1910.1000—Air contaminants.

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

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

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

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

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

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

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

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

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

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

Code of Federal Regulations

E = (Ca Ta Cb Tb . . .Cn Tn)÷8

Where:

E is the equivalent exposure for the working shift.

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

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

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

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

Two hours exposure at 150 ppm

Two hours exposure at 75 ppm

Four hours exposure at 50 ppm

Substituting this information in the formula, we have

(2×150 2×75 4×50)÷8=81.25 ppm

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

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

Code of Federal Regulations

Em=(C1÷L1 C2÷L2) . . .(Cn÷Ln)

Where:

Em is the equivalent exposure for the mixture.

C is the concentration of a particular contaminant.

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

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

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

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

Substituting in the formula, we have:

Em=500÷1,000 45÷200 40÷200

Em=0.500 0.225 0.200

Em=0.925

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

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

Table Z-1—Limits for Air Contaminants

Tips

Substance	CAS No. (c)	ppm (a) 1	mg/m3 (b) 1	Skin designation
Acetaldehyde	75-07-0	200	360
Acetic acid	64-19-7	10	25
Acetic anhydride	108-24-7	5	20
Acetone	67-64-1	1000	2400
Acetonitrile	75-05-8	40	70
2-Acetylaminofluorine; see 1910.1014	53-96-3
Acetylene dichloride; see 1,2-Dichloroethylene.
Acetylene tetrabromide	79-27-6	1	14
Acrolein	107-02-8	0.1	0.25
Acrylamide	79-06-1		0.3	X
Acrylonitrile; see 1910.1045	107-13-1
Aldrin	309-00-2		0.25	X
Allyl alcohol	107-18-6	2	5	X
Allyl chloride	107-05-1	1	3
Allyl glycidyl ether (AGE)	106-92-3	(C)10	(C)45
Allyl propyl disulfide	2179-59-1	2	12
alpha-Alumina	1344-28-1
Total dust			15
Respirable fraction			5
Aluminum, metal (as Al)	7429-90-5
Total dust			15
Respirable fraction			5
4-Aminodiphenyl; see 1910.1011	92-67-1
2-Aminoethanol; see Ethanolamine.
2-Aminopyridine	504-29-0	0.5	2
Ammonia	7664-41-7	50	35
Ammonium sulfamate	7773-06-0
Total dust			15
Respirable fraction			5
n-Amyl acetate	628-63-7	100	525
sec-Amyl acetate	626-38-0	125	650
Aniline and homologs	62-53-3	5	19	X
Anisidine (o-, p-isomers)	29191-52-4		0.5	X
Antimony and compounds (as Sb)	7440-36-0		0.5
ANTU (alpha Naphthylthiourea)	86-88-4		0.3
Arsenic, inorganic compounds (as As); see 1910.1018	7440-38-2
Arsenic, organic compounds (as As)	7440-38-2		0.5
Arsine	7784-42-1	0.05	0.2
Asbestos; see 1910.1001	(4)
Azinphos-methyl	86-50-0		0.2	X
Barium, soluble compounds (as Ba)	7440-39-3		0.5
Barium sulfate	7727-43-7
Total dust			15
Respirable fraction			5
Benomyl	17804-35-2
Total dust			15
Respirable fraction			5
Benzene; see 1910.1028	71-43-2
Code of Federal Regulations 10
See Table Z-2 for the limits applicable in the operations or sectors excluded in 1910.1028 d
Benzidine; see 1910.1010	92-87-5
p-Benzoquinone; see Quinone.
Benzo(a)pyrene; see Coal tar pitch volatiles.
Benzoyl peroxide	94-36-0		5
Benzyl chloride	100-44-7	1	5
Beryllium and beryllium compounds (as Be)	7440-41-7		(2)
Biphenyl; see Diphenyl.
Bismuth telluride, Undoped	1304-82-1
Total dust			15
Respirable fraction			5
Boron oxide	1303-86-2
Total dust			15
Boron trifluoride	7637-07-2	(C)1	(C)3
Bromine	7726-95-6	0.1	0.7
Bromoform	75-25-2	0.5	5	X
Butadiene (1,3-Butadiene); See 29 CFR 1910.1051 ; 29 CFR 1910.19(l)	106-99-0	1 ppm/5 ppm STEL
Butanethiol; see Butyl mercaptan.
2-Butanone (Methyl ethyl ketone)	78-93-3	200	590
2-Butoxyethanol	111-76-2	50	240	X
n-Butyl-acetate	123-86-4	150	710
sec-Butyl acetate	105-46-4	200	950
tert-Butyl acetate	540-88-5	200	950
n-Butyl alcohol	71-36-3	100	300
sec-Butyl alcohol	78-92-2	150	450
tert-Butyl alcohol	75-65-0	100	300
Butylamine	109-73-9	(C)5	(C)15	X
tert-Butyl chromate (as CrO3); see 1910.1026 6	1189-85-1
n-Butyl glycidyl ether (BGE)	2426-08-6	50	270
Butyl mercaptan	109-79-5	10	35
p-tert-Butyltoluene	98-51-1	10	60
Cadmium (as Cd); see 1910.1027	7440-43-9
Calcium carbonate	1317-65-3
Total dust			15
Respirable fraction			5
Calcium hydroxide	1305-62-0
Total dust			15
Respirable fraction			5
Calcium oxide	1305-78-8		5
Calcium silicate	1344-95-2
Total dust			15
Respirable fraction			5
Calcium sulfate	7778-18-9
Total dust			15
Respirable fraction			5
Camphor, synthetic	76-22-2		2
Carbaryl (Sevin)	63-25-2		5
Carbon black	1333-86-4		3.5
Carbon dioxide	124-38-9	5000	9000
Carbon disulfide	75-15-0		(2)
Carbon monoxide	630-08-0	50	55
Carbon tetrachloride	56-23-5		(2)
Cellulose	9004-34-6
Total dust			15
Respirable fraction			5
Chlordane	57-74-9		0.5	X
Chlorinated camphene	8001-35-2		0.5	X
Chlorinated diphenyl oxide	55720-99-5		0.5
Chlorine	7782-50-5	(C)1	(C)3
Chlorine dioxide	10049-04-4	0.1	0.3
Chlorine trifluoride	7790-91-2	(C)0.1	(C)0.4
Chloroacetaldehyde	107-20-0	(C)1	(C)3
a-Chloroacetophenone (Phenacyl chloride)	532-27-4	0.05	0.3
Chlorobenzene	108-90-7	75	350
o-Chlorobenzylidene malononitrile	2698-41-1	0.05	0.4
Chlorobromomethane	74-97-5	200	1050
2-Chloro-1,3-butadiene; see beta-Chloroprene.
Chlorodiphenyl (42% Chlorine) (PCB)	53469-21-9		1	X
Chlorodiphenyl (54% Chlorine) (PCB)	11097-69-1		0.5	X
1-Chloro-2,3-epoxypropane; see Epichlorohydrin.
Code of Federal Regulations 11
2-Chloroethanol; see Ethylene chlorohydrin.
Chloroethylene; see Vinyl chloride.
Chloroform (Trichloromethane)	67-66-3	(C)50	(C)240
bis(Chloromethyl) ether; see 1910.1008	542-88-1
Chloromethyl methyl ether; see 1910.1006	107-30-2
1-Chloro-1-nitropropane	600-25-9	20	100
Chloropicrin	76-06-2	0.1	0.7
beta-Chloroprene	126-99-8	25	90	X
2-Chloro-6-(trichloromethyl) pyridine	1929-82-4
Total dust			15
Respirable fraction			5
Chromium (II) compounds.
(as Cr)	7440-47-3		0.5
Chromium (III) compounds.
(as Cr)	7440-47-3		0.5
Chromium (VI) compounds; See 1910.1026 5
Chromium metal and insol. salts (as Cr)	7440-47-3		1
Chrysene; see Coal tar pitch volatiles.
Clopidol	2971-90-6
Total dust			15
Respirable fraction			5
Coal dust (less than 5% SiO2), respirable fraction			(3)
Coal dust (greater than or equal to 5% SiO2), respirable fraction			(3)
Coal tar pitch volatiles (benzene soluble fraction), anthracene, BaP, phenanthrene, acridine, chrysene, pyrene	65966-93-2		0.2
Cobalt metal, dust, and fume (as Co)	7440-48-4		0.1
Coke oven emissions; see 1910.1029.
Copper	7440-50-8
Fume (as Cu)			0.1
Dusts and mists (as Cu)			1
Cotton dust e; see 1910.1043			1
Crag herbicide (Sesone)	136-78-7
Total dust			15
Respirable fraction			5
Cresol, all isomers	1319-77-3	5	22	X
Crotonaldehyde	123-73-9;4170-30-3	2	6
Cumene	98-82-8	50	245	X
Cyanides (as CN)	(4)		5	X
Cyclohexane	110-82-7	300	1050
Cyclohexanol	108-93-0	50	200
Cyclohexanone	108-94-1	50	200
Cyclohexene	110-83-8	300	1015
Cyclopentadiene	542-92-7	75	200
2,4-D (Dichlorophenoxyacetic acid)	94-75-7		10
Decaborane	17702-41-9	0.05	0.3	X
Demeton (Systox)	8065-48-3		0.1	X
Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone)	123-42-2	50	240
1,2-Diaminoethane; see Ethylenediamine.
Diazomethane	334-88-3	0.2	0.4
Diborane	19287-45-7	0.1	0.1
1,2-Dibromo-3-chloropropane (DBCP); see 1910.1044	96-12-8
1,2-Dibromoethane; see Ethylene dibromide.
Dibutyl phosphate	107-66-4	1	5
Dibutyl phthalate	84-74-2		5
o-Dichlorobenzene	95-50-1	(C)50	(C)300
p-Dichlorobenzene	106-46-7	75	450
3,′-Dichlorobenzidine; see 1910.1007	91-94-1
Dichlorodifluoromethane	75-71-8	1000	4950
1,3-Dichloro-5,5-dimethyl hydantoin	118-52-5		0.2
Dichlorodiphenyltrichloroethane (DDT)	50-29-3		1	X
1,1-Dichloroethane	75-34-3	100	400
1,2-Dichloroethane; see Ethylene dichloride.
1,2-Dichloroethylene	540-59-0	200	790
Dichloroethyl ether	111-44-4	(C)15	(C)90	X
Dichloromethane; see Methylene chloride.
Dichloromonofluoromethane	75-43-4	1000	4200
1,1-Dichloro-1-nitroethane	594-72-9	(C)10	(C)60
1,2-Dichloropropane; see Propylene dichloride.
Dichlorotetrafluoroethane	76-14-2	1000	7000
Dichlorvos (DDVP)	62-73-7		1	X
Code of Federal Regulations 12
Dicyclopentadienyl iron	102-54-5
Total dust			15
Respirable fraction			5
Dieldrin	60-57-1		0.25	X
Diethylamine	109-89-7	25	75
2-Diethylaminoethanol	100-37-8	10	50	X
Diethyl ether; see Ethyl ether.
Difluorodibromomethane	75-61-6	100	860
Diglycidyl ether (DGE)	2238-07-5	(C)0.5	(C)2.8
Dihydroxybenzene; see Hydroquinone.
Diisobutyl ketone	108-83-8	50	290
Diisopropylamine	108-18-9	5	20	X
4-Dimethylaminoazobenzene; see 1910.1015	60-11-7
Dimethoxymethane; see Methylal.
Dimethyl acetamide	127-19-5	10	35	X
Dimethylamine	124-40-3	10	18
Dimethylaminobenzene; see Xylidine
Dimethylaniline (N,N-Dimethylaniline)	121-69-7	5	25	X
Dimethylbenzene; see Xylene.
Dimethyl-1,2-dibromo-2,2-dichloroethyl phosphate	300-76-5		3
Dimethylformamide	68-12-2	10	30	X
2,6-Dimethyl-4-heptanone; see Diisobutyl ketone.
1,1-Dimethylhydrazine	57-14-7	0.5	1	X
Dimethylphthalate	131-11-3		5
Dimethyl sulfate	77-78-1	1	5	X
Dinitrobenzene (all isomers)			1	X
(ortho)	528-29-0
(meta)	99-65-0
(para)	100-25-4
Dinitro-o-cresol	534-52-1		0.2	X
Dinitrotoluene	25321-14-6		1.5	X
Dioxane (Diethylene dioxide)	123-91-1	100	360	X
Diphenyl (Biphenyl)	92-52-4	0.2	1
Diphenylmethane diisocyanate; see Methylene bisphenyl isocyanate.
Dipropylene glycol methyl ether	34590-94-8	100	600	X
Di-sec octyl phthalate (Di-(2-ethylhexyl) phthalate)	117-81-7		5
Emery	12415-34-8
Total dust			15
Respirable fraction			5
Endrin	72-20-8		0.1	X
Epichlorohydrin	106-89-8	5	19	X
EPN	2104-64-5		0.5	X
1,2-Epoxypropane; see Propylene oxide.
2,3-Epoxy-1-propanol; see Glycidol.
Ethanethiol; see Ethyl mercaptan.
Ethanolamine	141-43-5	3	6
2-Ethoxyethanol (Cellosolve)	110-80-5	200	740	X
2-Ethoxyethyl acetate (Cellosolve acetate)	111-15-9	100	540	X
Ethyl acetate	141-78-6	400	1400
Ethyl acrylate	140-88-5	25	100	X
Ethyl alcohol (Ethanol)	64-17-5	1000	1900
Ethylamine	75-04-7	10	18
Ethyl amyl ketone (5-Methyl-3-heptanone)	541-85-5	25	130
Ethyl benzene	100-41-4	100	435
Ethyl bromide	74-96-4	200	890
Ethyl butyl ketone (3-Heptanone)	106-35-4	50	230
Ethyl chloride	75-00-3	1000	2600
Ethyl ether	60-29-7	400	1200
Ethyl formate	109-94-4	100	300
Ethyl mercaptan	75-08-1	(C)10	(C)25
Ethyl silicate	78-10-4	100	850
Ethylene chlorohydrin	107-07-3	5	16	X
Ethylenediamine	107-15-3	10