Wherever this section applies, an employee's exposure to any substance listed in Table Z - Shipyards of this section shall be limited in accordance with the requirements of the following paragraphs of this section.
(a)
(1) Substances with limits preceded by “C” - Ceiling values. An employee's exposure to any substance in Table Z - Shipyards, 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 over a working day.
(2) Other Substances - 8-hour Time Weighted Averages. An employee's exposure to any substance in Table Z - Shipyards, 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)-(c) [Reserved]
(d) Computation formula. 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 1915 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 1915 for the material 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 - Shipyards. 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 1915.
The value of Em shall not exceed unity (1).
(ii) To illustrate the formula prescribed in paragraph (d)(2)(i) of this section, consider the following exposures:
| Substance | Actual concentration of 8 hour exposure (ppm) | 8 hr. TWA PEL (ppm) | 
|---|---|---|
| B | 500 | 1000 | 
| C | 45 | 200 | 
| D | 40 | 200 | 
Since Em is less than unity (1), the exposure combination is within acceptable limits.
Table Z - Shipyards
| Substance | CAS No.d | ppma * | mg/m3 b * | Skin Designation | 
|---|---|---|---|---|
| Abate; see Temephos | ||||
| Acetaldehyde | 75-07-0 | 200 | 360 | - | 
| Acetic acid | 64-19-7 | 10 | 25 | - | 
| Acetic anhydride | 108-24-7 | 5 | 20 | - | 
| Acetone | 67-64-1 | 1000 | 2400 | - | 
| Acetonitrile | 75-05-8 | 40 | 70 | - | 
| 2-Acetylaminofluorine; see § 1915.1014 | 53-96-3 | |||
| Acetylene | 74-86-2 | E | ||
| Acetylene dichloride; see 1,2-Dichloroethylene | ||||
| Acetylene tetrabromide | 79-27-6 | 1 | 14 | - | 
| Acrolein | 107-02-8 | 0.1 | 0.25 | - | 
| Acrylamide | 79-06-1 | - | 0.3 | X | 
| Acrylonitrile; see § 1915.1045 | 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, (as Al) Metal | 7429-90-5 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Alundum; see alpha-Alumina | ||||
| 4-Aminodiphenyl; see § 1915.1011 | 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 | - | 
| Argon | 7440-37-1 | E | ||
| Arsenic, inorganic compounds (as As); see § 1915.1018 | 7440-38-2 | - | - | - | 
| Arsenic, organic compounds (as As) | 7440-38-2 | - | 0.5 | - | 
| Arsine | 7784-42-1 | 0.05 | 0.2 | - | 
| Asbestos; see 1915.1001 | ||||
| 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 | - | |
| Benzeneg; see § 1915.1028 | 71-43-2 | |||
| Benzidine; see § 1915.1010 | 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 1915.1024(q) | 7440-41-7 | 0.002 | ||
| Biphenyl; see Diphenyl | ||||
| Bismuth telluride, Undoped | 1304-82-1 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Bisphenol A; see Diglycidyl ether | ||||
| Boron oxide | 1303-86-2 | |||
| Total dust | - | 15 | - | |
| Boron tribromide | 10294-33-4 | 1 | 10 | - | 
| Boron trifluoride | 7637-07-2 | (C)1 | (C)3 | - | 
| Bromine | 7726-95-6 | 0.1 | 0.7 | - | 
| Bromine pentafluoride | 7789-30-2 | 0.1 | 0.7 | - | 
| Bromoform | 75-25-2 | 0.5 | 5 | X | 
| Butadiene (1,3-Butadiene); see 29 CFR 1910.1051; 29 CFR 1910.19(l) | 106-99-0 | 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 1915.1026n | 1189-85-1 | |||
| n-Butyl glycidyl ether (BGE) | 2426-08-6 | 50 | 270 | - | 
| Butyl mercaptan | 109-79-5 | 0.5 | 1.5 | - | 
| p-tert-Butyltoluene | 98-51-1 | 10 | 60 | - | 
| Cadmium dust fume (as Cd); see 1915.1027 | 7440-43-9 | - | - | - | 
| Calcium carbonate | 1317-65-3 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Calcium hydroxide | 1305-62-0 | - | - | - | 
| Calcium hydroxide | ||||
| 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 | 20 | 60 | X | 
| Carbon monoxide | 630-08-0 | 50 | 55 | - | 
| Carbon tetrachloride | 56-23-5 | 10 | 65 | X | 
| 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 | 1 | 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 | 50 | 240 | - | 
| bis(Chloromethyl) ether; see § 1915.1008 | 542-88-1 | |||
| Chloromethyl methyl ether; see § 1915.1006 | 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 1915.1026o | ||||
| 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 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 | - | 
| Copper | 7440-50-8 | |||
| Fume (as Cu) | - | 0.1 | - | |
| Dusts and mists (as Cu) | - | 1 | - | |
| Corundum; see Emery | ||||
| Cotton dust (raw) | - | 1 | ||
| Crag herbicide (Sesone) | 136-78-7 | |||
| Total dust | - | 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) | Varies with Compound | - | 5 | - | 
| Cyanogen | 460-19-5 | 10 | - | - | 
| Cyclohexane | 110-82-7 | 300 | 1050 | - | 
| Cyclohexanol | 108-93-0 | 50 | 200 | - | 
| Cyclohexanone | 108-94-1 | 50 | 200 | - | 
| Cyclohexene | 110-83-8 | 300 | 1015 | - | 
| Cyclonite | 121-82-4 | - | 1.5 | X | 
| Cyclopentadiene | 542-92-7 | 75 | 200 | - | 
| 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 (CBCP); see § 1915.1044 | 96-12-8 | - | ||
| 1,2-Dibromoethane; see Ethylene dibromide | ||||
| Dibutyl phosphate | 107-66-4 | 1 | 5 | - | 
| Dibutyl phthalate | 84-74-2 | - | 5 | - | 
| Dichloroacetylene | 7572-29-4 | (C)0.1 | (C)0.4 | - | 
| o-Dichlorobenzene | 95-50-1 | (C)50 | (C)300 | - | 
| p-Dichlorobenzene | 106-46-7 | 75 | 450 | - | 
| 3,3′-Dichlorobenzidine; see § 1915.1007 | 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 | - | 
| Diethylene triamine | 111-40-0 | (C)10 | (C)42 | X | 
| Diethyl ether; see Ethyl ether | ||||
| Difluorodibromomethane | 75-61-6 | 100 | 860 | - | 
| Diglycidyl ether (DGE) | 2238-07-5 | (C)0.5 | (C)2.8 | - | 
| Dihydroxybenzene; see Hydroquinone | ||||
| Diisobutyl ketone | 108-83-8 | 50 | 290 | - | 
| Diisopropylamine | 108-18-9 | 5 | 20 | X | 
| 4-Dimethylaminoazobenzene; see § 1915.1015 | 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 | 77-78-3 | 1 | 5 | X | 
| Dinitrobenzene (all isomers) | 1 | X | ||
| (ortho) | 528-29-0 | |||
| (meta) | 99-65-0 | |||
| (para) | 100-25-4 | |||
| Dinitro-o-cresol | 534-52-1 | - | 0.2 | X | 
| Dinitrotoluene | 25321-14-6 | - | 1.5 | X | 
| Dioxane (Diethylene dioxide) | 123-91-1 | 100 | 360 | X | 
| Diphenyl (Biphenyl) | 92-52-4 | 0.2 | 1 | - | 
| Diphenylamine | 122-39-4 | - | 10 | - | 
| Diphenylmethane diisocyanate; see Methylene bisphenyl isocyanate | ||||
| Dipropylene glycol methyl ether | 34590-94-8 | 100 | 600 | X | 
| Di-sec octyl phthalate (Di-(2-ethylhexyl) phthalate) | 117-81-7 | - | 5 | - | 
| Emery | 12415-34-8 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Endosulfan | 115-29-7 | - | 0.1 | X | 
| Endrin | 72-20-8 | - | 0.1 | X | 
| Epichlorohydrin | 106-89-8 | 5 | 19 | X | 
| EPN | 2104-64-5 | - | 0.5 | X | 
| 1,2-Epoxypropane; see Propylene oxide | ||||
| 2,3-Epoxy-1-propanol; see Glycidol | ||||
| Ethane | 74-84-0 | E | ||
| Ethanethiol; see Ethyl mercaptan | ||||
| Ethanolamine | 141-43-5 | 3 | 6 | - | 
| 2-Ethoxyethanol (Cellosolve) | 110-80-5 | 200 | 740 | X | 
| 2-Ethoxyethyl acetate (Cellosolve acetate) | 111-15-9 | 100 | 540 | X | 
| Ethyl acetate | 141-78-6 | 400 | 1400 | - | 
| Ethyl acrylate | 140-88-5 | 25 | 100 | X | 
| Ethyl alcohol (Ethanol) | 64-17-5 | 1000 | 1900 | - | 
| Ethylamine | 75-04-7 | 10 | 18 | - | 
| Ethyl amyl ketone (5-Methyl-3-heptanone) | 541-85-5 | 25 | 130 | - | 
| Ethyl benzene | 100-41-4 | 100 | 435 | - | 
| Ethyl bromide | 74-96-4 | 200 | 890 | - | 
| Ethyl butyl ketone (3-Heptanone) | 106-35-4 | 50 | 230 | - | 
| Ethyl chloride | 75-00-3 | 1000 | 2600 | - | 
| Ethyl ether | 60-29-7 | 400 | 1200 | - | 
| Ethyl formate | 109-94-4 | 100 | 300 | - | 
| Ethyl mercaptan | 75-08-1 | 0.5 | 1 | - | 
| Ethyl silicate | 78-10-4 | 100 | 850 | - | 
| Ethylene | 74-85-1 | E | ||
| Ethylene chlorohydrin | 107-07-3 | 5 | 16 | X | 
| Ethylenediamine | 107-15-3 | 10 | 25 | - | 
| Ethylene dibromide | 106-93-4 | (C)25 | (C)190 | X | 
| Ethylene dichloride (1,2-Dichloroethane) | 107-06-2 | 50 | 200 | - | 
| Ethylene glycol dinitrate | 628-96-6 | (C)0.2 | (C)1 | X | 
| Ethylene glycol methyl acetate; see Methyl cellosolve acetate | ||||
| Ethyleneimine; see § 1915.1012 | 151-56-4 | |||
| Ethylene oxide; see § 1915.1047 | 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 | - | 
| Fibrous Glass | ||||
| Total dust | 15 | - | ||
| Respirable fraction | - | 5 | - | |
| Fluorides (as F) | Varies with compound | - | 2.5 | - | 
| Fluorine | 7782-41-4 | 0.1 | 0.2 | - | 
| Fluorotrichloromethane (Trichlorofluoromethane) | 75-69-4 | 1000 | 5600 | - | 
| Formaldehyde; see § 1915.1048 | 50-00-0 | |||
| Formic acid | 64-18-6 | 5 | 9 | - | 
| Furfural | 98-01-1 | 5 | 20 | X | 
| Furfuryl alcohol | 98-00-0 | 50 | 200 | - | 
| Gasoline | 8006-61-9 | A3 | - | |
| 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 | (2) | (2) | (2) | 
| 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 | - | 
| Helium | 7440-59-7 | E | ||
| Heptachlor | 76-44-8 | - | 0.5 | X | 
| Heptane (n-Heptane) | 142-82-5 | 500 | 2000 | - | 
| Hexachloroethane | 67-72-1 | 1 | 10 | X | 
| Hexachloronaphthalene | 1335-87-1 | - | 0.2 | X | 
| n-Hexane | 110-54-3 | 500 | 1800 | - | 
| 2-Hexanone (Methyl n-butyl ketone) | 591-78-6 | 100 | 410 | - | 
| Hexone (Methyl isobutyl ketone) | 108-10-1 | 100 | 410 | - | 
| sec-Hexyl acetate | 108-84-9 | 50 | 300 | - | 
| Hydrazine | 302-01-2 | 1 | 1.3 | X | 
| Hydrogen | 1333-74-0 | E | ||
| Hydrogen bromide | 10035-10-6 | 3 | 10 | - | 
| Hydrogen chloride | 7647-01-0 | (C)5 | (C)7 | - | 
| Hydrogen cyanide | 74-90-8 | 10 | 11 | X | 
| Hydrogen fluoride (as F) | 7664-39-3 | 3 | 2 | - | 
| Hydrogen peroxide | 7722-84-1 | 1 | 1.4 | - | 
| Hydrogen selenide (as Se) | 7783-07-5 | 0.05 | ||
| Hydrogen sulfide | 7783-06-4 | 10 | 15 | - | 
| Hydroquinone | 123-31-9 | - | 2 | - | 
| Indene | 95-13-6 | 10 | 45 | - | 
| Indium and compounds (as In) | 7440-74-6 | - | 0.1 | - | 
| Iodine | 7553-56-2 | (C)0.1 | (C)1 | - | 
| Iron oxide fume | 1309-37-1 | - | 10 | - | 
| Iron salts (soluble) (as Fe) | Varies with compound | - | 1 | - | 
| Isoamyl acetate | 123-92-2 | 100 | 525 | - | 
| Isoamyl alcohol (primary and secondary) | 123-51-3 | 100 | 360 | - | 
| Isobutyl acetate | 110-19-0 | 150 | 700 | - | 
| Isobutyl alcohol | 78-83-1 | 100 | 300 | - | 
| Isophorone | 78-59-1 | 25 | 140 | - | 
| Isopropyl acetate | 108-21-4 | 250 | 950 | - | 
| Isopropyl alcohol | 67-63-0 | 400 | 980 | - | 
| Isopropylamine | 75-31-0 | 5 | 12 | - | 
| Isopropyl ether | 108-20-3 | 500 | 2100 | - | 
| Isopropyl glycidyl ether (IGE) | 4016-14-2 | 50 | 240 | - | 
| Kaolin | 1332-58-7 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Ketene | 463-51-4 | 0.5 | 0.9 | - | 
| Lead, inorganic (as Pb); see § 1915.1025 | 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 | ||
| 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 | 0.1 | X | |
| Mercury (organo) alkyl compounds (as Hg) | 7439-97-6 | - | 0.01 | X | 
| Mercury (vapor) (as Hg) | 7439-97-6 | - | 0.1 | X | 
| Mesityl oxide | 141-79-7 | 25 | 100 | - | 
| Methane | 74-82-8 | E | ||
| Methanethiol; see Methyl mercaptan | ||||
| Methoxychlor | 72-43-5 | |||
| Total dust | - | 15 | - | |
| 2-Methoxyethanol (Methyl cellosolve) | 109-86-4 | 25 | 80 | X | 
| 2-Methoxyethyl acetate (Methyl cellosolve acetate) | 110-49-6 | 25 | 120 | X | 
| Methyl acetate | 79-20-9 | 200 | 610 | - | 
| Methyl acetylene (Propyne) | 74-99-7 | 1000 | 1650 | - | 
| Methyl acetylene-propadiene mixture (MAPP) | 1000 | 1800 | - | |
| Methyl acrylate | 96-33-3 | 10 | 35 | X | 
| Methylal (Dimethoxy-methane) | 109-87-5 | 1000 | 3100 | - | 
| Methyl alcohol | 67-56-1 | 200 | 260 | - | 
| Methylamine | 74-89-5 | 10 | 12 | - | 
| Methyl amyl alcohol; see Methyl isobutyl carbinol | ||||
| Methyl n-amyl ketone | 110-43-0 | 100 | 465 | - | 
| Methyl bromide | 74-83-9 | (C)20 | (C)80 | X | 
| Methyl butyl ketone; see 2-Hexanone | ||||
| Methyl cellosolve; see 2-Methoxyethanol | ||||
| Methyl cellosolve acetate; see 2-Methoxyethyl acetate | ||||
| Methyl chloride | 74-87-3 | 100 | 210 | - | 
| 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; see § 1910.1052 | ||||
| Methyl ethyl ketone (MEK); see 2-Butanone | ||||
| Methyl formate | 107-31-3 | 100 | 250 | - | 
| Methyl hydrazine (Monomethyl hydrazine) | 60-34-4 | (C)0.2 | (C)0.35 | X | 
| Methyl iodide | 74-88-4 | 5 | 28 | X | 
| Methyl isoamyl ketone | 110-12-3 | 100 | 475 | - | 
| Methyl isobutyl carbinol | 108-11-2 | 25 | 100 | X | 
| Methyl isobutyl ketone; see Hexone | ||||
| Methyl isocyanate | 624-83-9 | 0.02 | 0.05 | X | 
| Methyl mercaptan | 74-93-1 | 0.5 | 1 | - | 
| Methyl methacrylate | 80-62-6 | 100 | 410 | 100 | 
| Methyl propyl ketone; see 2-Pentanone | ||||
| Methyl silicate | 681-84-5 | 5 | 30 | - | 
| alpha-Methyl styrene | 98-83-9 | (C)100 | (C)480 | - | 
| Methylene bisphenyl isocyanate (MDI) | 101-68-8 | (C)0.02 | (C)0.2 | - | 
| Mica; see Silicates | ||||
| Mineral wool | ||||
| Total dust | - | 15 | - | |
| Respirable dust | - | 5 | - | |
| 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 § 1915.1004 | 134-32-7 | |||
| beta-Naphthylamine; see § 1915.1009 | 91-59-8 | - | ||
| Neon | 7440-01-9 | |||
| 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 § 1915.1003 | 92-93-3 | |||
| Nitroethane | 79-24-3 | 100 | 310 | - | 
| Nitrogen | 7727-37-9 | E | ||
| Nitrogen dioxide | 10102-44-0 | (C)5 | (C)9 | - | 
| Nitrogen trifluoride | 7783-54-2 | 10 | 29 | - | 
| Nitroglycerin | 55-63-0 | (C)0.2 | (C)2 | X | 
| Nitromethane | 75-52-5 | 100 | 250 | - | 
| 1-Nitropropane | 108-03-2 | 25 | 90 | - | 
| 2-Nitropropane | 79-46-9 | 25 | 90 | - | 
| N-Nitrosodimethylamine; see § 1915.1016 | 62-79-9 | - | ||
| Nitrotoluene (all isomers) | 5 | 30 | X | |
| o-isomer | 88-72-2; | |||
| m-isomer | 99-08-1; | |||
| p-isomer | 99-99-0 | |||
| Nitrotrichloromethane; see Chloropicrin | ||||
| Nitrous oxide | 10024-97-2 | E | ||
| Octachloronaphthalene | 2234-13-1 | - | 0.1 | X | 
| Octane | 111-65-9 | 400 | 1900 | - | 
| Oil mist, mineral | 8012-95-1 | - | 5 | - | 
| Osmium tetroxide (as Os) | 20816-12-0 | - | 0.002 | - | 
| Oxalic acid | 144-62-7 | - | 1 | - | 
| Oxygen difluoride | 7783-41-7 | 0.05 | 0.1 | - | 
| Ozone | 10028-15-6 | 0.1 | 0.2 | - | 
| Paraquat, respirable dust | 4685-14-7; | - | 0.5 | X | 
| 1910-42-5; | ||||
| 2074-50-2 | ||||
| Parathion | 56-38-2 | - | 0.1 | - | 
| Particulates not otherwise regulated | ||||
| Total dust organic and inorganic | - | 15 | - | |
| PCB; see Chlorodiphenyl (42% and 54% chlorine) | ||||
| Pentaborane | 19624-22-7 | 0.005 | 0.01 | - | 
| Pentachloronaphthalene | 1321-64-8 | - | 0.5 | X | 
| Pentachlorophenol | 87-86-5 | - | 0.5 | X | 
| Pentaerythritol | 115-77-5 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Pentane | 109-66-0 | 500 | 1500 | - | 
| 2-Pentanone (Methyl propyl ketone) | 107-87-9 | 200 | 700 | - | 
| Perchloroethylene (Tetrachloroethylene) | 127-18-4 | 100 | 670 | - | 
| Perchloromethyl mercaptan | 594-42-3 | 0.1 | 0.8 | - | 
| Perchloryl fluoride | 7616-94-6 | 3 | 13.5 | - | 
| Perlite | 93763-70-3 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Petroleum distillates (Naphtha)(Rubber Solvent) | A3 | - | ||
| Phenol | 108-95-2 | 5 | 19 | X | 
| p-Phenylene diamine | 106-50-3 | - | 0.1 | X | 
| Phenyl ether, vapor | 101-84-8 | 1 | 7 | - | 
| Phenyl ether-biphenyl mixture, vapor | 1 | 7 | - | |
| Phenylethylene; see Styrene | ||||
| Phenyl glycidyl ether (PGE) | 122-60-1 | 10 | 60 | - | 
| Phenylhydrazine | 100-63-0 | 5 | 22 | X | 
| Phosdrin (Mevinphos) | 7786-34-7 | - | 0.1 | X | 
| Phosgene (Carbonyl chloride) | 75-44-5 | 0.1 | 0.4 | - | 
| Phosphine | 7803-51-2 | 0.3 | 0.4 | - | 
| Phosphoric acid | 7664-38-2 | - | 1 | - | 
| Phosphorus (yellow) | 7723-14-0 | - | 0.1 | - | 
| Phosphorus pentachloride | 10026-13-8 | - | 1 | - | 
| Phosphorus pentasulfide | 1314-80-3 | - | 1 | - | 
| Phosphorus trichloride | 7719-12-2 | 0.5 | 3 | - | 
| Phthalic anhydride | 85-44-9 | 2 | 12 | - | 
| Picloram | 1918-02-1 | |||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Picric acid | 88-89-1 | - | 0.1 | - | 
| Piperazine dihydrochloride | 142-64-3 | - | - | 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 | - | |
| Polytetrafluoroethylene decomposition products | A2 | |||
| Portland cement | 65997-15-1 | |||
| Total dust | 15 | - | 10 | |
| Respirable fraction | 5 | - | - | |
| Propargyl alcohol | 107-19-7 | 1 | - | X | 
| beta-Propriolactone; see § 1915.1013 | 57-57-8 | |||
| Propionic acid | 79-09-4 | - | - | - | 
| n-Propyl acetate | 109-60-4 | 200 | 840 | - | 
| n-Propyl alcohol | 71-23-8 | 200 | 500 | - | 
| n-Propyl nitrate | 627-13-4 | 25 | 110 | - | 
| Propylene dichloride | 78-87-5 | 75 | 350 | - | 
| Propylene imine | 75-55-8 | 2 | 5 | X | 
| Propylene oxide | 75-56-9 | 100 | 240 | - | 
| Propyne; see Methyl acetylene | ||||
| Pyrethrum | 8003-34-7 | - | 5 | - | 
| Pyridine | 110-86-1 | 5 | 15 | - | 
| Quinone | 106-51-4 | 0.1 | 0.4 | - | 
| RDX; see Cyclonite | ||||
| Rhodium (as Rh), metal fume and insoluble compounds | 7440-16-6 | - | 0.1 | - | 
| Rhodium (as Rh), soluble compounds | 7440-16-6 | - | 0.001 | - | 
| Ronnel | 299-84-3 | - | 10 | - | 
| Rotenone | 83-79-4 | - | 5 | - | 
| Rouge | - | |||
| Total dust | - | 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 | (2) | (2) | (2) | 
| Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica | 61790-53-2 | (2) | (2) | (2) | 
| Silica, crystalline, respirable dust | ||||
| Cristobalite; see 1915.1053 | 14464-46-1 | |||
| Quartz; see 1915.10535 | 14808-60-7 | |||
| Tripoli (as quartz); see 1915.10535 | 1317-95-9 | |||
| Tridymite; see 1915.1053 | 15468-32-3 | |||
| Silica, fused, respirable dust | 60676-86-0 | (2) | (2) | (2) | 
| Silicates (less than 1% crystalline silica) | ||||
| Mica (respirable dust) | 12001-26-2 | (2) | (2) | (2) | 
| Soapstone, total dust | - | (2) | (2) | (2) | 
| Soapstone, respirable dust | - | (2) | (2) | (2) | 
| Talc (containing asbestos) | - | (3) | (3) | (3) | 
| Talc (containing no asbestos), respirable dust | 14807-96-6 | (2) | (2) | (2) | 
| Tremolite, asbestiform | (3) | (3) | (3) | |
| 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 | 200 | 1150 | - | 
| Strychnine | 57-24-9 | - | 0.15 | - | 
| Styrene | 100-42-5 | 100 | 420 | 50 | 
| 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 | 
| Teflon decomposition products | A2 | |||
| Tellurium and compounds (as Te) | 13494-80-9 | - | 0.1 | - | 
| Tellurium hexafluoride (as Te) | 7783-80-4 | 0.02 | 0.2 | - | 
| Temephos | 3383-96-8 | |||
| Total dust | - | 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 | - | 0.1 | X | 
| Tetrahydrofuran | 109-99-9 | 200 | 590 | - | 
| Tetramethyl lead, (as Pb) | 75-74-1 | - | 0.15 | X | 
| Tetramethyl succinonitrile | 3333-52-6 | 0.5 | 3 | X | 
| Tetranitromethane | 509-14-8 | 1 | 8 | - | 
| Tetryl (2,4,6-Trinitrophenylmethylnitramine) | 479-45-8 | - | 1.5 | X | 
| Thallium, soluble compounds (as Tl) | 7440-28-0 | - | 0.1 | X | 
| 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 | - | 
| Tin oxide (as Sn) | 21651-19-4 | - | - | - | 
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Titanium dioxide | 13463-67-7 | |||
| Total dust | - | 15 | - | |
| Toluene | 108-88-3 | 200 | 750 | 100 | 
| Toluene-2,4-diisocyanate (TDI) | 584-84-9 | (C)0.02 | (C)0.14 | - | 
| o-Toluidine | 95-53-4 | 5 | 22 | X | 
| Toxaphene; see Chlorinated camphene | ||||
| Tremolite; see Silicates | ||||
| Tributyl phosphate | 126-73-8 | - | 5 | - | 
| 1,1,1-Trichloroethane; see Methyl chloroform | ||||
| 1,1,2-Trichloroethane | 79-00-5 | 10 | 45 | X | 
| Trichloroethylene | 79-01-6 | 100 | 535 | - | 
| Trichloromethane; see Chloroform | ||||
| Trichloronaphthalene | 1321-65-9 | - | 5 | X | 
| 1,2,3-Trichloropropane | 96-18-4 | 50 | 300 | - | 
| 1,1,2-Trichloro-1,2,2-trifluoroethane | 76-13-1 | 1000 | 7600 | - | 
| Triethylamine | 121-44-8 | 25 | 100 | - | 
| Trifluorobromomethane | 75-63-8 | 1000 | 6100 | - | 
| Trimethyl benzene | 25551-13-7 | 25 | 120 | - | 
| 2,4,6-Trinitrophenyl; see Picric acid | ||||
| 2,4,6-Trinitrophenylmethylnitramine; see Tetryl | ||||
| 2,4,6-Trinitrotoluene (TNT) | 118-96-7 | - | 1.5 | X | 
| Triorthocresyl phosphate | 78-30-8 | - | 0.1 | - | 
| Triphenyl phosphate | 115-86-6 | - | 3 | - | 
| Tungsten (as W) | 7440-33-7 | |||
| Insoluble compounds | - | 5 | - | |
| Soluble compounds | - | 1 | - | |
| Turpentine | 8006-64-2 | 100 | 560 | - | 
| Uranium (as U) | 7440-61-1 | |||
| Soluble compounds | - | 0.2 | - | |
| Insoluble compounds | - | 0.2 | - | |
| Vanadium | 1314-62-1 | |||
| Respirable dust (as V2 O5) | - | (C)0.5 | - | |
| Fume (as V2 O5) | - | (C)0.1 | - | |
| Vegetable oil mist | ||||
| Total dust | - | 15 | - | |
| Respirable fraction | - | 5 | - | |
| Vinyl benzene; see Styrene | ||||
| Vinyl chloride; see § 1915.1017 | 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 | 
Mineral Dusts
| Substance | mppcf(j) | 
|---|---|
| SILICA: | |
| Crystalline | 250(k) | 
| Quartz. Threshold Limit calculated from the formula(p) | % SiO2 + 5 | 
| Cristobalite | |
| Amorphous, including natural diatomaceous earth | 20 | 
| SILICATES (less than 1% crystalline silica) | |
| Mica | 20 | 
| Portland cement | 50 | 
| Soapstone | 20 | 
| Talc (non-asbestiform) | 20 | 
| Talc (fibrous), use asbestos limit | - | 
| Graphite (natural) | 15 | 
| Inert or Nuisance Particulates:(m) | 50 (or 15 mg/m3 whichever is the smaller) of total dust <1% SiO2 | 
| Conversion factors | |
| mppcf × 35.3 = million particles per cubic meter = particles per c.c. | 
[58 FR 35514, July 1, 1993, as amended at 61 FR 56856, Nov. 4, 1996; 62 FR 1619, Jan. 10, 1997; 67 FR 44545, July 3, 2002; 71 FR 10377, Feb. 28, 2006; 71 FR 36009, June 23, 2006; 76 FR 80740, Dec. 27, 2011; 81 FR 16874, Mar. 2 2016; 81 FR 31167, May 19, 2016; 81 FR 60273, Sept. 2, 2016; 82 FR 2744, Jan. 9, 2017]