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Current Occupational Exposure Limits for Ontario Workplaces Required under Regulation 833

  • Issued: June 29, 2015
  • Content last reviewed: June 2015
  • Historical Occupational Exposure Limits for Ontario Workplaces Required under Regulation 833: 2010-2012 | 2013-2015

Employers are required under section 4 of Regulation 833, Control of Exposure to Biological or Chemical Agents (the “Regulation”), to limit the exposure of workers to specified hazardous biological or chemical agents in accordance with the values set out in the “Ontario Table” (which is Table 1 in the Regulation) or, if the agent is not listed in the Ontario Table, the 2013 ACGIH Table that is incorporated by reference in the Regulation.

For ease of reference, the following table contains all specific occupational exposure limits an employer must implement under s. 4 of the Regulation, i.e. it sets out information found in both the Ontario Table in Regulation 833 and the ACGIH Table.

In addition, the table includes listings (i.e. Petroleum ether, Rubber solvent and VM&P Naphtha) not included in either the Ontario Table or the ACGIH Table. The Ministry recommends that OELs for those substances be calculated using the recommended method referenced.

An employer has a duty and shall take all measures reasonably necessary in the circumstances to protect workers from exposure to a hazardous biological or chemical agent.

This table should not be solely relied upon to determine the exposure limits for substances. In order to determine all exposure limits, including excursion limits for a substance, please refer to the official version of the Regulation.

A B C D E F G H I J K – L M N O P Q – R S T U – V W – X – Y – Z

Go to endnotes and abbreviations at the bottom of the page.

Occupational Exposure Limits for Ontario Workplaces: A
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Acetaldehyde [75-07-0]   C 25 ppm  
  Acetic acid [64-19-7] 10 ppm 15 ppm  
  Acetic anhydride [108-24-7] ppm ppm  
  Acetone [67-64-1] 500 ppm 750 ppm  
  Acetone cyanohydrin [75-86-5], as CN   C 5 mg/m3 Skin
  Acetonitrile [75-05-8] 20 ppm   Skin
  Acetophenone [98-86-2] 10 ppm    
  Acetylene [74-86-2] Simple asphyxiant Simple asphyxiant  
  Acetylsalicylic acid (Aspirin) [50-78-2] mg/m3    
  Acrolein [107-02-8]   C 0.1 ppm Skin
  Acrylamide [79-06-1] 0.03 mg/m3 (IFV)   Skin
  Acrylic acid [79-10-7] ppm   Skin
  * Acrylonitrile [107-13-1] ppm C 10 ppm Skin
  Adipic acid [124-04-9] mg/m3    
  Adiponitrile [111-69-3] ppm   Skin
  Alachlor [15972-60-8] mg/m3 (IFV)    
  Aldrin [309-00-2]
0.05 mg/m3 (IFV)   Skin
Aliphatic hydrocarbon gases      
Alkane [C1-C4], except Butane, All isomers 1,000 ppm    
Butane, All isomers [106-97-8]; [75-28-5] 800 ppm    
  Allyl alcohol [107-18-6] 0.5 ppm   Skin
  Allyl bromide [106-95-6] 0.1 ppm 0.2 ppm Skin
  Allyl chloride [107-05-1] ppm ppm Skin
  Allyl glycidyl ether (AGE) [106-92-3] ppm    
  Allyl propyl disulfide [2179-59-1] 0.5 ppm    
  Aluminum metal [7429-90-5] and insoluble compounds mg/m3 (R)    
  4-Aminodiphenyl [92-67-1] (L)   Skin
  2-Aminopyridine [504-29-0] 0.5 ppm    
  Amitrole [61-82-5] 0.2 mg/m3    
  Ammonia [7664-41-7] 25 ppm 35 ppm  
  Ammonium chloride fume [12125-02-9] 10 mg/m3 20 mg/m3  
  Ammonium perfluorooctanoate [3825-26-1] 0.01 mg/m3   Skin
  Ammonium sulfamate [7773-06-0] 10 mg/m3    
  tert-Amyl methyl ether (TAME) [994-05-8] 20 ppm    
  Aniline [62-53-3] ppm   Skin
  o-Anisidine [90-04-0] 0.5 mg/m3   Skin
  p-Anisidine [104-94-9] 0.5 mg/m3   Skin
  Antimony [7440-36-0] and compounds, as Sb 0.5 mg/m3    
  Antimony hydride [7803-52-3] 0.1 ppm    
  Antimony trioxide [1309-64-4] production (L)    
  ANTU [86-88-4] 0.3 mg/m3   Skin
  Argon [7440-37-1] Simple asphyxiant Simple asphyxiant  
  * Arsenic, elemental arsenic and inorganic compounds [7440-38-2], and organic compounds (only where both inorganic and organic compounds are present), as As. 0.01 mg/m3 0.05 mg/m3  
  Arsine [7784-42-1] 0.005 ppm    
  * Asbestos - All forms [1332-21-4] 0.1 f/cc (F)    
  * Actinolite [77536-66-4] 0.1 f/cc (F)    
  * Amosite [12172-73-5] 0.1 f/cc (F)    
  * Anthophyllite [77536-67-5] 0.1 f/cc (F)    
  * Chrysotile [132207-32-0] 0.1 f/cc (F)    
  * Crocidolite [12001-28-4] 0.1 f/cc (F)    
  * Tremolite [77536-68-6] 0.1 f/cc (F)    
  Asphalt (Bitumen) fume [8052-42-4],
as benzene-soluble aerosol
0.5 mg/m3 (I)    
  Atrazine [1912-24-9] mg/m3    
  Azinphos-methyl [86-50-0] 0.2 mg/m3 (IFV)   Skin

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Occupational Exposure Limits for Ontario Workplaces: B
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Barium [7440-39-3] and soluble compounds,
as Ba
0.5 mg/m3    
  Barium sulfate [7727-43-7] 10 mg/m3    
  Benomyl [17804-35-2] mg/m3 (I)    
  Benz[a]anthracene [56-55-3] (L)    
Benzaldehyde [100-52-7]   ppm
17 mg/m3
 
  * Benzene [71-43-2] 0.5 ppm 2.5 ppm Skin
  Benzidine [92-87-5] (L)   Skin
  Benzo[b]fluoranthene [205-99-2] (L)    
  Benzo[a]pyrene [50-32-8] (L)    
  Benzotrichloride [98-07-7]   C 0.1 ppm Skin
  Benzoyl chloride [98-88-4]   C 0.5 ppm  
  Benzoyl peroxide [94-36-0] mg/m3    
  Benzyl acetate [140-11-4] 10 ppm    
  Benzyl chloride [100-44-7] ppm    
Beryllium and its compounds, as Be [7440-41-7] 0.002 mg/m3 0.01 mg/m3  
  Biphenyl [92-52-4] 0.2 ppm    
  Bismuth telluride      
  Undoped [1304-82-1] 10 mg/m3    
  Se-doped, as Bi2Te3 mg/m3    
  Borate compounds, Inorganic [1330-43-4; 1303-96-4; 10043-35-3; 12179-04-3] mg/m3 (I) mg/m3 (I)  
  Boron oxide [1303-86-2] 10 mg/m3    
  Boron tribromide [10294-33-4]   C 1 ppm  
  Boron trifluoride [7637-07-2]   C 1 ppm  
  Bromacil [314-40-9] 10 mg/m3    
  Bromine [7726-95-6] 0.1 ppm 0.2 ppm  
  Bromine pentafluoride [7789-30-2] 0.1 ppm    
  Bromoform [75-25-2] 0.5 ppm    
  1-Bromopropane [106-94-5] 10 ppm    
  1,3-Butadiene [106-99-0] ppm    
Butane, All isomers [106-97-8; 75-28-5] See Aliphatic Hydrocarbon gases See Aliphatic Hydrocarbon gases  
  n-Butanol [71-36-3] 20 ppm    
  sec-Butanol [78-92-2] 100 ppm    
  tert-Butanol [75-65-0] 100 ppm    
  Butenes, All isomers [106-98-9; 107-01-7; 590-18-1; 624-64-6; 25167-67-3] 250 ppm    
  Isobutene [115-11-7] 250 ppm    
  2-Butoxyethanol (EGBE) [111-76-2] 20 ppm    
  2-Butoxyethyl acetate (EGBEA) [112-07-2] 20 ppm    
  n-Butyl acetate [123-86-4] 150 ppm 200 ppm  
  sec-Butyl acetate [105-46-4] 200 ppm    
  tert-Butyl acetate [540-88-5] 200 ppm    
  n-Butyl acrylate [141-32-2] ppm    
  n-Butylamine [109-73-9]   C 5 ppm Skin
  Butylated hydroxytoluene (BHT) [128-37-0] mg/m3 (IFV)    
  tert-Butyl chromate, as CrO3 [1189-85-1]   C 0.1 mg/m3 Skin
  n-Butyl glycidyl ether (BGE) [2426-08-6] ppm   Skin
  n-Butyl lactate [138-22-7] ppm    
  n-Butyl mercaptan [109-79-5] 0.5 ppm    
  o-sec-Butylphenol [89-72-5] ppm   Skin
  p-tert-Butyl toluene [98-51-1] ppm    

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Occupational Exposure Limits for Ontario Workplaces: C
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Cadmium [7440-43-9]
Cadmium compounds, as Cd
0.01 mg/m3
0.002 mg/m3 (R)
   
Calcium chloride [10043-52-4] mg/m3    
  Calcium chromate [13765-19-0], as Cr 0.001 mg/m3    
  Calcium cyanamide [156-62-7] 0.5 mg/m3    
  Calcium hydroxide [1305-62-0] mg/m3    
  Calcium oxide [1305-78-8] mg/m3    
  Calcium silicate - synthetic nonfibrous [1344-95-2] 10 mg/m3 (E)    
  Calcium sulfate [7778-18-9; 10034-76-1; 10101-41-4; 13397-24-5)] 10 mg/m3 (I)    
  Camphor, synthetic [76-22-2] ppm ppm  
  Caprolactam [105-60-2] mg/m3 (IFV)    
  Captafol [2425-06-1] 0.1 mg/m3   Skin
  Captan [133-06-2] mg/m3 (I)    
  Carbaryl [63-25-2] 0.5 mg/m3 (IFV)   Skin
  Carbofuran [1563-66-2] 0.1 mg/m3 (IFV)    
  Carbon black [1333-86-4] mg/m3 (I)    
  Carbon dioxide [124-38-9] 5,000 ppm 30,000 ppm  
  Carbon disulfide [75-15-0] ppm   Skin
Carbon monoxide [630-08-0] 25 ppm    
  Carbon tetrabromide [558-13-4] 0.1 ppm 0.3 ppm  
Carbon tetrachloride [56-23-5] ppm ppm Skin
  Carbonyl fluoride [353-50-4] ppm ppm  
  Carbonyl sulfide [463-58-1] 5 ppm    
  Catechol [120-80-9] ppm   Skin
  Cellulose [9004-34-6] 10 mg/m3    
  Cesium hydroxide [21351-79-1] mg/m3    
Charcoal, except activated [16291-96-6] 10 mg/m3    
  Chlordane [57-74-9] 0.5 mg/m3   Skin
  Chlorinated camphene [8001-35-2] 0.5 mg/m3 mg/m3 Skin
Chlorinated diphenyl oxides [55720-99-5] 0.5 mg/m3 mg/m3  
  Chlorine [7782-50-5] 0.5 ppm ppm  
  Chlorine dioxide [10049-04-4] 0.1 ppm 0.3 ppm  
  Chlorine trifluoride [7790-91-2]   C 0.1 ppm  
  Chloroacetaldehyde [107-20-0]   C 1 ppm  
  Chloroacetone [78-95-5]   C 1 ppm Skin
  2-Chloroacetophenone [532-27-4] 0.05 ppm    
  Chloroacetyl chloride [79-04-9] 0.05 ppm 0.15 ppm Skin
  Chlorobenzene [108-90-7] 10 ppm    
o-Chlorobenzaldehyde [89-98-5]   ppm
23 mg/m3
 
  o-Chlorobenzylidene malononitrile [2698-41-1]   C 0.05 ppm Skin
  Chlorobromomethane [74-97-5] 200 ppm    
  Chlorodifluoromethane [75-45-6] 1,000 ppm    
Chlorodiphenyl (42% chlorine) [53469-21-9]
Chlorodiphenyl (54% chlorine) [11097-69-1]
See Polychlorinated Biphenyls (PCBs) See Polychlorinated Biphenyls (PCBs)  
  Chloroform [67-66-3] 10 ppm    
  bis(Chloromethyl) ether [542-88-1] 0.001 ppm    
  Chloromethyl methyl ether [107-30-2] (L)    
  1-Chloro-1-nitropropane [600-25-9] ppm    
  Chloropentafluoroethane [76-15-3] 1,000 ppm    
  Chloropicrin [76-06-2] 0.1 ppm    
  1-Chloro-2-propanol [127-00-4] and
2-Chloro-1-propanol [78-89-7]
ppm   Skin
  β-Chloroprene [126-99-8] 10 ppm   Skin
  2-Chloropropionic acid [598-78-7] 0.1 ppm   Skin
  o-Chlorostyrene [2039-87-4] 50 ppm 75 ppm  
  o-Chlorotoluene [95-49-8] 50 ppm    
  Chlorpyrifos [2921-88-2] 0.1 mg/m3 (IFV)   Skin
  Chromite ore processing (Chromate), as Cr 0.05 mg/m3    
  Chromium [7440-47-3] and inorganic compounds, as Cr      
  Metal and Cr III compounds 0.5 mg/m3    
  Water- soluble Cr VI compounds 0.05 mg/m3    
  Insoluble Cr VI compounds 0.01 mg/m3    
  Chromyl chloride [14977-61-8] 0.025 ppm    
  Chrysene [218-01-9] (L)    
  Citral [5392-40-5] 5 ppm (IFV)   Skin
  Clopidol [2971-90-6] mg/m3 (IFV)    
  Coal dust      
  Anthracite 0.4 mg/m3 (R)    
  Bituminous 0.9 mg/m3 (R)    
  Coal tar pitch volatiles [65996-93-2],
as benzene soluble aerosol
0.2 mg/m3    
  Cobalt [7440-48-4] and inorganic compounds, as Co 0.02 mg/m3    
  Cobalt carbonyl [10210-68-1], as Co 0.1 mg/m3    
  Cobalt hydrocarbonyl [16842-03-8], as Co 0.1 mg/m3    
N-Cocomorpholine [1541-81-7] ppm
52 mg/m3
  Skin
  * Coke Oven Emissions1 0.15 mg/m3    
  Copper [7440-50-8]      
  Fume 0.2 mg/m3    
  Dusts and mists, as Cu 1 mg/m3    
  Cotton dust, raw, untreated 0.1 mg/m3 (T)    
  Coumaphos [56-72-4] 0.05 mg/m3 (IFV)   Skin
Coumarone-Indene Resins (total dust) [63393-89-5] 5 mg/m3    
  Cresol, All isomers [1319-77-3; 95-48-7; 108-39-4; 106-44-5] 20 mg/m3 (IFV)   Skin
  Crotonaldehyde [4170-30-3]   C 0.3 ppm Skin
  Crufomate [299-86-5] mg/m3    
  Cumene [98-82-8] 50 ppm    
  Cyanamide [420-04-2] mg/m3    
  Cyanogen [460-19-5] 10 ppm    
  Cyanogen chloride [506-77-4]   C 0.3 ppm  
  Cyclohexane [110-82-7] 100 ppm    
  Cyclohexanol [108-93-0] 50 ppm   Skin
  Cyclohexanone [108-94-1] 20 ppm 50 ppm Skin
  Cyclohexene [110-83-8] 300 ppm    
  Cyclohexylamine [108-91-8] 10 ppm    
  Cyclonite [121-82-4] 0.5 mg/m3   Skin
  Cyclopentadiene [542-92-7] 75 ppm    
  Cyclopentane [287-92-3] 600 ppm    
  Cyhexatin [13121-70-5] mg/m3    
Cymene (sum of o-,m-and p-isomers) [25155-15-1] 50 ppm
274 mg/m3
  Skin

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Occupational Exposure Limits for Ontario Workplaces: D
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  2,4-D [94-75-7] 10 mg/m3 (I)   Skin
  DDT [50-29-3] mg/m3    
  Decaborane [17702-41-9] 0.05 ppm 0.15 ppm Skin
  Demeton [8065-48-3] 0.05 mg/m3 (IFV)   Skin
  Demeton-S-methyl [919-86-8] 0.05 mg/m3 (IFV)   Skin
  Diacetone alcohol [123-42-2] 50 ppm    
  Diacetyl [431-03-8] 0.01 ppm 0.02 ppm  
  Diazinon [333-41-5] 0.01 mg/m3 (IFV)   Skin
  Diazomethane [334-88-3] 0.2 ppm    
  Diborane [19287-45-7] 0.1 ppm    
  2-N-Dibutylaminoethanol [102-81-8] 0.5 ppm   Skin
  Dibutyl phenyl phosphate [2528-36-1] 0.3 ppm   Skin
  Dibutyl phosphate [107-66-4] mg/m3 (IFV)   Skin
  Dibutyl phthalate [84-74-2] mg/m3    
  Dichloroacetic acid [79-43-6] 0.5 ppm   Skin
  Dichloroacetylene [7572-29-4]   C 0.1 ppm  
  o-Dichlorobenzene [95-50-1] 25 ppm 50 ppm  
  p-Dichlorobenzene [106-46-7] 10 ppm    
  3,3'-Dichlorobenzidine [91-94-1] (L)   Skin
  1,4-Dichloro-2-butene [764-41-0] 0.005 ppm   Skin
  Dichlorodifluoromethane [75-71-8] 1,000 ppm    
  1,3-Dichloro-5,5-dimethyl hydantoin [118-52-5] 0.2 mg/m3 0.4 mg/m3  
  1,1-Dichloroethane [75-34-3] 100 ppm    
1,1 Dichloroethene [75-35-4] 1 ppm
4 mg/m3
20 ppm
80 mg/m3
 
1,3-Dichloro-2-Propanol [96-23-1]   ppm
mg/m3
Skin
  1,2-Dichloroethylene, All isomers [540-59-0; 156-59-2; 156-60-5] 200 ppm    
  Dichloroethyl ether [111-44-4] ppm 10 ppm Skin
  Dichlorofluoromethane [75-43-4] 10 ppm    
  Dichloromethane [75-09-2] 50 ppm    
  1,1-Dichloro-1-nitroethane [594-72-9] ppm    
  1,3-Dichloropropene [542-75-6] ppm   Skin
  2,2-Dichloropropionic acid [75-99-0] mg/m3(I)    
  Dichlorotetrafluoroethane [76-14-2] 1,000 ppm    
  Dichlorvos (DDVP) [62-73-7] 0.1 mg/m3 (IFV)   Skin
  Dicrotophos [141-66-2] 0.05 mg/m3 (IFV)   Skin
  Dicyclopentadiene [77-73-6] ppm    
  Dicyclopentadienyl iron, as Fe [102-54-5] 10 mg/m3    
  Dieldrin [60-57-1] 0.1 mg/m3 (IFV)   Skin
  Diesel fuel [68334-30-5; 68476-30-2; 68476-31-3; 68476-34-6; 77650-28-3],
as total hydrocarbons
100 mg/m3 (IFV)   Skin
  Diethanolamine [111-42-2] mg/m3 (IFV)   Skin
  Diethylamine [109-89-7] ppm 15 ppm Skin
  2-Diethylaminoethanol [100-37-8] ppm   Skin
  Diethylene glycol monobutyl ether [112- 34-5] 10 ppm (IFV)    
Diethylene glycol monoethyl ether [111- 90-0] 30 ppm
165 mg/m3
   
  Diethylene triamine [111-40-0] ppm   Skin
Di(2-ethylhexyl)phthalate (DEHP) [117-81-7] mg/m3 mg/m3  
  N,N-Diethylhydroxylamine [3710-84-7] 2 ppm    
  Diethyl ketone [96-22-0] 200 ppm 300 ppm  
  Diethyl phthalate [84-66-2] mg/m3    
  Difluorodibromomethane [75-61-6] 100 ppm    
  Diglycidyl ether (DGE) [2238-07-5] 0.01 ppm    
Diisodecyl phthalate [26761-40-0] mg/m3    
  Diisobutyl ketone [108-83-8] 25 ppm    
  Diisopropylamine [108-18-9] ppm   Skin
  N,N-Dimethylacetamide [127-19-5] 10 ppm   Skin
  Dimethylamine [124-40-3] ppm 15 ppm  
3-(Dimethylamino) propylamine [109-55-7] 0.5 ppm
mg/m3
  Skin
  Dimethylaniline [121-69-7] ppm 10 ppm Skin
  Dimethyl carbamoyl chloride [79-44-7] 0.005 ppm   Skin
N, N-Dimethyl-cyclohexylamine [98-94-2]   ppm
26 mg/m3
 
  Dimethyl disulfide [624-92-0] 0.5 ppm   Skin
  Dimethylethoxysilane [14857-34-2] 0.5 ppm 1.5 ppm  
N, N-Dimethyl-ethanolamine [108-01-0] ppm
11 mg/m3
ppm
22 mg/m3
 
  Dimethylformamide [68-12-2] 10 ppm   Skin
  1,1-Dimethylhydrazine [57-14-7] 0.01 ppm   Skin
  Dimethyl phthalate [131-11-3] mg/m3    
  Dimethyl sulfate [77-78-1] 0.1 ppm   Skin
  Dimethyl sulfide [75-18-3] 10 ppm    
Dimethyl terephthalate [120-61-6] mg/m3    
Dimethyl 2,3,5,6-tetracholoroterephthalate [1861-32-1] mg/m3    
  Dinitrobenzene, All isomers [528-29-0; 99-65-0; 100-25-4; 25154-54-5] 0.15 ppm   Skin
  Dinitro-o-cresol [534-52-1] 0.2 mg/m3   Skin
  3,5-Dinitro-o-toluamide [148-01-6] mg/m3    
  Dinitrotoluene [25321-14-6] 0.2 mg/m3   Skin
  1,4-Dioxane [123-91-1] 20 ppm   Skin
  Dioxathion [78-34-2] 0.1 mg/m3 (IFV)   Skin
  1,3-Dioxolane [646-06-0] 20 ppm    
  Diphenylamine [122-39-4] 10 mg/m3    
  Dipropyl ketone [123-19-3] 50 ppm    
Dipropylene glycol monomethyl ether acetate [88917-22-0] 100 ppm
776 mg/m3
150 ppm
1,164 mg/m3
 
Diquat [2764-72-9; 85-00-7; 6385-62-2] 0.5 mg/m3
0.1 mg/m3 (R)
  Skin
  Disulfiram [97-77-8] mg/m3    
  Disulfoton [298-04-4] 0.05 mg/m3 (IFV)   Skin
  Diuron [330-54-1] 10 mg/m3    
  Divinyl benzene [1321-74-0] 10 ppm    
  Dodecyl mercaptan [112-55-0] 0.1 ppm    

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Occupational Exposure Limits for Ontario Workplaces: E
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Endosulfan [115-29-7] 0.1 mg/m3 (IFV)   Skin
  Endrin [72-20-8] 0.1 mg/m3   Skin
Enflurane [13838-16-9] ppm
16 mg/m3
   
  Epichlorohydrin [106-89-8] 0.5 ppm   Skin
  EPN [2104-64-5] 0.1 mg/m3 (I)   Skin
  Ethane [74-84-0] See Aliphatic Hydrocarbon gases See Aliphatic Hydrocarbon gases  
  Ethanol [64-17-5]   1,000 ppm  
  Ethanolamine [141-43-5] ppm ppm  
  Ethion [563-12-2] 0.05 mg/m3 (IFV)   Skin
  2-Ethoxyethanol (EGEE) [110-80-5] ppm   Skin
  2-Ethoxyethyl acetate (EGEEA) [111-15-9] ppm   Skin
  Ethyl acetate [141-78-6] 400 ppm    
  Ethyl acrylate [140-88-5] ppm 15 ppm  
  Ethylamine [75-04-7] ppm 15 ppm Skin
  Ethyl amyl ketone [541-85-5] 10 ppm    
  Ethyl benzene [100-41-4] 20 ppm    
  Ethyl bromide [74-96-4] ppm   Skin
  Ethyl tert-butyl ether (ETBE) [637-92-3] 25 ppm    
  Ethyl butyl ketone [106-35-4] 50 ppm 75 ppm  
  Ethyl chloride [75-00-3] 100 ppm   Skin
  Ethyl cyanoacrylate [7085-85-0] 0.2 ppm    
Ethyl-3-ethoxy propionate [763-69-9] 50 ppm
300 mg/m3
   
  Ethylene [74-85-1] 200 ppm    
  Ethylene chlorohydrin [107-07-3]   C 1 ppm Skin
  Ethylenediamine [107-15-3] 10 ppm   Skin
Ethylene dibromide [106-93-4] (L)   Skin
  Ethylene dichloride [107-06-2] 10 ppm    
  Ethylene glycol [107-21-1]   C 100 mg/m3 (H)  
Ethylene glycol dimethyl ether [110-71-4] ppm
18 mg/m3
  Skin
  Ethylene glycol dinitrate (EGDN) [628-96-6] 0.05 ppm   Skin
Ethylene glycol mono-n-propyl ether [2807-30-9] 25 ppm
110 mg/m3
  Skin
Ethylene glycol mononitrate [16051-48-2] 0.05 ppm
0.22 mg/m3
  Skin
  * Ethylene oxide [75-21-8] ppm
1.8 mg/m3
10 ppm
18 mg/m3
 
  Ethyleneimine [151-56-4] 0.05 ppm 0.1 ppm Skin
  Ethyl ether [60-29-7] 400 ppm 500 ppm  
  Ethyl formate [109-94-4]   100 ppm  
  2-Ethylhexanoic acid [149-57-5] mg/m3 (IFV)    
  Ethylidene norbornene [16219-75-3]   C 5 ppm  
  Ethyl mercaptan [75-08-1] 0.5 ppm    
Ethyl methacrylate [97-63-2] 50 ppm 100 ppm  
  N-Ethylmorpholine [100-74-3] ppm   Skin
  Ethyl silicate [78-10-4] 10 ppm    

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Occupational Exposure Limits for Ontario Workplaces: F
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Fenamiphos [22224-92-6] 0.05 mg/m3 (IFV)   Skin
  Fensulfothion [115-90-2] 0.01 mg/m3 (IFV)   Skin
  Fenthion [55-38-9] 0.05 mg/m3 (IFV)   Skin
  Ferbam [14484-64-1] mg/m3 (I)    
  Ferrovanadium dust [12604-58-9] mg/m3 mg/m3  
Flour dust See Wheat Flour Dust (total dust) See Wheat Flour Dust (total dust)  
  Fluorides, as F 2.5 mg/m3    
  Fluorine [7782-41-4] ppm ppm  
  Fonofos [944-22-9] 0.01 mg/m3 (IFV)   Skin
Forane [26675-46-7] ppm
15 mg/m3
   
Formaldehyde [50-00-0]   STELppm
C 1.5 ppm
 
  Formamide [75-12-7] 10 ppm   Skin
  Formic acid [64-18-6] ppm 10 ppm  
  Furfural [98-01-1] ppm   Skin
  Furfuryl alcohol [98-00-0] 10 ppm 15 ppm Skin

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Occupational Exposure Limits for Ontario Workplaces: G
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Gallium arsenide [1303-00-0] 0.0003 mg/m3 (R)    
  Gasoline [86290-81-5] 300 ppm 500 ppm  
  Germanium tetrahydride [7782-65-2] 0.2 ppm    
  Glutaraldehyde [111-30-8], activated and inactivated   C 0.05 ppm  
  Glycerin mist [56-81-5] 10 mg/m3    
  Glycidol [556-52-5] ppm    
  Glyoxal [107-22-2] 0.1 mg/m3 (IFV)    
  Grain dust (oat, wheat, barley) mg/m3    
  Graphite (all forms except graphite fibers) [7782-42-5] mg/m3 (R)    

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Occupational Exposure Limits for Ontario Workplaces: H
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Hafnium [7440-58-6] and compounds, as Hf 0.5 mg/m3    
Halothane [151-67-7] ppm
16 mg/m3
   
  Helium [7440-59-7] Simple asphyxiant Simple asphyxiant  
  Heptachlor [76-44-8] and
Heptachlor epoxide [1024-57-3]
0.05 mg/m3   Skin
  Heptane, All isomers [142-82-5; 590-35-2; 565-59-3; 108-08-7; 591-76-4; 589-34-4] 400 ppm 500 ppm  
Heptyl acetate [112-06-1] 50 ppm
320 mg/m3
   
  Hexachlorobenzene [118-74-1] 0.002 mg/m3   Skin
  Hexachlorobutadiene [87-68-3] 0.02 ppm   Skin
  Hexachlorocyclopentadiene [77-47-4] 0.01 ppm    
  Hexachloroethane [67-72-1] ppm   Skin
  Hexachloronaphthalene [1335-87-1] 0.2 mg/m3   Skin
  Hexafluoroacetone [684-16-2] 0.1 ppm   Skin
  Hexafluoropropylene [116-15-4] 0.1 ppm    
  Hexahydrophthalic anhydride, All isomers [85-42-7; 13149-00-3; 14166-21-3]   C 0.005 mg/m3 (IFV)  
Hexamethylenetetramine (HMT) [100-97-0]   0.35 ppm
mg/m3
 
Hexamethyl phosphoramide [680-31-9] (L)   Skin
  n-Hexane [110-54-3] 50 ppm   Skin
  Hexane, Other isomers 500 ppm 1,000 ppm  
  1,6-Hexanediamine [124-09-4] 0.5 ppm    
  1-Hexene [592-41-6] 50 ppm    
  sec-Hexyl acetate [108-84-9] 50 ppm    
Hexyl acetate (isomeric mixture) [88230-35-7] 50 ppm
294 mg/m3
   
  Hexylene glycol [107-41-5]   C 25 ppm  
  Hydrazine [302-01-2] 0.01 ppm   Skin
  Hydrogen [1333-74-0] Simple asphyxiant Simple asphyxiant  
Hydrogenated terphenyls2 [61788-32-7] 0.5 ppm    
  Hydrogen bromide [10035-10-6]   C 2 ppm  
  Hydrogen chloride [7647-01-0]   C 2 ppm  
  Hydrogen cyanide and Cyanide salts, as CN
Hydrogen cyanide [74-90-8]
Cyanide salts [592-01-8; 151-50-8; 143-33-9]
  C 4.7 ppm
C 5 mg/m3
Skin
  Hydrogen fluoride [7664-39-3], as F 0.5ppm C 2 ppm Skin
  Hydrogen peroxide [7722-84-1] ppm    
  Hydrogen selenide [7783-07-5], as Se 0.05 ppm    
Hydrogen sulfide [7783-06-4] 10 ppm 15 ppm  
  Hydroquinone [123-31-9] mg/m3    
  2-Hydroxypropyl acrylate [999-61-1] 0.5 ppm   Skin

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Occupational Exposure Limits for Ontario Workplaces: I
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Indene [95-13-6] ppm    
  Indium [7440-74-6] and compounds, as In 0.1 mg/m3    
  Iodine and Iodides      
  Iodine [7553-56-2] 0.01 ppm (IFV) 0.1 ppm (V)  
  Iodides 0.01 ppm (IFV)    
  Iodoform [75-47-8] 0.6 ppm    
  Iron oxide (Fe2 O3) [1309-37-1] mg/m3 (R)    
  Iron pentacarbonyl [13463-40-6], as Fe 0.1 ppm 0.2 ppm  
  Iron salts, soluble, as Fe mg/m3    
  Isoamyl alcohol [123-51-3] 100 ppm 125 ppm  
  Isobutanol [78-83-1] 50 ppm    
  Isobutyl acetate [110-19-0] 150 ppm    
  Isobutyl nitrite [542-56-3]   C 1 ppm (IFV)  
  * Isocyanates, organic compounds      
  * Toluene diisocyanate (TDI) [584-84-9] [91-08-7] 0.005 ppm C 0.02 ppm  
  * Methylene bisphenyl isocyanate (MDI) [101-68-8] 0.005 ppm C 0.02 ppm  
  * Hexamethylene diisocyanate (HDI) [822-06-0] 0.005 ppm C 0.02 ppm  
  * Isophorone diisocyanate (IPDI) [4098-71-9] 0.005 ppm C 0.02 ppm  
  * Methylene bis (4-cyclohexylisocyanate) [5124-30-1] 0.005 ppm C 0.02 ppm  
  * Methyl isocyanate [624-83-9]

0.02 ppm   Skin
  Isooctyl alcohol [26952-21-6] 50 ppm   Skin
  Isophorone [78-59-1]   C 5 ppm  
  2-Isopropoxyethanol [109-59-1] 25 ppm   Skin
  Isopropyl acetate [108-21-4] 100 ppm 200 ppm  
  Isopropylamine [75-31-0] ppm 10 ppm  
Isopropylaminoethanols [109-56-8; 121-93-7]   400 ppm
1,900 mg/m3
 
  N-Isopropylaniline [768-52-5] ppm   Skin
Isosorbide dinitrate [87-33-2] 0.2 mg/m3   Skin
  Isopropyl ether [108-20-3] 250 ppm 310 ppm  
  Isopropyl glycidyl ether (IGE) [4016-14-2] 50 ppm 75 ppm  

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Occupational Exposure Limits for Ontario Workplaces: K-L
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Kaolin [1332-58-7] mg/m3  (E,  R)    
  Kerosene [8008-20-6; 64742-81-0] / Jet fuels,
as total hydrocarbon vapour
200 mg/m3 (P)   Skin
  Ketene [463-51-4] 0.5 ppm 1.5 ppm  
  * Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb      
  * Elemental lead, inorganic and organic compounds of lead, as Pb except tetraethyl lead [78-00-2] 0.05 mg/m3   Skin (organic compounds)
  * Tetraethyl lead, as Pb [78-00-2] 0.10 mg/m3 0.30 mg/m3  
  * Lead chromate [7758-97-6]      
  * as Pb (see listing for Lead [7439-92-1]) 0.05 mg/m3    
  * as Cr 0.012 mg/m3    
Lincomycin [154-21-2] 0.1 mg/m3    
  Lindane [58-89-9] 0.5 mg/m3   Skin
  Lithium hydride [7580-67-8] 0.025 mg/m3    
  L.P.G. (Liquefied petroleum gas) [68476-85-7] See Aliphatic Hydrocarbons gases See Aliphatic Hydrocarbons gases  
Lithium hydroxide
     
Anhydrous [1310-65-2]   mg/m3  
Monohydrate [1310-66-3]   mg/m3  

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Occupational Exposure Limits for Ontario Workplaces: M
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Magnesium oxide [1309-48-4] 10 mg/m3 (I)    
  Malathion [121-75-5] mg/m3 (IFV)   Skin
  Maleic anhydride [108-31-6] 0.01 mg/m3 (IFV)    
Manganese [7439-96-5] and
inorganic compounds, as Mn
0.2 mg/m3    
  Manganese cyclopentadienyl tricarbonyl
[12079-65-1], as Mn
0.1 mg/m3   Skin
  * Mercury [7439-97-6], elemental mercury, inorganic and organic compounds of mercury, as Hg      
  * All forms of except alkyl, as Hg 0.025 mg/m3   Skin
  * Alkyl compounds of, as Hg 0.01 mg/m3 0.03 mg/m3 Skin
  Mesityl oxide [141-79-7] 15 ppm 25 ppm  
  Methacrylic acid [79-41-4] 20 ppm    
  Methane [74-82-8] See Aliphatic Hydrocarbons gases See Aliphatic Hydrocarbons gases  
  Methanol [67-56-1] 200 ppm 250 ppm Skin
  Methomyl [16752-77-5] 2.5 mg/m3    
  Methoxychlor [72-43-5] 10 mg/m3    
  2-Methoxyethanol (EGME) [109-86-4] 0.1 ppm   Skin
  2-Methoxyethyl acetate (EGMEA) [110-49-6] 0.1 ppm   Skin
Methoxyflurane [76-38-0] ppm
13 mg/m3
   
  (2-Methoxymethylethoxy) propanol (DPGME) [34590-94-8] 100 ppm 150 ppm Skin
  4-Methoxyphenol [150-76-5] mg/m3    
  1-Methoxy-2-propanol (PGME) [107-98-2] 50 ppm 100 ppm  
  Methyl acetate [79-20-9] 200 ppm 250 ppm  
  Methyl acetylene [74-99-7] 1,000 ppm    
  Methyl acetylene-propadiene mixture (MAPP) [59355-75-8] 1,000 ppm 1,250 ppm  
  Methyl acrylate [96-33-3] ppm   Skin
  Methylacrylonitrile [126-98-7] ppm   Skin
  Methylal [109-87-5] 1,000 ppm    
  Methylamine [74-89-5] ppm 15 ppm  
Methyl n-amyl ketone [110-43-0] 25 ppm
115 mg/m3
   
  N-Methyl aniline [100-61-8] 0.5 ppm   Skin
  Methyl bromide [74-83-9] ppm   Skin
Methyl tert-butyl ether (MTBE) [1634-04-4] 40 ppm    
Methyl n-butyl ketone [591-78-6] ppm
mg/m3
  Skin
  Methyl chloride [74-87-3] 50 ppm 100 ppm Skin
  Methyl chloroform [71-55-6] 350 ppm 450 ppm  
  Methyl 2-cyanoacrylate [137-05-3] 0.2 ppm    
  Methylcyclohexane [108-87-2] 400 ppm    
  Methylcyclohexanol [25639-42-3] 50 ppm    
  o-Methylcyclohexanone [583-60-8] 50 ppm 75 ppm Skin
  2-Methylcyclopentadienyl manganese tricarbonyl [12108-13-3], as Mn 0.2 mg/m3   Skin
  Methyl demeton [8022-00-2] 0.05 mg/m3 (IFV)   Skin
4,4'-Methylene bis(2-chloroaniline) (MBOCA; MOCA®) [101-14-4] 0.0005 ppm
0.005 mg/m3
  Skin
4,4'-Methylene dianiline [101-77-9] 0.04 mg/m3   Skin
  Methyl ethyl ketone (MEK) [78-93-3] 200 ppm 300 ppm  
  Methyl ethyl ketone peroxide [1338-23-4]   C 0.2 ppm  
  Methyl formate [107-31-3] 100 ppm 150 ppm  
  Methyl hydrazine [60-34-4] 0.01 ppm   Skin
  Methyl iodide [74-88-4] ppm   Skin
  Methyl isoamyl ketone [110-12-3] 20 ppm 50 ppm  
  Methyl isobutyl carbinol [108-11-2] 25 ppm 40 ppm Skin
  Methyl isobutyl ketone [108-10-1] 20 ppm 75 ppm  
  Methyl isopropyl ketone [563-80-4] 20 ppm    
  Methyl mercaptan [74-93-1] 0.5 ppm    
  Methyl methacrylate [80-62-6] 50 ppm 100 ppm  
  1-Methyl naphthalene [90-12-0] and
2-Methyl naphthalene [91-57-6]
0.5 ppm   Skin
  Methyl parathion [298-00-0] 0.02 mg/m3 (IFV)   Skin
  Methyl propyl ketone [107-87-9]   150 ppm  
N-Methyl-2-pyrrolidone [872-50-4] 400 mg/m3    
  Methyl silicate [681-84-5] ppm    
  α-Methyl styrene [98-83-9] 10 ppm    
  Methyl vinyl ketone [78-94-4]   C 0.2 ppm Skin
  Metribuzin [21087-64-9] mg/m3    
  Mevinphos [7786-34-7] 0.01 mg/m3 (IFV)   Skin
  Mica [12001-26-2] mg/m3 (R)    
Mineral Spirits 525 mg/m3    
  Mineral oil [8012-95-1], excluding metal working fluids      
  Pure, highly and severely refined mg/m3 (I)    
  Poorly and mildly refined (L)    
  Molybdenum [7439-98-7], as Mo      
  Soluble compounds 0.5 mg/m3 (R)    
  Metal and insoluble compounds 10 mg/m3 (I)
mg/m3 (R)
   
  Monochloroacetic acid [79-11-8] 0.5 ppm (IFV)   Skin
  Monocrotophos [6923-22-4] 0.05 mg/m3 (IFV)   Skin
  Morpholine [110-91-8] 20 ppm   Skin

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Occupational Exposure Limits for Ontario Workplaces: N
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Naled [300-76-5] 0.1 mg/m3 (IFV)   Skin
  Naphthalene [91-20-3] 10 ppm 15 ppm Skin
  β-Naphthylamine [91-59-8] (L)    
  Natural gas [8006-14-2] See Aliphatic hydrocarbons gases See Aliphatic hydrocarbons gases  
  Natural rubber latex [9006-04-6],
as inhalable allergenic proteins
0.0001 mg/m3 (I)   Skin
  Neon [7440-01-9] Simple asphyxiant Simple asphyxiant  
Nepheline syenite (total dust) [37244-96-5] 10 mg/m3    
Nickel      
Elemental/metal [7440-02-0] mg/m3 (I)    
Insoluble compounds, as Ni [7440-02-0] 0.2 mg/m3 (I)    
Soluble compounds, as Ni [7440-02-0] 0.1 mg/m3 (I)    
Nickel subsulfide, as Ni [12035-72-2] 0.1 mg/m3 (I)    
  Nickel carbonyl [13463-39-3], as Ni 0.05 ppm    
  Nicotine [54-11-5] 0.5 mg/m3   Skin
  Nitrapyrin [1929-82-4] 10 mg/m3 20 mg/m3  
  Nitric acid [7697-37-2] ppm ppm  
  Nitric oxide [10102-43-9] 25 ppm    
  p-Nitroaniline [100-01-6] mg/m3   Skin
  Nitrobenzene [98-95-3] ppm   Skin
  p-Nitrochlorobenzene [100-00-5] 0.1 ppm   Skin
  4-Nitrodiphenyl [92-93-3] (L)   Skin
  Nitroethane [79-24-3] 100 ppm    
  Nitrogen [7727-37-9] Simple asphyxiant Simple asphyxiant  
Nitrogen dioxide [10102-44-0] ppm ppm  
  Nitrogen trifluoride [7783-54-2] 10 ppm    
  Nitroglycerin (NG) [55-63-0] 0.05 ppm   Skin
  Nitromethane [75-52-5] 20 ppm    
  1-Nitropropane [108-03-2] 25 ppm    
  2-Nitropropane [79-46-9] 10 ppm    
N-Nitrosamines, including
n-Nitrosodimethylamine [62-75-9]
(L)   Skin
  Nitrotoluene, All isomers [88-72-2; 99-08-1; 99-99-0] ppm   Skin
  5-Nitro-o-toluidine [99-55-8] mg/m3 (I)    
Nitrous oxide [10024-97-2] 25 ppm
45 mg/m3
   
  Nonane [111-84-2]
All isomers
200 ppm
(d)
   

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Occupational Exposure Limits for Ontario Workplaces: O
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Octachloronaphthalene [2234-13-1] 0.1 mg/m3 0.3 mg/m3 Skin
  Octane, All isomers [111-65-9] 300 ppm    
  Osmium tetroxide [20816-12-0], as Os 0.0002 ppm 0.0006 ppm  
  Oxalic acid [144-62-7] mg/m3 mg/m3  
  p,p'-Oxybis(benzenesulfonyl hydrazide) [80-51-3] 0.1 mg/m3 (I)    
  Oxygen difluoride [7783-41-7]   C 0.05 ppm  
Ozone [10028-15-6] 0.1 ppm
0.2 mg/m3
0.3 ppm
0.6 mg/m3
 

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Occupational Exposure Limits for Ontario Workplaces: P
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Paraffin wax fume [8002-74-2] mg/m3    
Paraquat [4685-14-7] 0.1 mg/m3    
  Parathion [56-38-2] 0.05 mg/m3 (IFV)   Skin
Particles (Insoluble or Poorly Soluble) Not Otherwise Specified (PNOS) 10 mg/m3 (I)
mg/m3(R)
   
Penicillin (total dust) [1406-05-9] 0.1 mg/m3    
  Pentaborane [19624-22-7] 0.005 ppm 0.015 ppm  
  Pentachloronaphthalene [1321-64-8] 0.5 mg/m3   Skin
  Pentachloronitrobenzene [82-68-8] 0.5 mg/m3    
  Pentachlorophenol [87-86-5] 0.5 mg/m3   Skin
  Pentaerythritol [115-77-5] 10 mg/m3    
Pentaerythritol tetrabenzoate [4196-86-5]   mg/m3  
  Pentane, All isomers [78-78-4; 109-66-0; 463-82-1] 600 ppm    
  2,4-Pentanedione [123-54-6] 25 ppm   Skin
  Pentyl acetate, All isomers [628-63-7; 626-38-0; 123-92-2; 625-16-1; 624-41-9; 620-11-1] 50 ppm 100 ppm  
  Perchloromethyl mercaptan [594-42-3] 0.1 ppm    
  Perchloryl fluoride [7616-94-6] ppm ppm  
  Perfluorobutyl ethylene [19430-93-4] 100 ppm    
  Perfluoroisobutylene [382-21-8]   C 0.01 ppm  
  Persulfates, as persulfate 0.1 mg/m3    
Petroleum coke (total dust) [64741-79-3] 3.5 mg/m3 (a)    
  Petroleum ether (d)    
  Phenol [108-95-2] ppm   Skin
  Phenothiazine [92-84-2] mg/m3   Skin
2-Phenoxyethanol [122-99-6] 25 ppm
141 mg/m3
  Skin
  N-Phenyl-β-naphthylamine [135-88-6] (L)    
  o-Phenylenediamine [95-54-5] 0.1 mg/m3    
  m-Phenylenediamine [108-45-2] 0.1 mg/m3    
  p-Phenylenediamine [106-50-3] 0.1 mg/m3    
  Phenyl ether [101-84-8], vapor ppm ppm  
  Phenyl glycidyl ether (PGE) [122-60-1] 0.1 ppm   Skin
  Phenylhydrazine [100-63-0] 0.1 ppm   Skin
  Phenyl mercaptan [108-98-5] 0.1 ppm   Skin
  Phenylphosphine [638-21-1]   C 0.05 ppm  
  Phorate [298-02-2] 0.05 mg/m3 (IFV)   Skin
  Phosgene [75-44-5] 0.1 ppm    
  Phosphine [7803-51-2] 0.3 ppm ppm  
  Phosphoric acid [7664-38-2] mg/m3 mg/m3  
  Phosphorus (yellow) [12185-10-3] 0.1 mg/m3    
  Phosphorus oxychloride [10025-87-3] 0.1 ppm    
  Phosphorus pentachloride [10026-13-8] 0.1 ppm    
  Phosphorus pentasulfide [1314-80-3] mg/m3 mg/m3  
  Phosphorus trichloride [7719-12-2] 0.2 ppm 0.5 ppm  
  Phthalic anhydride [85-44-9] ppm    
  m-Phthalodinitrile [626-17-5] mg/m3 (IFV)    
  o-Phthalodinitrile [91-15-6] mg/m3 (IFV)    
  Picloram [1918-02-1] 10 mg/m3    
  Picric acid [88-89-1] 0.1 mg/m3   Skin
  Pindone [83-26-1] 0.1 mg/m3    
  Piperazine [110-85-0] and salts, as piperazine 0.03 ppm (IFV)    
Platinum [7440-06-4]      
Metal mg/m3    
Water-soluble compounds of, including chloroplatinates (as Pt) 0.002 mg/m3    
  Polyvinyl chloride (PVC) [9002-86-2] 1 mg/m3 (R)    
Polychlorinated biphenyls (PCBs)2 0.05 mg/m3    
  Portland cement [65997-15-1] mg/m3 (E, R)    
  Potassium hydroxide [1310-58-3]   C 2 mg/m3  
Poultry dust (total dust) mg/m3    
  Propane [74-98-6] See Aliphatic hydrocarbons gases See Aliphatic hydrocarbons gases  
  Propane sultone [1120-71-4] (L)    
  n-Propanol (n-Propyl alcohol) [71-23-8] 100 ppm    
  2-Propanol [67-63-0] 200 ppm 400 ppm  
  Propargyl alcohol [107-19-7] ppm   Skin
  β-Propiolactone [57-57-8] 0.5 ppm    
  Propionaldehyde [123-38-6] 20 ppm    
  Propionic acid [79-09-4] 10 ppm    
  Propoxur [114-26-1] 0.5 mg/m3    
  n-Propyl acetate [109-60-4] 200 ppm 250 ppm  
  Propylene [115-07-1] 500 ppm    
  Propylene dichloride [78-87-5] 10 ppm    
  Propylene glycol dinitrate [6423-43-4] 0.05 ppm   Skin
1,2-Propylene glycol [57-55-6] 50 ppm (V)
155 mg/m3 (V)
10 mg/m3 (H)(b)
   
Propylene glycol monomethyl ether acetate [108-65-6] 50 ppm
270 mg/m3
   
  Propylene oxide [75-56-9] ppm    
  Propyleneimine [75-55-8] 0.2 ppm 0.4 ppm Skin
  n-Propyl nitrate [627-13-4] 25 ppm 40 ppm  
  Pyrethrum [8003-34-7] mg/m3    
  Pyridine [110-86-1] ppm    

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Occupational Exposure Limits for Ontario Workplaces: Q-R
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Quinone [106-51-4] 0.1 ppm    
  Resorcinol [108-46-3] 10 ppm 20 ppm  
  Rhodium [7440-16-6], as Rh      
  Metal and Insoluble compounds mg/m3    
  Soluble compounds 0.01 mg/m3    
  Ronnel [299-84-3] mg/m3 (IFV)    
  Rosin core solder thermal decomposition products (colophony) [8050-09-7] (L)    
  Rotenone (commercial) [83-79-4] mg/m3    
  Rubber Solvent (Naphtha) [8030-30-6] (d)    

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Occupational Exposure Limits for Ontario Workplaces: S
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Selenium [7782-49-2] and compounds, as Se 0.2 mg/m3    
Selenium hexafluoride [7783-79-1], as Se 0.025 ppm
0.1 mg/m3
   
  Sesone [136-78-7] 10 mg/m3    
Shellac dust (total dust) [9000-59-3] 10 mg/m3    
  * Silica, Crystalline      
  * Quartz/Tripoli [14808-60-7; 1317-95-9] 0.10 mg/m3 (R)    
  * Cristobalite [14464-46-1] 0.05 mg/m3 (R)    
Silica fume [69012-64-2] mg/m3 (R)    
Silica fused [60676-86-0] 0.1 mg/m3 (R)    
Silicon carbide [409-21-2]      
Non-fibrous 10 mg/m3 (I) (E)
3 mg/m3 (R)(E)
   
Fibrous (including whiskers) 0.1 f/cc(R)(F)    
  Silicon tetrahydride [7803-62-5] ppm    
  Silver [7440-22-4]      
  Metal, dust and fume 0.1 mg/m3    
  Soluble Compounds, as Ag 0.01 mg/m3    
Sisal dust (total dust) mg/m3    
Soap dust [68918-36-5] mg/m3    
  Sodium azide [26628-22-8]      
  as Sodium azide   C 0.29 mg/m3  
  as Hydrazoic acid vapour   C 0.11 ppm  
  Sodium bisulfite [7631-90-5] mg/m3    
  Sodium fluoroacetate [62-74-8] 0.05 mg/m3   Skin
  Sodium hydroxide [1310-73-2]   C 2 mg/m3  
  Sodium metabisulfite [7681-57-4] mg/m3    
Spectinomycin [1695-77-8] mg/m3    
  Starch [9005-25-8] 10 mg/m3    
  Stearates (J) 10 mg/m3    
  Stoddard solvent [8052-41-3] 100 ppm    
140 Degree F Flash Aliphatic Solvent, Type of Stoddard Solvent 525 mg/m3    
  Strontium chromate [7789-06-2], as Cr 0.0005 mg/m3    
  Strychnine [57-24-9] 0.15 mg/m3    
Styrene - monomer [100-42-5] 35 ppm 100 ppm  
  Subtilisins [1395-21-7; 9014-01-1], as
crystalline active enzyme
  C 0.00006 mg/m3  
  Sucrose [57-50-1] 10 mg/m3    
  Sulfometuron methyl [74222-97-2] mg/m3    
  Sulfotepp (TEDP) [3689-24-5] 0.1 mg/m3 (IFV)   Skin
Sulfur dioxide [7446-09-5] ppm
5.2 mg/m3
ppm
10.4 mg/m3
 
  Sulfur hexafluoride [2551-62-4] 1,000 ppm    
  Sulfuric acid [7664-93-9] 0.2 mg/m3 (T)    
  Sulfur monochloride [10025-67-9]   C 1 ppm  
  Sulfur pentafluoride [5714-22-7]   C 0.01 ppm  
  Sulfur tetrafluoride [7783-60-0]   C 0.1 ppm  
  Sulfuryl fluoride [2699-79-8] ppm 10 ppm  
  Sulprofos [35400-43-2] 0.1 mg/m3 (IFV)   Skin
Synthetic Vitreous Fibres (Man Made Mineral Fibres)      
Continuous filament glass fibres 5 mg/m3 (I)
f/cc (F)
   
Glass wool fibres f/cc (F)    
Refractory ceramic fibres 0.5 f/cc (F)    
Rock wool fibres f/cc (F)    
Slag wool fibres f/cc (F)    
Special purpose glass fibres f/cc (F)    
Synthetic Vitreous Fibres, not otherwise classified (excluding fibrous glass dust and mineral wool fibre) f/cc (F) (c)    

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Occupational Exposure Limits for Ontario Workplaces: T
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  2,4,5-T [93-76-5] 10 mg/m3    
Talc [14807-96-6], containing no asbestos mg/m3 (R)(E)
2 f/cc (K)
   
  Tellurium [13494-80-9] and compounds (NOS), as Te, excluding hydrogen telluride 0.1 mg/m3    
Tellurium hexafluoride [7783-80-4], as Te 0.01 ppm
0.1 mg/m3
   
  Temephos [3383-96-8] mg/m3 (IFV)   Skin
  Terbufos [13071-79-9] 0.01 mg/m3 (IFV)   Skin
  Terephthalic acid [100-21-0] 10 mg/m3    
  Terphenyls [26140-60-3]   C 5 mg/m3  
  1,1,2,2-Tetrabromoethane [79-27-6] 0.1 ppm (IFV)    
  1,1,1,2-Tetrachloro-2,2-difluoroethane [76-11-9] 100 ppm    
  1,1,2,2-Tetrachloro-1,2-difluoroethane [76-12-0] 50 ppm    
  1,1,2,2-Tetrachloroethane [79-34-5] ppm   Skin
  Tetrachloroethylene [127-18-4] 25 ppm 100 ppm  
Tetrachlorophathalic anhydride [117-08-8] 0.1 mg/m3    
Tetrachlorophenol [25167-83-3] 0.5 mg/m3   Skin
  Tetrachloronaphthalene [1335-88-2] mg/m3    
  Tetraethyl pyrophosphate (TEPP) [107-49-3] 0.01 mg/m3 (IFV)   Skin
  Tetrafluoroethylene [116-14-3] ppm    
  Tetrahydrofuran [109-99-9] 50 ppm 100 ppm Skin
  Tetrakis (hydroxymethyl) phosphonium salts
Tetrakis (hydroxymethyl) phosphonium chloride [124-64-1]
Tetrakis (hydroxymethyl) phosphonium sulfate [55566-30-8]

mg/m3

mg/m3
   
  Tetramethyl succinonitrile [3333-52-6] 0.5 ppm   Skin
  Tetranitromethane [509-14-8] 0.005 ppm    
Tetrasodium pyrophosphate [7722-88-5] mg/m3    
  Tetryl [479-45-8] 1.5 mg/m3    
  Thallium [7440-28-0] and
compounds, as Tl
0.02 mg/m3 (I)   Skin
  4,4' Thiobis (6-tert-butyl-m-cresol) [96-69-5] mg/m3 (I)    
  Thioglycolic acid [68-11-1] ppm   Skin
  Thionyl chloride [7719-09-7]   C 0.2 ppm  
  Thiram [137-26-8] 0.05 mg/m3 (IFV)    
Tin [7440-31-5], as Sn      
Metal mg/m3    
Oxide and inorganic compounds, as Sn, except tin hydride mg/m3    
Organic compounds, as Sn 0.1 mg/m3   Skin (organic compounds)
  Titanium dioxide [13463-67-7] 10 mg/m3    
o-Tolidine [119-93-7] (L)   Skin
  Toluene [108-88-3] 20 ppm    
  o-Toluidine [95-53-4] ppm   Skin
  m-Toluidine [108-44-1] ppm   Skin
  p-Toluidine [106-49-0] ppm   Skin
  Tributyl phosphate [126-73-8] mg/m3 (IFV)    
  Trichloroacetic acid [76-03-9] ppm    
  1,2,4-Trichlorobenzene [120-82-1]   C 5 ppm  
  1,1,2-Trichloroethane [79-00-5] 10 ppm   Skin
  Trichloroethylene [79-01-6] 10 ppm 25 ppm  
  Trichlorofluoromethane [75-69-4]   C 1,000 ppm  
  Trichloronaphthalene [1321-65-9] mg/m3   Skin
  1,2,3-Trichloropropane [96-18-4] 10 ppm   Skin
  1,1,2-Trichloro-1,2,2-trifluoroethane [76-13-1] 1,000 ppm 1,250 ppm  
  Trichlorphon [52-68-6] mg/m3 (I)    
Triethanolamine [102-71-6] 0.5 ppm
3.1 mg/m3
   
  Triethylamine [121-44-8] ppm ppm Skin
Triethylenediamine [280-57-9] ppm
4.6 mg/m3
  Skin
Triethylenetetramine [112-24-3] 0.5 ppm
mg/m3
  Skin
  Trifluorobromomethane [75-63-8] 1,000 ppm    
  1,3,5-Triglycidyl-s-triazinetrione [2451-62-9] 0.05 mg/m3    
  Trimellitic anhydride [552-30-7] 0.0005 mg/m3 (IFV) 0.002 mg/m3 (IFV) Skin
Trimethoxyvinylsilane [2768-02-7]   10 ppm
60 mg/m3
 
  Trimethylamine [75-50-3] ppm 15 ppm  
  Trimethyl benzene (mixed isomers) [25551-13-7] 25 ppm    
  Trimethyl phosphite [121-45-9] ppm    
  2,4,6-Trinitrotoluene (TNT) [118-96-7] 0.1 mg/m3   Skin
  Triorthocresyl phosphate [78-30-8] 0.1 mg/m3   Skin
  Triphenyl phosphate [115-86-6] mg/m3    
Trixylylphosphate [25155-23-1] 0.1 mg/m3    
  Tungsten [7440-33-7], as W      
  Metal and insoluble compounds mg/m3 10 mg/m3  
  Soluble compounds mg/m3 mg/m3  
  Turpentine [8006-64-2] and selected monoterpenes [80-56-8; 127-91-3; 13466-78-9] 20 ppm    

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Occupational Exposure Limits for Ontario Workplaces: U-V
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Uranium (natural) [7440-61-1]
Soluble and insoluble compounds, as U
0.2 mg/m3 0.6 mg/m3  
  n-Valeraldehyde [110-62-3] 50 ppm    
  Vanadium pentoxide [1314-62-1] as V 0.05 mg/m3 (I)    
  Vinyl acetate [108-05-4] 10 ppm 15 ppm  
  Vinyl bromide [593-60-2] 0.5 ppm    
  * Vinyl chloride [75-01-04] ppm    
  4-Vinyl cyclohexene [100-40-3] 0.1 ppm    
  Vinyl cyclohexene dioxide [106-87-6] 0.1 ppm   Skin
  Vinyl fluoride [75-02-5] ppm    
  N-Vinyl-2-pyrrolidone [88-12-0] 0.05 ppm    
Vinylidene chloride [75-35-4] See 1,1-Dichloroethene [75-35-4] See 1,1-Dichloroethene [75-35-4]  
  Vinylidene fluoride [75-38-7] 500 ppm    
  Vinyl toluene [25013-15-4] 50 ppm 100 ppm  
  VM & P Naphtha [8032-32-4] (d)    

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Occupational Exposure Limits for Ontario Workplaces: W-X-Y-Z
Ontario Table Listings Agent [CAS No.] Time-Weighted Average Limit (TWA) Short-Term Exposure Limit (STEL) / Ceiling Limit (C) Notations
  Warfarin [81-81-2] 0.1 mg/m3    
Wheat flour dust (total dust) mg/m3    
Wood dust      
Certain hardwoods as beech and oak mg/m3    
Softwood mg/m3 10 mg/m3  
  Xylene [1330-20-7] (o, m & p isomers) [95-47-6; 108-38-3; 106-42-3] 100 ppm 150 ppm  
  m-Xylene α,α'- diamine [1477-55-0]   C 0.1 mg/m3 Skin
  Xylidine (mixed isomers) [1300-73-8] 0.5 ppm (IFV)   Skin
  Yttrium [7440-65-5] and compounds, as Y mg/m3    
  Zinc chloride fume [7646-85-7] mg/m3 mg/m3  
  Zinc chromates [13530-65-9; 11103-86-9; 37300-23-5], as Cr 0.01 mg/m3    
  Zinc oxide [1314-13-2] mg/m3 (R) 10 mg/m3 (R)  
  Zirconium [7440-67-7] and compounds, as Zr mg/m3 10 mg/m3  

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Endnotes and Abbreviations

  • ◊ Denotes agents listed in Ontario Table in Regulation 833
  • * Denotes designated substance according to O. Reg. 490/09
  • ¹ Means the benzene soluble fraction of total particulate matter of the substances emitted into the atmosphere from metallurgical coke ovens including condensed vapours and solid particulates.
  • ² As sum of components assayed by chromatographic procedure with reference to the bulk sample.
  • [CAS No.] - CAS Registry Number.
  • f/cc - Fibres per cubic centimetre of air.
  • mg/m3 - Milligrams of the agent per cubic metre of air.
  • ppm- Parts of the agent per million parts of air by volume.
  • Skin - Danger of cutaneous absorption.
  • (E)  The value is for particulate matter containing no asbestos and < 1 per cent crystalline silica.
  • (F)  Respirable fibres: length > 5μm; aspect ratio ≥3:1, as determined by the membrane filter method at 400-450 times magnification (4-mm objective), using phase-contrast illumination.
  • (H)  Aerosol only.
  • (I) Inhalable fraction.
  • (IFV) Inhalable fraction and vapour.
  • (J) Does not include stearates of toxic metals.
  • (K) Should not exceed 2 mg/m3 respirable particulate mass.
  • (L)  Exposure by all routes should be carefully controlled to levels as low as possible.
  • (P) Application restricted to conditions in which there are negligible aerosol exposures.
  • (R) Respirable fraction.
  • (T) Thoracic fraction.
  • (V) Vapour and aerosol.
  • (a) Provided that the total dust contains less than 0.7 per cent vanadium.
  • (b) For assessing the visibility in a work environment where 1,2-propylene glycol aerosol is present.
  • (c) A secondary limit of 5 mg/m3 (total dust) is recommended to deal with dusty operations where fibre counts are usually difficult to determine. Where both types of measurements are made simultaneously, the more restrictive limit should be used to assess the exposures.
  • (d) See MOL document Determination of Occupational Exposure Limits for Certain Refined Hydrocarbon Solvent Vapour Mixtures.
A B C D E F G H I J K – L M N O P Q – R S T U – V W – X – Y – Z

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