0.2 mg/m3 0.2 mg/m3 0.2 mg/m3
n-Hexane 110-54-3 500 1800 50 ppm 50 ppm 50 ppm
2-Hexanone (Methyl n-butyl ketone) 591-78-6 100 410 1 ppm
(ST) 10 ppm		 1 ppm 5 ppm
(ST) 10 ppm
Hexone (Methyl isobutyl ketone) 108-10-1 100 410 50 ppm
(ST) 75 ppm		 50 ppm
(ST) 75 ppm		 20 ppm
(ST) 75 ppm
sec-Hexyl acetate 108-84-9 50 300 50 ppm 50 ppm 50 ppm
Hydrazine 302-01-2 1 1.3 0.01 ppm Ca
(C) 0.03 ppm [2-hr]
See Appendix A		 0.01 ppm
Hydrogen bromide 10035-10-6 3 10 (C) 3 ppm (C) 3 ppm (C) 2 ppm
Hydrogen chloride 7647-01-0 (C) 5 (C) 7 0.3 ppm
(C) 2 ppm		 (C) 5 ppm (C) 2 ppm
Hydrogen cyanide 74-90-8 10 11 (C) 4.7 ppm (ST) 4.7 ppm (C) 4.7 ppm
Hydrogen fluoride (as F) 7664-39-3 See Annotated Z-2 See Annotated Z-2
Hydrogen peroxide 7722-84-1 1 1.4 1 ppm 1 ppm 1 ppm
Hydrogen selenide (as Se) 7783-07-5 0.05 0.2 0.05 ppm 0.05 ppm 0.05 ppm
Hydrogen sulfide 7783-06-4 See Annotated Z-2 See Annotated Z-2
Hydroquinone 123-31-9 ........ 2 2 mg/m3 (C) 2 mg/m3 [15-min] 1 mg/m3
Iodine 7553-56-2 (C) 0.1 (C) 1 (C) 0.1 ppm (C) 0.1 ppm 0.01 ppm (IFV)
(ST) 0.1 ppm (V)
Iron oxide 1309-37-1   10 (fume) 5 mg/m3 (fume) 5 mg/m3 (dust and fume) 5 mg/m3 (resp.)
Isoamyl acetate 123-92-2 100 525 50 ppm
(ST) 100 ppm		 100 ppm 50 ppm
(ST) 100 ppm
Isoamyl alcohol (primary and secondary) 123-51-3 100 360 100 ppm
(ST) 125 ppm		 100 ppm
(ST) 125 ppm		 100 ppm
(ST) 125 ppm
Isobutyl acetate 110-19-0 150 700 150 ppm 150 ppm (n)
Isobutyl alcohol 78-83-1 100 300 50 ppm 50 ppm 50 ppm
Isophorone 78-59-1 25 140 4 ppm 4 ppm (C) 5 ppm
Isopropyl acetate 108-21-4 250 950 250 ppm
(ST) 310 ppm		 See Appendix D (p)
Isopropyl alcohol 67-63-0 400 980 400 ppm
(ST) 500 ppm		 400 ppm
(ST) 500 ppm		 200 ppm
(ST) 400 ppm
Isopropylamine 75-31-0 5 12 5 ppm
(ST) 10 ppm		 See Appendix D 5 ppm
(ST) 10 ppm
Isopropyl ether 108-20-3 500 2100 250 ppm 500 ppm 250 ppm
(ST) 310 ppm
Isopropyl glycidyl ether (IGE) 4016-14-2 50 240 50 ppm
(ST) 75 ppm		 (C) 50 ppm [15-min] 50 ppm
(ST) 75 ppm
Kaolin 1332-58-7          
Total dust     15   10 mg/m3  
Respirable fraction     5 2 mg/m3
(no asbestos, < 1% crystalline silica)		 5 mg/m3 2 mg/m3 (no asbestos and < 1% crystalline silica)
Ketene 463-51-4 0.5 0.9 0.5 ppm
(ST) 1.5 ppm		 0.5 ppm
(ST) 1.5 ppm		 0.5 ppm
(ST) 1.5 ppm
Lead inorganic (as Pb);
see 1910.1025		 7439-92-1     0.05 mg/m3
See Section 5198		 0.05 mg/m3
See Appendix C		 0.05 mg/m3
Limestone 1317-65-3     see PNOR   See calcium carbonate
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Lindane 58-89-9   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3
Lithium hydride 7580-67-8   0.025 0.025 mg/m3 0.025 mg/m3 (C) 0.05 mg/m3 (IHL)
L.P.G. (Liquified petroleum gas) 68476-85-7 1000 1800 1000 ppm 1000 ppm See TLV® book Appendix F (D, EX)
Magnesite 546-93-0     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Magnesium oxide fume - Total Particulate 1309-48-4   15 10 mg/m3 See Appendix D 10 mg/m3 (IHL)
Malathion - Total dust 121-75-5   15 10 mg/m3 10 mg/m3 1 mg/m3 (IFV)
Maleic anhydride 108-31-6 0.25 1 0.1 ppm 1 mg/m3 0.01 mg/m3 (IFV)
Manganese compounds (as Mn) 7439-96-5   (C) 5 0.2 mg/m3 1 mg/m3
(ST) 3 mg/m3		 0.02 mg/m3 (resp.)
0.1 mg/m3 (IHL)
(for elemental and inorganic compounds)
Manganese fume (as Mn) 7439-96-5   (C) 5 0.2 mg/m3 1 mg/m3
(ST) 3 mg/m3		 0.02 mg/m3 (resp.)
0.1 mg/m3 (IHL)
(for elemental and inorganic compounds)
Marble 1317-65-3     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Mercury (aryl and inorganic) (as Hg) 7439-97-6 See Annotated Z-2 See Annotated Z-2
Mercury (organo) alkylcompounds (as Hg) 7439-97-6 See Annotated Z-2 See Annotated Z-2
Mercury (vapor) (as Hg) 7439-97-6 See Annotated Z-2 See Annotated Z-2
Mesityl oxide 141-79-7 25 100 15 ppm
(ST) 25 ppm		 10 ppm 15 ppm
(ST) 25 ppm
Methanethiol; see Methyl mercaptan            
Methoxychlor - Total dust 72-43-5   15 10 mg/m3 Ca
See Appendix A		 10 mg/m3
2-Methoxyethanol; (Methyl cellosolve) 109-86-4 25 80 5 ppm 0.1 ppm 0.1 ppm
2-Methoxyethyl acetate (Methyl cellosolve acetate) 110-49-6 25 120 5 ppm 0.1 ppm 0.1 ppm
Methyl acetate 79-20-9 200 610 200 ppm
(ST) 250 ppm		 200 ppm
(ST) 250 ppm		 200 ppm
(ST) 250 ppm
Methyl acetylene (Propyne) 74-99-7 1000 1650 1000 ppm 1000 ppm 1000 ppm (EX)
Methyl acetylene propadiene mixture (MAPP)   1000 1800 1000 ppm
(ST) 1250 ppm		 1000 ppm
(ST) 1250 ppm		 1000 ppm (EX)
(ST) 1250 ppm (EX)
Methyl acrylate 96-33-3 10 35 10 ppm 10 ppm 2 ppm
Methylal (Dimethoxy-methane) 109-87-5 1000 3100 1000 ppm 1000 ppm 1000 ppm
Methyl alcohol 67-56-1 200 260 200 ppm
(ST) 250 ppm
(C) 1000 ppm		 200 ppm
(ST) 250 ppm		 200 ppm
(ST) 250 ppm
Methylamine 74-89-5 10 12 5 ppm
(ST) 15 ppm		 10 ppm 5 ppm
(ST) 15 ppm
Methyl amyl alcohol; see Methyl Isobutylcarbinol            
Methyl n-amyl ketone 110-43-0 100 465 50 ppm 100 ppm 50 ppm
Methyl bromide 74-83-9 (C) 20 (C) 80 1 ppm
(ST) 20 ppm		 Ca
See Appendix A		 1 ppm
Methyl butyl ketone; see 2-Hexanone            
Methyl cellosolve; see 2-Methoxyethanol            
Methyl cellosolve acetate; see 2-Methoxyethylacetate            
Methyl chloride 74-87-3 See Annotated Z-2 See Annotated Z-2
Methyl chloroform (1,1,1-Trichloro-ethane) 71-55-6 350 1900 350 ppm
(ST) 450 ppm
(C) 800 ppm		 (C) 350 ppm [15-min]
See Appendix C
(Chloroethanes)		 350 ppm
(ST) 450 ppm
Methylcyclohexane 108-87-2 500 2000 400 ppm 400 ppm 400 ppm
Methylcyclohexanol 25639-42-3 100 470 50 ppm 50 ppm 50 ppm
o-Methylcyclohexanone 583-60-8 100 460 50 ppm
(ST) 75 ppm		 50 ppm
(ST) 75 ppm		 50 ppm
(ST) 75 ppm
Methylene chloride 75-09-2 See Annotated Z-2 See Annotated Z-2
Methyl ethyl ketone (MEK); see 2-Butanone            
Methyl formate 107-31-3 100 250 100 ppm
(ST) 150 ppm		 100 ppm
(ST) 150 ppm		 50 ppm
(ST) 100 ppm
Methyl hydrazine (Monomethylhydrazine) 60-34-4 (C) 0.2 (C) 0.35 0.01 ppm Ca
(C) 0.04 ppm [2-hr]
See Appendix A		 0.01 ppm
Methyl iodide 74-88-4 5 28 2 ppm Ca
2 ppm
See Appendix A		 2 ppm
Methyl isoamyl ketone 110-12-3 100 475 50 ppm 50 ppm 20 ppm
(ST) 50 ppm
Methyl isobutyl carbinol 108-11-2 25 100 25 ppm
(ST) 40 ppm		 25 ppm
(ST) 40 ppm		 25 ppm
(ST) 40 ppm
Methyl isobutyl ketone; see Hexone            
Methyl isocyanate 624-83-9 0.02 0.05 0.02 ppm 0.02 ppm 0.02 ppm
(ST) 0.06 ppm
Methyl mercaptan 74-93-1 (C) 10 (C) 20 0.5 ppm (C) 0.5 ppm [15-min] 0.5 ppm
Methyl methacrylate 80-62-6 100 410 50 ppm
(ST) 100 ppm		 100 ppm 50 ppm
(ST) 100 ppm
Methyl propyl ketone; see 2-Pentanone            
alpha-Methyl styrene 98-83-9 (C) 100 (C) 480 50 ppm
(ST) 100 ppm		 50 ppm
(ST) 100 ppm		 10 ppm
Methylene bisphenyl isocyanate (MDI) 101-68-8 (C) 0.02 (C) 0.2 0.005 ppm 0.05 mg/m3
(C) 0.2 mg/m3 [10-min]		 0.005 ppm
Mica; see Silicates   See Annotated Z-3 See Annotated Z-3
Molybdenum (as Mo) 7439-98-7          
Soluble compounds     5 0.5 mg/m3 See Appendix D 0.5 mg/m3 (resp.)
Insoluble Compounds - Total dust     15 10 mg/m3 See Appendix D  
Insoluble Compounds       3 mg/m3 (resp.)   10 mg/m3 (IHL)
3 mg/m3 (resp.)
Monomethyl aniline 100-61-8 2 9 0.5 ppm 0.5 ppm 0.5 ppm
Monomethyl hydrazine; see Methyl hydrazine            
Morpholine 110-91-8 20 70 20 ppm
(ST) 30 ppm		 20 ppm
(ST) 30 ppm		 20 ppm
Naphtha (Coal tar) 8030-30-6 100 400 100 ppm 100 ppm See TLV® book Appendix H
Naphthalene 91-20-3 10 50 0.1 ppm 10 ppm
(ST) 15 ppm		 10 ppm
alpha-Naphthylamine; see 1910.1004 134-32-7     See Section 5209 Ca
See Appendix A		  
beta-Naphthylamine; see 1910.1009 91-59-8     See Section 5209 Ca
See Appendix A		 Exposure by all routes should be carefully controlled to levels as low as possible.
Nickel carbonyl (as Ni) 13463-39-3 0.001 0.007 0.001 ppm Ca
0.001 ppm
See Appendix A		 (C) 0.05 ppm
Nickel, metal and insoluble compounds (as Ni) 7440-02-0   1 metal 0.5 mg/m3
insoluble 0.1 mg/m3		 Ca
0.015 mg/m3
See Appendix A		 elemental: 1.5 mg/m3 (IHL); insoluble inorganic compounds: 0.2 mg/m3 (IHL)
Nickel, soluble compounds (as Ni) 7440-02-0   1 0.05 mg/m3 Ca
0.015 mg/m3		 soluble inorganic compounds: 0.1 mg/m3 (IHL)
Nicotine 54-11-5   0.5 0.075 ppm 0.5 mg/m3 0.5 mg/m3
Nitric acid 7697-37-2 2 5 2 ppm
(ST) 4 ppm		 2 ppm
(ST) 4 ppm		 2 ppm
(ST) 4 ppm
Nitric oxide 10102-43-9 25 30 25 ppm 25 ppm 25 ppm
p-Nitroaniline 100-01-6 1 6 3 mg/m3 3 mg/m3 3 mg/m3
Nitrobenzene 98-95-3 1 5 1 ppm 1 ppm 1 ppm
p-Nitrochlorobenzene 100-00-5   1 0.1 ppm Ca
See Appendix A		 0.1 ppm
4-Nitrodiphenyl; see 1910.1003 92-93-3     See Section 5209 Ca
See Appendix A		 Exposure by all routes should be carefully controlled to levels as low as possible.
Nitroethane 79-24-3 100 310 100 ppm 100 ppm 100 ppm
Nitrogen dioxide 10102-44-0 (C) 5 (C) 9 (ST) 1 ppm (ST) 1 ppm 0.2 ppm
Nitrogen trifluoride 7783-54-2 10 29 10 ppm 10 ppm 10 ppm
Nitroglycerin 55-63-0 (C) 0.2 (C) 2 0.05 ppm for mixture of nitroglycerine and ethylene glycol dinitrate
(ST) 0.1 mg/m3		 (ST) 0.1 mg/m3 0.05 ppm
Nitromethane 75-52-5 100 250 2 ppm See Appendix D 20 ppm
1-Nitropropane 108-03-2 25 90 25 ppm 25 ppm 25 ppm
2-Nitropropane 79-46-9 25 90 10 ppm Ca
See Appendix A		 10 ppm
N-Nitrosodimethylamine; see 1910.1016       See Section 5209 Ca
See Appendix A		 Exposure by all routes should be carefully controlled to levels as low as possible.
Nitrotoluene (all isomers)   5 30 2 ppm 2 ppm 2 ppm
o-isomer 88-72-2          
m-isomer 99-08-1          
p-isomer 99-99-0          
Nitrotrichloromethane; see Chloropicrin            
Octachloronaphthalene 2234-13-1   0.1 0.1 mg/m3
(ST) 0.3 mg/m3		 0.1 mg/m3
(ST) 0.3 mg/m3		 0.1 mg/m3
(ST) 0.3 mg/m3
Octane 111-65-9 500 2350 300 ppm
(ST) 375 ppm		 75 ppm
(C) 385 ppm [15-min]		 300 ppm
Oil mist, mineral 8012-95-1   5 5 mg/m3 (excluding vapor) 5 mg/m3
(ST) 10 mg/m3		 5 mg/m3 (IHL; excluding metal working fluids, pure highly and severely refined)
(For poorly and mildly refined: exposure by all routes should be carefully controlled to levels as low as possible.)
Osmium tetroxide (as Os) 20816-12-0   0.002 0.002 mg/m3
(ST) 0.006 mg/m3		 0.002 mg/m3
(ST) 0.006 mg/m3		 0.0016 mg/m3
(ST) 0.0047 mg/m3
Oxalic acid 144-62-7   1 1 mg/m3
(ST) 2 mg/m3		 1 mg/m3
(ST) 2 mg/m3		 1 mg/m3
(ST) 2 mg/m3
Oxygen difluoride 7783-41-7 0.05 0.1 (C) 0.05 ppm (C) 0.05 ppm (C) 0.05 ppm
Ozone 10028-15-6 0.1 0.2 0.1 ppm
(ST) 0.3 ppm		 (C) 0.1 ppm 0.05-0.20 ppm depending on workload and time
(See TLV® Documentation on Ozone)
Paraquat, respirable dust 4685-14-7   0.5     0.05 mg/m3(IHL), as the cation
  1910-42-5     0.1 mg/m3 0.1 mg/m3  
  2074-50-2          
Parathion 56-38-2   0.1 0.1 mg/m3 0.05 mg/m3 0.05 mg/m3 (IFV)
Particulates Not Otherwise Regulated (PNOR)(i)         See Appendix D See TLV® book Appendix B
Total dust     15 10 mg/m3    
Respirable fraction     5 5 mg/m3    
PCB; see Chlorodiphenyl (42% and 54% chlorine)            
Pentaborane 19624-22-7 0.005 0.01 0.005 ppm
(ST) 0.015 ppm		 0.005 ppm
(ST) 0.015 ppm		 0.005 ppm
(ST) 0.015 ppm
Pentachloronaphthalene 1321-64-8   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3 (IFV)
Pentachlorophenol 87-86-5   0.5 0.5 mg/m3 0.5 mg/m3 0.5 mg/m3
(ST) 1 mg/m3
Pentaerythritol 115-77-5     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
Pentane 109-66-0 1000 2950 600 ppm 120 ppm
(C) 610 ppm [15-min]		 1000 ppm
2-Pentanone (Methylpropyl ketone) 107-87-9 200 700 200 ppm
(ST) 250 ppm		 150 ppm (ST) 150 ppm
Perchloroethylene (Tetrachloroethylene) 127-18-4 See Annotated Z-2 See Annotated Z-2
Perchloromethyl mercaptan 594-42-3 0.1 0.8 0.1 ppm 0.1 ppm 0.1 ppm
Perchloryl fluoride 7616-94-6 3 13.5 3 ppm
(ST) 6 ppm		 3 ppm
(ST) 6 ppm		 3 ppm
(ST) 6 ppm
Petroleum distillates (Naphtha) (Rubber Solvent)   500 2000 1600 mg/m3 350 mg/m3
(C) 1800 mg/m3 [15-min]		 See TLV® book Appendix H
Phenol 108-95-2 5 19 5 ppm 5 ppm
(C) 15.6 ppm [15-min]		 5 ppm
p-Phenylene diamine 106-50-3   0.1 0.1 mg/m3 0.1 mg/m3 0.1 mg/m3
Phenyl ether, vapor 101-84-8 1 7 1 ppm 1 ppm 1 ppm
(ST) 2 ppm
Phenyl ether-biphenyl mixture, vapor   1 7   1 ppm  
Phenylethylene; see Styrene            
Phenyl glycidyl ether (PGE) 122-60-1 10 60 0.1 ppm Ca
(C) 1 ppm [15-min]
See Appendix A		 0.1 ppm
Phenylhydrazine 100-63-0 5 22 5 ppm
(ST) 10 ppm		 Ca
(C) 0.14 ppm [2-hr]
See Appendix A		 0.1 ppm
Phosdrin (Mevinphos) 7786-34-7   0.1 0.01 ppm
(ST) 0.03 ppm		 0.01 ppm
(ST) 0.03 ppm		 0.01 mg/m3 (IFV)
Phosgene (Carbonyl chloride) 75-44-5 0.1 0.4 0.1 ppm 0.1 ppm
(C) 0.2 ppm [15-min]		 0.1 ppm
Phosphine 7803-51-2 0.3 0.4 0.3 ppm
(ST) 1 ppm		 0.3 ppm
(ST) 1 ppm		 0.05 ppm
(C) 0.15 ppm
Phosphoric acid 7664-38-2   1 1 mg/m3
(ST) 3 mg/m3		 1 mg/m3
(ST) 3 mg/m3		 1 mg/m3
(ST) 3 mg/m3
Phosphorus (yellow) 7723-14-0   0.1 0.1 mg/m3 0.1 mg/m3 0.1 mg/m3
Phosphorus pentachloride 10026-13-8   1 0.1 ppm 1 mg/m3 0.1 ppm
Phosphorus pentasulfide 1314-80-3   1 1 mg/m3
(ST) 3 mg/m3		 1 mg/m3
(ST) 3 mg/m3		 1 mg/m3
(ST) 3 mg/m3
Phosphorus trichloride 7719-12-2 0.5 3 0.2 ppm
(ST) 0.5 ppm		 0.2 ppm
(ST) 0.5 ppm		 0.2 ppm
(ST) 0.5 ppm
Phthalic anhydride 85-44-9 2 12 1 ppm 6 mg/m3 0.002 mg/m3 (IFV)
(ST) 0.005 mg/m3 (IFV)
Picloram 1918-0-21          
Total dust     15 10 mg/m3 See Appendix D 10 mg/m3
Respirable fraction     5 5 mg/m3    
Picric acid 88-89-1   0.1 0.1 mg/m3 0.1 mg/m3
(ST) 0.3 mg/m3		 0.1 mg/m3
Pindone (2-Pivalyl-1,3-indandione) 83-26-1   0.1 0.1 mg/m3 0.1 mg/m3 0.1 mg/m3
Plaster of paris 26499-65-0     See PNOR   See TLV® for calcium sulfate
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Platinum (as Pt) Metal 7440-06-4     1 mg/m3 1 mg/m3 1 mg/m3
Soluble Salts     0.002 0.002 mg/m3 0.002 mg/m3 0.002 mg/m3
Portland cement 65997-15-1     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3 1 mg/m3 (no asbestos and < 1% crystalline silica)
Propane 74-98-6 1000 1800 1000 ppm 1000 ppm See TLV® book Appendix F (D, EX)
beta-Propriolactone; see 1910.1013 57-57-8     0.5 ppm
See Section 5209		 Ca
See Appendix A		 0.5 ppm
n-Propyl acetate 109-60-4 200 840 200 ppm
(ST) 250 ppm		 200 ppm
(ST) 250 ppm		 (p)
n-Propyl alcohol 71-23-8 200 500 200 ppm
(ST) 250 ppm		 200 ppm
(ST) 250 ppm		 100 ppm
n-Propyl nitrate 627-13-4 25 110 25 ppm
(ST) 40 ppm		 25 ppm
(ST) 40 ppm		 25 ppm
(ST) 40 ppm
Propylene dichloride 78-87-5 75 350 75 ppm
(ST) 110 ppm		 Ca
See Appendix A		 10 ppm
Propylene imine 75-55-8 2 5 2 ppm Ca
2 ppm
See Appendix A		 0.2 ppm
(ST) 0.4 ppm
Propylene oxide 75-56-9 100 240 2 ppm Ca
See Appendix A		 2 ppm
Propyne; see Methylacetylene            
Pyrethrum 8003-34-7   5 5 mg/m3 5 mg/m3 5 mg/m3
Pyridine 110-86-1 5 15 5 ppm 5 ppm 1 ppm
Quinone 106-51-4 0.1 0.4 0.1 ppm 0.4 mg/m3 0.1 ppm
RDX: see Cyclonite            
Rhodium (as Rh), metal fume and insoluble compounds 7440-16-6   0.1 0.1 mg/m3 0.1 mg/m3 1 mg/m3
Rhodium (as Rh), soluble compounds 7440-16-6   0.001 0.001 mg/m3 0.001 mg/m3 0.01 mg/m3
Ronnel 299-84-3   15 10 mg/m3 10 mg/m3 5 mg/m3 (IFV)
Rotenone 83-79-4   5 5 mg/m3 5 mg/m3 5 mg/m3
Rouge       See PNOR See Appendix D See iron oxide
Total dust     15 10 mg/m3    
Respirable fraction     5 5 mg/m3    
Selenium compounds (as Se) 7782-49-2   0.2 0.2 mg/m3 0.2 mg/m3 0.2 mg/m3
Selenium hexafluoride (as Se) 7783-79-1 0.05 0.4 0.05 ppm 0.05 ppm 0.05 ppm
Silica, amorphous, precipitated and gel 112926-00-8 See Annotated Z-3 See Annotated Z-3
Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica 61790-53-2 See Annotated Z-3 See Annotated Z-3
Silica, crystalline, respirable dust      
Cristobalite; see 1910.1053(m) 14464-46-1    

0.05 mg/m3
(See Sections 1532.3 & 5204)

 

 Ca
0.05 mg/m3
See Appendix A		 0.025 mg/m3 (resp.) for α-quartz and cristobalite
Quartz: see 1910.1053(m) 14808-60-7     0.05 mg/m3
(See Sections 1532.3 & 5204)		 Ca
0.05 mg/m3
See Appendix A		 0.025 mg/m3 (resp.) for α-quartz and cristobalite
Tripoli (as quartz); see 1910.1053(m) 1317-95-9     0.05 mg/m3
(See Sections 1532.3 & 5204)

Ca
0.05 mg/m3
See Appendix A

 0.025 mg/m3 (resp.) for α-quartz and cristobalite
Tridymite; see 1910.1053(m) 15468-32-3     0.05 mg/m3
(See Sections 1532.3 & 5204)

Ca
0.05 mg/m3
See Appendix A

  
Silica, fused, respirable dust 60676-86-0 See Annotated Z-3 See Annotated Z-3
Silicates (less than 1% crystalline silica)      
Mica (respirable dust) 12001-26-2 See Annotated Z-3 See Annotated Z-3
Soapstone, total dust   See Annotated Z-3 See Annotated Z-3
Soapstone, respirable dust   See Annotated Z-3 See Annotated Z-3
Talc (containing asbestos): use asbestos limit: see 29 CFR 1910.1001   See Annotated Z-3 See Annotated Z-3
Talc (containing no asbestos), respirable dust 14807-96-6 See Annotated Z-3 See Annotated Z-3
Tremolite, asbestiform; see 1910.1001   See Annotated Z-3 See Annotated Z-3
Silicon 7440-21-3     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Silicon carbide 409-21-2     See PNOR   Fibrous (including whiskers) 0.1 f/cc
Nonfibrous: 10 mg/m3 (IHL) (no asbestos and < 1% crystalline silica)
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3 3 mg/m3 (resp., no asbestos and < 1% crystalline silica)
Silver, metal and soluble compounds (as Ag) 7440-22-4   0.01 0.01 mg/m3 0.01 mg/m3 Metal, dust, and fume: 0.1 mg/m3;
Soluble compounds, as Ag: 0.01 mg/m3
Soapstone   See Annotated Z-3 See Annotated Z-3
Sodium fluoroacetate 62-74-8   0.05 0.05 mg/m3
(ST) 0.15 mg/m3		 0.05 mg/m3
(ST) 0.15 mg/m3		 0.05 mg/m3
Sodium hydroxide 1310-73-2   2 (C) 2 mg/m3 (C) 2 mg/m3 (C) 2 mg/m3
Starch 9005-25-8     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
Stibine 7803-52-3 0.1 0.5 0.1 ppm 0.1 ppm 0.1 ppm
Stoddard solvent 8052-41-3 500 2900 100 ppm 350 mg/m3
(C) 1800 mg/m3 [15-min]		 100 ppm
Strychnine 57-24-9   0.15 0.15 mg/m3 0.15 mg/m3 0.15 mg/m3
Styrene 100-42-5 See Annotated Z-2 See Annotated Z-2
Sucrose 57-50-1     See PNOR    
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3
Respirable fraction     5 5 mg/m3 5 mg/m3  
Sulfur dioxide 7446-09-5 5 13 2 ppm
(ST) 5 ppm		 2 ppm
(ST) 5 ppm		 (ST) 0.25 ppm
Sulfur hexafluoride 2551-62-4 1000 6000 1000 ppm 1000 ppm 1000 ppm
Sulfuric acid 7664-93-9   1 0.1 mg/m3
(ST) 3 mg/m3		 1 mg/m3 0.2 mg/m3
(Thor.)
Sulfur monochloride 10025-67-9 1 6 (C) 1 ppm (C) 1 ppm (C) 1 ppm
Sulfur pentafluoride 5714-22-7 0.025 0.25 (C) 0.01 ppm (C) 0.01 ppm (C) 0.01 ppm
Sulfuryl fluoride 2699-79-8 5 20 5 ppm
(ST) 10 ppm		 5 ppm
(ST) 10 ppm		 5 ppm
(ST) 10 ppm
Systox; see Demeton            
2,4,5-T (2,4,5-tri-chlorophenoxyacetic acid) 93-76-5   10 10 mg/m3 10 mg/m3 10 mg/m3
Talc; see Silicates   See Annotated Z-3 See Annotated Z-3
Tantalum, metal and oxide dust 7440-25-7   5 5 mg/m3 5 mg/m3
(ST) 10 mg/m3		 See TLV® book Appendix G
TEDP (Sulfotep) 3689-24-5   0.2 0.2 mg/m3 0.2 mg/m3 0.1 mg/m3 (IFV)
Tellurium and compounds (as Te) 13494-80-9   0.1 0.1 mg/m3 0.1 mg/m3 0.1 mg/m3
(excluding hydrogen telluride)
Tellurium hexafluoride (as Te) 7783-80-4 0.02 0.2 0.02 ppm 0.02 ppm 0.02 ppm
Temephos 3383-96-8         1 mg/m3 (IHL)
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
TEPP (Tetraethyl pyrophosphate) 107-49-3   0.05 0.004 ppm 0.05 mg/m3 0.01 mg/m3 (IFV)
Terphenyls 26140-60-3 (C) 1 (C) 9 (C) 0.5 ppm (C) 0.5 ppm (C) 5 mg/m3
1,1,1,2-Tetrachloro-2,2-difluoroethane 76-11-9 500 4170 500 ppm 500 ppm 100 ppm
1,1,2,2-Tetrachloro-1,2-difluoroethane 76-12-0 500 4170 500 ppm 500 ppm 50 ppm
1,1,2,2-Tetrachloroethane 79-34-5 5 35 1 ppm Ca
1 ppm
See Appendix A
See Appendix C
(Chloroethanes)		 1 ppm
Tetrachoroethylene; see Perchloroethylene            
Tetrachloromethane; see Carbon tetrachloride            
Tetrachloronaphthalene 1335-88-2   2 2 mg/m3 2 mg/m3 2 mg/m3
Tetraethyl lead (as Pb) 78-00-2   0.075 0.075 mg/m3 0.075 mg/m3 0.1 mg/m3
Tetrahydrofuran 109-99-9 200 590 200 ppm
(ST) 250 ppm		 200 ppm
(ST) 250 ppm		 50 ppm
(ST) 100 ppm
Tetramethyl lead, (as Pb) 75-74-1   0.075 0.075 mg/m3 0.075 mg/m3 0.15 mg/m3
Tetramethyl succinonitrile 3333-52-6 0.5 3 0.5 ppm 3 mg/m3 0.5 mg/m3 (IFV)
Tetranitromethane 509-14-8 1 8 0.005 ppm 1 ppm 0.005 ppm
Tetryl (2,4,6-Trinitrophenylmethylnitramine) 479-45-8   1.5 1.5 mg/m3 1.5 mg/m3 1.5 mg/m3
Thallium, soluble compounds (as Tl) 7440-28-0   0.1 0.1 mg/m3 0.1 mg/m3 0.02 mg/m3 (IHL)
4,4'-Thiobis (6-tert,Butyl-m-cresol) 96-69-5         1 mg/m3 (IHL)
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Thiram 137-26-8   5 5 mg/m3 5 mg/m3 0.05 mg/m3 (IFV)
Tin, inorganic compounds (except oxides) (as Sn) 7440-31-5   2 2 mg/m3; also tin oxide; except SnH4 2 mg/m3; except tin oxides metal, oxide and inorganic compounds, except tin hydride and indium tin oxide, as Sn: 2 mg/m3 (IHL)
Tin, organic compounds (as Sn) 7440-31-5   0.1 0.1 mg/m3
(ST) 0.2 mg/m3		 0.1 mg/m3 except Cyhexatin 0.1 mg/m3
(ST) 0.2 mg/m3
Titanium dioxide - Total dust 13463-67-7   15 See PNOR Ca
(ultrafine particles)
2.4 mg/m3 (fine)
0.3 mg/m3 (ultrafine)
See Appendix A
See NIOSH Intelligence Bulletin 63		 10 mg/m3
Toluene 108-88-3 See Annotated Z-2 See Annotated Z-2
Toluene-2,4-diisocyanate (TDI) 584-84-9 (C) 0.02 (C) 0.14 0.005 ppm
(ST) 0.02 ppm
(C) 0.02 ppm		 Ca
See Appendix A

0.001 ppm (IFV)
(ST) 0.005 ppm (IFV)
o-Toluidine 95-53-4 5 22 2 ppm Ca
See Appendix A		 2 ppm
Toxaphene; see Chlorinated camphene            
Tremolite   See Annotated Z-3 See Annotated Z-3
Tributyl phosphate 126-73-8   5 0.2 ppm 0.2 ppm 5 mg/m3 (IFV)
1,1,1-Trichloroethane; see Methyl chloroform            
1,1,2-Trichloroethane 79-00-5 10 45 10 ppm Ca
10 ppm
See Appendix A
See Appendix C
(Chloroethanes)		 10 ppm
Trichloroethylene 79-01-6 See Annotated Z-2 See Annotated Z-2
Trichloromethane; see Chloroform            
Trichloronaphthalene 1321-65-9   5 5 mg/m3 5 mg/m3 5 mg/m3
1,2,3-Trichloropropane 96-18-4 50 300 10 ppm Ca
10 ppm
See Appendix A		 0.005 ppm
1,1,2-Trichloro-1,2,2-trifluoroethane 76-13-1 1000 7600 1000 ppm
(ST) 1250 ppm
(C) 2000 ppm		 1000 ppm
(ST) 1250 ppm		 1000 ppm
(ST) 1250 ppm
Triethylamine 121-44-8 25 100 (C) 1 ppm See Appendix D 0.5 ppm
(ST) 1 ppm
Trifluorobromomethane 75-63-8 1000 6100 1000 ppm 1000 ppm 1000 ppm
2,4,6-Trinitrophenol;see Picric acid            
2,4,6-Trinitrophenyl-methyl nitramine; see Tetryl            
2,4,6-Trinitrotoluene (TNT) 118-96-7   1.5 0.5 mg/m3 0.5 mg/m3 0.1 mg/m3 (IFV)
Triorthocresyl phosphate 78-30-8   0.1 0.1 mg/m3 0.1 mg/m3 0.02 mg/m3 (IFV)
Triphenyl phosphate 115-86-6   3 3 mg/m3 3 mg/m3 3 mg/m3
Turpentine 8006-64-2 100 560 100 ppm 100 ppm 20 ppm
Uranium (as U) 7440-61-1          
Soluble compounds     0.05 0.05 mg/m3 Ca
0.05 mg/m3,
See Appendix A		 0.2 mg/m3
(ST) 0.6 mg/m3
Insoluble compounds     0.25 0.2 mg/m3
(ST) 0.6 mg/m3		 Ca
0.2 mg/m3
(ST) 0.6 mg/m3
See Appendix A		 0.2 mg/m3
(ST) 0.6 mg/m3
Vanadium 1314-62-1         0.05 mg/m3 (IHL)
Vanadium pentoxide as V
Respirable dust (as V2O5)     (C) 0.5 0.05 mg/m3, vanadium pentoxide (C) 0.05 mg V/m3 [15-min],
except Vanadium metal and Vanadium carbide		  
Fume (as V2O5)     (C) 0.1 0.05 mg/m3 (C) 0.05 mg V/m3 [15-min]  
Vegetable oil mist       Vegetable oil mists (except castor, cashew nut or similar irritant oils)
See PNOR		    
Total dust     15 10 mg/m3 10 mg/m3  
Respirable fraction     5 5 mg/m3 5 mg/m3  
Vinyl benzene; see Styrene            
Vinyl chloride; see 1910.1017 75-01-4     1 ppm
See Section 5210		 Ca
See Appendix A		 1 ppm
Vinyl cyanide; see Acrylonitrile            
Vinyl toluene 25013-15-4 100 480 50 ppm 100 ppm 50 ppm
(ST) 100 ppm
Warfarin 81-81-2   0.1 0.1 mg/m3 0.1 mg/m3 0.01 mg/m3 (IHL)
Xylenes (o-, m-, p-isomers) 1330-20-7 100 435 100 ppm
(ST) 150 ppm
(C) 300 ppm		 100 ppm
(ST) 150 ppm		 100 ppm
(ST) 150 ppm
Xylidine 1300-73-8 5 25 0.5 ppm 2 ppm 0.5 ppm (IFV)
Yttrium 7440-65-5   1 1 mg/m3 1 mg/m3 1 mg/m3
Zinc chloride fume 7646-85-7   1 1 mg/m3
(ST) 2 mg/m3		 1 mg/m3
(ST) 2 mg/m3		 1 mg/m3
(ST) 2 mg/m3
Zinc oxide fume 1314-13-2   5 5 mg/m3
(ST) 10 mg/m3		 5 mg/m3
(ST) 10 mg/m3		 2 mg/m3 (resp.)
(ST) 10 mg/m3 (resp)
Zinc oxide 1314-13-2     See PNOR    
Total dust     15 10 mg/m3 5 mg/m3
(C) 15 mg/m3		  
Respirable fraction     5 5 mg/m3   2 mg/m3
(ST) 10 mg/m3
Zinc stearate 557-05-1         See TLV® Documentation on Stearates
Total dust     15 10 mg/m3 10 mg/m3 10 mg/m3 (IHL)
Respirable fraction     5   5 mg/m3 3 mg/m3(resp.)
Zirconium compounds (as Zr) 7440-67-7   5 5 mg/m3
(ST) 10 mg/m3		 5 mg/m3
(ST) 10 mg/m3		 5 mg/m3
(ST) 10 mg/m3

Annotated Z-1 Table Footnotes, Abbreviations, References

(a) The unshaded area on this page lists PELs from OSHA Table Z-1 in 29 CFR 1910.1000. The shaded area of this page lists other occupational exposure limits (OELs) from Cal/OSHA, NIOSH, and ACGIH®.

(b) Occupational Safety and Health Administration (OSHA) Permissible Exposure Limits (PELS) from 29 CFR 1910.1000 Z-1 Table [58 FR 35340, June 30, 1993; 58 FR 40191, July 27, 1993, as amended at 61 FR 56831, Nov. 4, 1996; 62 FR 1600, Jan 10,1997; 62 FR 42018, Aug. 4,1997; 71 FR 10373, Feb. 28, 2006; 71 FR 16673, Apr. 3, 2006; 71 FR 36008, June 23, 2006.]. [OSHA entries for respirable crystalline silica from 81 FR 16285, March 25, 2016; OSHA entries for beryllium and beryllium compounds from 82 FR 2470, January 9, 2017]. PELs are 8-hour time weighted averages (TWAs) unless otherwise indicated. OSHA enforces these limits under section 5(a)(2) of the OSH Act. In addition to the values listed in this table, the Z tables in 29 CFR 1910.1000 list skin absorption designations.

(c) The CAS number is for information only. Enforcement is based on the substance name. For an entry covering more than one metal compound measured as the metal, the CAS number for the metal is given - not CAS numbers for the individual compounds.

(d) Parts of vapor or gas per million parts of contaminated air by volume at 25 degrees C and 760 torr.

(e) Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when listed with a ppm entry, it is approximate.

(f) California Division of Occupational Safety and Health (Cal/OSHA) Permissible Exposure Limits (PELs) from Table AC-1 last viewed October 2, 2019, viewable at http://www.dir.ca.gov/title8/5155table_ac1.html. Cal/OSHA enforces its PELs in workplaces under its jurisdiction. Cal/OSHA has established occupational exposure limits for compounds not included in the OSHA Z Tables. Please see Cal/OSHA Table AC-1 for additional limits, the most current limits, and other designations such as skin absorption. The Cal/OSHA AC-1 table and regulations should be consulted for explanations.

(g) National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limits (RELs) from the NIOSH Pocket Guide to Chemical Hazards (https://www.cdc.gov/niosh/npg) (Web site last accessed on October 18, 2019). RELs are for up to 10-hour time weighted averages (TWAs) during a 40-hour work week unless otherwise indicated. NIOSH has established occupational exposure limits for compounds not included in the OSHA Z Tables. Please see the NIOSH Pocket Guide for additional limits, skin absorption and other designations, and explanations.

(h) ACGIH® Threshold Limit Values (TLVs®) (ACGIH® 2019). TLVs® are listed in the order of 8-hour time weighted averages (TWAs), STELs (ST), and Ceilings (C), if available. ACGIH® has established TLVs® for compounds not included in the OSHA Z Tables. Please see ACGIH® Documentation for additional limits, skin absorption and other designations, and explanations. The 2019 TLV® and BEI® Book and Documentation of the Threshold Limit Values on Chemical Substances, 7th Edition are available through the ACGIH® website at http://www.acgih.org. The TLVs® and BEIs® are copyrighted by ACGIH® and are not publicly available. Permission must be requested from ACGIH® to reproduce the TLVs® and BEIs®. Click here for permission request form.

(i) In 29 CFR 1000, all inert or nuisance dusts, whether mineral, inorganic, or organic, not listed specifically by substance name are covered by the Particulates Not Otherwise Regulated (PNOR) limit which is the same as the inert or nuisance dust limit of Table Z-3.

(j) The final benzene standard in 1910.1028 applies to all occupational exposures to benzene except in some circumstances the distribution and sale of fuels, sealed containers and pipelines, coke production, oil and gas drilling and production, natural gas processing, and the percentage exclusion for liquid mixtures; for the excepted subsegments, the benzene limits in Table Z-2 apply. See 1910.1028 for specific circumstances.

(k) See Table Z-2 for the exposure limits for any operations or sectors where the exposure limits in 1910.1026 are stayed or are otherwise not in effect.

(l) This 8-hour TWA applies to respirable dust as measured by a vertical elutriator cotton dust sampler or equivalent instrument. The time-weighted average applies to the cotton waste processing operations of waste recycling (sorting, blending, cleaning and willowing) and garnetting. See also 1910.1043 for cotton dust limits applicable to other sectors.

(m) See Table Z-3 for the exposure limit for any operations or sectors where the exposure limit in § 1910.1053 is stayed or is otherwise not in effect.

(n) For butyl acetate all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5]: TWA = 50 ppm; STEL = 150 ppm.

(o) See Table Z–2 for the exposure limits for any operations or sectors where the exposure limits in § 1910.1024 are stayed or otherwise not in effect.

(p) For propyl acetate isomers (108-21-4; 109-60-4): TWA = 100 ppm; STEL = 150 ppm.

(q) For dicyclopentadiene (77-73-6), including cyclopentadiene: TWA = 0.5 ppm; STEL = 1 ppm

Abbreviations

  • C = Ceiling limit
  • Ca = Potential occupational carcinogens
  • CAS No. = Chemical Abstract Service Number
  • D = Simple asphyxiant
  • EX = Explosion hazard: the substance is a flammable asphyxiant or excursions about the TLV® could approach 10% of the lower explosive limit
  • f/cm3 = fibers/cubic centimeter
  • f/cc = fibers/cubic centimeter
  • hr = hour
  • IHL = Inhalable
  • IFV = Inhalable Fraction and Vapor
  • m3 = cubic meters
  • min = Minute
  • mg/m3 = milligrams/meter cubed
  • PAH = Polycyclic aromatic hydrocarbons
  • PNOR = Particulates not otherwise regulated
  • ppm = parts per million
  • resp. = respirable
  • ST = Short Term Exposure Limit
  • Thor. = Thoracic fraction
  • TLV® = Threshold Limit Value
  • TWA – Time weighted average
  • V = Vapor and aerosol

References

ACGIH® 2019 Threshold Limit Values for Chemical Substances in the Work Environment. Adopted by ACGIH® with Intended Changes. See http://www.acgih.org/.

California Division of Occupational Safety and Health (Cal/OSHA) Table AC-1, Permissible Exposure Limits (PELs), in California Code of Regulations (CCR) Title 8 Section 5155, last viewed October 2, 2019. Viewable at http://www.dir.ca.gov/title8/5155table_ac1.html.

National Institute for Occupational Safety and Health (NIOSH) (2019) NIOSH Pocket Guide to Chemical Hazards. Department of Health and Human Services. Centers for Disease Control and Prevention. National Institute for Occupational Safety and Health (NIOSH). Web site last accessed on October 18, 2019. Available at https://www.cdc.gov/niosh/npg

Occupational Safety and Health Administration (OSHA) (2017) Air Contaminants. 29 CFR 1910.1000 [82 FR 2735, January 9, 2017]. Web site accessed on April 4, 2018. Available at https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000