29 CFR 1910.1000 : Labor (§ 0.735-1 To Parts 4908-4999) — (§ 1910.1000 To §§ 1910.1451-1910.1499) — Regulations Relating To Labor (Continued) (§ 1910.1000 To §§ 1910.1451-1910.1499) — Occupational Safety And Health Administration, Department Of Labor (Continued) (§ 1910.1000 To §§ 1910.1451-1910.1499) — Occupational Safety And Health Standards (Continued) (§ 1910.1000 To §§ 1910.1451-1910.1499) — Toxic And Hazardous Substances (§ 1910.1000 To §§ 1910.1451-1910.1499) — Air contaminants.

4 Aug 2016

An employee's exposure to any substance listed in Tables Z-1, Z-2, or Z-3 of this section shall be limited in accordance with the requirements of the following paragraphs of this section.

(a) Table Z-1 - (1) Substances with limits preceded by “C” - Ceiling Values. An employee's exposure to any substance in Table Z-1, the exposure limit of which is preceded by a “C”, shall at no time exceed the exposure limit given for that substance. If instantaneous monitoring is not feasible, then the ceiling shall be assessed as a 15-minute time weighted average exposure which shall not be exceeded at any time during the working day.

(2) Other substances - 8-hour Time Weighted Averages. An employee's exposure to any substance in Table Z-1, the exposure limit of which is not preceded by a “C”, shall not exceed the 8-hour Time Weighted Average given for that substance in any 8-hour work shift of a 40-hour work week.

(b) Table Z-2. An employee's exposure to any substance listed in Table Z-2 shall not exceed the exposure limits specified as follows:

(1) 8-hour time weighted averages. An employee's exposure to any substance listed in Table Z-2, in any 8-hour work shift of a 40-hour work week, shall not exceed the 8-hour time weighted average limit given for that substance in Table Z-2.

(2) Acceptable ceiling concentrations. An employee's exposure to a substance listed in Table Z-2 shall not exceed at any time during an 8-hour shift the acceptable ceiling concentration limit given for the substance in the table, except for a time period, and up to a concentration not exceeding the maximum duration and concentration allowed in the column under “acceptable maximum peak above the acceptable ceiling concentration for an 8-hour shift.”

(3) Example. During an 8-hour work shift, an employee may be exposed to a concentration of Substance A (with a 10 ppm TWA, 25 ppm ceiling and 50 ppm peak) above 25 ppm (but never above 50 ppm) only for a maximum period of 10 minutes. Such exposure must be compensated by exposures to concentrations less than 10 ppm so that the cumulative exposure for the entire 8-hour work shift does not exceed a weighted average of 10 ppm.

(c) Table Z-3. An employee's exposure to any substance listed in Table Z-3, in any 8-hour work shift of a 40-hour work week, shall not exceed the 8-hour time weighted average limit given for that substance in the table.

(d) Computation formulae. The computation formula which shall apply to employee exposure to more than one substance for which 8-hour time weighted averages are listed in subpart Z of 29 CFR part 1910 in order to determine whether an employee is exposed over the regulatory limit is as follows:

(1)(i) The cumulative exposure for an 8-hour work shift shall be computed as follows:

E = (Ca Ta + Cb Tb + . . .Cn Tn) ÷ 8

  • Where:

    • E is the equivalent exposure for the working shift.

    C is the concentration during any period of time T where the concentration remains constant.

    T is the duration in hours of the exposure at the concentration C.

  • The value of E shall not exceed the 8-hour time weighted average specified in subpart Z of 29 CFR part 1910 for the substance involved.

(ii) To illustrate the formula prescribed in paragraph (d)(1)(i) of this section, assume that Substance A has an 8-hour time weighted average limit of 100 ppm noted in Table Z-1. Assume that an employee is subject to the following exposure:

    Two hours exposure at 150 ppm

    Two hours exposure at 75 ppm

    Four hours exposure at 50 ppm

    Substituting this information in the formula, we have

(2 × 150 + 2 × 75 + 4 × 50) ÷ 8 = 81.25 ppm

    Since 81.25 ppm is less than 100 ppm, the 8-hour time weighted average limit, the exposure is acceptable.

(2)(i) In case of a mixture of air contaminants an employer shall compute the equivalent exposure as follows:

Em = (C1 ÷ L1 + C2 ÷ L2) + . . .(Cn ÷ Ln)

  • Where:

    • Em is the equivalent exposure for the mixture.

    C is the concentration of a particular contaminant.

    L is the exposure limit for that substance specified in subpart Z of 29 CFR part 1910.

  • The value of Em shall not exceed unity (1).

(ii) To illustrate the formula prescribed in paragraph (d)(2)(i) of this section, consider the following exposures:

Substance Actual concentration of 8-hour exposure (ppm) 8-hour TWA PEL (ppm)
B 500 1,000
C 45 200
D 40 200

    Substituting in the formula, we have:

    Em = 500 ÷ 1,000 + 45 ÷ 200 + 40 ÷ 200

    Em = 0.500 + 0.225 + 0.200

    Em = 0.925

  • Since Em is less than unity (1), the exposure combination is within acceptable limits.

(e) To achieve compliance with paragraphs (a) through (d) of this section, administrative or engineering controls must first be determined and implemented whenever feasible. When such controls are not feasible to achieve full compliance, protective equipment or any other protective measures shall be used to keep the exposure of employees to air contaminants within the limits prescribed in this section. Any equipment and/or technical measures used for this purpose must be approved for each particular use by a competent industrial hygienist or other technically qualified person. Whenever respirators are used, their use shall comply with 1910.134.

Table Z-1 - Limits for Air Contaminants

Substance CAS No. (c) ppm (a) 1 mg/m 3 (b) 1 Skin designation
Acetaldehyde 75-07-0 200 360
Acetic acid 64-19-7 10 25
Acetic anhydride 108-24-7 5 20
Acetone 67-64-1 1000 2400
Acetonitrile 75-05-8 40 70
2-Acetylaminofluorine; see 1910.1014 53-96-3
Acetylene dichloride; see 1,2-Dichloroethylene.
Acetylene tetrabromide 79-27-6 1 14
Acrolein 107-02-8 0.1 0.25
Acrylamide 79-06-1 0.3 X
Acrylonitrile; see 1910.1045 107-13-1
Aldrin 309-00-2 0.25 X
Allyl alcohol 107-18-6 2 5 X
Allyl chloride 107-05-1 1 3
Allyl glycidyl ether (AGE) 106-92-3 (C)10 (C)45
Allyl propyl disulfide 2179-59-1 2 12
alpha-Alumina 1344-28-1
Total dust 15
Respirable fraction 5
Aluminum, metal (as Al) 7429-90-5
Total dust 15
Respirable fraction 5
4-Aminodiphenyl; see 1910.1011 92-67-1
2-Aminoethanol; see Ethanolamine.
2-Aminopyridine 504-29-0 0.5 2
Ammonia 7664-41-7 50 35
Ammonium sulfamate 7773-06-0
Total dust 15
Respirable fraction 5
n-Amyl acetate 628-63-7 100 525
sec-Amyl acetate 626-38-0 125 650
Aniline and homologs 62-53-3 5 19 X
Anisidine (o-, p-isomers) 29191-52-4 0.5 X
Antimony and compounds (as Sb) 7440-36-0 0.5
ANTU (alpha Naphthylthiourea) 86-88-4 0.3
Arsenic, inorganic compounds (as As); see 1910.1018 7440-38-2
Arsenic, organic compounds (as As) 7440-38-2 0.5
Arsine 7784-42-1 0.05 0.2
Asbestos; see 1910.1001 ( 4)
Azinphos-methyl 86-50-0 0.2 X
Barium, soluble compounds (as Ba) 7440-39-3 0.5
Barium sulfate 7727-43-7
Total dust 15
Respirable fraction 5
Benomyl 17804-35-2
Total dust 15
Respirable fraction 5
Benzene; see 1910.1028 71-43-2
See Table Z-2 for the limits applicable in the operations or sectors excluded in 1910.1028 d
Benzidine; see 1910.1010 92-87-5
p-Benzoquinone; see Quinone.
Benzo(a)pyrene; see Coal tar pitch volatiles.
Benzoyl peroxide 94-36-0 5
Benzyl chloride 100-44-7 1 5
Beryllium and beryllium compounds (as Be) 7440-41-7 ( 2)
Biphenyl; see Diphenyl.
Bismuth telluride, Undoped 1304-82-1
Total dust 15
Respirable fraction 5
Boron oxide 1303-86-2
Total dust 15
Boron trifluoride 7637-07-2 (C)1 (C)3
Bromine 7726-95-6 0.1 0.7
Bromoform 75-25-2 0.5 5 X
Butadiene (1,3-Butadiene); See 29 CFR 1910.1051; 29 CFR 1910.19(l) 106-99-0 1 ppm/5 ppm STEL
Butanethiol; see Butyl mercaptan.
2-Butanone (Methyl ethyl ketone) 78-93-3 200 590
2-Butoxyethanol 111-76-2 50 240 X
n-Butyl-acetate 123-86-4 150 710
sec-Butyl acetate 105-46-4 200 950
tert-Butyl acetate 540-88-5 200 950
n-Butyl alcohol 71-36-3 100 300
sec-Butyl alcohol 78-92-2 150 450
tert-Butyl alcohol 75-65-0 100 300
Butylamine 109-73-9 (C)5 (C)15 X
tert-Butyl chromate (as CrO3); see 1910.1026 6 1189-85-1
n-Butyl glycidyl ether (BGE) 2426-08-6 50 270
Butyl mercaptan 109-79-5 10 35
p-tert-Butyltoluene 98-51-1 10 60
Cadmium (as Cd); see 1910.1027 7440-43-9
Calcium carbonate 1317-65-3
Total dust 15
Respirable fraction 5
Calcium hydroxide 1305-62-0
Total dust 15
Respirable fraction 5
Calcium oxide 1305-78-8 5
Calcium silicate 1344-95-2
Total dust 15
Respirable fraction 5
Calcium sulfate 7778-18-9
Total dust 15
Respirable fraction 5
Camphor, synthetic 76-22-2 2
Carbaryl (Sevin) 63-25-2 5
Carbon black 1333-86-4 3.5
Carbon dioxide 124-38-9 5000 9000
Carbon disulfide 75-15-0 ( 2)
Carbon monoxide 630-08-0 50 55
Carbon tetrachloride 56-23-5 ( 2)
Cellulose 9004-34-6
Total dust 15
Respirable fraction 5
Chlordane 57-74-9 0.5 X
Chlorinated camphene 8001-35-2 0.5 X
Chlorinated diphenyl oxide 55720-99-5 0.5
Chlorine 7782-50-5 (C)1 (C)3
Chlorine dioxide 10049-04-4 0.1 0.3
Chlorine trifluoride 7790-91-2 (C)0.1 (C)0.4
Chloroacetaldehyde 107-20-0 (C)1 (C)3
a-Chloroacetophenone (Phenacyl chloride) 532-27-4 0.05 0.3
Chlorobenzene 108-90-7 75 350
o-Chlorobenzylidene malononitrile 2698-41-1 0.05 0.4
Chlorobromomethane 74-97-5 200 1050
2-Chloro-1,3-butadiene; see beta-Chloroprene.
Chlorodiphenyl (42% Chlorine) (PCB) 53469-21-9 1 X
Chlorodiphenyl (54% Chlorine) (PCB) 11097-69-1 0.5 X
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
bis(Chloromethyl) ether; see 1910.1008 542-88-1
Chloromethyl methyl ether; see 1910.1006 107-30-2
1-Chloro-1-nitropropane 600-25-9 20 100
Chloropicrin 76-06-2 0.1 0.7
beta-Chloroprene 126-99-8 25 90 X
2-Chloro-6-(trichloromethyl) pyridine 1929-82-4
Total dust 15
Respirable fraction 5
Chromium (II) compounds.
(as Cr) 7440-47-3 0.5
Chromium (III) compounds.
(as Cr) 7440-47-3 0.5
Chromium (VI) compounds; See 1910.1026 5
Chromium metal and insol. salts (as Cr) 7440-47-3 1
Chrysene; see Coal tar pitch volatiles.
Clopidol 2971-90-6
Total dust 15
Respirable fraction 5
Coal dust (less than 5% SiO2), respirable fraction ( 3)
Coal dust (greater than or equal to 5% SiO2), respirable fraction ( 3)
Coal tar pitch volatiles (benzene soluble fraction), anthracene, BaP, phenanthrene, acridine, chrysene, pyrene 65966-93-2 0.2
Cobalt metal, dust, and fume (as Co) 7440-48-4 0.1
Coke oven emissions; see 1910.1029.
Copper 7440-50-8
Fume (as Cu) 0.1
Dusts and mists (as Cu) 1
Cotton dust e; see 1910.1043 1
Crag herbicide (Sesone) 136-78-7
Total dust 15
Respirable fraction 5
Cresol, all isomers 1319-77-3 5 22 X
Crotonaldehyde 123-73-9; 4170-30-3 2 6
Cumene 98-82-8 50 245 X
Cyanides (as CN) ( 4) 5 X
Cyclohexane 110-82-7 300 1050
Cyclohexanol 108-93-0 50 200
Cyclohexanone 108-94-1 50 200
Cyclohexene 110-83-8 300 1015
Cyclopentadiene 542-92-7 75 200
2,4-D (Dichlorophenoxyacetic acid) 94-75-7 10
Decaborane 17702-41-9 0.05 0.3 X
Demeton (Systox) 8065-48-3 0.1 X
Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone) 123-42-2 50 240
1,2-Diaminoethane; see Ethylenediamine.
Diazomethane 334-88-3 0.2 0.4
Diborane 19287-45-7 0.1 0.1
1,2-Dibromo-3-chloropropane (DBCP); see 1910.1044 96-12-8
1,2-Dibromoethane; see Ethylene dibromide.
Dibutyl phosphate 107-66-4 1 5
Dibutyl phthalate 84-74-2 5
o-Dichlorobenzene 95-50-1 (C)50 (C)300
p-Dichlorobenzene 106-46-7 75 450
3,′-Dichlorobenzidine; see 1910.1007 91-94-1
Dichlorodifluoromethane 75-71-8 1000 4950
1,3-Dichloro-5,5-dimethyl hydantoin 118-52-5 0.2
Dichlorodiphenyltrichloroethane (DDT) 50-29-3 1 X
1,1-Dichloroethane 75-34-3 100 400
1,2-Dichloroethane; see Ethylene dichloride.
1,2-Dichloroethylene 540-59-0 200 790
Dichloroethyl ether 111-44-4 (C)15 (C)90 X
Dichloromethane; see Methylene chloride.
Dichloromonofluoromethane 75-43-4 1000 4200
1,1-Dichloro-1-nitroethane 594-72-9 (C)10 (C)60
1,2-Dichloropropane; see Propylene dichloride.
Dichlorotetrafluoroethane 76-14-2 1000 7000
Dichlorvos (DDVP) 62-73-7 1 X
Dicyclopentadienyl iron 102-54-5
Total dust 15
Respirable fraction 5
Dieldrin 60-57-1 0.25 X
Diethylamine 109-89-7 25 75
2-Diethylaminoethanol 100-37-8 10 50 X
Diethyl ether; see Ethyl ether.
Difluorodibromomethane 75-61-6 100 860
Diglycidyl ether (DGE) 2238-07-5 (C)0.5 (C)2.8
Dihydroxybenzene; see Hydroquinone.
Diisobutyl ketone 108-83-8 50 290
Diisopropylamine 108-18-9 5 20 X
4-Dimethylaminoazobenzene; see 1910.1015 60-11-7
Dimethoxymethane; see Methylal.
Dimethyl acetamide 127-19-5 10 35 X
Dimethylamine 124-40-3 10 18
Dimethylaminobenzene; see Xylidine
Dimethylaniline (N,N-Dimethylaniline) 121-69-7 5 25 X
Dimethylbenzene; see Xylene.
Dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate 300-76-5 3
Dimethylformamide 68-12-2 10 30 X
2,6-Dimethyl-4-heptanone; see Diisobutyl ketone.
1,1-Dimethylhydrazine 57-14-7 0.5 1 X
Dimethylphthalate 131-11-3 5
Dimethyl sulfate 77-78-1 1 5 X
Dinitrobenzene (all isomers) 1 X
(ortho) 528-29-0
(meta) 99-65-0
(para) 100-25-4
Dinitro-o-cresol 534-52-1 0.2 X
Dinitrotoluene 25321-14-6 1.5 X
Dioxane (Diethylene dioxide) 123-91-1 100 360 X
Diphenyl (Biphenyl) 92-52-4 0.2 1
Diphenylmethane diisocyanate; see Methylene bisphenyl isocyanate.
Dipropylene glycol methyl ether 34590-94-8 100 600 X
Di-sec octyl phthalate (Di-(2-ethylhexyl) phthalate) 117-81-7 5
Emery 12415-34-8
Total dust 15
Respirable fraction 5
Endrin 72-20-8 0.1 X
Epichlorohydrin 106-89-8 5 19 X
EPN 2104-64-5 0.5 X
1,2-Epoxypropane; see Propylene oxide.
2,3-Epoxy-1-propanol; see Glycidol.
Ethanethiol; see Ethyl mercaptan.
Ethanolamine 141-43-5 3 6
2-Ethoxyethanol (Cellosolve) 110-80-5 200 740 X
2-Ethoxyethyl acetate (Cellosolve acetate) 111-15-9 100 540 X
Ethyl acetate 141-78-6 400 1400
Ethyl acrylate 140-88-5 25 100 X
Ethyl alcohol (Ethanol) 64-17-5 1000 1900
Ethylamine 75-04-7 10 18
Ethyl amyl ketone (5-Methyl-3-heptanone) 541-85-5 25 130
Ethyl benzene 100-41-4 100 435
Ethyl bromide 74-96-4 200 890
Ethyl butyl ketone (3-Heptanone) 106-35-4 50 230
Ethyl chloride 75-00-3 1000 2600
Ethyl ether 60-29-7 400 1200
Ethyl formate 109-94-4 100 300
Ethyl mercaptan 75-08-1 (C)10 (C)25
Ethyl silicate 78-10-4 100 850
Ethylene chlorohydrin 107-07-3 5 16 X
Ethylenediamine 107-15-3 10 25
Ethylene dibromide 106-93-4 ( 2)
Ethylene dichloride (1,2-Dichloroethane) 107-06-2 ( 2)
Ethylene glycol dinitrate 628-96-6 (C)0.2 (C)1 X
Ethylene glycol methyl acetate; see Methyl cellosolve acetate.
Ethyleneimine; see 1910.1012 151-56-4
Ethylene oxide; see 1910.1047 75-21-8
Ethylidene chloride; see 1,1-Dichloroethane.
N-Ethylmorpholine 100-74-3 20 94 X
Ferbam 14484-64-1
Total dust 15
Ferrovanadium dust 12604-58-9 1
Fluorides (as F) ( 4) 2.5
Fluorine 7782-41-4 0.1 0.2
Fluorotrichloromethane (Trichlorofluoromethane) 75-69-4 1000 5600
Formaldehyde; see 1910.1048 50-00-0
Formic acid 64-18-6 5 9
Furfural 98-01-1 5 20 X
Furfuryl alcohol 98-00-0 50 200
Grain dust (oat, wheat, barley) 10
Glycerin (mist) 56-81-5
Total dust 15
Respirable fraction 5
Glycidol 556-52-5 50 150
Glycol monoethyl ether; see 2-Ethoxyethanol.
Graphite, natural, respirable dust 7782-42-5 ( 3)
Graphite, synthetic
Total dust 15
Respirable fraction 5
Guthion; see Azinphos methyl.
Gypsum 13397-24-5
Total dust 15
Respirable fraction 5
Hafnium 7440-58-6 0.5
Heptachlor 76-44-8 0.5 X
Heptane (n-Heptane) 142-82-5 500 2000
Hexachloroethane 67-72-1 1 10 X
Hexachloronaphthalene 1335-87-1 0.2 X
n-Hexane 110-54-3 500 1800
2-Hexanone (Methyl n-butyl ketone) 591-78-6 100 410
Hexone (Methyl isobutyl ketone) 108-10-1 100 410
sec-Hexyl acetate 108-84-9 50 300
Hydrazine 302-01-2 1 1.3 X
Hydrogen bromide 10035-10-6 3 10
Hydrogen chloride 7647-01-0 (C)5 (C)7
Hydrogen cyanide 74-90-8 10 11 X
Hydrogen fluoride (as F) 7664-39-3 ( 2)
Hydrogen peroxide 7722-84-1 1 1.4
Hydrogen selenide (as Se) 7783-07-5 0.05 0.2
Hydrogen sulfide 7783-06-4 ( 2)
Hydroquinone 123-31-9 2
Iodine 7553-56-2 (C)0.1 (C)1
Iron oxide fume 1309-37-1 10
Isoamyl acetate 123-92-2 100 525
Isoamyl alcohol (primary and secondary) 123-51-3 100 360
Isobutyl acetate 110-19-0 150 700
Isobutyl alcohol 78-83-1 100 300
Isophorone 78-59-1 25 140
Isopropyl acetate 108-21-4 250 950
Isopropyl alcohol 67-63-0 400 980
Isopropylamine 75-31-0 5 12
Isopropyl ether 108-20-3 500 2100
Isopropyl glycidyl ether (IGE) 4016-14-2 50 240
Kaolin 1332-58-7
Total dust 15
Respirable fraction 5
Ketene 463-51-4 0.5 0.9
Lead, inorganic (as Pb); see 1910.1025 7439-92-1
Limestone 1317-65-3
Total dust 15
Respirable fraction 5
Lindane 58-89-9 0.5 X
Lithium hydride 7580-67-8 0.025
L.P.G. (Liquefied petroleum gas) 68476-85-7 1000 1800
Magnesite 546-93-0
Total dust 15
Respirable fraction 5
Magnesium oxide fume 1309-48-4
Total particulate 15
Malathion 121-75-5
Total dust 15 X
Maleic anhydride 108-31-6 0.25 1
Manganese compounds (as Mn) 7439-96-5 (C)5
Manganese fume (as Mn) 7439-96-5 (C)5
Marble 1317-65-3
Total dust 15
Respirable fraction 5
Mercury (aryl and inorganic) (as Hg) 7439-97-6 ( 2)
Mercury (organo) alkyl compounds (as Hg) 7439-97-6 ( 2)
Mercury (vapor) (as Hg) 7439-97-6 ( 2)
Mesityl oxide 141-79-7 25 100
Methanethiol; see Methyl mercaptan.
Methoxychlor 72-43-5
Total dust 15
2-Methoxyethanol (Methyl cellosolve) 109-86-4 25 80 X
2-Methoxyethyl acetate (Methyl cellosolve acetate) 110-49-6 25 120 X
Methyl acetate 79-20-9 200 610
Methyl acetylene (Propyne) 74-99-7 1000 1650
Methyl acetylene-propadiene mixture (MAPP) 1000 1800
Methyl acrylate 96-33-3 10 35 X
Methylal (Dimethoxy-methane) 109-87-5 1000 3100
Methyl alcohol 67-56-1 200 260
Methylamine 74-89-5 10 12
Methyl amyl alcohol; see Methyl isobutyl carbinol.
Methyl n-amyl ketone 110-43-0 100 465
Methyl bromide 74-83-9 (C)20 (C)80 X
Methyl butyl ketone; see 2-Hexanone.
Methyl cellosolve; see 2-Methoxyethanol.
Methyl cellosolve acetate; see 2-Methoxyethyl acetate.
Methyl chloride 74-87-3 ( 2)
Methyl chloroform (1,1,1-Trichloroethane) 71-55-6 350 1900
Methylcyclohexane 108-87-2 500 2000
Methylcyclohexanol 25639-42-3 100 470
o-Methylcyclohexanone 583-60-8 100 460 X
Methylene chloride 75-09-2 ( 2)
Methyl ethyl ketone (MEK); see 2-Butanone.
Methyl formate 107-31-3 100 250
Methyl hydrazine (Monomethyl hydrazine) 60-34-4 (C)0.2 (C)0.35 X
Methyl iodide 74-88-4 5 28 X
Methyl isoamyl ketone 110-12-3 100 475
Methyl isobutyl carbinol 108-11-2 25 100 X
Methyl isobutyl ketone; see Hexone.
Methyl isocyanate 624-83-9 0.02 0.05 X
Methyl mercaptan 74-93-1 (C)10 (C)20
Methyl methacrylate 80-62-6 100 410
Methyl propyl ketone; see 2-Pentanone.
alpha-Methyl styrene 98-83-9 (C)100 (C)480
Methylene bisphenyl isocyanate (MDI) 101-68-8 (C)0.02 (C)0.2
Mica; see Silicates.
Molybdenum (as Mo) 7439-98-7
Soluble compounds 5
Insoluble compounds.
Total dust 15
Monomethyl aniline 100-61-8 2 9 X
Monomethyl hydrazine; see Methyl hydrazine.
Morpholine 110-91-8 20 70 X
Naphtha (Coal tar) 8030-30-6 100 400
Naphthalene 91-20-3 10 50
alpha-Naphthylamine; see 1910.1004 134-32-7
beta-Naphthylamine; see 1910.1009 91-59-8
Nickel carbonyl (as Ni) 13463-39-3 0.001 0.007
Nickel, metal and insoluble compounds (as Ni) 7440-02-0 1
Nickel, soluble compounds (as Ni) 7440-02-0 1
Nicotine 54-11-5 0.5 X
Nitric acid 7697-37-2 2 5
Nitric oxide 10102-43-9 25 30
p-Nitroaniline 100-01-6 1 6 X
Nitrobenzene 98-95-3 1 5 X
p-Nitrochlorobenzene 100-00-5 1 X
4-Nitrodiphenyl; see 1910.1003 92-93-3
Nitroethane 79-24-3 100 310
Nitrogen dioxide 10102-44-0 (C)5 (C)9
Nitrogen trifluoride 7783-54-2 10 29
Nitroglycerin 55-63-0 (C)0.2 (C)2 X
Nitromethane 75-52-5 100 250
1-Nitropropane 108-03-2 25 90
2-Nitropropane 79-46-9 25 90
N-Nitrosodimethylamine; see 1910.1016.
Nitrotoluene (all isomers) 5 30 X
o-isomer 88-72-2
m-isomer 99-08-1
p-isomer 99-99-0
Nitrotrichloromethane; see Chloropicrin.
Octachloronaphthalene 2234-13-1 0.1 X
Octane 111-65-9 500 2350
Oil mist, mineral 8012-95-1 5
Osmium tetroxide (as Os) 20816-12-0 0.002
Oxalic acid 144-62-7 1
Oxygen difluoride 7783-41-7 0.05 0.1
Ozone 10028-15-6 0.1 0.2
Paraquat, respirable dust 4685-14-7; 1910-42-5; 2074-50-2 0.5 X
Parathion 56-38-2 0.1 X
Particulates not otherwise regulated (PNOR) f.
Total dust 15
Respirable fraction 5
PCB; see Chlorodiphenyl (42% and 54% chlorine).
Pentaborane 19624-22-7 0.005 0.01
Pentachloronaphthalene 1321-64-8 0.5 X
Pentachlorophenol 87-86-5 0.5 X
Pentaerythritol 115-77-5
Total dust 15
Respirable fraction 5
Pentane 109-66-0 1000 2950
2-Pentanone (Methyl propyl ketone) 107-87-9 200 700
Perchloroethylene (Tetrachloroethylene) 127-18-4 ( 2)
Perchloromethyl mercaptan 594-42-3 0.1 0.8
Perchloryl fluoride 7616-94-6 3 13.5
Petroleum distillates (Naphtha) (Rubber Solvent) 500 2000
Phenol 108-95-2 5 19 X
p-Phenylene diamine 106-50-3 0.1 X
Phenyl ether, vapor 101-84-8 1 7
Phenyl ether-biphenyl mixture, vapor 1 7
Phenylethylene; see Styrene.
Phenyl glycidyl ether (PGE) 122-60-1 10 60
Phenylhydrazine 100-63-0 5 22 X
Phosdrin (Mevinphos) 7786-34-7 0.1 X
Phosgene (Carbonyl chloride) 75-44-5 0.1 0.4
Phosphine 7803-51-2 0.3 0.4
Phosphoric acid 7664-38-2 1
Phosphorus (yellow) 7723-14-0 0.1
Phosphorus pentachloride 10026-13-8 1
Phosphorus pentasulfide 1314-80-3 1
Phosphorus trichloride 7719-12-2 0.5 3
Phthalic anhydride 85-44-9 2 12
Picloram 1918-02-1
Total dust 15
Respirable fraction 5
Picric acid 88-89-1 0.1 X
Pindone (2-Pivalyl-1,3-indandione) 83-26-1 0.1
Plaster of Paris 26499-65-0
Total dust 15
Respirable fraction 5
Platinum (as Pt) 7440-06-4
Metal
Soluble salts 0.002
Portland cement 65997-15-1
Total dust 15
Respirable fraction 5
Propane 74-98-6 1000 1800
beta-Propriolactone; see 1910.1013 57-57-8
n-Propyl acetate 109-60-4 200 840
n-Propyl alcohol 71-23-8 200 500
n-Propyl nitrate 627-13-4 25 110
Propylene dichloride 78-87-5 75 350
Propylene imine 75-55-8 2 5 X
Propylene oxide 75-56-9 100 240
Propyne; see Methyl acetylene.
Pyrethrum 8003-34-7 5
Pyridine 110-86-1 5 15
Quinone 106-51-4 0.1 0.4
RDX; see Cyclonite.
Rhodium (as Rh), metal fume and insoluble compounds 7440-16-6 0.1
Rhodium (as Rh), soluble compounds 7440-16-6 0.001
Ronnel 299-84-3 15
Rotenone 83-79-4 5
Rouge
Total dust 15
Respirable fraction 5
Selenium compounds (as Se) 7782-49-2 0.2
Selenium hexafluoride (as Se) 7783-79-1 0.05 0.4
Silica, amorphous, precipitated and gel 112926-00-8 ( 3)
Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica 61790-53-2 ( 3)
Silica, crystalline, respirable dust
Cristobalite; see 1910.1053 7 14464-46-1
Quartz; see 1910.1053 7 14808-60-7
Tripoli (as quartz); see 1910.1053 7 1317-95-9
Tridymite; see 1910.1053 7 15468-32-3
Silica, fused, respirable dust 60676-86-0 ( 3)
Silicates (less than 1% crystalline silica)
Mica (respirable dust) 12001-26-2 ( 3)
Soapstone, total dust ( 3)
Soapstone, respirable dust ( 3)
Talc (containing asbestos); use asbestos limit; see 29 CFR 1910.1001 ( 3)
Talc (containing no asbestos), respirable dust 14807-96-6 ( 3)
Tremolite, asbestiform; see 1910.1001.
Silicon 7440-21-3
Total dust 15
Respirable fraction 5
Silicon carbide 409-21-2
Total dust 15
Respirable fraction 5
Silver, metal and soluble compounds (as Ag) 7440-22-4 0.01
Soapstone; see Silicates.
Sodium fluoroacetate 62-74-8 0.05 X
Sodium hydroxide 1310-73-2 2
Starch 9005-25-8
Total dust 15
Respirable fraction 5
Stibine 7803-52-3 0.1 0.5
Stoddard solvent 8052-41-3 500 2900
Strychnine 57-24-9 0.15
Styrene 100-42-5 ( 2)
Sucrose 57-50-1
Total dust 15
Respirable fraction 5
Sulfur dioxide 7446-09-5 5 13
Sulfur hexafluoride 2551-62-4 1000 6000
Sulfuric acid 7664-93-9 1
Sulfur monochloride 10025-67-9 1 6
Sulfur pentafluoride 5714-22-7 0.025 0.25
Sulfuryl fluoride 2699-79-8 5 20
Systox; see Demeton.
2,4,5-T (2,4,5-trichlorophenoxyacetic acid) 93-76-5 10
Talc; see Silicates.
Tantalum, metal and oxide dust 7440-25-7 5
TEDP (Sulfotep) 3689-24-5 0.2 X
Tellurium and compounds (as Te) 13494-80-9 0.1
Tellurium hexafluoride (as Te) 7783-80-4 0.02 0.2
Temephos 3383-96-8
Total dust 15
Respirable fraction 5
TEPP (Tetraethyl pyrophosphate) 107-49-3 0.05 X
Terphenyls 26140-60-3 (C)1 (C)9
1,1,1,2-Tetrachloro-2,2-difluoroethane 76-11-9 500 4170
1,1,2,2-Tetrachloro-1,2-difluoroethane 76-12-0 500 4170
1,1,2,2-Tetrachloroethane 79-34-5 5 35 X
Tetrachloroethylene; see Perchloroethylene.
Tetrachloromethane; see Carbon tetrachloride.
Tetrachloronaphthalene 1335-88-2 2 X
Tetraethyl lead (as Pb) 78-00-2 0.075 X
Tetrahydrofuran 109-99-9 200 590
Tetramethyl lead (as Pb) 75-74-1 0.075 X
Tetramethyl succinonitrile 3333-52-6 0.5 3 X
Tetranitromethane 509-14-8 1 8
Tetryl (2,4,6-Trinitrophenylmethylnitramine) 479-45-8 1.5 X
Thallium, soluble compounds (as Tl) 7440-28-0 0.1 X
4,4′-Thiobis (6-tert, Butyl-m-cresol) 96-69-5
Total dust 15
Respirable fraction 5
Thiram 137-26-8 5
Tin, inorganic compounds (except oxides) (as Sn) 7440-31-5 2
Tin, organic compounds (as Sn) 7440-31-5 0.1
Titanium dioxide 13463-67-7
Total dust 15
Toluene 108-88-3 ( 2)
Toluene-2,4-diisocyanate (TDI) 584-84-9 (C)0.02 (C)0.14
o-Toluidine 95-53-4 5 22 X
Toxaphene; see Chlorinated camphene.
Tremolite; see Silicates.
Tributyl phosphate 126-73-8 5
1,1,1-Trichloroethane; see Methyl chloroform.
1,1,2-Trichloroethane 79-00-5 10 45 X
Trichloroethylene 79-01-6 ( 2)
Trichloromethane; see Chloroform.
Trichloronaphthalene 1321-65-9 5 X
1,2,3-Trichloropropane 96-18-4 50 300
1,1,2-Trichloro-1,2,2-trifluoroethane 76-13-1 1000 7600
Triethylamine 121-44-8 25 100
Trifluorobromomethane 75-63-8 1000 6100
2,4,6-Trinitrophenol; see Picric acid.
2,4,6-Trinitrophenylmethylnitramine; see Tetryl.
2,4,6-Trinitrotoluene (TNT) 118-96-7 1.5 X
Triorthocresyl phosphate 78-30-8 0.1
Triphenyl phosphate 115-86-6 3
Turpentine 8006-64-2 100 560
Uranium (as U) 7440-61-1
Soluble compounds 0.05
Insoluble compounds 0.25
Vanadium 1314-62-1
Respirable dust (as V2 O5) (C)0.5
Fume (as V2 O5) (C)0.1
Vegetable oil mist
Total dust 15
Respirable fraction 5
Vinyl benzene; see Styrene.
Vinyl chloride; see 1910.1017 75-01-4
Vinyl cyanide; see Acrylonitrile.
Vinyl toluene 25013-15-4 100 480
Warfarin 81-81-2 0.1
Xylenes (o-, m-, p-isomers) 1330-20-7 100 435
Xylidine 1300-73-8 5 25 X
Yttrium 7440-65-5 1
Zinc chloride fume 7646-85-7 1
Zinc oxide fume 1314-13-2 5
Zinc oxide 1314-13-2
Total dust 15
Respirable fraction 5
Zinc stearate 557-05-1
Total dust 15
Respirable fraction 5
Zirconium compounds (as Zr) 7440-67-7 5

1 The PELs are 8-hour TWAs unless otherwise noted; a (C) designation denotes a ceiling limit. They are to be determined from breathing-zone air samples.

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

(b) 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.

(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) 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.

(e) 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 cottom 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.

(f) 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.

2 See Table Z-2.

3 See Table Z-3.

4 Varies with compound.

5 See Table Z-2 for the exposure limit for any operations or sectors where the exposure limit in § 1910.1026 is stayed or is otherwise not in effect.

6 If the exposure limit in § 1910.1026 is stayed or is otherwise not in effect, the exposure limit is a ceiling of 0.1 mg/m 3.

7 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.

Table Z-2

Substance 8-hour time weighted average Acceptable ceiling concentration Acceptable maximum peak above the acceptable ceiling concentration for an 8-hr shift
Concentration Maximum duration
Benzene a (Z37.40-1969) 10 ppm 25 ppm 50 ppm 10 minutes.
Beryllium and beryllium compounds (Z37.29-1970) 2 µg/m 3 5 µg/m 3 25 µg/m 3 30 minutes.
Cadmium fume b (Z37.5-1970) 0.1 mg/m 3 0.3 mg/m 3
Cadmium dust b (Z37.5-1970) 0.2 mg/m 3 0.6 mg/m 3
Carbon disulfide (Z37.3-1968) 20 ppm 30 ppm 100 ppm 30 minutes.
Carbon tetrachloride (Z37.17-1967) 10 ppm 25 ppm 200 ppm 5 min. in any 4 hrs.
Chromic acid and chromates (Z37.7-1971) (as CrO3) c 1 mg/10m 3
Ethylene dibromide (Z37.31-1970) 20 ppm 30 ppm 50 ppm 5 minutes.
Ethylene dichloride (Z37.21-1969) 50 ppm 100 ppm 200 ppm 5 min. in any 3 hrs.
Fluoride as dust (Z37.28-1969) 2.5 mg/m 3
Formaldehyde; see 1910.1048
Hydrogen fluoride (Z37.28-1969) 3 ppm
Hydrogen sulfide (Z37.2-1966) 20 ppm 50 ppm 10 mins. once, only if no other meas. exp. occurs.
Mercury (Z37.8-1971) 1 mg/10m 3
Methyl chloride (Z37.18-1969) 100 ppm 200 ppm 300 ppm 5 mins. in any 3 hrs.
Methylene Chloride: See § 1919.52.
Organo (alkyl) mercury (Z37.30-1969) 0.01 mg/m 3 0.04 mg/m 3
Styrene (Z37.15-1969) 100 ppm 200 ppm 600 ppm 5 mins. in any 3 hrs.
Tetrachloroethylene (Z37.22-1967) 100 ppm 200 ppm 300 ppm 5 mins. in any 3 hrs.
Toluene (Z37.12-1967) 200 ppm 300 ppm 500 ppm 10 minutes.
Trichloroethylene (Z37.19-1967) 100 ppm 200 ppm 300 ppm 5 mins. in any 2 hrs.

a This standard applies to the industry segments exempt from the 1 ppm 8-hour TWA and 5 ppm STEL of the benzene standard at 1910.1028.

b This standard applies to any operations or sectors for which the Cadmium standard, 1910.1027, is stayed or otherwise not in effect.

c This standard applies to any operations or sectors for which the exposure limit in the Chromium (VI) standard, § 1910.1026, is stayed or is otherwise not in effect.

Table Z-3 - Mineral Dusts

Substance mppcf a mg/m 3
Silica:
Crystalline
Quartz (Respirable) f 250 b 10 mg/m 3 e
%SiO2+5 % SiO2+2
Cristobalite: Use 1/2 the value calculated from the count or mass formulae for quartz f
Tridymite: Use 1/2 the value calculated from the formulae for quartz f
Quartz (Total Dust)
Amorphous, including natural diatomaceous earth 20 _____ %SiO2
Silicates (less than 1% crystalline silica):
Mica 20
Soapstone 20
Talc (not containing asbestos) 20 c
Talc (containing asbestos) Use asbestos limit
Tremolite, asbestiform (see 29 CFR 1910.1001)
Portland cement 50
Graphite (Natural) 15
Coal Dust:
Respirable fraction less than 5% SiO2 2.4 mg/m> 3 e
10 mg/m 3 e
Respirable fraction greater than 5% SiO2 _____ %SiO2 + 2
Inert or Nuisance Dust: d
Respirable fraction 15 5 mg/m 3
Total dust 50 15 mg/m 3

Note - Conversion factors - mppcf × 35.3 = million particles per cubic meter = particles per c.c.

a Millions of particles per cubic foot of air, based on impinger samples counted by light-field techniques.

b The percentage of crystalline silica in the formula is the amount determined from airborne samples, except in those instances in which other methods have been shown to be applicable.

c Containing less than 1% quartz; if 1% quartz or more, use quartz limit.

d All inert or nuisance dusts, whether mineral, inorganic, or organic, not listed specifically by substance name are covered by this limit, which is the same as the Particulates Not Otherwise Regulated (PNOR) limit in Table Z-1.

e Both concentration and percent quartz for the application of this limit are to be determined from the fraction passing a size-selector with the following characteristics:

Aerodynamic diameter (unit density sphere) Percent passing selector
2 90
2.5 75
3.5 50
5.0 25
10 0

The measurements under this note refer to the use of an AEC (now NRC) instrument. The respirable fraction of coal dust is determined with an MRE; the figure corresponding to that of 2.4 mg/m 3 in the table for coal dust is 4.5 mg/m 3K.

f This standard applies to any operations or sectors for which the respirable crystalline silica standard, 1910.1053, is stayed or is otherwise not in effect.

29 CFR 1910.1000
[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; 81 FR 16861, Mar. 25, 2016; 81 FR 31167, May 18, 2016]