29 C.F.R. § 1910.1000

2020-08-17
§ 1910.1000 Air contaminants

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:

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

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.

8 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.

Table Z-2

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.

d This standard applies to any operations or sectors for which the exposure limits in the beryllium standard, § 1910.1024, are stayed or is otherwise not in effect.

Table Z-3 - Mineral Dusts

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:

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.

Substance

Actual concentration of 8-hour exposure (ppm)

8-hour TWA PEL (ppm)

B

500

1,000

C

45

200

D

40

200

Substance

CAS No. (c)

ppm (a)

mg/m (b)

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

()

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

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); see 1926.1124

7440-41-7

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

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

()

Carbon monoxide

630-08-0

50

55

Carbon tetrachloride

56-23-5

()

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

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

()

Coal dust (greater than or equal to 5% SiO2), respirable fraction

()

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; 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)

()

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

()

Ethylene dichloride (1,2-Dichloroethane)

107-06-2

()

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)

()

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

()

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

()

Hydrogen peroxide

7722-84-1

1

1.4

Hydrogen selenide (as Se)

7783-07-5

0.05

0.2

Hydrogen sulfide

7783-06-4

()

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

()

Mercury (organo) alkyl compounds (as Hg)

7439-97-6

()

Mercury (vapor) (as Hg)

7439-97-6

()

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

()

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

()

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).

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

()

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

()

Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica

61790-53-2

()

Silica, crystalline, respirable dust

Cristobalite; see 1910.1053

14464-46-1

Quartz; see 1910.1053

14808-60-7

Tripoli (as quartz); see 1910.1053

1317-95-9

Tridymite; see 1910.1053

15468-32-3

Silica, fused, respirable dust

60676-86-0

()

Silicates (less than 1% crystalline silica)

Mica (respirable dust)

12001-26-2

()

Soapstone, total dust

()

Soapstone, respirable dust

()

Talc (containing asbestos); use asbestos limit; see 29 CFR 1910.1001

()

Talc (containing no asbestos), respirable dust

14807-96-6

()

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

()

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

()

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

()

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

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 (Z37.40-1969)

10 ppm

25 ppm

50 ppm

10 minutes.

Beryllium and beryllium compounds (Z37.29-1970)

2 µg/m

5 µg/m

25 µg/m

30 minutes.

Cadmium fume (Z37.5-1970)

0.1 mg/m

0.3 mg/m

Cadmium dust (Z37.5-1970)

0.2 mg/m

0.6 mg/m

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)

1 mg/10m

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

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

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

0.04 mg/m

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.

Substance

mppcf

mg/m

Silica:

Crystalline

Quartz (Respirable)

250

10 mg/m

% SiO2 + 5

% SiO2 + 2

Cristobalite: Use the value calculated from the count or mass formulae for quartz

Tridymite: Use the value calculated from the formulae for quartz

Amorphous, including natural diatomaceous earth

20

80 mg/m

%SiO2

Silicates (less than 1% crystalline silica):

Mica

20

Soapstone

20

Talc (not containing asbestos)

20

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

10 mg/m

Respirable fraction greater than 5% SiO2

_____ %SiO2 + 2

Inert or Nuisance Dust:

Respirable fraction

15

5 mg/m

Total dust

50

15 mg/m

Aerodynamic diameter (unit density sphere)

Percent passing selector

2

90

2.5

75

3.5

50

5.0

25

10

0

[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; 81 FR 60272, Sept. 1, 2016; 82 FR 2735, Jan. 9, 2017]