Section 325.51108. Tables.

Rule 8. Tables G-1-A and G-2 read as follows:

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Abate		–	15	–	–	–	–	–
Acetaldehyde	75-07-0	100	180	150	270	–	–	–
Acetic acid	64-19-7	10	25	–	–	–	–	–
Acetic anhydride	108-24-7	–	–	–	–	5	20	–
Acetone	67-64-1	750	1800	1000	2400	–	–	–
Acetonitrile	75-05-8	40	70	60	105	–	–	–
2-Acetylaminofluorine; see OH Part 350, R 325.35001 to R 325.35011F	53-96-3
Acetylene dichloride; see 1,2-Dichloroethylene
Acetylene tetrabromide	79-27-6	1	14	–	–	–	–	–
Acetylsalicylic acid (Aspirin)	50-78-2	–	5	–	–	–	–	–
Acrolein	107-02-8	0.1	0.25	0.3	0.8	–	–	–
Acrylamide	79-06-1	–	0.03	–	–	–	–	x
Acrylic acid	79-10-7	10	30	–	–	–	–	x
Acrylonitrile; see OH Part 307, R 325.51501 to R 325.51527F	107-13-1	2	4.34	10	21.7

 

 

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Aldrin	309-00-2	–	0.25	–	–	–	–	x
Allyl alcohol	107-18-6	2	5	4	10	–	–	x
Allyl chloride	107-05-1	1	3	2	6	–	–	–
Allyl glycidyl ether (AGE)	106-92-3	5	22	10	44	–	–	–
Allyl propyl disulfide	2179-59-1	2	12	3	18	–	–	–
Alumina (aluminum oxide)	1344-28-1	–	5	–	–	–	–	–
Respirable fraction
Total dust		–	10	–	–	–	–	–
Aluminum (as Al) Alkyls Metal Respirable dust Total dust Pyro powders Soluble salts Welding fumes*	7429-90-5	– – – – – – –	2   5 15 5 2 5	– – – – – – –	– – – – – – –	– – – – – – –	– – – – – – –	– – – – – – –
4-Aminodiphenyl; see OH Part 350, R 325.35001 to R 325.35011F	92-67-1
2-Aminoethanol; see Ethanolamine
2-Aminopyridine	504-29-0	0.5	2	–	–	–	–	–
Amitrole	61-82-5	–	0.2	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Ammonia	7664-41-7	–	–	35	24	–	–	–
Ammonium chloride fume	12125-02- 9	–	10	–	20	–	–	–
Ammonium sulfamate	7773-06-0	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
n-Amyl acetate	628-63-7	100	525	–	–	–	–	–
sec-Amyl acetate	626-38-0	125	650	–	–	–	–	–
Aniline and homologues	62-53-3	2	8	–	–	–	–	x
Anisidine (o- and 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, organic compounds (as As)	7440-38-2	–	0.5	–	–	–	–	–
Arsenic, inorganic compounds (as As); see OH Part 308, R 325.51601 to R 325.51628F	7440-38-2		0.01
Arsine	7784-42-1	0.05	0.2	–	–	–	–	–
		TWA		STEL
Asbestos; see OH Part 305, R 325.51311 to R 325.51312F	Varies	0.1f÷cc		–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
		ppmB	mg÷m3C	ppmB	mg÷m3C
Atrazine	1912-24-9	–	5	–	–	–	–	–
Azinphos-methyl	86-50-0	–	0.2	–	–	–	–	x
Barium, soluble compounds (as Ba)	7440-39-3	–	0.5	–	–	–	–	–
Barium sulfate	7727-43-7	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
Benomyl Respirable dust Total dust	17804-35- 2	– –	5 10	– –	– –	– –	– –	– –
BenzeneE; see OH Part 311, R 325.77101 to R 325.77115F and table G- 2 for limits applicable in theoperations or sectors excluded in R 325.77101E	71-43-2	1	3.19	5	15.97
Benzidine; see OH Part 350, R 325.35001 to R 325.35011F	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	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Beryllium and beryllium compounds (as Be)	7440-41-7	See table G-2
Biphenyl; see Diphenyl
Bismuth telluride, Undoped	1304-82-1	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Bismuth telluride, Se-doped		–	5	–	–	–	–	–
Borates, Tetra, Sodium Salts Anhydrous Decahydrate Pentahydrate	1330-43-4 1303-96-4 12179-04- 3	– – –	10 10 10	– – –	– – –	– – –	– – –	– – –
Boron oxide, Total dust	1303-86-2	–	10	–	–	–	–	–
Boron tribromide	10294-33- 4	–	–	–	–	1	10	–
Boron trifluoride	7637-07-2	–	–	–	–	1	3	–
Bromacil	314-40-9	1	10	–	–	–	–	–
Bromine	7726-95-6	0.1	0.7	0.3	2	–	–	–
Bromine pentafluoride	7789-30-2	0.1	0.7	–	–	–	–	–
Bromoform	75-25-2	0.5	5	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
1,3-Butadiene; see OH Part 312, R 325.50091 to R 325.50092F	106-99-0	1	2.2	5	11.1	–	–	–
Butane	106-97-8	800	1900	–	–	–	–	–
Butanethiol; see Butyl mercaptan
2-Butanone (Methyl ethyl ketone)	78-93-3	200	590	300	885	–	–	–
2-Butoxyethanol	111-76-2	25	120	–	–	–	–	x
n-Butyl acetate	123-86-4	150	710	200	950	–	–	–
sec-Butyl acetate	105-46-4	200	950	–	–	–	–	–
tert-Butyl acetate	540-88-5	200	950	–	–	–	–	–
Butyl acrylate	141-32-2	10	55	–	–	–	–	–
n–Butyl alcohol (n-butanol)	71-36-3	–	–	–	–	50	150	x
sec-Butyl alcohol (sec-butanol)	78-92-2	100	305	–	–	–	–	–
tert-Butyl alcohol (tert-butanol)	75-65-0	100	300	150	450	–	–	–
Butylamine	109-73-9	–	–	–	–	5	15	x
tert-Butyl chromate (as Cr+6); see OH Part 315, R 325.50141 to R 325.50143F, G	1189-85-1	–	0.005 (5 μg÷m3)	–	–	–	–	x
n-Butyl glycidyl ether (BGE)	2426-08-6	25	135	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
n-Butyl lactate	138-22-7	5	25	–	–	–	–	–
Butyl mercaptan	109-79-5	0.5	1.5	–	–	–	–	–
o-sec-Butylphenol	89-72-5	5	30	–	–	–	–	x
p-tert-Butyltoluene	98-51-1	10	60	20	120	–	–	–
Cadmium; see OH Part 309, R 325.51851 to R 325.51886F	7440-43-9	–	0.005	–	–	–	–	–
Calcium carbonate,	1317-65-3	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Calcium cyanamide	156-62-7	–	0.5	–	–	–	–	–
Calcium hydroxide	1305-62-0	–	5	–	–	–	–	–
Calcium oxide	1305-78-8	–	5	–	–	–	–	–
Calcium silicate,	1344-95-2	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Calcium sulfate,	7778-18-9	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Camphor, synthetic	76-22-2	–	2	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Caprolactam,	105-60-2	– 5	1 20	– 10	3 40	– –	– –	– –
Dust Vapor
Captafol (DifolatanR)	2425-06-1	–	0.1	–	–	–	–	–
Captan	133-06-2	–	5	–	–	–	–	–
Carbaryl (SevinR)	63-25-2	–	5	–	–	–	–	–
Carbofuran (FuradanR)	1563-66-2	–	0.1	–	–	–	–	–
Carbon black	1333-86-4	–	3.5	–	–	–	–	–
Carbon dioxide	124-38-9	10,000	18,000	30,000	54,000	–	–	–
Carbon disulfide	75-15-0	4	12	12	36	–	–	x
Carbon monoxide	630-08-0	35	40	–	–	200	229	–
Carbon tetrabromide	558-13-4	0.1	1.4	0.3	4	–	–	–
Carbon tetrachloride (Tetrachloromethane)	56-23-5	2	12.6	–	–	–	–	x
Carbonyl fluoride	353-50-4	2	5	5	15	–	–	–
Catechol (Pyrocatechol)	120-80-9	5	20	–	–	–	–	x
Cellulose,	9004-34-6	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–

 

 

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Cesium hydroxide	21351-79- 1	–	2	–	–	–	–	–
Chlordane	57-74-9	–	0.5	–	–	–	–	x
Chlorinated camphene (Toxaphone)	8001-35-2	–	0.5	–	1	–	–	x
Chlorinated diphenyl oxide	55720-99- 5 or 31242-93- 0	–	0.5	–	–	–	–	–
Chlorine	7782-50-5	0.5	1.5	1	3	–	–	–
Chlorine dioxide	10049-04- 4	0.1	0.3	0.3	0.9	–	–	–
Chlorine trifluoride	7790-91-2	–	–	–	–	0.1	0.4	–
Chloroacetaldehyde	107-20-0	–	–	–	–	1	3	–
2-Chloroacetophenone (Phenacyl chloride)	532-27-4	0.5	0.3	–	–	–	–	–
Chloroacetyl chloride	79-04-9	0.5	0.2	–	–	–	–	–
Chlorobenzene	108-90-7	75	350	–	–	–	–	–
o-Chlorobenzylidene malononitrile	2698-41-1	–	–	–	–	0.05	0.4	x
Chlorobromomethane	74-97-5	200	1050	–	–	–	–	–
2-Chloro-1,3-                                              - Chloroprene

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Chlorodifluoromethane	75-45-6	1000	3500	–	–	–	–	–
Chlorodiphenyl (42% Chlorine) (PCB)	53469-21- 9	–	1	–	–	–	–	x
Chlorodiphenyl (54% Chlorine) (PCB)	11097-69- 1	–	0.5	–	–	–	–	x
1-Chloro-2,3-epoxy propane; see Epichlorohydrin
2-Chloroethanol; see Ethylene chlorohydrin
Chloroethylene; see Vinyl chloride
Chloroform (Trichloromethane)	67-66-3	2	9.78	–	–	–	–	–
bis (Chloromethyl) ether; see OH Part 350, R 325.35001 to R 325.35011F	542-88-1
Chloromethyl methyl ether; see OH Part 350, R 325.35001 to R 325.35011F	107-30-2
1-Chloro-1-nitropropane	600-25-9	4	10	–	–	–	–	–
Chloropentafluoroethane	76-15-3	1000	6320	–	–	–	–	–
Chloropicrin	76-06-2	0.1	0.7	–	–	–	–	–
beta-Chloroprene	126-99-8	10	35	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
o-Chlorostyrene	2039-87-4	50	285	75	428	–	–	–
o-Chlorotoluene	95-49-8	50	250	–	–	–	–	–
2-Chloro-6-(trichloromethyl) pyridine,	1929-82-4	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Chlorpyrifos	2921-88-2	–	0.2	–	–	–	–	x
Chromic acid and chromates (as Cr+6); see OH Part 315, R 325.50141 to R 325.50143F, G	Varies with compound	–	0.005 (5 μg÷m3)	–	–	–	–	–
Chromium (II) compounds (as Cr)	7440-47-3	–	0.5	–	–	–	–	–
Chromium (III) compounds (as Cr)	7440-47-3	–	0.5	–	–	–	–	–
Chromium (VI) compounds; see OH Part 315, R 325.50141 to R 325.50143F, G	Varies with compound		(5 μg÷m3)
Chromium metal (as Cr)	7440-47-3	–	1	–	–	–	–	–
Chrysene; see Coal tar pitch volatile
Clopidol	2971-90-6	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Coal dust (less than 5% SiO2) Respirable dust	–	–	2	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Coal dust (greater than or equal to 5% SiO2), Respirable dust	–	–	0.1	–	–	–	–	–
Coal tar pitch volatile (as benzene solubles) anthracene, BaP, phenanthrene, acridine, crysene, pyrene	65996-93- 2	–	0.2	–	–	–	–	–
Cobalt metal, dust, and fume (as Co)	7440-48-4	–	0.05	–	–	–	–	–
Cobalt carbonyl (as Co)	10210-68- 1	–	0.1	–	–	–	–	–
Cobalt hydrocarbonyl (as Co)	16842-03- 8	–	0.1	–	–	–	–	–
Coke oven emissions; see OH Part 314, R 325.50101 to R 325.50136F	–	–	0.15 (150 μg÷m3)	–	–	–	–	–
Copper,	7440-50-8	–	1	–	–	–	–	–
Dusts and mists (as Cu)
Fume (as Cu)		–	0.1	–	–	–	–	–
Cotton dust (raw)	–	–	1	–	–	–	–	–
Crag herbicide (Sesone)	136-78-7	–	10	–	–	–	–	–
Total dust
Respirable fraction		–	5	–	–	–	–	–
Cresol, all isomers	1319-77-3	5	22	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Crotonaldehyde	123-73-9 4170-30-3	2	6	–	–	–	–	–
Crufomate	299-86-5	–	5	–	–	–	–	–
Cumene	98-82-8	50	245	–	–	–	–	x
Cyanamide	420-04-2	–	2	–	–	–	–	–
Cyanides (as CN)	Varies with compound	–	5	–	–	–	–	x
Cyanogen	460-19-5	10	20	–	–	–	–	–
Cyanogen chloride	506-77-4	–	–	–	–	0.3	0.6	–
Cyclohexane	110-82-7	300	1050	–	–	–	–	–
Cyclohexanol	108-93-0	50	200	–	–	–	–	x
Cyclohexanone	108-94-1	25	100	–	–	–	–	x
Cyclohexene	110-83-8	300	1015	–	–	–	–	–
Cyclohexylamine	108-91-8	10	40	–	–	–	–	–
Cyclonite	121-82-4	–	1.5	–	–	–	–	x
Cyclopentadiene	542-92-7	75	200	–	–	–	–	–
Cyclopentane	287-92-3	600	1720	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Cyhexatin	13121-70- 5	–	5	–	–	–	–	–
2,4-D (Dichlorophenoxyacetic acid)	94-75-7	–	10	–	–	–	–	–
Decaborane	17702-41- 9	0.05	0.3	0.15	0.9	–	–	x
Demeton (SystoxR)	8065-48-3	–	0.1	–	–	–	–	x
Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone)	123-42-2	50	240	–	–	–	–	–
1,2-Diaminoethane; see Ethylenediamine
Diazinon	333-41-5	–	0.1	–	–	–	–	x
Diazomethane	334-88-3	0.2	0.4	–	–	–	–	–
Diborane	19287-45- 7	0.1	0.1	–	–	–	–	–
2-N-Dibutylaminoethanol	102-81-8	2	14	–	–	–	–	–
Dibutyl phosphate	107-66-4	1	5	2	10	–	–	–
Dibutyl phthalate	84-74-2	–	5	–	–	–	–	–
Dichloroacetylene	7572-29-4	–	–	–	–	0.1	0.4	–
o-Dichlorobenzene	95-50-1	–	–	–	–	50	300	–
p-Dichlorobenzene	106-46-7	75	450	110	675	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
3,3'-Dichlorobenzidine; see OH Part 350, R 325.35001 to R 325.35011F	91-94-1
Dichlorodifluoromethane	75-71-8	1000	4950	–	–	–	–	–
1,3-Dichloro-5,5-dimethyl hydantoin	118-52-5	–	0.2	–	0.4	–	–	–
Dichlorodiphenyltri-chloroethane (DDT)	50-29-3	–	1	–	–	–	–	x
1,1-Dichloroethane	75-34-3	100	400	–	–	–	–	–
1,2-Dichloroethylene	540-59-0	200	790	–	–	–	–	–
Dichloroethyl ether	111-44-4	5	30	10	60	–	–	x
Dichlorofluoromethane	75-43-4	10	40	–	–	–	–	–
Dichloromethane; see Methylene chloride
1,1-Dichloro-1-nitroethane	594-72-9	2	10	–	–	–	–	–
1,2-Dichloropropane; see Propylene dichloride
1,3-Dichloropropene	542-75-6	1	5	–	–	–	–	x
2,2-Dichloropropionic acid	75-99-0	1	6	–	–	–	–	–
Dichlorotetrafluoroethane	76-14-2	1000	7000	–	–	–	–	–
Dichlorvos (DDVP)	62-73-7	–	1	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Dicrotophos	141-66-2	–	0.25	–	–	–	–	x
Dicyclopentadiene	77-73-6	5	30	–	–	–	–	–
Dicyclopentadienyl iron,	102-54-5	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
Dieldrin	60-57-1	–	0.25	–	–	–	–	x
Diethanolamine	111-42-2	3	15	–	–	–	–	–
Diethylamine	109-89-7	10	30	25	75	–	–	–
2-Diethylaminoethanol	100-37-8	10	50	–	–	–	–	x
Diethylene triamine	111-40-0	1	4	–	–	–	–	x
Diethyl ether; see Ethyl ether
Diethyl ketone	96-22-0	200	705	–	–	–	–	–
Diethyl phthalate	84-66-2	–	5	–	–	–	–	–
Difluorodibromomethane	75-61-6	100	860	–	–	–	–	–
Diglycidyl ether (DGE)	2238-07-5	0.1	0.5	–	–	–	–	–
Dihydroxybenzene; see Hydroquinone
Diisobutyl ketone	108-83-8	25	150	–	–	–	–	–
Diisopropylamine	108-18-9	5	20	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
4-Dimethylaminoazobenzene; see OH Part 350, R 325.35001 to R 325.35011F	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	10	50	–	–	x
Dimethylbenzene; see Xylene
Dimethyl-1,2-dibromo-2,2- dichloroethyl phosphate	300-76-5	–	3	–	–	–	–	x
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	0.1	0.5	–	–	–	–	x
Dinitolmide (3,5-Dinitro-o-toluamide)	148-01-6	–	5	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Dinitrobenzene (all isomers) (meta-) (ortho) (para-)	99-65-0 528-29-0 100-25-4	–	1	–	–	–	–	x
Dinitro-o-cresol	534-52-1	–	0.2	–	–	–	–	x
Dinitrotoluene	25321-14- 6	–	1.5	–	–	–	–	x
Dioxane (Diethylene dioxide)	123-91-1	25	90	–	–	–	–	x
Dioxathion (Delnav)	78-34-2	–	0.2	–	–	–	–	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	150	900	–	–	x
Dipropyl ketone	123-19-3	50	235	–	–	–	–	–
Diquat	2768-72-9	–	0.5	–	–	–	–	–
Di-sec-octyl phthalate [Di(2-ethylhexyl)phthalate]	117-81-7	–	5	–	10	–	–	–
Disulfiram	97-77-8	–	2	–	–	–	–	–
Disulfoton	298-04-4	–	0.1	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
2,6-Di-tert-butyl-p-cresol (Butylated hydroxytoluene)	128-37-0	–	10	–	–	–	–	–
Diuron	330-54-1	–	10	–	–	–	–	–
Divinyl benzene	1321-74-0	10	50	–	–	–	–	–
Emery, Respirable dust	1302-74-5	–	5	–	–	–	–	–
Total dust		–	10	–	–	–	–	–
Endosulfan	115-29-7	–	0.1	–	–	–	–	x
Endrin	72-20-8	–	0.1	–	–	–	–	x
Epichlorohydrin	106-89-8	2	8	–	–	–	–	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	8	6	15	–	–	–
Ethion	563-12-2	–	0.4	–	–	–	–	x
2-Ethoxyethanol (EGEE)	110-80-5	200	740	–	–	–	–	x
2-Ethoxyethyl acetate (Cellosolve acetate)	111-15-9	100	540	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Ethyl acetate	141-78-6	400	1400	–	–	–	–	–
Ethyl acrylate	140-88-5	5	20	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	125	545	–	–	–
Ethyl bromide	74-96-4	200	890	250	1100	–	–	–
Ethyl butyl ketone (3-Heptanone)	106-35-4	50	230	–	–	–	–	–
Ethyl chloride	75-00-3	1000	2600	–	–	–	–	–
Ethyl ether	60-29-7	400	1200	500	1500	–	–	–
Ethyl formate	109-94-4	100	300	–	–	–	–	–
Ethyl mercaptan	75-08-1	0.5	1	–	–	–	–	–
Ethyl silicate	78-10-4	10	85	–	–	–	–	–
Ethylene chlorohydrin	107-07-3	–	–	–	–	1	3	x
Ethylenediamine	107-15-3	10	25	–	–	–	–	–
Ethylene dibromide	106-93-4	See table G-2

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Ethylene dichloride	107-06-2	1	4	2	8	–	–	–
Ethylene glycol	107-21-1	–	–	–	–	50	125	–
Ethylene glycol dinitrate (EGDN)	628-96-6	–	–	–	0.1	–	–	x
Ethylene glycol methyl acetate (EGME); see Methyl cellosolve acetate
Ethyleneimine; see OH Part 350, R 325.35001 to R 325.35011F	151-56-4
Ethylene oxide; see OH Part 304, R 325.51151 to R 325.51177F	75-21-8	1	1.8	5	9.0	-	-	-
Ethylidene chloride; see 1,1- Dichloroethane
Ethylidene norbornene	16219-75- 3	–	–	–	–	5	25	–
N-Ethylmorpholine	100-74-3	5	23	–	–	–	–	x
Fenamiphos	22224-92- 6	–	0.1	–	–	–	–	x
Fensulfothion (Dasanit)	115-90-2	–	0.1	–	–	–	–	–
Fenthion	55-38-9	–	0.2	–	–	–	–	x
Ferbam, Dust	14484-64- 1	–	10	–	–	–	–	–
Ferrovanadium dust	12604-58- 9	–	1	–	3	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Fluorides (as F)	Varies with compound	–	2.5	–	–	–	–	–
Fluorine	7782-41-4	0.1	0.2	–	–	–	–	–
Fluorotrichloromethane (Trichlorofluoromethane)	75-69-4	–	–	–	–	1000	5600	–
Fonofos	944-22-9	–	0.1	–	–	–	–	x
Formaldehyde; see OH Part 306, R 325.51451 to R 325.51477F	50-00-0	0.75	0.9	2	2.5
Formamide	75-12-7	20	30	30	45	–	–	–
Formic acid	64-18-6	5	9	–	–	–	–	–
Furfural	98-01-1	2	8	–	–	–	–	x
Furfuryl alcohol	98-00-0	10	40	15	60	–	–	x
Gasoline	8006-61-9	300	900	500	1500	–	–	–
Germanium tetrahydride	7782-65-2	0.2	0.6	–	–	–	–	–
Glutaraldehyde	111-30-8	–	–	–	–	0.2	0.8	–
Glycerin,	56-81-5	–	5	–	–	–	–	–
Respirable mist
Total mist		–	10	–	–	–	–	–
Glycidol	556-52-5	25	75	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Glycol monoethyl ether; see 2- Ethoxyethanol
Grain dust (Oat, wheat, barley)	–	–	10	–	–	–	–	–
Graphite, natural Respirable dust	7782-42-5	–	2.5	–	–	–	–	–
Graphite, synthetic,	–	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
GuthionR; see Azinphos methyl
Gypsum, Respirable dust Total dust	13397-24- 5	– –	5 15	– –	– –	– –	– –	– –
Hafnium	7440-58-6	–	0.5	–	–	–	–	–
Heptachlor	76-44-8	–	0.5	–	–	–	–	x
Heptane (n-Heptane)	142-82-5	400	1600	500	2000	–	–	–
Hexachlorobutadiene	87-68-3	–	0.02	0.24	–	–	–	–
Hexachlorocyclopentadiene	77-47-4	0.01	0.1	–	–	–	–	–
Hexachloroethane	67-72-1	1	10	–	–	–	–	x
Hexachloronaphthalene	1335-87-1	–	0.2	–	–	–	–	x
Hexafluoroacetone	684-16-2	0.1	0.7	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
n-Hexane	110-54-3	50	180	–	–	–	–	–
Hexane isomers	Varies with compound	500	1800	1000	3600	–	–	–
2-Hexanone (Methyl n-butyl ketone)	591-78-6	5	20	–	–	–	–	–
Hexone (Methyl isobutyl ketone)	108-10-1	50	205	75	300	–	–	–
sec-Hexyl acetate	108-84-9	50	300	–	–	–	–	–
Hexylene glycol	107-41-5	–	–	–	–	25	125	–
Hydrazine	302-01-2	0.1	0.1	–	–	–	–	x
Hydrogenated terphenyls	61788-32- 7	0.5	5	–	–	–	–	–
Hydrogen bromide	10035-10- 6	–	–	–	–	3	10	–
Hydrogen chloride	7647-01-0	–	–	–	–	5	7	–
Hydrogen cyanide	74-90-8	–	–	4.7	5	–	–	x
Hydrogen fluoride (as F)	7664-39-3	3	–	6	–	–	–	–
Hydrogen peroxide	7722-84-1	1	1.4	–	–	–	–	–
Hydrogen selenide (as Se)	7783-07-5	0.05	0.2	–	–	–	–	–
Hydrogen sulfide	7783-06-4	10	14	15	21	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Hydroquinone	123-31-9	–	2	–	–	–	–	–
2-Hydroxypropyl acrylate	999-61-1	0.5	3	–	–	–	–	x
Indene	95-13-6	10	45	–	–	–	–	–
Indium and compounds (as In)	7440-74-6	–	0.1	–	–	–	–	–
Iodine	7553-56-2	–	–	–	–	0.1	1	–
Iodoform	75-47-8	0.6	10	–	–	–	–	–
Iron oxide fume	1309-37-1	–	10	–	–	–	–	–
Iron pentacarbonyl (as Fe)	13463-40- 6	0.1	0.8	0.2	1.6	–	–	–
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	125	450	–	–	–
Isobutyl acetate	110-19-0	150	700	–	–	–	–	–
Isobutyl alcohol	78-83-1	50	150	–	–	–	–	–
Isooctyl alcohol	26952-21- 6	50	270	–	–	–	–	x
Isophorone	78-59-1	4	23	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Isophorone diisocyanate (IPDI)	4098-71-9	0.005	–	0.02	–	–	–	x
2-Isopropoxyethanol	109-59-1	25	105	–	–	–	–	–
Isopropyl acetate	108-21-4	250	950	310	1185	–	–	–
Isopropyl alcohol	67-63-0	400	980	500	1225	–	–	–
Isopropylamine	75-31-0	5	12	10	24	–	–	–
N-Isopropylaniline	768-52-5	2	10	–	–	–	–	x
Isopropyl ether	108-20-3	500	2100	–	–	–	–	–
Isopropyl glycidyl ether (IGE)	4016-14-2	50	240	75	360	–	–	–
Kaolin,	–	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
Ketene	463-51-4	0.5	0.9	1.5	3	–	–	–
Lead inorganic (as Pb); see OH Part 310, R 325.51901 to R 325.51958F	7439-92-1	–	0.05 (50 μg÷m3)	–	–	–	–	–
Limestone, (calcium carbonate)	1317-65-3	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Lindane	58-89-9	–	0.5	–	–	–	–	x
Lithium hydride	7580-67-8	–	0.025	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
L.P.G. (Liquified petroleum gas)	68476-85- 7	1000	1800	–	–	–	–	–
Magnesite,	546-93-0	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Magnesium oxide fume, Total particulate	1309-48-4	–	10	–	–	–	–	–
Malathion dust	121-75-5	–	10	–	–	–	–	x
Maleic anhydride	108-31-6	1	–	–	–	–	–	–
Manganese,	7439-96-5	– –	– 1	– –	– 3	– –	5 –	– –
Compounds (as Mn) Fume (as Mn)
Manganese cyclopentadienyl tricarbonyl (as Mn)	12079-65- 1	–	0.1	–	–	–	–	x
Manganese tetroxide (as Mn)	1317-35-7	–	1	–	–	–	–	–
Marble (calcium carbonate),	1317-65-3	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Mercury	7439-97-6	– –	– 0.01	– –	– 0.03	– –	0.1 –	x x
Inorganic and aryl compounds (As Hg) Organic compounds (as Hg)
Vapor (as Hg)		–	0.05	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Mesityl oxide	141-79-7	15	60	25	100	–	–	–
Methacrylic acid	79-41-4	20	70	–	–	–	–	x
Methanethiol; see Methyl mercaptan
Methomyl (Lannate)	16752-77- 5	–	2.5	–	–	–	–	–
Methoxychlor dust	72-43-5	–	10	–	–	–	–	–
2-Methoxyethanol; see Methyl cellosolve
4-Methoxyphenol	150-76-5	–	5	–	–	–	–	–
Methyl acetate	79-20-9	200	610	250	760	–	–	–
Methyl acetylene (Propyne)	74-99-7	1000	1650	–	–	–	–	–
Methyl acetylene-propadiene mixture (MAPP)	–	1000	1800	1250	2250	–	–	–
Methyl acrylate	96-33-3	10	35	–	–	–	–	x
Methylacrylonitrile	126-98-7	1	3	–	–	–	–	x
Methylal (Dimethoxymethane)	109-87-5	1000	3100	–	–	–	–	–
Methyl alcohol	67-56-1	200	260	250	325	–	–	x
Methylamine	74-89-5	10	12	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Methyl amyl alcohol; see Methyl isobutyl carbinol
Methyl n-amyl ketone	110-43-0	100	465	–	–	–	–	–
Methyl bromide	74-83-9	5	20	–	–	–	–	x
Methyl n-butyl ketone; see 2-Hexanone
Methyl cellosolve (2-Methoxyethanol)	109-86-4	25	80	–	–	–	–	x
Methyl cellosolve acetate (2-Methoxyethyl acetate)	110-49-6	25	120	–	–	–	–	x
Methyl chloride	74-87-3	50	105	100	210	–	–	–
Methyl chloroform  (1,1,1- Trichloroethane)	71-55-6	350	1900	450	2450	–	–	–
Methyl 2-cyanoacrylate	137-05-3	2	8	4	16	–	–	–
Methylcyclohexane	108-87-2	400	1600	–	–	–	–	–
Methylcyclohexanol	25639-42- 3	50	235	–	–	–	–	–
o-Methylcyclohexanone	583-60-8	50	230	75	345	–	–	x
Methylcyclopentadienyl manganese tricarbonyl (as Mn)	12108-13- 3	–	0.2	–	–	–	–	x
Methyl demeton	8022-00-2	–	0.5	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
4,4'-Methylene bis(2-chloroaniline) (MBOCA)	101-14-4	0.02	0.22	–	–	–	–	x
Methylene bis(4-cyclohexylisocyanate) (MCBI)	5124-30-1	–	–	–	–	0.01	0.11	–
Methylene bisphenyl isocyanate (MDI)	101-68-8	–	–	–	–	0.02	0.2	–
Methylene chloride, see OH Part 313, R 325.51651 to R 325.51652F	75-09-2	25	87	125	434
Methylenedianiline (MDA); see OH Part 303, R 325.50051 to R 325.50076F	101-77-9	10 ppb**	0.08 mg÷m3	100 ppb**	0.8 mg÷m3	–	–	–
Methyl ethyl ketone (MEK); see 2- Butanone
Methyl ethyl ketone peroxide (MEKP)	1338-23-4	–	–	–	–	0.7	5	–
Methyl formate	107-31-3	100	250	150	375	–	–	–
Methyl hydrazine	60-34-4	–	–	–	–	0.2	0.35	x
Methyl iodide	74-88-4	2	10	–	–	–	–	x
Methyl isoamyl ketone	110-12-3	50	240	–	–	–	–	–
Methyl isobutyl carbinol	108-11-2	25	100	40	165	–	–	x
Methyl isobutyl ketone; see Hexone
Methyl isocyanate (MIC)	624-83-9	0.02	0.05	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Methyl isopropyl ketone	563-80-4	200	705	–	–	–	–	–
Methyl mercaptan	74-93-1	0.5	1	–	–	–	–	–
Methyl methacrylate	80-62-6	100	410	–	–	–	–
Methyl parathion	298-00-0	–	0.2	–	–	–	–	x
Methyl propyl ketone; see 2-Pentanone
Methyl silicate	681-84-5	1	6	–	–	5	30	–
alpha-Methyl styrene	98-83-9	50	240	100	485	–	–	–
Metribuzin	21087-64- 9	–	5	–	–	–	–	–
Mica; see Silicates
Molybdenum, (as Mo)	7439-98-7	–	10	–	–	–	–	–
Insoluble compounds
Soluble compounds		–	5	–	–	–	–	–
Monocrotophos (AzodrinR)	6923-22-4	–	0.25	–	–	–	–	–
Monomethyl aniline	100-61-8	0.5	2	–	–	–	–	x
Morpholine	110-91-8	20	70	30	105	–	–	x
Naphtha (Coal tar)	8030-30-6	100	400	–	–	–	–	–
Naphthalene	91-20-3	10	50	15	75	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
alpha-Naphthylamine; see OH Part 350, R 325.35001 to R 325.35011F	134-32-7
beta-Naphthylamine; see OH Part 350, R 325.35001 to R 325.35011F	91-59-8
Nickel carbonyl (as Ni)	13463-39- 3	0.001	0.007	–	–	–	–	–
Nickel,	7440-02-0	–	1	–	–	–	–	–
Metal and insoluble compounds (as Ni)
Soluble compounds (as Ni)		–	0.1	–	–	–	–	–
Nicotine	54-11-5	–	0.5	–	–	–	–	x
Nitric acid	7697-37-2	2	5	4	10	–	–	–
Nitric oxide	10102-43- 9	25	30	–	–	–	–	–
p-Nitroaniline	100-01-6	–	3	–	–	–	–	x
Nitrobenzene	98-95-3	1	5	–	–	–	–	x
p-Nitrochlorobenzene	100-00-5	–	1	–	–	–	–	x
4-Nitrodiphenyl; see OH Part 350, R 325.35001 to R 325.35011F	92-93-3
Nitroethane	79-24-3	100	310	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Nitrogen dioxide	10102-44- 0	–	–	1	1.8	–	–	–
Nitrogen trifluoride	7783-54-2	10	29	–	–	–	–	–
Nitroglycerin	55-63-0	–	–	–	0.1	–	–	x
Nitromethane	75-52-5	100	250	–	–	–	–	–
1-Nitropropane	108-03-2	25	90	–	–	–	–	–
2-Nitropropane	79-46-9	10	35	–	–	–	–	–
N-Nitrosodimethylamine; see OH Part 350, R 325.35001 to R 325.35011F	62-75-9
Nitrotoluene o-isomer m-isomer p-isomer	88-72-2 99-08-1 99-99-0	2	11	–	–	–	–	x
Nitrotrichloromethane; see Chloropicrin
Nonane	111-84-2	200	1050	–	–	–	–	–
Octachloronaphthalene	2234-13-1	–	0.1	–	0.3	–	–	x
Octane	111-65-9	300	1450	375	1800	–	–	–
Oil mist, mineral	8012-95-1	–	5	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Osmium tetroxide (as Os)	20816-12- 0	–	0.002	–	0.006	–	–	–
Oxalic acid	144-62-7	–	1	–	2	–	–	–
Oxygen difluoride	7783-41-7	–	–	–	–	0.05	0.1	–
Ozone	10028-15- 6	0.1	0.2	0.3	0.6	–	–	–
Paraffin wax fume	8002-74-2	–	2	–	–	–	–	–
Paraquat, respirable dust	1910-42-5 2074-50-2 4685-14-7	–	0.1	–	–	–	–	x
Parathion	56-38-2	–	0.1	–	–	–	–	x
Particulates not otherwise regulated,	–	–	5	–	–	–	–	–
Respirable dust	–
Total dust	–	–	15	–	–	–	–	–
Pentaborane	19624-22- 7	0.005	0.01	0.015	0.03	–	–	–
Pentachloronaphthalene	1321-64-8	–	0.5	–	–	–	–	x
Pentachlorophenol	87-86-5	–	0.5	–	–	–	–	x
Pentaerythritol,	115-77-5	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Pentane	109-66-0	600	1800	750	2250	–	–	–
2-Pentanone (Methyl propyl ketone)	107-87-9	200	700	250	875	–	–	–
Perchloroethylene (Tetrachloroethylene)	127-18-4	25	170	–	–	–	–	–
Perchloromethyl mercaptan	594-42-3	0.1	0.8	–	–	–	–	–
Perchloryl fluoride	7616-94-6	3	14	6	28	–	–	–
Perlite Respirable dust Total dust	93763-70- 3	– –	5 15	– –	– –	– –	– –	– –
Petroleum distillates (Naphtha) (Rubber solvent)		400	1600	–	–	–	–	–
Phenol	108-95-2	5	19	–	–	–	–	x
Phenothiazine	92-84-2	–	5	–	–	–	–	x
p-Phenylenediamine	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	1	6	–	–	–	–	–
Phenylhydrazine	100-63-0	5	20	10	45	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Phenyl mercaptan	108-98-5	0.5	2	–	–	–	–	–
Phenylphosphine	638-21-1	–	–	–	–	0.05	0.25	–
Phorate	298-02-2	–	0.05	–	0.2	–	–	x
Phosdrin (MevinphosR)	7786-34-7	–	0.1	–	0.3	–	–	x
Phosgene (Carbonyl chloride)	75-44-5	0.1	0.4	–	–	–	–	–
Phosphine	7803-51-2	0.3	0.4	1	1	–	–	–
Phosphoric acid	7664-38-2	–	1	–	3	–	–	–
Phosphorus (yellow)	7723-14-0	–	0.1	–	–	–	–	–
Phosphorus oxychloride	10025-87- 3	0.1	0.6	–	–	–	–	–
Phosphorus pentachloride	10026-13- 8	–	1	–	–	–	–	–
Phosphorus pentasulfide	1314-80-3	–	1	–	3	–	–	–
Phosphorus trichloride	7719-12-2	0.2	1.5	0.5	3	–	–	–
Phthalic anhydride	85-44-9	1	6	–	–	–	–	–
m-Phthalodinitrile	626-17-5	–	5	–	–	–	–	–
Picloram,	1918-02-1	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Picric acid	88-89-1	–	0.1	–	–	–	–	x
Piperazine dihydrochloride	142-64-3	–	5	–	–	–	–	–
Pindone (2-Pivalyl-1,3-indandione)	83-26-1	–	0.1	–	–	–	–	–
Plaster of Paris (Calcium sulfate), Respirable dust Total dust	26499-65- 0	– –	5 15	– –	– –	– –	– –	– –
Platinum (as Pt)	7440-06-4	–	1	–	–	–	–	–
Metal
Soluble salts		–	0.002	–	–	–	–	–
Portland cement, Respirable dust Total dust	65997-15- 1	– –	5 10	– –	– –	– –	– –	– –
Potassium hydroxide	1310-58-3	–	–	–	–	–	2	–
Propane	74-98-6	1000	1800	–	–	–	–	–
Propargyl alcohol	107-19-7	1	2	–	–	–	–	x
beta-Propriolactone; see OH Part 350, R 325.35001 to R 325.35011F	57-57-8
Propionic acid	79-09-4	10	30	–	–	–	–	–
Propoxur (Baygon)	114-26-1	–	0.5	–	–	–	–	–
n-Propyl acetate	109-60-4	200	840	250	1050	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
n-Propyl alcohol	71-23-8	200	500	250	625	–	–	–
n-Propyl nitrate	627-13-4	25	105	40	170	–	–	–
Propylene dichloride	78-87-5	75	350	110	510	–	–	–
Propylene glycol dinitrate	6423-43-4	0.05	0.3	–	–	–	–	–
Propylene glycol monomethyl ether	107-98-2	100	360	150	540	–	–	–
Propylene imine	75-55-8	2	5	–	–	–	–	x
Propylene oxide	75-56-9	20	50	–	–	–	–	–
Propyne; see Methyl acetylene
Pyrethrum	8003-34-7	–	5	–	–	–	–	–
Pyridine	110-86-1	5	15	–	–	–	–	–
Quinone	106-51-4	0.1	0.4	–	–	–	–	–
Resorcinol	108-46-3	10	45	20	90	–	–	–
Rhodium,	7440-16-6	– –	0.1 0.1	– –	– –	– –	– –	– –
Insoluble compounds (as Rh) Metal fume (as Rh)
Soluble compounds (as Rh)		–	0.001	–	–	–	–	–
Ronnel	299-84-3	–	10	–	–	–	–	–
Rosin core solder pyrolysis products, as formaldehyde	–	–	0.1	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Rotenone	83-79-4	–	5	–	–	–	–	–
Rouge,	–	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
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	–	6	–	–	–	–	–
Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica	61790-53- 2	–	6	–	–	–	–	–
Silica, crystalline cristobalite, Respirable dust	14464-46- 1	–	0.05	–	–	–	–	–
Silica, crystalline quartz, Respirable dust	14808-60- 7	–	0.1	–	–	–	–	–
Silica, crystalline tridymite, Respirable dust	15468-32- 3	–	0.05	–	–	–	–	–
Silica, crystalline tripoli, Respirable dust	1317-95-9	–	0.1	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
			TWA		STELD		Ceiling
Substance		CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Silica, fused, Respirable dust		60676-86- 0	–	0.1	–	–	–	–	–
Silicates (less than 1% crystalline silica)
	Mica, respirable dust	12001-26- 2	–	3	–	–	–	–	–
	Soapstone, respirable dust	–	–	3	–	–	–	–	–
	Soapstone, total dust	–	–	6	–	–	–	–	–
	Talc (containing asbestos); use asbestos limit	–	OH Part 305 “Asbestos for General Industry,” R 325.51311 to R 325.
	Talc (containing no asbestos), respirable dust	14807-96- 6	–	2	–	–	–	–	–
	Tremolite	–	OH Part 305 “Asbestos for General Industry,” R 325.51311 to R 325.51312
Silicon, Respirable dust Total dust		7440-21-3	– –	5 10	– –	– –	– –	– –	– –
Silicon carbide, Respirable dust Total dust		409-21-2	– –	5 10	– –	– –	– –	– –	– –
Silicon tetrahydride		7803-62-5	5	7	–	–	–	–	–
Silver, metal and soluble compounds (as Ag)		7440-22-4	–	0.01	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Soapstone; see Silicates
Sodium azide (as HN3) (as NaN3)	26628-22- 8	– –	– –	– –	– –	0.1 –	– 0.3	x x
Sodium bisulfite	7631-90-5	–	5	–	–	–	–	–
Sodium fluoroacetate	62-74-8	–	0.05	–	0.15	–	–	x
Sodium hydroxide	1310-73-2	–	–	–	–	–	2	–
Sodium metabisulfite	7681-57-4	–	5	–	–	–	–	–
Starch,	9005-25-8	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–
Stibine	7803-52-3	0.1	0.5	–	–	–	–	–
Stoddard solvent	8052-41-3	100	525	–	–	–	–	–
Strychnine	57-24-9	–	0.15	–	–	–	–	–
Styrene	100-42-5	50	215	100	425	–	–	–
Subtilisins (Proteolytic enzymes)	9014-01-1	–	–	–	0.00006 (60 min.)	–	–	–
Sucrose,	57-50-1	–	5	–	–	–	–	–
Respirable dust
Total dust		–	15	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Sulfur dioxide	7446-09-5	2	5	5	10	–	–	–
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	–	–	–	–	0.01	0.1	–
Sulfur tetrafluoride	7783-60-0	–	–	–	–	0.1	0.4	–
Sulfuryl fluoride	2699-79-8	5	20	10	40	–	–	–
Sulprofos	35400-43- 2	–	1	–	–	–	–	–
SystoxR; see Demeton
2,4,5-T (2,4,5-trichlorophenoxyacetic acid)	93-76-5	–	10	–	–	–	–	–
Talc; see Silicates
Tantalum, metal and oxide dust	7440-25-7	–	5	–	–	–	–	–
TEDP (Sulfotep)	3689-24-5	–	0.2	–	–	–	–	x
Tellurium and compounds (as Te)	13494-80- 9	–	0.1	–	–	–	–	–
Tellurium hexafluoride (as Te)	7783-80-4	0.02	0.2	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Temephos,	3383-96-8	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
TEPP	107-49-3	–	0.05	–	–	–	–	x
Terphenyls	26140-60- 3	–	–	–	–	0.5	5	–
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	1	7	–	–	–	–	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	250	735	–	–	–
Tetramethyl lead (as Pb)	75-74-1	–	0.075	–	–	–	–	x
Tetramethyl succinonitrile	3333-52-6	0.5	3	–	–	–	–	x
Tetranitromethane	509-14-8	1	8	–	–	–	–	–
Tetrasodium pyrophosphate	7722-88-5	–	5	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
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	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
Thioglycolic acid	68-11-1	1	4	–	–	–	–	x
Thionyl chloride	7719-09-7	–	–	–	–	1	5	–
Thiram	137-26-8	–	5	–	–	–	–	–
Tin, Inorganic compounds (except	7440-31-5 7440-31-5 21651-19- 4	– – –	2 0.1 2	– – –	– – –	– – –	– – –	– x –
oxides) (as Sn) Organic compounds (as Sn) Oxides (as Sn)
Titanium dioxide Total dust	13463-67- 7	–	10	–	–	–	–	–
Toluene	108-88-3	100	375	150	560	–	–	–
Toluene-2,4-diisocyanate (TDI)	584-84-9	0.005	0.04	0.02	0.15	–	–	–
m-Toluidine	108-44-1	2	9	–	–	–	–	x
o-Toluidine	95-53-4	5	22	–	–	–	–	x
p-Toluidine	106-49-0	2	9	–	–	–	–	x

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Toxaphene; see Chlorinated camphene
Tremolite; see Silicates
Tributyl phosphate	126-73-8	0.2	2.5	–	–	–	–	–
Trichloroacetic acid	76-03-9	1	7	–	–	–	–	–
1,2,4-Trichlorobenzene	120-82-1	–	–	–	–	5	40	–
1,1,1-Trichloroethane; see Methyl chloroform
1,1,2-Trichloroethane	79-00-5	10	45	–	–	–	–	x
Trichloroethylene	79-01-6	50	270	200	1080	–	–	–
Trichloromethane; see Chloroform
Trichloronaphthalene	1321-65-9	–	5	–	–	–	–	x
1,2,3-Trichloropropane	96-18-4	10	60	–	–	–	–	–
1,1,2-Trichloro-1,2,2-trifluoroethane	76-13-1	1000	7600	1250	9500	–	–	–
Triethylamine	121-44-8	10	40	15	60	–	–	–
Trifluorobromomethane	75-63-8	1000	6100	–	–	–	–	–
Trimellitic anhydride	552-30-7	0.005	0.04	–	–	–	–	–
Trimethylamine	75-50-3	10	24	15	36	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Trimethyl benzene	25551-13- 7	25	125	–	–	–	–	–
Trimethyl phosphite	121-45-9	2	10	–	–	–	–	–
2,4,6-Trinitrophenol; see Picric acid
2,4,6-Trinitrophenylmethylnitramine; see Tetryl
2,4,6-Trinitrotoluene (TNT)	118-96-7	–	0.5	–	–	–	–	x
Triorthocresyl phosphate	78-30-8	–	0.1	–	–	–	–	x
Triphenyl amine	603-34-9	–	5	–	–	–	–	–
Triphenyl phosphate	115-86-6	–	3	–	–	–	–	–
Tungsten	7440-33-7	– –	5 1	– –	10 3	– –	–	–
Insoluble compounds (as W) Soluble compounds (as W)
Turpentine	8006-64-2	100	560	–	–	–	–	–
Uranium (as U)	7440-61-1	–	0.2	–	0.6	–	–	–
Insoluble compounds
Soluble compounds		–	0.05	–	-	–	–	–
n-Valeraldehyde	110-62-3	50	175	–	–	–	–	–
Vanadium pentoxide	1314-62-1	–	0.05	–	–	–	–	–
Fume (as V2O5)
Respirable dust (as V2O5)		–	0.05	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Vegetable oil mists	–	–	5	–	–	–	–	–
Respirable mist
Total mist		–	15	–	–	–	–	–
Vinyl acetate	108-05-4	10	30	20	60	–	–	–
Vinyl benzene; see Styrene
Vinyl bromide	593-60-2	5	20	–	–	–	–	–
Vinyl chloride; see OH Part 302, R 325.51401 to R 325.51414F	75-01-4	1	2.5	5	12.8
Vinyl cyanide; see Acrylonitrile
Vinyl cyclohexene dioxide	106-87-6	10	60	–	–	–	–	x
Vinylidene chloride (1,1- Dichloroethylene)	75-35-4	1	4	–	–	–	–	–
Vinyl toluene	25013-15- 4	100	480	–	–	–	–	–
VM & P Naphtha	8032-32-4	300	1350	400	1800	–	–	–
Warfarin	81-81-2	–	0.1	–	–	–	–	–
Welding fumes (Total particulate)*	–	–	5	–	–	–	–	–
Wood dust, all soft and hard woods (except Western red cedar)	–	–	5	–	10	–	–	–
Wood dust, Western red cedar	–	–	2.5	–	–	–	–	–

TABLE G-1-A.  EXPOSURE LIMITS FOR AIR CONTAMINANTS
		TWA		STELD		Ceiling
Substance	CAS No.A	ppmB	mg÷m3C	ppmB	mg÷m3C	ppmB	mg÷m3C	Skin Designation
Xylene (o-,m-,p-isomers) (Dimethyl benzene)	1330-20-7	100	435	150	655	–	–	–
m-Xylene-alpha, alpha’-diamine	1477-55-0	–	–	–	–	–	0.1	x
Xylidine	1300-73-8	2	10	–	–	–	–	x
Yttrium	7440-65-5	–	1	–	–	–	–	–
Zinc chloride fume	7646-85-7	–	1	–	2	–	–	–
Zinc chromates (as Cr+6); see OH Part 315, R 325.50141 to R 325.50143F, G	Varies with compound	–	0.005 (5 μg÷m3)	–	–	–	–	–
Zinc oxide fume	1314-13-2	–	5	–	10	–	–	–
Zinc oxide,	1314-13-2	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
Zinc stearate	557-05-1	–	5	–	–	–	–	–
Respirable dust
Total dust		–	10	–	–	–	–	–
Zirconium compounds (as Zr)	7440-67-7	–	5	–	10	–	–	–

TABLE G-2. EXPOSURE LIMITS FOR AIR CONTAMINATES
Substance		8-hour, time-weighted average	Acceptable ceiling concentration	Acceptable maximum peak above the acceptable ceiling concentration for an 8-hour workshift.
				Concentration	Maximum duration
S	BenzeneE,F	10 ppm	25 ppm	50 ppm	10 minutes
	Beryllium and beryllium compounds	2 µg÷m3	5 µg÷m3	25 µg÷m3	30 minutes
S	Ethylene dibromide	20 ppm	30 ppm	50 ppm	5 minutes
Note:  S above signifies that skin contact shall not be allowed.

*	As determined from breathing-zone air samples.
**	Parts per billion.
A	The CAS number is for information only. Enforcement is based on the substance name.   For an entry covering more than 1 metal compound measured as the metal, the CAS number for the metal is given - not the CAS number for the individual compounds.
B	Parts of vapor or gas per million parts of contaminated air by volume at 25°C and 760 torr.
C	Approximate milligrams of substance per cubic meter of air.
D	Duration is for 15 minutes, unless otherwise noted.
E	The final benzene standard in OH Part 311, R 325.77101 to R 325.77115 applies to all occupational exposures to benzene, except some subsegments of industry where exposures are consistently under the action level.  These subsegments include 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 G-2 apply.
F	Caution--this rule contains extensive requirements for exposure to these substances.
G	If the exposure limit in §1910.1026 (adopted by reference in OH Part 315, R 325.50141 to R 325.50143) is stayed or is otherwise not in effect, the exposure limit is a ceiling of 0.1 mg÷m3.

History: 1990 AACS; 2001 AACS; 2013 MR 6, Eff. March 20, 2013