1. LawStack
  2. Title 29 - Labor
  3. Subtitle B - Regulations Relating to Labor
  4. Chapter XVII - Occupational Safety and Health Administration, Department of Labor
  5. Part 1926 - Safety and Health Regulations for Construction
  6. Subpart D - Occupational Health and Environmental Controls
  7. 29 CFR § 1926.55
29 CFR § 1926.55
Gases, vapors, fumes, dusts, and mists
July 28, 2023
CFR
Editorial Note on Part 1926

Editorial Notes:

1. At 44 FR 8577, Feb. 9, 1979, and corrected at 44 FR 20940, Apr. 6, 1979, OSHA reprinted without change the entire text of 29 CFR part 1926 together with certain General Industry Occupational Safety and Health Standards contained in 29 CFR part 1910, which have been identified as also applicable to construction work. This republication developed a single set of OSHA regulations for both labor and management forces within the construction industry.

2. Nomenclature changes to part 1926 appear at 84 FR 21597, May 14, 2019.

§ 1926.55 Gases, vapors, fumes, dusts, and mists.

(a) Employers must limit an employee's exposure to any substance listed in Table 1 or 2 of this section in accordance with the following:

(1) Substances with limits preceded by (C)—Ceiling Values. An employee's exposure, as determined from breathing-zone air samples, to any substance in Table 1 of this section with a permissible exposure limit preceded by (C) must at no time exceed the exposure limit specified for that substance. If instantaneous monitoring is not feasible, then the employer must assess the ceiling as a 15-minute time-weighted average exposure that the employer cannot exceed at any time during the working day.

(2) Other substances—8-hour Time Weighted Averages. An employee's exposure, as determined from breathing-zone air samples, to any substance in Table 1 or 2 of this section with a permissible exposure limit not preceded by (C) must not exceed the limit specified for that substance measured as an 8-hour time-weighted average in any work shift.

(b) To achieve compliance with paragraph (a) of this section, administrative or engineering controls must first be implemented whenever feasible. When such controls are not feasible to achieve full compliance, protective equipment or 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 technical measures used for this purpose must first 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 § 1926.103.

(c) Paragraphs (a) and (b) of this section do not apply to the exposure of employees to airborne asbestos, tremolite, anthophyllite, or actinolite dust. Whenever any employee is exposed to airborne asbestos, tremolite, anthophyllite, or actinolite dust, the requirements of § 1926.1101 shall apply.

(d) Paragraphs (a) and (b) of this section do not apply to the exposure of employees to formaldehyde. Whenever any employee is exposed to formaldehyde, the requirements of § 1910.1048 of this title shall apply.

Table 1 to § 1926.55—Permissible Exposure Limits for Airborne Contaminants

Open Table
Substance CAS No.d ppma mg/m3 b Skin
designation *
Abate; see Temephos
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 § 1926.1114 53–96–3
Acetylene 74–86–2 E
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 § 1926.1145 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 — —
Respirable fraction — —
Alundum; see alpha-Alumina
4-Aminodiphenyl; see § 1926.1111 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 —
Argon 7440–37–1 E
Arsenic, inorganic compounds (as As); see § 1926.1118 7440–38–2 — — —
Arsenic, organic compounds (as As) 7440–38–2 — 0.5 —
Arsine 7784–42–1 0.05 0.2 —
Asbestos; see § 1926.1101
Azinphos-methyl 86–50–0 — 0.2 X
Barium, soluble compounds (as Ba) 7440–39–3 — 0.5 —
Benzeneg; see § 1926.1128 71–43–2
Benzidine; see § 1926.1110 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); see 1926.1124(q) 7440–41–7 — 0.002 —
Biphenyl; see Diphenyl
Bisphenol A; see Diglycidyl ether
Boron oxide 1303–86–2
Total dust — 15 —
Boron tribromide 10294–33–4 1 10 —
Boron trifluoride 7637–07–2 (C)1 (C)3 —
Bromine 7726–95–6 0.1 0.7 —
Bromine pentafluoride 7789–30–2 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 STEL 1 ppm/5 ppm —
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 1926.1126n 1189–85–1
n-Butyl glycidyl ether (BGE) 2426–08–6 50 270 —
Butyl mercaptan 109–79–5 0.5 1.5 —
p-tert-Butyltoluene 98–51–1 10 60 —
Cadmium (as Cd); see 1926.1127 7440–43–9
Calcium carbonate 1317–65–3
Total dust — —
Respirable fraction — —
Calcium oxide 1305–78–8 — 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 20 60 X
Carbon monoxide 630–08–0 50 55 —
Carbon tetrachloride 56–23–5 10 65 X
Cellulose 9004–34–6
Total dust — —
Respirable fraction — —
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 1 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 § 1926.1108 542–88–1
Chloromethyl methyl ether; see § 1926.1106 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
Chromium (II) compounds
(as Cr) 7440–47–3 — 0.5 —
Chromium (III) compounds
(as Cr) 7440–47–3 — 0.5 —
Chromium (VI) compounds; See 1926.1126o
Chromium metal and insol. salts (as Cr) 7440–47–3 — 1 —
Chrysene; see Coal tar pitch volatiles
Coal tar pitch volatiles (benzene soluble fraction), anthracene, BaP, phenanthrene, acridine, chrysene, pyrene 65996–93–2 — 0.2 —
Cobalt metal, dust, and fume (as Co) 7440–48–4 — 0.1 —
Copper 7440–50–8
Fume (as Cu) — 0.1 —
Dusts and mists (as Cu) — 1 —
Corundum; see Emery
Cotton dust (raw) — 1
Crag herbicide (Sesone) 136–78–7
Total dust — —
Respirable fraction — —
Cresol, all isomers 1319–77–3 5 22 X
Crotonaldehyde 123–73–9; 2 6
4170–30–3
Cumene 98–82–8 50 245 X
Cyanides (as CN) Varies with Compound — 5 X
Cyanogen 460–19–5 10 — —
Cyclohexane 110–82–7 300 1050 —
Cyclohexanol 108–93–0 50 200 —
Cyclohexanone 108–94–1 50 200 —
Cyclohexene 110–83–8 300 1015 —
Cyclonite 121–82–4 — 1.5 X
Cyclopentadiene 542–92–7 75 200 —
DDT, see Dichlorodiphenyltrichloroethane
DDVP, see Dichlorvos
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 § 1926.1144 96–12–8 —
1,2-Dibromoethane; see Ethylene dibromide
Dibutyl phosphate 107–66–4 1 5 —
Dibutyl phthalate 84–74–2 — 5 —
Dichloroacetylene 7572–29–4 (C)0.1 (C)0.4 —
o-Dichlorobenzene 95–50–1 (C)50 (C)300 —
p-Dichlorobenzene 106–46–7 75 450 —
3,3′-Dichlorobenzidine; see § 1926.1107 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
Dieldrin 60–57–1 — 0.25 X
Diethylamine 109–89–7 25 75 —
2-Diethylaminoethanol 100–37–8 10 50 X
Diethylene triamine 111–40–0 (C)10 (C)42 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 § 1926.1115 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 77–78–3 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 —
Diphenylamine 122–39–4 — 10 —
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 — —
Respirable fraction — —
Endosulfan 115–29–7 — 0.1 X
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
Ethane 74–84–0 E
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 0.5 1 —
Ethyl silicate 78–10–4 100 850 —
Ethylene 74–85–1 E
Ethylene chlorohydrin 107–07–3 5 16 X
Ethylenediamine 107–15–3 10 25 —
Ethylene dibromide 106–93–4 (C)25 (C)190 X
Ethylene dichloride (1,2-Dichloroethane) 107–06–2 50 200 —
Ethylene glycol dinitrate 628–96–6 (C)0.2 (C)1 X
Ethylene glycol methyl acetate; see Methyl cellosolve acetate
Ethyleneimine; see § 1926.1112 151–56–4
Ethylene oxide; see § 1926.1147 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 —
Fibrous Glass
Total dust —
Respirable fraction — —
Fluorides (as F) Varies with compound — 2.5 —
Fluorine 7782–41–4 0.1 0.2 —
Fluorotrichloromethane (Trichlorofluoromethane) 75–69–4 1000 5600 —
Formaldehyde; see § 1926.1148 50–00–0
Formic acid 64–18–6 5 9 —
Furfural 98–01–1 5 20 X
Furfuryl alcohol 98–00–0 50 200 —
Gasoline 8006–61–9 A3 —
Glycerin (mist) 56–81–5
Total dust — —
Respirable fraction — —
Glycidol 556–52–5 50 150 —
Glycol monoethyl ether; see 2-Ethoxyethanol
Graphite, natural, respirable dust 7782–42–5 (2) (2) (2)
Graphite, synthetic
Total dust — —
Respirable fraction — —
Guthion; see Azinphos methyl
Gypsum 13397–24–5
Total dust — —
Respirable fraction — —
Hafnium 7440–58–6 — 0.5 —
Helium 7440–59–7 E
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 1333–74–0 E
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 3 2 —
Hydrogen peroxide 7722–84–1 1 1.4 —
Hydrogen selenide (as Se) 7783–07–5 0.05 .02 —
Hydrogen sulfide 7783–06–4 10 15 —
Hydroquinone 123–31–9 — 2 —
Indene 95–13–6 10 45 —
Indium and compounds (as In) 7440–74–6 — 0.1 —
Iodine 7553–56–2 (C)0.1 (C)1 —
Iron oxide fume 1309–37–1 — 10 —
Iron salts (soluble) (as Fe) Varies with compound — 1 —
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 — —
Respirable fraction — —
Ketene 463–51–4 0.5 0.9 —
Lead, inorganic (as Pb); see 1926.62 7439–92–1
Limestone 1317–65–3
Total dust — —
Respirable fraction — —
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 — —
Respirable fraction — —
Magnesium oxide fume 1309–48–4
Total particulate 15 — —
Malathion 121–75–5
Total dust — 15 X
Maleic anhydride 108–31–6 0.25
Manganese compounds (as Mn) 7439–96–5 — (C)5 —
Manganese fume (as Mn) 7439–96–5 — (C)5 —
Marble 1317–65–3
Total dust — —
Respirable fraction — —
Mercury (aryl and inorganic)(as Hg) 7439–97–6 0.1 X
Mercury (organo) alkyl compounds (as Hg) 7439–97–6 — 0.01 X
Mercury (vapor) (as Hg) 7439–97–6 — 0.1 X
Mesityl oxide 141–79–7 25 100 —
Methane 74–82–8 E
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
Methylene chloride; see § 1910.1052
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 75–09–2 500 1740 —
Methylenedianiline (MDA) 101–77–9
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 0.5 1 —
Methyl methacrylate 80–62–6 100 410 —
Methyl propyl ketone; see 2-Pentanone
Methyl silicate 681–84–5 (C)5 (C)30 —
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 § 1926.1104 134–32–7
beta-Naphthylamine; see § 1926.1109 91–59–8 —
Neon 7440–01–9 E
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 § 1926.1103 92–93–3
Nitroethane 79–24–3 100 310 —
Nitrogen 7727–37–9 E
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 § 1926.1116 62–79–9 —
Nitrotoluene (all isomers) 5 30 X
o-isomer 88–72–2;
m-isomer 99–08–1;
p-isomer 99–99–0
Nitrotrichloromethane; see Chloropicrin
Nitrous oxide 10024–97–2 E
Octachloronaphthalene 2234–13–1 — 0.1 X
Octane 111–65–9 400 1900 —
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; — 0.5 X
1910–42–5;
2074–50–2
Parathion 56–38–2 — 0.1 X
Particulates not otherwise regulated
Total dust organic and inorganic — 15 —
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 — —
Respirable fraction — —
Pentane 109–66–0 500 1500 —
2-Pentanone (Methyl propyl ketone) 107–87–9 200 700 —
Perchloroethylene (Tetrachloroethylene) 127–18–4 100 670 —
Perchloromethyl mercaptan 594–42–3 0.1 0.8 —
Perchloryl fluoride 7616–94–6 3 13.5 —
Petroleum distillates (Naphtha)(Rubber Solvent) A3 —
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 —
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 — —
Respirable fraction — —
Platinum (as Pt) 7440–06–4
Metal — — —
Soluble salts — 0.002 —
Polytetrafluoroethylene decomposition products A2
Portland cement 65997–15–1
Total dust — 15 —
Respirable fraction 5 —
Propane 74–98–6 E
Propargyl alcohol 107–19–7 1 — X
beta-Propriolactone; see § 1926.1113 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 — 10 —
Rotenone 83–79–4 — 5 —
Rouge
Total dust — —
Respirable fraction — —
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 (2) (2) (2)
Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica 61790–53–2 (2) (2) (2)
Silica, crystalline, respirable dust
Cristobalite; see 1926.1153 14464–46–1
Quartz; see 1926.11535 14808–60–7
Tripoli (as quartz); see 1926.11535 1317–95–9
Tridymite; see 1926.1153 15468–32–3
Silica, fused, respirable dust 60676–86–0 (2) (2) (2)
Silicates (less than 1% crystalline silica)
Mica (respirable dust) 12001–26–2 (2) (2) (2)
Soapstone, total dust (2) (2) (2)
Soapstone, respirable dust (2) (2) (2)
Talc (containing asbestos); use asbestos limit; see § 1926.1101
Talc (containing no asbestos), respirable dust 14807–96–6 (2) (2) (2)
Tremolite, asbestiform; see § 1926.1101
Silicon carbide 409–21–2
Total dust — —
Respirable fraction — —
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 — —
Respirable fraction — —
Stibine 7803–52–3 0.1 0.5 —
Stoddard solvent 8052–41–3 200 1150 —
Strychnine 57–24–9 — 0.15 —
Styrene 100–42–5 (C)100 (C)420 —
Sucrose 57–50–1
Total dust — —
Respirable fraction — —
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
Teflon decomposition products A2
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 — —
Respirable fraction — —
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 — 0.1 X
Tetrahydrofuran 109–99–9 200 590 —
Tetramethyl lead, (as Pb) 75–74–1 — 0.15 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
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 —
Tin oxide (as Sn) 21651–19–4 — — —
Total dust — —
Respirable fraction — —
Titanium dioxide 13463–67–7
Total dust — —
Toluene 108–88–3 200 750 —
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 79–01–6 100 535 —
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 —
Trimethyl benzene 25551–13–7 25 120 —
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 —
Tungsten (as W) 7440–33–7
Insoluble compounds — 5 —
Soluble compounds — 1 —
Turpentine 8006–64–2 100 560 —
Uranium (as U) 7440–61–1
Soluble compounds — 0.2 —
Insoluble compounds — 0.2 —
Vanadium 1314–62–1
Respirable dust (as V2 O5) — (C)0.5 —
Fume (as V2 O5) — (C)0.1 —
Vegetable oil mist
Total dust — —
Respirable fraction — —
Vinyl benzene; see Styrene
Vinyl chloride; see § 1926.1117 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 —
Zirconium compounds (as Zr) 7440–67–7 — 5

Table 2 to § 1926.55—Mineral Dusts

Open Table
Substance mppcf(j)
SILICA:
Crystalline 250(k)
Quartz. Threshold Limit calculated from the formula(p) % SiO2 + 5
Cristobalite
Amorphous, including natural diatomaceous earth 20
SILICATES (less than 1% crystalline silica)
Mica 20
Portland cement 50
Soapstone 20
Talc (non-asbestiform) 20
Talc (fibrous), use asbestos limit —
Graphite (natural) 15
Inert or Nuisance Particulates:(m) 50 (or 15 mg/m3 whichever is the smaller) of total dust <1% SiO2
[Inert or Nuisance Dusts includes all mineral, inorganic, and organic dusts as indicated by examples in TLV's appendix D]
Conversion factors
mppcf × 35.3 = million particles per cubic meter = particles per c.c.

Footnotes to Tables 1 and 2 of this section:

1 [Reserved]

2 See Table 2 of this section.

3 Use Asbestos Limit § 1926.1101.

4 [Reserved]

5 See Table 2 of this section for the exposure limit for any operations or sectors where the exposure limit in § 1926.1153 is stayed or is otherwise not in effect.

* An “X” designation in the “Skin Designation” column indicates that the substance is a dermal hazard.

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 [Reserved]

d 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.

e–f [Reserved]

g For sectors excluded from § 1926.1128 the limit is 10 ppm TWA.

h-i [Reserved]

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

k 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.

l [Reserved]

m Covers all organic and inorganic particulates not otherwise regulated. Same as Particulates Not Otherwise Regulated.

n If the exposure limit in § 1926.1126 is stayed or is otherwise not in effect, the exposure limit is a ceiling of 0.1 mg/m3.

o If the exposure limit in § 1926.1126 is stayed or is otherwise not in effect, the exposure limit is 0.1 mg/m3 (as CrO3) as an 8-hour TWA.

p This standard applies to any operations or sectors for which the respirable crystalline silica standard, 1926.1153, is stayed or otherwise is not in effect.

q This standard applies to any operations or sectors for which the beryllium standard, 1926.1124, is stayed or otherwise is not in effect.

The 1970 TLV uses letter designations instead of a numerical value as follows:

A1 [Reserved]

A2 Polytetrafluoroethylene decomposition products. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentrations should be minimal.

A3 Gasoline and/or Petroleum Distillates. The composition of these materials varies greatly and thus a single TLV for all types of these materials is no longer applicable. The content of benzene, other aromatics and additives should be determined to arrive at the appropriate TLV.

E Simple asphyxiants. The limiting factor is the available oxygen which shall be at least 19.5% and be within the requirements addressing explosion in part 1926.

[39 FR 22801, June 24, 1974, as amended at 51 FR 37007, Oct. 17, 1986; 52 FR 46312, Dec. 4, 1987; 58 FR 35089, June 30, 1993; 61 FR 9249, 9250, Mar. 7, 1996; 61 FR 56856, Nov. 4, 1996; 62 FR 1619, Jan. 10, 1997; 71 FR 10381, Feb. 28, 2006; 71 FR 36009, June 23, 2006; 81 FR 16875, Mar. 25, 2016; 81 FR 31168, May 18, 2016; 81 FR 60273, Sept. 1, 2016; 82 FR 2750, Jan. 9, 2017; 84 FR 21576, May 14, 2019]

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