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2007 Exposure Limits for Air Contaminants (PELs, TLVs & STELs)

Document Number: 232

Definitions:

TLV - Threshold Limit Value. An estimate of the average safe airborne concentration of a substance in representative conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect. TLVs are published annually by the ACGIH (American Conference of Governmental Industrial Hygienists).

PEL - Permissible Exposure Limit. The OSHA limits of employee exposure to chemicals; found primarily in 29 CFR 1910.1000, Table Z-1.

STEL - Short Term Exposure Limit, the maximum concentration for a continuous 15-minute exposure period. Ceiling - The maximum allowable concentration to which an employee may be exposed.

IDLH - Immediately Dangerous to Life and Health, is the concentration of an airborne chemical which may cause irreversible health effects or death. NIOSH

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Acetaldehyde	-	200	25 ACGIH	2000 ++
Acetic Acid	10	10	15 ACGIH	50
Acetic Anhydride	5	5	-	200
Acetone	500	1000	750 ACGIH	2500
Acetonitrile	40	40	-	500
Acetylene tetrabromide (1,1,2,2 Tetrabromoethane)	0.1	1	-	8
Acrolein	-	0.1	0.1 ACGIH	2
Acrylamide	0.03	0.3 mg/m3	-	60 mg/m3++
Aldrin	0.05	0.25 mg/m3	-	25 mg/m3++
Allyl alcohol	0.5	2	4 NIOSH	20
Allyl chloride	1	1	2 ACGIH / NIOSH	250
Allyl glycidyl ether	1	10 +	10 NIOSH	50
Allyl propyl disulfide	0.5	2	3 NIOSH	-
alpha-Alumina (td)	10 mg/m3	15 mg/m3	-	-
alpha-Alumina (rf)		5 mg/m3	-	-
Aluminum, metal (td)	10 mg/m3	15 mg/m3	-	-
Aluminum metal (rf)	-	5 mg/m3	-	-
2-Aminopyridine	0.5	0.5	-	5
Ammonia	25	50	35 ACGIH / NIOSH	300
Ammonium sulfamate (td)	10 mg/m3	15 mg/m3	-	1500 mg/m3
Ammonium sulfamate (rf)	-	5 mg/m3	-	-
n-Amyl acetate (1-Pentyl acetate)	50	100	100 ACGIH	1000
sec-Amyl acetate (2-Pentyl acetate)	50	125	100 ACGIH	1000
Aniline and homologs	2	5	-	100 ++
Anisidine o-, p-isomers	0.1	0.5 mg/m3	-	50 mg/m3 ++
Antimony & compounds	0.5 mg/m3	0.5 mg/m3	-	50 mg/m3
ANTU	0.3 mg/m3	0.3 mg/m3	-	100 mg/m3
Arsenic, org. comp.	0.01 mg/m3	0.5 mg/m3	-	-
Arsine	0.005	0.05	0.002 mg/m3 NIOSH	3 ++
Azinphos-methyl	0.2 mg/m3	0.2 mg/m3	-	10 mg/m3

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Barium, sol. comp.	0.5 mg/m3	0.5 mg/m3	-	50 mg/m3
Barium sulfate (td)	10 mg/m3	15 mg/m3	-	-
Barium sulfate (rf)	-	5 mg/m3	-	-
Benomyl (td)	10 mg/m3	15 mg/m3	-	-
Benomyl (rf)	-	5 mg/m3	-	-
Benzene *See 29 CFR 1910.1028	0.5	1*	5* OSHA 2.5 ACGIH 1 NIOSH	500 ++
Benzoyl peroxide	5 mg/m3	5 mg/m3	-	1500 mg/m3
Benzyl chloride	1	1	1 / 15min NIOSH	10
Beryllium	0.002 mg/m3	0.002 mg/m3	0.005 ; 0.025 30 min peak/8hr shift OSHA 0.0005 mg/m3 NIOSH	4 mg/m3 ++
Bismuth telluride undoped (td)	10 mg/m3	15 mg/m3	-	-
Bismuth telluride undoped (rf)	-	5 mg/m3	-	-
Boron oxide (td)	10 mg/m3	15 mg/m3	-	2000 mg/m3
Boron trifluoride	1 +	1 +	1 NIOSH	25
Bromine	0.1	0.1	0.2 ACGIH 0.3 NIOSH	3
Bromoform	0.5	0.5	-	850
1,3 Butadiene	2	1	5 OSHA	2000 ++ (LEL)
2-Butanone (MEK)	200	200	300 ACGIH / NIOSH	3000
2-Butoxyethanol	20	50	-	700
n-Butyl-acetate	150	150	200 ACGIH / NIOSH	1700 (LEL)
sec-Butyl acetate	200	200	-	1700 (LEL)
tert-Butyl acetate	200	200	-	1500 (LEL)
n-Butyl alcohol (n-Butanol)	20	100	50 NIOSH	1400 (LEL)
sec-Butyl alcohol (sec-Butanol)	100	150	150 NIOSH	2000
tert-Butyl alcohol (tert-Butanol)	100	100	150 NIOSH	1600
Butylamine	5 +	5 +	5 NIOSH	300
tert-Butyl chromate See 29 CFR 1910.1026	0.1 mg/m3+	0.1 mg/m3+	-	15 mg/m3 ++
n-Butyl glycidyl ether	3	50	5.6 /15min NIOSH	250
Butyl mercaptan	0.5	10	0.5 /15min NIOSH	500
p-tert-Butyl-1-toluene	1	10	20 NIOSH	100

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Cadmium fume See 29 CFR 1910.1027	-	0.3 mg/m3		9 mg/m3 ++
Cadmium dust See 29 CFR 1910.1027	-	0.3 mg/m3		9 mg/m3 ++
Calcium carbonate (td) (Limestone)	-	15 mg/m3	-	-
Calcium carbonate (rf)	-	5 mg/m3	-	-
Calcium hydroxide (td)	5 mg/m3	15 mg/m3	-	-
Calcium hydroxide (rf)	-	5 mg/m3	-	-
Calcium oxide	2 mg/m3	5 mg/m3	-	25 mg/m3
Calcium silicate (td)	10 mg/m3	15 mg/m3	-	-
Calcium silicate (rf)	-	5 mg/m3	-	-
Calcium sulfate (td)	10 mg/m3	15 mg/m3	-	-
Calcium sulfate (rf)	-	5 mg/m3	-	-
Camphor, synthetic	12 mg/m3	2 mg/m3	19 mg/m3 ACGIH	200 mg/m3
Carbaryl	5 mg/m3	5 mg/m3	-	100 mg/m3
Carbon black	3.5 mg/m3	3.5 mg/m3	-	1750 mg/m3 ++
Carbon dioxide	5000	5000	30,000 ACGIH / NIOSH	40,000
Carbon disulfide	1	2 mg/m3	10 NIOSH	500
Carbon monoxide	25	50	200 NIOSH	1200
Carbon tetrachloride	5	2 mg/m3	10 ACGIH 2 / 60 min NIOSH	200 ++
Cellulose (td)	10 mg/m3	15 mg/m3	-	-
Cellulose (rf)	-	5 mg/m3	-	-
Chlorodane	0.5 mg/m3	0.5 mg/m3	-	100 mg/m3++
Chlorinated camphene	0.5 mg/m3	0.5 mg/m3	-	200 mg/m3++
Chlorinated diphenyl oxide	0.5 mg/m3	0.5 mg/m3	-	5 mg/m3
Chlorine	0.5	1 +	1 ACGIH 0.5 NIOSH	10
Chlorine dioxide	0.1	0.1	0.3 ACGIH / NIOSH	5
Chlorine trifluoride	0.1 +	0.1 +	0.1 NIOSH	20
Chloroacetaldehyde	1 +	1 +	1 NIOSH	45
a-chloroacetophenone	0.05	0.05	-	15 mg/m3
Chlorobenzene	10	75	-	1000
o-Chlorobenzylidene malononitrile	0.05+	0.05	0.05 NIOSH	2 mg/m3
Chlorobromomethane	200	200	-	2000
Chlorodiphenyl (42% Cl)	1 mg/m3	1 mg/m3	-	5 mg/m3++
Chlorobiphenyl (54% Cl)	0.5 mg/m3	0.5 mg/m3	-	5 mg/m3++
Chloroform	10	50+	2 /60min NIOSH	500 ++
1-Chloro-1-nitro- propane	2	20	-	100
Chloropicrin	0.1	0.1	-	2
beta-Chloroprene	10	25	1 / 15min NIOSH	300
2-Chloro-6-trichloro- methyl) pyridine (td)	10 mg/m3	15 mg/m3	20 mg/m3	-
2-Chloro-6-(trichloro methyl) pyridine (rf)	-	5 mg/m3	-	-
Chromic acids and Chromate	0.05 mg/m3	4	-	15 mg/m3 ++
Chromium (II) compounds	0.5 mg/m3	0.5 mg/m3	-	250 mg/m3
Chromium (III) compounds	0.5 mg/m3	0.5 mg/m3	-	25 mg/m3
Chromium metal and insoluble salts	-	1 mg/m3	-	250 mg/m3
Clopidol (td)	10 mg/m3	15 mg/m3	-	-
Clopidol (rf)	-	5 mg/m3	-	-
Coal dust (less than 5% SiO (2) anthracite	0.4 mg/m3	3 mg/m3	-	-
Coal dust (greater or equal to 5% SiO(2) bituminous	0.9 mg/m3	3 mg/m3	-	-
Coal tar pitch volatiles	0.2 mg/m3	0.2 mg/m3	-	80 mg/m3++
Cobalt metal, dust, and fume	0.02 mg/m3	0.1 mg/m3	-	20 mg/m3
Copper fume	0.2 mg/m3	0.1 mg/m3	0.1 mg/m3 ACGIH	100 mg/m3
Copper dusts and mists	1 mg/m3	1 mg/m3	-	100 mg/m3
Cotton dust	0.2 mg/m3	1 mg/m3	-	100 mg/m3
Crag herbicide (td) (Sesone)	10 mg/m3	15 mg/m3	-	500 mg/m3
Crag herbicide (rf)	-	5 mg/m3	-	-
Cresol, all isomers	5	5	-	250
Crotonaldehyde	0.3 +	2	-	50
Cumene	50	50	-	900 (LEL)
Cyanides	-	5 mg/m3	-	25 mg/m3
Cyclohexane	100	300	-	1300 (LEL)
Cyclohexanol	50	50	-	400
Cyclohexanone	20	50	-	700
Cyclohexene	300	300	-	2000
Cyclopentadiene	75	75	-	750

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
2,4-D (Dichlorophenoxyacetic acid)	10 mg/m3	10 mg/m3	-	100 mg/m3
Decaborane	0.05	0.05	0.15 ACGIH / NIOSH	15 mg/m3
Demeton	0.05 mg/m3	0.1 mg/m3	-	10 mg/m3
Diacetone alcohol	50	50	-	1800 (LEL)
Diazomethane	0.2	0.2	-	2
Diborane	0.1	0.1	-	15
Dibutyl phosphate	1	1	2 ACGIH / NIOSH	30
Dibutyl phthalate	5 mg/m3	5 mg/m3	-	4000 mg/m3
o-Dichlorobenzene	25	50+	50 ACGIH / NIOSH	200
p-Dichlorobenzene	10	75	-	150 ++
Dichlorodifluoromethane	1000	1000	-	15,000
1,3 Dichloro 5,5 dimethyl hydantoin	0.2 mg/m3	0.2 mg/m3	-	5 mg/m3
Dichlorodiphenyltri-chloroethane (DDT)	1 mg/m3	1 mg/m3	-	500 mg/m3 ++
1,1 Dichloroethane	100	100	-	3000
1,2-Dichloroethylene	200	200	-	1000
Dichloroethyl ether	5	15 +	10 ACGIH / NIOSH	100 ++
Dichloromono- fluomethane (Dichlorofluoromethane)	10	1000	-	5000
1,1 Dichloro-1- nitroethane	2	10 +	-	25
Dichlorotetra- fluoroethane	1000	1000	-	15,000
Dichlorvos (DDVP)	0.1 mg/m3	1 mg/m3	-	100 mg/m3
Dicyclopentadienyl iron (td)	10 mg/m3	15 mg/m3	-	-
Dicyclopentadienyl iron (rf)	-	5 mg/m3	-	-
Dieldrin	0.25 mg/m3	0.25 mg/m3	-	50 mg/m3++
Diethylamine	5	25	15 ACGIH 12 NIOSH	200
2-Diethylaminoethanol	2	10	-	100
Difluorodibromomethane	100	100	-	2000
Diglycidyl ether (DGE)	0.01	0.5 +	-	10 ++
Diisobutyl ketone	25	50	-	500
Diisopropylamine	5	5	-	200
Dimethyl acetamide	10	10	-	300
Dimethylamine	5	10	15 ACGIH	500
Dimethylaniline (N,N-Dimethylaniline)	5	5	10 ACGIH / NIOSH	100
Dimethyl-1,2-dibromo- 2,2-dichloroethyl phosphate (NALED)	0.1 mg/m3	3 mg/m3	-	200 mg/m3
Dimethylformamide	10	10	-	500
1,1-Dimethylhydrazine	0.01	0.5	0.06 / 120min NIOSH	15++
Dimethylphthalate	5 mg/m3	5 mg/m3	-	2000 mg/m3
Dimethyl sulfate	0.1	1	-	7++
Dinitrobenzene (all isomers)	0.15	1 mg/m3	-	50 mg/m3
Dinitro-o-cresol	0.2 mg/m3	0.2 mg/m3	-	5 mg/m3
Dinitrotoluene	0.2 mg/m3	1.5 mg/m3	-	50 mg/m3++
Dioxane (Diethylene dioxide)	20	100	1 / 30min NIOSH	500 ++
Diphenyl (Biphenyl)	0.2	0.2	-	100 mg/m3
Dipropylene glycol methyl ether DPGME [2-(Methoxymethylethoxy)propanol]	100	100	150 ACGIH / NIOSH	600
Di-sec octyl phthalate (Di-(2-ethylhexyl) phthalate) DEHP	5 mg/m3	5 mg/m3	-	5000 mg/m3

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Emery (td)	10 mg/m3	15 mg/m3	-	-
Emery (rf)	-	5 mg/m3	-	-
Endosulfan	0.1 mg/m3	-	-	-
Endrin	0.1 mg/m3	0.1 mg/m3	-	2 mg/m3
Epichlorohydrin	0.5	5	-	75++
EPN	0.1 mg/m3	0.5 mg/m3	-	5 mg/m3
Ethanolamine	3	3	6 ACGIH / NIOSH	30
2-Ethoxyethanol (Cellosolve)	5	200	-	500
2-Ethoxyethyl acetate (cellosolve acetate)	5	100	-	500
Ethyl acetate	400	400	-	2000 (LEL)
Ethyl acrylate	5	25	15 ACGIH	300 ++
Ethyl alcohol (Ethanol)	1000	1000	-	3300 (LEL)
Ethylamine	5	10	15 ACGIH	600
Ethyl amyl ketone (5- Methyl-3-heptanone)	10	25	-	-
Ethyl benzene	100	100	125 ACGIH / NIOSH	800 (LEL)
Ethyl bromide	5	200	-	2000
Ethyl butyl ketone (3- Heptanone)	50	50	75 ACGIH	1000
Ethyl chloride	100	1000	-	3800 (LEL)
Ethyl ether	400	400	500 ACGIH	1900
Ethyl formate	100	100	-	1500
Ethyl mercaptan	0.5	10 +	0.5 / 15min NIOSH	500
Ethyl silicate	10	100	-	700
Ethylene chlorohydrin	1 +	5	1 NIOSH	7
Ethylenediamine	10	10	-	1000
Ethylene dibromide	-	2 mg/m3	30;50/5 min peak 8hr OSHA 0.13 /15 min NIOSH	100 ++
Ethylene dichloride	10	2 mg/m3	2 NIOSH	50 ++
Ethylene glycol dinitrate	0.05	0.2 +	-	75 mg/m3
N-Ethylmorpholine	5	20	-	100

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Ferbam (td)	10 mg/m3	15 mg/m3	-	800 mg/m3
Ferrovanadium dust	1 mg/m3	1 mg/m3	3 mg/m3 ACGIH / NIOSH	500 mg/m3
Fluorides (as F)	2.5 mg/m3	2.5 mg/m3	-	250 mg/m3
Fluorine	1	0.1	2 ACGIH	25
Fluorotrichloromethane (Trichlorofluoromethane)	1000 +	1000	1000 NIOSH	2000
Formaldehyde See 29 CFR 1910.1048	0.3 +	0.75	0.1 / 15min NIOSH	20 ++
Formic acid	5	5	10 ACGIH	30
Furfural	2	5	-	100
Furfuryl alcohol	10	50	15 ACGIH / NIOSH	75

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Glycerin (td)	10 mg/m3	15 mg/m3	-	-
Glycerin (rf)	-	5 mg/m3	-	-
Glycidol	2	50	-	150
Grain dust (oat, wheat, barley)	4 mg/m3	10 mg/m3	-	-
Graphite, natural	2 mg/m3	3 mg/m3	-	1250 mg/m3
Graphite, synthetic (td)	2 mg/m3	15 mg/m3	-	-
Graphite, synthetic (rf)	-	5 mg/m3	-	-
Gypsum (td)	10 mg/m3	15 mg/m3	-	-
Gypsum (rf)	-	5 mg/m3	-	-

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Hafnium	0.5 mg/m3	0.5 mg/m3	-	50 mg/m3
Heptachlor	0.05 mg/m3	0.5 mg/m3	-	35 mg/m3 ++
Heptane (n-Heptane)	400	500	500 ACGIH 440 / 15min NIOSH	750
Hexachloroethane	1	1	-	300++
Hexachloronaph- thalene	0.2 mg/m3	0.2 mg/m3	-	2 mg/m3
n-Hexane	50	500	-	1100 (LEL)
2-Hexanone (Methyl n-butyl ketone)	5	100	10 ACGIH	1600
Hexone (Methyl isobutyl ketone)	50	100	75 ACGIH / NIOSH	500
sec-Hexyl acetate	50	50	-	500
Hydrazine	0.01	1	-	50 ++
Hydrogen bromide	2 +	3	3 NIOSH	30
Hydrogen chloride	2 +	5 +	5 NIOSH	50
Hydrogen cyanide	4.7+	10	4.7 NIOSH	50
Hydrogen fluoride	0.5	2 mg/m3	2 ACGIH 6 / 15min NIOSH	30
Hydrogen peroxide	1	1	-	75
Hydrogen selenide (as Se)	0.05	0.05	-	1
Hydrogen sulfide	10	2 mg/m3	15 ACGIH 10 NIOSH	100
Hydroquinone	2 mg/m3	2 mg/m3	2 mg/m3 / 15min NIOSH	50 mg/m3

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Iodine	0.1 +	0.1 +	0.1 NIOSH	2
Iron oxide fume	5 mg/m3	10 mg/m3	-	2500 mg/m3
Isoamyl acetate (Isopentyl acetate)	50	100	100 ACGIH	1000
Isoamyl alcohol (primary and secondary)	100	100	125 ACGIH / NIOSH	500
Isobutyl acetate	150	150	-	1300 (LEL)
Isobutyl alcohol	50	100	-	1600
Isophorone	5 +	25	-	200
Isopropyl acetate	100	250	200 ACGIH	1800
Isopropyl alcohol (2-Propanol)	200	400	400 ACGIH 500 NIOSH	2000 (LEL)
Isopropylamine	5	5	10 ACGIH	750
Isopropyl ether	250	500	310 ACGIH	1400 (LEL)
Isopropyl glycidyl ether (IGE)	50	50	75 ACGIH 50 / 15min NIOSH	400

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Kaolin (td)	2 mg/m3	15 mg/m3	-	-
Kaolin (rf)	-	5 mg/m3	-	-
Ketene	0.5	0.5	1.5 ACGIH / NIOSH	5
Limestone (td)	-	15 mg/m3	-	-
Limestone (rf)	-	5 mg/m3	-	-
Lindane	0.5 mg/m3	0.5 mg/m3	-	50 mg/m3
Lithium hydride	0.025 mg/m3	0.025 mg/m3	-	0.5 mg/m3
L.P.G. (Liquefied petroleum gas)	1000	1000	-	2000 (LEL)

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Magnesite (td)	-	15 mg/m3	-	-
Magnesite (rf)	-	5 mg/m3	-	-
Magnesium oxide fume (total particulate)	10 mg/m3	15 mg/m3	-	750 mg/m3
Malathion (td)	1 mg/m3	15 mg/m3	-	250 mg/m3
Maleic anhydride	0.1	0.25	-	10 mg/m3
Manganese compounds (as Mn)	0.2 mg/m3	5 mg/m3+	3 mg/m3 NIOSH	500 mg/m3
Manganese fume (as Mn)	0.2 mg/m3	5 mg/m3+	3 mg/m3 NIOSH	500 mg/m3
Marble (td)	-	15 mg/m3	-	-
Marble (rf)	-	5 mg/m3	-	-
Mercury (aryl and inorganic)	0.025 mg/m3	2 mg/m3	0.1 mg/m3 OSHA/ NIOSH	10 mg/m3
Mercury (organo) alkyl compounds	0.025 mg/m3	2 mg/m3	0.1 mg/m3 OSHA/ NIOSH	2 mg/m3
Mercury (vapor)	0.025 mg/m3	2 mg/m3	0.1 mg/m3 OSHA/ NIOSH	-
Mesityl oxide	15	25	25	1400 (LEL)
Methoxychlor (td)	10 mg/m3	15 mg/m3	-	5000 mg/m3++
2-Methoxyethanol (Methyl cellosolve)	0.1	25	-	200
2-Methoxyethyl acetate (Methyl cellosolve acetate)	0.1	25	-	200
Methyl acetate	200	200	250 ACGIH / NIOSH	3100 (LEL)
Methyl acetylene (propyne)	1000	1000	-	1700 (LEL)
Methyl acetylene- propadiene mixture (MAPP)	1000	1000	1250 ACGIH / NIOSH	3400 (LEL)
Methyl acrylate	2	10	-	250
Methylal (Dimetoxy- methane)	1000	1000	-	2200 (LEL)
Methyl alcohol	200	200	250 ACGIH / NIOSH	6000
Methylamine	5	10	15 ACGIH	100
Methyl n-amyl ketone	50	100	-	800
Methyl bromide	1	20 +	-	250++
Methyl chloride	50	2 mg/m3	100 ACGIH	2000 ++
Methyl chloroform (1,1,1- Trichloroethane)	350	350	450 ACGIH 350 NIOSH	700
Methylcyclohexane	400	500	-	1200 (LEL)
Methylcyclohexanol	50	100	-	500
o-Methylcyclohexanone	50	100	75 ACGIH / NIOSH	600
Methylene chloride (Dichloromethane) See 29 CFR 1910.1003	50	2 mg/m3	-	2300
Methylene bisphenyl isocyanate (MDI)	0.005	0.02+	0.02 NIOSH	75 mg/m3
Methyl formate	100	100	150 ACGIH / NIOSH	4500
Methyl hydrazine (Mono- methyl hydrazine)	0.01	0.2+	0.4 NIOSH	20++
Methyl iodide	2	5	-	100++
Methyl isoamyl ketone	50	100	-	-
Methyl isobutyl carbinol	25	25	40 ACGIH / NIOSH	400
Methyl isocyanate	0.02	0.02	-	3
Methyl mercaptan	0.5	10 +	0.5 / 15min NIOSH	150
Methyl methacrylate	50	100	100 ACGIH	1000
alpha-Methyl styrene	50	100 +	100 ACGIH / NIOSH	700
Molybdenum (as Mo) Soluble compounds	0.5 mg/m3	5 mg/m3	-	1000 mg/m3
Molybdenum (as Mo) Insoluble compounds (td)	10 mg/m3 I 3 mg/m3 R	15 mg/m3	-	5000 mg/m3
Monomethyl aniline (N-Methyl aniline)	0.5	2	-	100
Morpholine	20	20	30 NIOSH	1400 (LEL)

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Naphtha (Coal tar)	400	100	-	1000 (LEL)
Naphthalene	10	10	15 ACGIH / NIOSH	250
Nickel carbonyl (as Ni)	0.05	0.001	-	2++
Nickel, metal and insoluble compounds (as Ni)	0.2 mg/m3	1 mg/m3	-	10 mg/m3++
Nickel, soluble compounds (as Ni)	0.1 mg/m3	1 mg/m3	-	++
Nicotine	0.5 mg/m3	0.5 mg/m3	-	5 mg/m3
Nitric acid	2	2	4 ACGIH / NIOSH	25
Nitric oxide	25	25	-	100
p-Nitroaniline	3 mg/m3	1	-	300 mg/m3
Nitrobenzene	1	1	-	200
p-Nitrochlorobenzene	0.1	1 mg/m3	-	100 mg/m3 ++
Nitroethane	100	100	-	1000
Nitrogen dioxide	3	5+	5 ACGIH 1 NIOSH	20
Nitrogen trifluoride	10	10	-	1000
Nitroglycerin	0.05	0.2+	0.1 mg/m3 NIOSH	75 mg/m3
Nitromethane	20	100	-	750
1-Nitropropane	25	25	-	1000
2-Nitropropane	10	25	-	100 ++
Nitrotoluene (all isomers)	2	5	-	200
Octachloronaphthalene	0.1 mg/m3	0.1 mg/m3	0.3 mg/m3+	Unknown
Octane	300	500	385 / 15min NIOSH	1000
Oil mist, mineral	5 mg/m3	5 mg/m3	10 mg/m3 ACGIH/ NIOSH	2500 mg/m3
Osmium tetroxide (as Os)	0.0002	0.002 mg/m3	0.0006 ACGIH / NIOSH	1 mg/m3
Oxalic acid	1 mg/m3	1 mg/m3	2 mg/m3	500 mg/m3
Oxygen difluoride	0.05+	0.05	0.05 ACGIH / NIOSH	0.5
Ozone	0.1 light work	0.1	0.1 NIOSH	5

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Paraquat (rd)	0.5 mg/m3	0.5 mg/m3	-	1 mg/m3
Parathion	0.05 mg/m3	0.1 mg/m3	-	10 mg/m3
Particulates not other- wise regulated (PNOR) (td)	10 mg/m3	15 mg/m3	-	-
Particulates not other- wise regulated (PNOR) (rf)	3 mg/m3	5 mg/m3	-	-
Pentaborane	0.005	0.005	0.015 ACGIH / NIOSH	1
Pentachloronaphthalene	0.5 mg/m3	0.5 mg/m3	-	Unknown
Pentachlorophenol	0.5 mg/m3	0.5 mg/m3	-	2.5 mg/m3
Pentaerythritol (td)	10 mg/m3	15 mg/m3	-	-
Pentaerythritol (rf)	-	5 mg/m3	-	-
Pentane	600	1000	610 / 15min NIOSH	1500 (LEL)
2-Pentanone (Methyl propyl ketone)	150+	200	250	1500
Perchloroethylene (Tetrachloroethylene)	10	2 mg/m3	25 ACGIH	150 ++
Perchloromethyl mercaptan	0.1	0.1	-	10
Perchloryl fluoride	3	3	6 ACGIH / NIOSH	100
Perlite (td)	-	15 mg/m3	-	-
Perlite (rf)	-	5 mg/m3	-	-
Petroleum distillates (Naphtha) (Rubber Solvent)	See Specific	500	1800 mg/m3 NIOSH	1100 (LEL)
Phenol	5	5	15.6 /15min NIOSH	250
p-Phenylene diamine	0.1 mg/m3	0.1 mg/m3	-	25 mg/m3
Phenyl ether, vapor	1	1	2 ACGIH	100
Phenyl ether-biphenyl mixture, vapor	-	1	-	10
Phenyl glycidyl ether (PGE)	0.1	10	1 /15min NIOSH	100++
Phenylhydrazine	0.1	5	0.14 /120min NIOSH	15++
Phosdrin (mevinphos)	0.01 mg/m3	0.1 mg/m3	0.03 NIOSH	4
Phosgene (Carbonyl chloride)	0.1	0.1	0.2 / 15min NIOSH	2
Phosphine	0.3	0.3	1 ACGIH / NIOSH	50
Phosphoric acid	1 mg/m3	1 mg/m3	3 mg/m3 ACGIH / NIOSH	1000 mg/m3
Phosphorus (yellow)	0.02	0.1 mg/m3	-	5 mg/m3
Phosphorus pentachloride	0.1	1 mg/m3	-	70 mg/m3
Phosphorus pentasulfide	1 mg/m3	1 mg/m3	3 mg/m3	250 mg/m3
Phosphorus trichloride	0.2	0.5	0.5	25
Phthalic anhydride	1	2	-	60 mg/m3
Picloram (td)	10 mg/m3	15 mg/m3	-	-
Picloram (rf)	-	5 mg/m3	-	-
Picric acid	0.1 mg/m3	0.1 mg/m3	-	75 mg/m3
Pindone (2-Pivalyl-1, 3-indandione)	0.1 mg/m3	0.1 mg/m3	-	100 mg/m3
Plaster of Paris (td)	-	15 mg/m3	-	-
Plaster of Paris (rf)	-	5 mg/m3	-	-
Platinum (as Pt) Soluble salts	0.002 mg/m3	0.002 mg/m3	-	4 mg/m3
Portland cement (td)	10 mg/m3	15 mg/m3	-	5000 mg/m3
Portland cement (rf)	-	5 mg/m3	-	-
Propane (Aliphatic hydrocarbon gases)	1000	1000	-	2100 (LEL)
n-Propyl acetate	200	200	250 ACGIH / NIOSH	1700
n-Propyl alcohol (n-Propanol)	100	200	250 NIOSH	800
Propylene dichloride	10	75	-	400++
Propylene imine	2	2	-	100++
Propylene oxide	20	100	-	400++
n-Propyl nitrate	25	25	40 ACGIH / NIOSH	500
Pyrethrum	5 mg/m3	5 mg/m3	-	5000 mg/m3
Pyridine	1	5	-	1000

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Quinone	0.1	0.1	-	100 mg/m3
Rhodium, metal fume and insoluble compounds	1 mg/m3	0.1 mg/m3	-	100 mg/m3
Rhodium, soluble compounds	0.01 mg/m3	0.001 mg/m3	-	2 mg/m3
Ronnel	5 mg/m3	15 mg/m3	-	300 mg/m3
Rotenone	5 mg/m3	5 mg/m3	-	2500 mg/m3
Rouge (td)	-	15 mg/m3	-	-
Rouge (rf)	-	5 mg/m3	-	-

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Selenium compounds (as Se)	0.2 mg/m3	0.2 mg/m3	-	1 mg/m3
Selenium hexafluoride (as Se)	0.05	0.05	-	2
Silica, amorphous, precipitated and gel	-	3 mg/m3	-	3000 mg/m3
Silica, amorphous, diatomaceous earth	-	3 mg/m3	-	3000 mg/m3
Silica, crystalline cristobalite	0.025 mg/m3	3 mg/m3	-	25 mg/m3 ++
Silica, crystalline quartz	0.025 mg/m3	3 mg/m3	-	50 mg/m3 ++
Silica, crystalline tripoli	-	3 mg/m3	-	50 mg/m3 ++
Silica, crystalline tridymite	-	3 mg/m3	-	25 mg/m3
Silica, fused	-	3 mg/m3	-	-
Silicates (lees than 1% crystalline silica) mica	3 mg/m3	3 mg/m3	-	1500
Soapstone (td)	6 mg/m3	3 mg/m3	-	3000 mg/m3
Soapstone (rf)	3 mg/m3	3 mg/m3	-	3000 mg/m3
Silicon (td)	-	15 mg/m3	-	-
Silicon (rf)	3 mg/m3	5 mg/m3	-	-
Silicon carbide (td)	10 mg/m3	15 mg/m3	-	-
Silicon carbide (rf)	-	5 mg/m3	-	-
Silver, metal and soluble compounds (as Ag)	0.1 mg/m3	0.01 mg/m3	-	10 mg/m3
Sodium fluoro- acetate	0.05 mg/m3	0.05 mg/m3	-	2.5 mg/m3
Sodium hydroxide	2 mg/m3+	2 mg/m3	2 mg/m3 NIOSH	10 mg/m3
Starch (td)	10 mg/m3	15 mg/m3	-	-
Starch (rf)	-	5 mg/m3	-	-
Stibine (Antimony hydride)	0.1	0.1	-	5
Stoddard solvent	100	500	1800 mg/m3 /15min NIOSH	20,000 mg/m3
Strychnine	0.15 mg/m3	0.15 mg/m3	-	3 mg/m3
Styrene	20	2 mg/m3	40 ACGIH 100 NIOSH	700
Sucrose (td)	10 mg/m3	15 mg/m3	-	-
Sucrose (rf)	-	5 mg/m3	-	-
Sulfur dioxide	2	5	5 ACGIH / NIOSH	100
Sulfur hexafluoride	1000	1000	-	-
Sulfuric acid	0.2 mg/m3	1 mg/m3	3 mg/m3+	15 mg/m3
Sulfur monochloride	1+	1	1 NIOSH	5
Sulfur pentafluoride	0.01+	0.025	0.01 NIOSH	1
Sulfuryl fluoride	5	5	10 ACGIH / NIOSH	200

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
2,4,5-T (2,4,5-trichloro- phenoxyacetic acid)	10 mg/m3	10 mg/m3	-	250 mg/m3
Talc (containing asbestos) See 29 CFR 1910.1001	0.1 f/cc (F)	3 mg/m3	-	1000 mg/m3 ++
Talc (containing no asbestos)	2 mg/m3	3 mg/m3	-	1000 mg/m3
Tantalum, metal and oxide dust	5 mg/m3	5 mg/m3	-	2500 mg/m3
TEDP (Sulfotep)	0.1 mg/m3	0.2 mg/m3	-	10 mg/m3
Tellurium and compounds (as Te)	0.1 mg/m3	0.1 mg/m3	-	25 mg/m3
Tellurium hexafluoride (as Te)	0.02	0.02	-	1
Temephos (td)	1 mg/m3	15 mg/m3	-	-
Temephos (rf)	-	5 mg/m3	-	-
TEPP (Tetraethyl pyrophosphate)	0.01 mg/m3	0.05 mg/m3	-	5 mg/m3
Terphenyls	0.53 +	1 +	0.5 NIOSH	500 mg/m3
1,1,1,2-Tetrachloro-2, 2-difluoroethane	500	500	-	2000
1,1,2,2-Tetrachloro-1, 2-difluoroethane	500	500	-	2000
1,1,2,2-Tetrachloroethane	1	5	-	100++
Tetrachloronaphthalene	2 mg/m3	2 mg/m3	-	Unknown
Tetraethyl lead (as Pb)	0.1 mg/m3	0.075 mg/m3	-	40 mg/m3
Tetrahydrofuran	50	200	100 ACGIH 250 NIOSH	2000 (LEL)
Tetramethyl lead (as Pb)	0.15 mg/m3	0.075 mg/m3	-	40 mg/m3
Tetramethyl succinonitrile	0.5	0.5	-	5
Tetranitromethane	0.005	1	-	4
Tetryl (2,4,6-Trinitro-phenylmethylnitramine)	1.5 mg/m3	1.5 mg/m3	-	750 mg/m3
Thallium, soluble compounds (as Tl)	0.1 mg/m3	0.1 mg/m3	-	15 mg/m3
4,4'-Thiobis (6-tert, Butyl-m-cresol) (td)	10 mg/m3	15 mg/m3	-	-
4,4'-Thiobis (6-tert, Butyl-m-cresol) (rf)	-	5 mg/m3	-	-
Thiram	1 mg/m3	5 mg/m3	-	100 mg/m3
Tin, inorganic compounds (except oxides) (as Sn)	2 mg/m3	2 mg/m3	-	100 mg/m3
Tin, organic compounds (as Sn)	0.1 mg/m3	0.1 mg/m3	-	25 mg/m3
Titanium dioxide (td)	10 mg/m3	15 mg/m3	-	5000 mg/m3 ++
Toluene	20	200	300 OSHA 500 /10min peak 150 NIOSH	500
Toluene-2,4-diisocyanate (TDI)	0.005	0.02+	-	2.5++
o-Toluidine	2	5	-	50++
Tributyl phosphate	0.2	5 mg/m3	-	30
1,1,2-Trichloroethane	10	10	-	100++
Trichloroethylene	10	2 mg/m3	25 ACGIH	1000 ++
Trichloronaphthalene	5 mg/m3	5 mg/m3	-	Unknown
1,2,3-Trichloropropane	10	50	-	100++
1,1,2-Trichloro-1,2,2- trifluoroethane	1000	1000	1250 ACGIH / NIOSH	2000
Triethylamine	1	25	3 ACGIH	200
Trifluorobromo- methane	1000	1000	-	40,000
2,4,6-Trinitrotoluene (TNT)	0.1 mg/m3	1.5 mg/m3	-	500 mg/m3
Triorthocresyl phosphate	0.1 mg/m3	0.1 mg/m3	-	40 mg/m3
Triphenyl phosphate	3 mg/m3	3 mg/m3	-	1000 mg/m3
Turpentine	20	100	-	800

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Uranium (as U) Soluble compounds	0.2 mg/m3	0.05 mg/m3	-	10 mg/m3++
Uranium (as U) Insoluble compounds	0.2 mg/m3	0.25 mg/m3	-	10 mg/m3++
Vanadium (rd) (as V2O5)	0.05 mg/m3	0.5 mg/m3 +	0.5 mg/m3	35 mg/m3
Vanadium (fume) (as V2O5)	0.05 mg/m3	0.1 mg/m3 +	0.1 mg/m3	35 mg/m3
Vegetable oil mist (td)	-	15 mg/m3	-	-
Vegetable oil mist (rf)	-	5 mg/m3	-	-
Vinyl toluene	50	100	100 ACGIH	400
Warfarin	0.1 mg/m3	0.1 mg/m3	-	100 mg/m3

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

Chemical Name	TLV ppm	PEL ppm	STEL/Ceiling ppm	IDLH ppm
Xylenes (o-, m-, p-isomers)	100	100	150 ACGIH / NIOSH	900
Xylidine	0.5	5	-	50
Yttrium	1 mg/m3	1 mg/m3	-	500 mg/m3
Zinc chloride fume	1 mg/m3	1 mg/m3	2 mg/m3 ACGIH / NIOSH	50 mg/m3
Zinc oxide fume	-	5 mg/m3	-	500 mg/m3
Zinc oxide (td)	2 mg/m3	15 mg/m3	-	500 mg/m3
Zinc oxide (rf)	-	5 mg/m3	-	500 mg/m3
Zinc stearate (td)	10 mg/m3	15 mg/m3	-	-
Zinc stearate (rf)	-	5 mg/m3	-	-
Zirconium compounds (as Zr)	5 mg/m3	5 mg/m3	10 mg/m3	25 mg/m3

" + " indicates a Ceiling Value

" ++ " indicates that the chemical is believed, by NIOSH, to be a potential Carcinogen.

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Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.