[Code of Federal Regulations]
[Title 29, Volume 6]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1910.1000]

[Page 7-19]
 
                             TITLE 29--LABOR
 
CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT 
                                OF LABOR
 
PART 1910--OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED)--Table of Contents
 
                Subpart Z--Toxic and Hazardous Substances
 
Sec. 1910.1000  Air contaminants.

    Authority: Sections 4, 6, and 8 of the Occupational Safety and 
Health Act of 1970 (29 U.S.C. 653, 655, and 657); Secretary of Labor's 
Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-
90 (55 FR 9033), 6-96 (62 FR 111), and 3-2000 (65 FR 50017), as 
applicable, and 29 CFR part 1911.
    All of subpart Z issued under section 6(b) of the Occupational 
Safety and Health Act of 1970 (29 U.S.C 653), except those substances 
that have exposure limits in Tables Z-1, Z-2, and Z-3 of 29 CFR 
1910.1000. Section 1910.1000 also issued under section (6)(a) of the Act 
(29 U.S.C. 655(a)). Section 1910.1000, Tables Z-1, Z-2, and Z-3 also 
issued under 5 U.S.C. 553, but not under 29 CFR part 1911, except for 
the inorganic arsenic, benzene, and cotton dust listings.
    Section 1910.1001 also issued under section 107 of the Contract Work 
Hours and Safety Standards Act (40 U.S.C. 333) and 5 U.S.C. 553.
    Section 1910.1002 also issued under 5 U.S.C. 553, but not under 29 
U.S.C. 655 or 29 CFR part 1911.
    Sections 1910.1018, 1910.1029, and 1910.1200 also issued under 29 
U.S.C. 653.

    Source: 39 FR 23502, June 27, 1974, unless otherwise noted. 
Redesignated at 40 FR 23072, May 28, 1975.


    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.

[[Page 8]]

    (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

(2x150+2x75+4x50)/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:

------------------------------------------------------------------------
                                                  Actual
                                              concentration
                  Substance                     of 8-hour     8-hour TWA
                                                 exposure     PEL (ppm)
                                                  (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

[[Page 9]]

are used, their use shall comply with 1910.134.
    (f) Effective dates. The exposure limits specified have been in 
effect with the method of compliance specified in paragraph (e) of this 
section since May 29, 1971.

                                     Table Z-1--Limits for Air Contaminants
----------------------------------------------------------------------------------------------------------------
                                                                          mg/m\3\ (b)
                 Substance                    CAS No. (c)    ppm (a) \1\      \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        7440-38-2
 1910.1018.
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

[[Page 10]]


Butadiene (1,3-Butadiene); See 29 CFR             106-99-0  1 ppm/5 ppm   ...........  .........................
 1910.1051; 29 CFR 1910.19(l).                                  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).............       1189-85-1  ............     (C)0.1    X
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      .........................
Chromic acid and chromates (as CrO3)......           (\4\)                  (\2\)
Chromium (II) compounds.
    (as Cr)...............................       7440-47-3  ............        0.5    .........................
Chromium (III) compounds.
    (as Cr)...............................       7440-47-3  ............        0.5    .........................

[[Page 11]]


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                                   (\3\)
 fraction.
Coal dust (greater than or equal to 5%                                      (\3\)
 SiO2), respirable fraction.
Coal tar pitch volatiles (benzene soluble       65966-93-2  ............        0.2    .........................
 fraction), anthracene, BaP, phenanthrene,
 acridine, chrysene, pyrene.
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;         2            6
                                                 4170-30-3
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-          123-42-2        50          240      .........................
 pentanone).
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            96-12-8
 1910.1044.
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

[[Page 12]]


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            300-76-5  ............        3      .........................
 phosphate.
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)         117-81-7  ............        5      .........................
 phthalate).
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                             75-69-4      1000         5600      .........................
 (Trichlorofluoromethane).
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      .........................

[[Page 13]]


    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

[[Page 14]]


    Total dust............................                  ............       15      .........................
2-Methoxyethanol (Methyl cellosolve)......        109-86-4        25           80      X
2-Methoxyethyl acetate (Methyl cellosolve         110-49-6        25          120      X
 acetate).
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        7440-02-0  ............        1      .........................
 Ni).
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

[[Page 15]]


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;  ............        0.5    X
                                                1910-42-5;
                                                 2074-50-2
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                          500         2000      .........................
 Solvent).
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        7440-16-6  ............        0.1    .........................
 compounds.
Rhodium (as Rh), soluble compounds........       7440-16-6  ............        0.001  .........................

[[Page 16]]


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,          61790-53-2                  (\3\)
 containing less than 1% crystalline
 silica.
Silica, crystalline cristobalite,               14464-46-1                  (\3\)
 respirable dust.
Silica, crystalline quartz, respirable          14808-60-7                  (\3\)
 dust.
Silica, crystalline tripoli (as quartz),         1317-95-9                  (\3\)
 respirable dust.
Silica, crystalline tridymite, respirable       15468-32-3                  (\3\)
 dust.
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         ..............                  (\3\)
     asbestos limit; see 29 CFR 1910.1001.
    Talc (containing no asbestos),              14807-96-6                  (\3\)
     respirable dust.
    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          7440-22-4  ............        0.01   .........................
 Ag).
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              93-76-5  ............       10      .........................
 acid).
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

[[Page 17]]


Tetranitromethane.........................        509-14-8         1            8      .........................
Tetryl (2,4,6-                                    479-45-8  ............        1.5    X
 Trinitrophenylmethylnitramine).
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)         7440-31-5  ............        2      .........................
 (as Sn).
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  deg.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.

[[Page 18]]


(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.


                                                    Table Z-2
----------------------------------------------------------------------------------------------------------------
                                                                            Acceptable maximum peak above the
                                                                         acceptable ceiling concentration for an
           Substance                 8-hour time     Acceptable ceiling                 8-hr shift
                                  weighted average      concentration   ----------------------------------------
                                                                            Concentration      Maximum duration
----------------------------------------------------------------------------------------------------------------
Benzenea (Z37.40-1969).........  10 ppm............  25 ppm............  50 ppm............  10 minutes.
Beryllium and beryllium          2 [mu]g/m3........  5 [mu]g/m3........  25 [mu]g/m3.......  30 minutes.
 compounds (Z37.29-1970).
Cadmium fumeb (Z37.5-1970).....  0.1 mg/m3.........  0.3 mg/m3.........  ..................  ...................
Cadmium dustb (Z37.5-1970).....  0.2 mg/m3.........  0.6 mg/m3.........
Carbon disulfide (Z37.3-1968)..  20 ppm............  30 ppm............  100 ppm...........  30 minutes.
Carbon tetrachloride (Z37.17-    10 ppm............  25 ppm............  200 ppm...........  5 min. in any 4
 1967).                                                                                       hrs.
Chromic acid and chromates       ..................  1 mg/10m3.........
 (Z37.7-1971).
Ethylene dibromide (Z37.31-      20 ppm............  30 ppm............  50 ppm............  5 minutes.
 1970).
Ethylene dichloride (Z37.21-     50 ppm............  100 ppm...........  200 ppm...........  5 min. in any 3
 1969).                                                                                       hrs.
Fluoride as dust (Z37.28-1969).  2.5 mg/m3.........  ..................  ..................  ...................
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/10m3.........  ..................  ...................
Methyl chloride (Z37.18-1969)..  100 ppm...........  200 ppm...........  300 ppm...........  5 mins. in any 3
                                                                                              hrs.
Methylene Chloride: See Sec.
 1919.52..
Organo (alkyl) mercury (Z37.30-  0.01 mg/m3........  0.04 mg/m3........  ..................  ...................
 1969).
Styrene (Z37.15-1969)..........  100 ppm...........  200 ppm...........  600 ppm...........  5 mins. in any 3
                                                                                              hrs.
Tetrachloroethylene (Z37.22-     100 ppm...........  200 ppm...........  300 ppm...........  5 mins. in any 3
 1967).                                                                                       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.


                        Table Z-3--Mineral Dusts
------------------------------------------------------------------------
                   Substance                      mppcf a      mg/m\3\
------------------------------------------------------------------------
Silica:
Crystalline
                                                   250 b      10 mg/m\3\
                                                                  e
    Quartz (Respirable).......................   ----------   ----------
                                                    %SiO2+5   % SiO2 + 2

                                                              30 mg/m\3\
    Quartz (Total Dust).......................  ...........   ----------
                                                              % SiO2 + 2

  Cristobalite: Use \1/2\ the value calculated
   from the count or mass formulae for quartz
  Tridymite: Use \1/2\ the value calculated
   from the formulae for quartz
                                                              80 mg/m\3\
Amorphous, including natural diatomaceous                20   ----------
 earth........................................                     %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


[[Page 19]]


Graphite (Natural)............................           15

Coal Dust:

  Respirable fraction less than 5% SiO2.......  ...........     2.4 mg/
                                                                m\3\ e

                                                              10 mg/m3 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 x 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:


------------------------------------------------------------------------
                                                        Percent passing
      Aerodynamic diameter (unit density sphere)            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/m3 in the table for
  coal dust is 4.5 mg/m3K.


[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]