Current occupational exposure limits for Ontario workplaces under Regulation 833
Read this page to learn about current exposure limits to specific biological or chemical substances for workers in Ontario.
Overview
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 2017 ACGIH Table that is incorporated by reference in the Regulation.
For ease of reference, the following table contains all specific occupational exposure limits (OELs) 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.
Consultations
The 2021 consultation on new and revised occupational exposure limits is closed. The results of the consultation and proposal are under consideration.
Resources
OEL adjustment tool for irregular work shifts (“Quebec model”)
Use this tool to calculate the adjusted workplace exposure limit for an unusual or extended work shift.
Code for medical surveillance for designated substances
Learn how physicians should conduct surveillance programs of designated substances.
Determining occupational exposure limits for certain refined hydrocarbon solvent vapour mixtures
Learn about the recommended method for determining occupational exposure limits for certain refined hydrocarbon solvent vapour mixtures like petroleum ether, rubber solvent and VM&P Naphtha.
Alphabetical listings
Occupational exposure limits for Ontario workplaces: A
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Acetaldehyde [75-07-0] | none | C 25 ppm | none |
| none | Acetamide [60-35-5] | 1 ppm (IFV) | none | none |
| none | Acetic acid [64-19-7] | 10 ppm | 15 ppm | none |
| none | Acetic anhydride [108-24-7] | 1 ppm | 3 ppm | none |
| none | Acetone [67-64-1] | 250 ppm | 500 ppm | none |
| none | Acetone cyanohydrin [75-86-5], as CN | none | C 5 mg/m3 | Skin |
| none | Acetonitrile [75-05-8] | 20 ppm | none | Skin |
| none | Acetophenone [98-86-2] | 10 ppm | none | none |
| none | Acetylene [74-86-2] | (EX), Simple asphyxiant (D); section 7.1 Regulation 833 applies | (EX), Simple asphyxiant (D); section 7.1 Regulation 833 applies | none |
| none | Acetylsalicylic acid (Aspirin) [50-78-2] | 5 mg/m3 | none | none |
| none | Acrolein [107-02-8] | none | C 0.1 ppm | Skin |
| none | Acrylamide [79-06-1] | 0.03 mg/m3 (IFV) | none | Skin |
| none | Acrylic acid [79-10-7] | 2 ppm | none | Skin |
| Ontario Table, designated substance | Acrylonitrile [107-13-1] | 2 ppm | C 10 ppm | Skin |
| none | Adipic acid [124-04-9] | 5 mg/m3 | none | none |
| none | Adiponitrile [111-69-3] | 2 ppm | none | Skin |
| none | Alachlor [15972-60-8] | 1 mg/m3 (IFV) | none | none |
| none | Aldrin [309-00-2] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Allyl alcohol [107-18-6] | 0.5 ppm | none | Skin |
| none | Allyl bromide [106-95-6] | 0.1 ppm | 0.2 ppm | Skin |
| none | Allyl chloride [107-05-1] | 1 ppm | 2 ppm | Skin |
| none | Allyl glycidyl ether (AGE) [106-92-3] | 1 ppm | none | none |
| none | Allyl propyl disulfide [2179-59-1] | 0.5 ppm | none | none |
| none | Aluminum metal [7429-90-5] and insoluble compounds | 1 mg/m3 (R) | none | none |
| none | 4-Aminodiphenyl [92-67-1] | (L) | none | Skin |
| none | 2-Aminopyridine [504-29-0] | 0.5 ppm | none | none |
| none | Amitrole [61-82-5] | 0.2 mg/m3 | none | none |
| none | Ammonia [7664-41-7] | 25 ppm | 35 ppm | none |
| none | Ammonium chloride, fume [12125-02-9] | 10 mg/m3 | 20 mg/m3 | none |
| none | Ammonium perfluorooctanoate [3825-26-1] | 0.01 mg/m3 | none | Skin |
| none | Ammonium sulfamate [7773-06-0] | 10 mg/m3 | none | none |
| none | tert-Amyl methyl ether (TAME) [994-05-8] | 20 ppm | none | none |
| none | Aniline [62-53-3] | 2 ppm | none | Skin |
| none | o-Anisidine [90-04-0] | 0.5 mg/m3 | none | Skin |
| none | p-Anisidine [104-94-9] | 0.5 mg/m3 | none | Skin |
| none | Antimony [7440-36-0] and compounds, as Sb | 0.5 mg/m3 | none | none |
| none | Antimony hydride [7803-52-3] | 0.1 ppm | none | none |
| none | Antimony trioxide [1309-64-4] production | (L) | none | none |
| none | ANTU [86-88-4] | 0.3 mg/m3 | none | Skin |
| none | Argon [7440-37-1] |
Simple asphyxiant (D); section 7.1 Regulation 833 applies |
Simple asphyxiant (D); section 7.1 Regulation 833 applies | none |
| Ontario Table, designated substance | 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 | none |
| none | Arsine [7784-42-1] | 0.005 ppm | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] | 0.1 f/cc (F) | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] – Actinolite [77536-66-4] |
0.1 f/cc (F) | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] – Amosite [12172-73-5] |
0.1 f/cc (F) | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] – Anthophyllite [77536-67-5] |
0.1 f/cc (F) | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] – Chrysotile [132207-32-0] |
0.1 f/cc (F) | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] – Crocidolite [12001-28-4] |
0.1 f/cc (F) | none | none |
| Ontario Table, designated substance | Asbestos – All forms [1332-21-4] – Tremolite [77536-68-6] |
0.1 f/cc (F) | none | none |
| none | Asphalt (Bitumen) fume [8052-42-4], as benzene-soluble aerosol |
0.5 mg/m3 (I) | none | none |
| none | Atrazine [1912-24-9] (and related symmetrical triazines) | 2 mg/m3 (I) | none | none |
| none | Azinphos-methyl [86-50-0] | 0.2 mg/m3 (IFV) | none | Skin |
Occupational exposure limits for Ontario workplaces: B
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Barium [7440-39-3] and soluble compounds, as Ba |
0.5 mg/m3 | none | none |
| none | Barium sulfate [7727-43-7] | 5 mg/m3 (I)(E) | none | none |
| none | Benomyl [17804-35-2] | 1 mg/m3 (I) | none | none |
| none | Benz[a]anthracene [56-55-3] | (L) | none | none |
| Ontario Table | Benzaldehyde [100-52-7] | none | 4 ppm 17 mg/m3 |
none |
| Ontario Table, designated substance | Benzene [71-43-2] | 0.5 ppm | 2.5 ppm | Skin |
| none | Benzidine [92-87-5] | (L) | none | Skin |
| none | Benzo[b]fluoranthene [205-99-2] | (L) | none | none |
| none | Benzo[a]pyrene [50-32-8] | (L) | none | none |
| none | Benzotrichloride [98-07-7] | none | C 0.1 ppm | Skin |
| none | Benzoyl chloride [98-88-4] | none | C 0.5 ppm | none |
| none | Benzoyl peroxide [94-36-0] | 5 mg/m3 | none | none |
| none | Benzyl acetate [140-11-4] | 10 ppm | none | none |
| none | Benzyl chloride [100-44-7] | 1 ppm | none | none |
| none | Beryllium and compounds, as Be [7440-41-7] | 0.00005 mg/m3 (I) | none | Skin (Soluble compounds only) |
| none | Biphenyl [92-52-4] | 0.2 ppm | none | none |
| none | Bismuth telluride [1304-82-1] – Undoped, as Bi2Te3 |
10 mg/m3 | none | none |
| none | Bismuth telluride [1304-82-1] – Se-doped, as Bi2Te3 |
5 mg/m3 | none | none |
| none | Borate compounds, Inorganic [1303-96-4;1330-43-4;10043-35-3; 12179-04-3] | 2 mg/m3 (I) | 6 mg/m3 (I) | none |
| none | Boron oxide [1303-86-2] | 10 mg/m3 | none | none |
| none | Boron trichloride [10294-33-4] | none | C 0.7 ppm | none |
| none | Boron tribromide [10294-3 |
none | C 0.7 ppm | none |
| none | Boron trifluoride [7637-07-2] | 0.1 ppm | C 0.7 ppm | none |
| none | Bromacil [314-40-9] | 10 mg/m3 | none | none |
| none | Bromine [7726-95-6] | 0.1 ppm | 0.2 ppm | none |
| none | Bromine pentafluoride [7789-30-2] | 0.1 ppm | none | none |
| none | Bromoform [75-25-2] | 0.5 ppm | none | none |
| none | 1-Bromopropane [106-94-5] | 0.1 ppm | none | none |
| none | 1,3-Butadiene [106-99-0] | 2 ppm | none | none |
| none | Butane, All isomers [75-28-5;106-97-8] | none | 1000 ppm (EX) | none |
| none | n-Butanol [71-36-3] | 20 ppm | none | none |
| none | sec-Butanol [78-92-2] | 100 ppm | none | none |
| none | tert-Butanol [75-65-0] | 100 ppm | none | none |
| none | Butenes, All isomers [106-98-9; 107-01-7; 590-18-1; 624-64-6; 25167-67-3] | 250 ppm | none | none |
| none | Butenes, All isomers [106-98-9; 107-01-7; 590-18-1; 624-64-6; 25167-67-3] – Isobutene [115-11-7] |
250 ppm | none | none |
| none | 2-Butoxyethanol (EGBE) [111-76-2] | 20 ppm | none | none |
| none | 2-Butoxyethyl acetate (EGBEA) [112-07-2] | 20 ppm | none | none |
| none | Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5] | 50 ppm | 150 ppm | none |
| none | n-Butyl acrylate [141-32-2] | 2 ppm | none | none |
| none | n-Butylamine [109-73-9] | none | C 5 ppm | Skin |
| none | Butylated hydroxytoluene (BHT) [128-37-0] | 2 mg/m3 (IFV) | none | none |
| none | tert-Butyl chromate, as CrO3 [1189-85-1] | none | C 0.1 mg/m3 | Skin |
| none | n-Butyl glycidyl ether (BGE) [2426-08-6] | 3 ppm | none | Skin |
| none | n-Butyl lactate [138-22-7] | 5 ppm | none | none |
| none | n-Butyl mercaptan [109-79-5] | 0.5 ppm | none | none |
| none | o-sec-Butylphenol [89-72-5] | 5 ppm | none | Skin |
| none | p-tert-Butyl toluene [98-51-1] | 1 ppm | none | none |
Occupational exposure limits for Ontario workplaces: C
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Cadmium [7440-43-9] | 0.01 mg/m3 | none | none |
| none | Cadmium [7440-43-9] – Cadmium compounds, as Cd |
0.002 mg/m3 (R) | none | none |
| none | Cadusafos [95465-99-9] | 0.001 mg/m3 (IFV) | none | Skin |
| Ontario Table | Calcium chloride [10043-52-4] | 5 mg/m3 | none | none |
| none | Calcium chromate [13765-19-0], as Cr | 0.001 mg/m3 | none | none |
| none | Calcium cyanamide [156-62-7] | 0.5 mg/m3 | none | none |
| none | Calcium hydroxide [1305-62-0] | 5 mg/m3 | none | none |
| none | Calcium oxide [1305-78-8] | 2 mg/m3 | none | none |
| none | Calcium silicate, naturally occurring as Wollastonite [13983-17-0] | 1 mg/m3 (I)(E) | none | none |
| none | Calcium sulfate [7778-18-9; 10034-76-1; 10101-41-4; 13397-24-5)] | 10 mg/m3 (I) | none | none |
| none | Camphor, synthetic [76-22-2] | 2 ppm | 3 ppm | none |
| none | Caprolactam [105-60-2] | 5 mg/m3 (IFV) | none | none |
| none | Captafol [2425-06-1] | 0.1 mg/m3 (IFV) | none | Skin |
| none | Captan [133-06-2] | 5 mg/m3 (I) | none | none |
| none | Carbaryl [63-25-2] | 0.5 mg/m3 (IFV) | none | Skin |
| none | Carbofuran [1563-66-2] | 0.1 mg/m3 (IFV) | none | none |
| none | Carbon black [1333-86-4] | 3 mg/m3 (I) | none | none |
| none | Carbon dioxide [124-38-9] | 5,000 ppm | 30,000 ppm | none |
| none | Carbon disulfide [75-15-0] | 1 ppm | none | Skin |
| Carbon monoxide [630-08-0] | 25 ppm | none | none | |
| none | Carbon tetrabromide [558-13-4] | 0.1 ppm | 0.3 ppm | none |
| Ontario Table | Carbon tetrachloride [56-23-5] | 2 ppm | 3 ppm | Skin |
| none | Carbonyl fluoride [353-50-4] | 2 ppm | 5 ppm | none |
| none | Carbonyl sulfide [463-58-1] | 5 ppm | none | none |
| none | Catechol [120-80-9] | 5 ppm | none | Skin |
| none | Cellulose [9004-34-6] | 10 mg/m3 | none | none |
| none | Cesium hydroxide [21351-79-1] | 2 mg/m3 | none | none |
| Ontario Table | Charcoal, except activated [16291-96-6] | 10 mg/m3 | none | none |
| none | Chlordane [57-74-9] | 0.5 mg/m3 | none | Skin |
| none | Chlorinated camphene [8001-35-2] | 0.5 mg/m3 | 1 mg/m3 | Skin |
| Ontario Table | Chlorinated diphenyl oxides [55720-99-5] | 0.5 mg/m3 | 2 mg/m3 | none |
| none | Chlorine [7782-50-5] | 0.5 ppm | 1 ppm | none |
| none | Chlorine dioxide [10049-04-4] | 0.1 ppm | 0.3 ppm | none |
| none | Chlorine trifluoride [7790-91-2] | none | C 0.1 ppm | none |
| none | Chloroacetaldehyde [107-20-0] | none | C 1 ppm | none |
| none | Chloroacetone [78-95-5] | none | C 1 ppm | Skin |
| none | 2-Chloroacetophenone [532-27-4] | 0.05 ppm | none | none |
| none | Chloroacetyl chloride [79-04-9] | 0.05 ppm | 0.15 ppm | Skin |
| none | Chlorobenzene [108-90-7] | 10 ppm | none | none |
| Ontario Table | o-Chlorobenzaldehyde [89-98-5] | none | 4 ppm 23 mg/m3 |
none |
| none | o-Chlorobenzylidene malononitrile [2698-41-1] | none | C 0.05 ppm | Skin |
| none | Chlorobromomethane [74-97-5] | 200 ppm | none | none |
| none | Chlorodifluoromethane [75-45-6] | 1,000 ppm | none | none |
| Ontario Table | Chlorodiphenyl (42% chlorine) [53469-21-9] Chlorodiphenyl (54% chlorine) [11097-69-1] |
See Polychlorinated Biphenyls (PCBs) | See Polychlorinated Biphenyls (PCBs) | none |
| none | Chloroform [67-66-3] | 10 ppm | none | none |
| none | bis(Chloromethyl) ether [542-88-1] | 0.001 ppm | none | none |
| none | Chloromethyl methyl ether [107-30-2] | (L) | none | none |
| none | 1-Chloro-1-nitropropane [600-25-9] | 2 ppm | none | none |
| none | Chloropentafluoroethane [76-15-3] | 1,000 ppm | none | none |
| none | Chloropicrin [76-06-2] | 0.1 ppm | none | none |
| none | 1-Chloro-2-propanol [127-00-4] and 2-Chloro-1-propanol [78-89-7] |
1 ppm | none | Skin |
| none | β-Chloroprene [126-99-8] | 1 ppm | none | Skin |
| none | 2-Chloropropionic acid [598-78-7] | 0.1 ppm | none | Skin |
| none | o-Chlorostyrene [2039-87-4] | 50 ppm | 75 ppm | none |
| none | o-Chlorotoluene [95-49-8] | 50 ppm | none | none |
| none | Chlorpyrifos [2921-88-2] | 0.1 mg/m3 (IFV) | none | Skin |
| none | Chromite ore processing (Chromate), as Cr | 0.05 mg/m3 | none | none |
| none | Chromium [7440-47-3] and inorganic compounds, as Cr – Metal and Cr III compounds |
0.5 mg/m3 | none | none |
| none | Chromium [7440-47-3] and inorganic compounds, as Cr – Water-soluble Cr VI compounds |
0.05 mg/m3 | none | none |
| none | Chromium [7440-47-3] and inorganic compounds, as Cr – Insoluble Cr VI compounds |
0.01 mg/m3 | none | none |
| none | Chromyl chloride [14977-61-8] | 0.025 ppm | none | none |
| none | Chrysene [218-01-9] | (L) | none | none |
| none | Citral [5392-40-5] | 5 ppm (IFV) | none | Skin |
| none | Clopidol [2971-90-6] | 3 mg/m3 (IFV) | none | none |
| none | Coal dust – Anthracite |
0.4 mg/m3 (R) | none | none |
| none | Coal dust – Bituminous |
0.9 mg/m3 (R) | none | none |
| none | Coal tar pitch volatiles [65996-93-2], as benzene soluble aerosol |
0.2 mg/m3 | none | none |
| none | Cobalt [7440-48-4] and inorganic compounds, as Co | 0.02 mg/m3 | none | none |
| none | Cobalt carbonyl [10210-68-1], as Co | 0.1 mg/m3 | none | none |
| none | Cobalt hydrocarbonyl [16842-03-8], as Co | 0.1 mg/m3 | none | none |
| Ontario Table | N-Cocomorpholine [1541-81-7] | 5 ppm 52 mg/m3 |
none | Skin |
| Ontario Table, designated substance | Coke Oven Emissions1 | 0.15 mg/m3 | none | none |
| none | Copper – Fume, as Cu |
0.2 mg/m3 | none | none |
| none | Copper – Dusts and mists, as Cu |
1 mg/m3 | none | none |
| none | Cotton dust, raw, untreated | 0.1 mg/m3 (T) | none | none |
| none | Coumaphos [56-72-4] | 0.05 mg/m3 (IFV) | none | Skin |
| Ontario Table | Coumarone-Indene Resins (total dust) [63393-89-5] | 5 mg/m3 | none | none |
| none | Cresol, All isomers [1319-77-3; 95-48-7; 108-39-4; 106-44-5] | 20 mg/m3 (IFV) | none | Skin |
| none | Crotonaldehyde [4170-30-3] | none | C 0.3 ppm | Skin |
| none | Crufomate [299-86-5] | 5 mg/m3 | none | none |
| none | Cumene [98-82-8] | 50 ppm | none | none |
| none | Cyanamide [420-04-2] | 2 mg/m3 | none | none |
| none | Cyanogen [460-19-5] | none | C 5 ppm | none |
| none | Cyanogen bromide [506-68-3] | none | C 0.3 ppm | none |
| none | Cyanogen chloride [506-77-4] | none | C 0.3 ppm | none |
| none | Cyclohexane [110-82-7] | 100 ppm | none | none |
| none | Cyclohexanol [108-93-0] | 50 ppm | none | Skin |
| none | Cyclohexanone [108-94-1] | 20 ppm | 50 ppm | Skin |
| none | Cyclohexene [110-83-8] | 300 ppm | none | none |
| none | Cyclohexylamine [108-91-8] | 10 ppm | none | none |
| none | Cyclonite [121-82-4] | 0.5 mg/m3 | none | Skin |
| none | Cyclopentadiene [542-92-7] | 75 ppm | none | none |
| none | Cyclopentane [287-92-3] | 600 ppm | none | none |
| none | Cyhexatin [13121-70-5] | 5 mg/m3 | none | none |
| Ontario Table | Cymene (sum of o-,m-and p-isomers) [25155-15-1] | 50 ppm 274 mg/m3 |
none | Skin |
Occupational exposure limits for Ontario workplaces: D
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | 2,4-D [94-75-7] | 10 mg/m3 (I) | none | none |
| none | DDT [50-29-3] | 1 mg/m3 | none | none |
| none | Decaborane [17702-41-9] | 0.05 ppm | 0.15 ppm | Skin |
| none | Demeton [8065-48-3] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Demeton-S-methyl [919-86-8] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Diacetone alcohol [123-42-2] | 50 ppm | none | none |
| none | Diacetyl [431-03-8] | 0.01 ppm | 0.02 ppm | none |
| none | Diazinon [333-41-5] | 0.01 mg/m3 (IFV) | none | Skin |
| none | Diazomethane [334-88-3] | 0.2 ppm | none | none |
| none | Diborane [19287-45-7] | 0.1 ppm | none | none |
| none | 2-N-Dibutylaminoethanol [102-81-8] | 0.5 ppm | none | Skin |
| none | Dibutyl phenyl phosphate [2528-36-1] | 0.3 ppm | none | Skin |
| none | Dibutyl phosphate [107-66-4] | 5 mg/m3 (IFV) | none | Skin |
| none | Dibutyl phthalate [84-74-2] | 5 mg/m3 | none | none |
| none | Dichloroacetic acid [79-43-6] | 0.5 ppm | none | Skin |
| none | Dichloroacetylene [7572-29-4] | none | C 0.1 ppm | none |
| none | o-Dichlorobenzene [95-50-1] | 25 ppm | 50 ppm | none |
| none | p-Dichlorobenzene [106-46-7] | 10 ppm | none | none |
| none | 3,3'-Dichlorobenzidine [91-94-1] | (L) | none | Skin |
| none | 1,4-Dichloro-2-butene [764-41-0] | 0.005 ppm | none | Skin |
| none | Dichlorodifluoromethane [75-71-8] | 1,000 ppm | none | none |
| none | 1,3-Dichloro-5,5-dimethyl hydantoin [118-52-5] | 0.2 mg/m3 | 0.4 mg/m3 | none |
| none | 1,1-Dichloroethane [75-34-3] | 100 ppm | none | none |
| Ontario Table | 1,1 Dichloroethene [75-35-4] | 1 ppm 4 mg/m3 |
20 ppm 80 mg/m3 |
none |
| none | 1,2-Dichloroethylene, All isomers [540-59-0; 156-59-2; 156-60-5] | 200 ppm | none | none |
| none | Dichloroethyl ether [111-44-4] | 5 ppm | 10 ppm | Skin |
| none | Dichlorofluoromethane [75-43-4] | 10 ppm | none | none |
| none | Dichloromethane [75-09-2] | 50 ppm | none | none |
| none | 1,1-Dichloro-1-nitroethane [594-72-9] | 2 ppm | none | none |
| Ontario Table | 1,3-Dichloro-2-Propanol [96-23-1] | none | 1 ppm 5 mg/m3 |
Skin |
| none | 1,3-Dichloropropene [542-75-6] | 1 ppm | none | Skin |
| none | 2,2-Dichloropropionic acid [75-99-0] | 5 mg/m3(I) | none | none |
| none | Dichlorotetrafluoroethane [76-14-2] | 1,000 ppm | none | none |
| none | Dichlorvos (DDVP) [62-73-7] | 0.1 mg/m3 (IFV) | none | Skin |
| none | Dicrotophos [141-66-2] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Dicyclopentadiene [77-73-6] | 5 ppm | none | none |
| none | Dicyclopentadienyl iron, as Fe [102-54-5] | 10 mg/m3 | none | none |
| none | Dieldrin [60-57-1] | 0.1 mg/m3 (IFV) | none | Skin |
| none | Diesel fuel [68334-30-5; 68476-30-2; 68476-31-3; 68476-34-6; 77650-28-3], as total hydrocarbons |
100 mg/m3 (IFV) | none | Skin |
| none | Diethanolamine [111-42-2] | 1 mg/m3 (IFV) | none | Skin |
| none | Diethylamine [109-89-7] | 5 ppm | 15 ppm | Skin |
| none | 2-Diethylaminoethanol [100-37-8] | 2 ppm | none | Skin |
| none | Diethylene glycol monobutyl ether [112- 34-5] | 10 ppm (IFV) | none | none |
| Ontario Table | Diethylene glycol monoethyl ether [111- 90-0] | 30 ppm 165 mg/m3 |
none | none |
| none | Diethylene triamine [111-40-0] | 1 ppm | none | Skin |
| Ontario Table | Di(2-ethylhexyl)phthalate (DEHP) [117-81-7] | 3 mg/m3 | 5 mg/m3 | none |
| none | N,N-Diethylhydroxylamine [3710-84-7] | 2 ppm | none | none |
| none | Diethyl ketone [96-22-0] | 200 ppm | 300 ppm | none |
| none | Diethyl phthalate [84-66-2] | 5 mg/m3 | none | none |
| none | Difluorodibromomethane [75-61-6] | 100 ppm | none | none |
| none | Diglycidyl ether (DGE) [2238-07-5] | 0.01 ppm | none | none |
| Ontario Table | Diisodecyl phthalate [26761-40-0] | 5 mg/m3 | none | none |
| none | Diisobutyl ketone [108-83-8] | 25 ppm | none | none |
| none | Diisopropylamine [108-18-9] | 5 ppm | none | Skin |
| none | N,N-Dimethyl acetamide [127-19-5] | 10 ppm | none | Skin |
| none | Dimethylamine [124-40-3] | 5 ppm | 15 ppm | none |
| none | Bis(2-Dimethylaminoethyl)ether [3033-62-3] | 0.05 ppm | 0.15 ppm | Skin |
| Ontario Table | 3-(Dimethylamino) propylamine [109-55-7] | 0.5 ppm 2 mg/m3 |
none | Skin |
| none | Dimethylaniline [121-69-7] | 5 ppm | 10 ppm | Skin |
| none | Dimethyl carbamoyl chloride [79-44-7] | 0.005 ppm | none | Skin |
| Ontario Table | N, N-Dimethyl-cyclohexylamine [98-94-2] | none | 5 ppm 26 mg/m3 |
none |
| none | Dimethyl disulfide [624-92-0] | 0.5 ppm | none | Skin |
| none | Dimethylethoxysilane [14857-34-2] | 0.5 ppm | 1.5 ppm | none |
| Ontario Table | N, N-Dimethyl-ethanolamine [108-01-0] | 3 ppm 11 mg/m3 |
6 ppm 22 mg/m3 |
none |
| none | Dimethylformamide [68-12-2] | 10 ppm | none | Skin |
| none | 1,1-Dimethylhydrazine [57-14-7] | 0.01 ppm | none | Skin |
| none | Dimethyl phthalate [131-11-3] | 5 mg/m3 | none | none |
| none | Dimethyl sulfate [77-78-1] | 0.1 ppm | none | Skin |
| none | Dimethyl sulfide [75-18-3] | 10 ppm | none | none |
| Ontario Table | Dimethyl terephthalate [120-61-6] | 5 mg/m3 | none | none |
| Ontario Table | Dimethyl 2,3,5,6-tetracholoroterephthalate [1861-32-1] | 5 mg/m3 | none | none |
| none | Dinitrobenzene, All isomers [528-29-0; 99-65-0; 100-25-4; 25154-54-5] | 0.15 ppm | none | Skin |
| none | Dinitro-o-cresol [534-52-1] | 0.2 mg/m3 | none | Skin |
| none | 3,5-Dinitro-o-toluamide [148-01-6] | 1 mg/m3 | none | none |
| none | Dinitrotoluene [25321-14-6] | 0.2 mg/m3 | none | Skin |
| none | 1,4-Dioxane [123-91-1] | 20 ppm | none | Skin |
| none | Dioxathion [78-34-2] | 0.1 mg/m3 (IFV) | none | Skin |
| none | 1,3-Dioxolane [646-06-0] | 20 ppm | none | none |
| none | Diphenylamine [122-39-4] | 10 mg/m3 | none | none |
| none | Dipropyl ketone [123-19-3] | 50 ppm | none | none |
| Ontario Table | Dipropylene glycol monomethyl ether acetate [88917-22-0] | 100 ppm 776 mg/m3 |
150 ppm 1,164 mg/m3 |
none |
| Ontario Table | Diquat [2764-72-9; 85-00-7; 6385-62-2] | 0.5 mg/m3 0.1 mg/m3 (R) |
none | Skin |
| none | Disulfiram [97-77-8] | 2 mg/m3 | none | none |
| none | Disulfoton [298-04-4] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Diuron [330-54-1] | 10 mg/m3 | none | none |
| none | Divinyl benzene [1321-74-0] | 10 ppm | none | none |
| none | Dodecyl mercaptan [112-55-0] | 0.1 ppm | none | none |
Occupational exposure limits for Ontario workplaces: E
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Endosulfan [115-29-7] | 0.1 mg/m3 (IFV) | none | Skin |
| none | Endrin [72-20-8] | 0.1 mg/m3 | none | Skin |
| Ontario Table | Enflurane [13838-16-9] | 2 ppm 16 mg/m3 |
none | none |
| none | Epichlorohydrin [106-89-8] | 0.5 ppm | none | Skin |
| none | EPN [2104-64-5] | 0.1 mg/m3 (I) | none | Skin |
| none | Ethane [74-84-0] | (EX), Simple asphyxiant (D); section 7.1 of Regulation 833 applies | (EX), Simple asphyxiant (D); section 7.1 of Regulation 833 applies | none |
| none | Ethanol [64-17-5] | none | 1,000 ppm | none |
| none | Ethanolamine [141-43-5] | 3 ppm | 6 ppm | none |
| none | Ethion [563-12-2] | 0.05 mg/m3 (IFV) | none | Skin |
| none | 2-Ethoxyethanol (EGEE) [110-80-5] | 5 ppm | none | Skin |
| none | 2-Ethoxyethyl acetate (EGEEA) [111-15-9] | 5 ppm | none | Skin |
| none | Ethyl acetate [141-78-6] | 400 ppm | none | none |
| none | Ethyl acrylate [140-88-5] | 5 ppm | 15 ppm | none |
| none | Ethylamine [75-04-7] | 5 ppm | 15 ppm | Skin |
| none | Ethyl amyl ketone [541-85-5] | 10 ppm | none | none |
| none | Ethyl benzene [100-41-4] | 20 ppm | none | none |
| none | Ethyl bromide [74-96-4] | 5 ppm | none | Skin |
| none | Ethyl tert-butyl ether (ETBE) [637-92-3] | 25 ppm | none | none |
| none | Ethyl butyl ketone [106-35-4] | 50 ppm | 75 ppm | none |
| none | Ethyl chloride [75-00-3] | 100 ppm | none | Skin |
| none | Ethyl cyanoacrylate [7085-85-0] | 0.2 ppm | none | none |
| Ontario Table | Ethyl-3-ethoxy propionate [763-69-9] | 50 ppm 300 mg/m3 |
none | none |
| none | Ethylene [74-85-1] | 200 ppm | none | none |
| none | Ethylene chlorohydrin [107-07-3] | none | C 1 ppm | Skin |
| none | Ethylenediamine [107-15-3] | 10 ppm | none | Skin |
| Ontario Table | Ethylene dibromide [106-93-4] | (L) | none | Skin |
| none | Ethylene dichloride [107-06-2] | 10 ppm | none | none |
| none | Ethylene glycol [107-21-1] | 25 ppm (V) |
50 ppm (V) C 10 mg/m3 (I)(H) |
none |
| Ontario Table | Ethylene glycol dimethyl ether [110-71-4] | 5 ppm 18 mg/m3 |
none | Skin |
| none | Ethylene glycol dinitrate (EGDN) [628-96-6] | 0.05 ppm | none | Skin |
| Ontario Table | Ethylene glycol mono-n-propyl ether [2807-30-9] | 25 ppm 110 mg/m3 |
none | Skin |
| Ontario Table | Ethylene glycol mononitrate [16051-48-2] | 0.05 ppm 0.22 mg/m3 |
none | Skin |
| Ontario Table, designated substance | Ethylene oxide [75-21-8] | 1 ppm 1.8 mg/m3 |
10 ppm 18 mg/m3 |
none |
| none | Ethyleneimine [151-56-4] | 0.05 ppm | 0.1 ppm | Skin |
| none | Ethyl ether [60-29-7] | 400 ppm | 500 ppm | none |
| none | Ethyl formate [109-94-4] | none | 100 ppm | none |
| none | 2-Ethylhexanoic acid [149-57-5] | 5 mg/m3 (IFV) | none | none |
| none | Ethylidene norbornene [16219-75-3] | 2 ppm | 4 ppm | none |
| Ontario Table, designated substance | Ethyl isocyanate [109-90-0] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| none | Ethyl mercaptan [75-08-1] | 0.5 ppm | none | none |
| Ontario Table | Ethyl methacrylate [97-63-2] | 50 ppm | 100 ppm | none |
| none | N-Ethylmorpholine [100-74-3] | 5 ppm | none | Skin |
| none | Ethyl silicate [78-10-4] | 10 ppm | none | none |
Occupational exposure limits for Ontario workplaces: F
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Fenamiphos [22224-92-6] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Fensulfothion [115-90-2] | 0.01 mg/m3 (IFV) | none | Skin |
| none | Fenthion [55-38-9] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Ferbam [14484-64-1] | 5 mg/m3 (I) | none | none |
| none | Ferrovanadium dust [12604-58-9] | 1 mg/m3 | 3 mg/m3 | none |
| Ontario Table | Flour dust | See Wheat Flour Dust (total dust) | See Wheat Flour Dust (total dust) | none |
| none | Fluorides, as F | 2.5 mg/m3 | none | none |
| none | Fluorine [7782-41-4] | 1 ppm | 2 ppm | none |
| none | Folpet [133-07-3] | 1 mg/m3 (I) | none | none |
| none | Fonofos [944-22-9] | 0.01 mg/m3 (IFV) | none | Skin |
| Ontario Table | Forane [26675-46-7] | 2 ppm 15 mg/m3 |
none | none |
| Ontario Table | Formaldehyde [50-00-0] | none | STEL 1 ppm C 1.5 ppm |
none |
| none | Formamide [75-12-7] | 10 ppm | none | Skin |
| none | Formic acid [64-18-6] | 5 ppm | 10 ppm | none |
| none | Furfural [98-01-1] | 0.2 ppm | none | Skin |
| none | Furfuryl alcohol [98-00-0] | 0.2 ppm | none | Skin |
Occupational exposure limits for Ontario workplaces: G
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Gallium arsenide [1303-00-0] | 0.0003 mg/m3 (R) | none | none |
| none | Gasoline [86290-81-5] | 300 ppm | 500 ppm | none |
| none | Germanium tetrahydride [7782-65-2] | 0.2 ppm | none | none |
| none | Glutaraldehyde [111-30-8], activated and inactivated | none | C 0.05 ppm | none |
| none | Glycidol [556-52-5] | 2 ppm | none | none |
| none | Glyoxal [107-22-2] | 0.1 mg/m3 (IFV) | none | none |
| none | Grain dust (oat, wheat, barley) | 4 mg/m3 | none | none |
| none | Graphite (all forms except graphite fibers) [7782-42-5] | 2 mg/m3 (R) | none | none |
Occupational exposure limits for Ontario workplaces: H
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Hafnium [7440-58-6] and compounds, as Hf | 0.5 mg/m3 | none | none |
| Ontario Table | Halothane [151-67-7] | 2 ppm 16 mg/m3 |
none | none |
| none | Hard metals containing Cobalt [7440-48-4] and Tungsten carbide [12070-12-1], as Co | none | none | |
| none | Helium [7440-59-7] | Simple asphyxiant (D); section 7.1 of Regulation 833 applies | Simple asphyxiant (D); section 7.1 of Regulation 833 applies | none |
| none | Heptachlor [76-44-8] and Heptachlor epoxide [1024-57-3] |
0.05 mg/m3 | none | Skin |
| none | 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 | none |
| Ontario Table | Heptyl acetate [112-06-1] | 50 ppm 320 mg/m3 |
none | none |
| none | Hexachlorobenzene [118-74-1] | 0.002 mg/m3 | none | Skin |
| none | Hexachlorobutadiene [87-68-3] | 0.02 ppm | none | Skin |
| none | Hexachlorocyclopentadiene [77-47-4] | 0.01 ppm | none | none |
| none | Hexachloroethane [67-72-1] | 1 ppm | none | Skin |
| none | Hexachloronaphthalene [1335-87-1] | 0.2 mg/m3 | none | Skin |
| none | Hexafluoroacetone [684-16-2] | 0.1 ppm | none | Skin |
| none | Hexafluoropropylene [116-15-4] | 0.1 ppm | none | none |
| none | Hexahydrophthalic anhydride, All isomers [85-42-7; 13149-00-3; 14166-21-3] | none | C 0.005 mg/m3 (IFV) | none |
| Ontario Table, designated substance | Hexamethylene diisocyanate [822-06-0] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| Ontario Table | Hexamethylenetetramine (HMT) [100-97-0] | none | 0.35 ppm 2 mg/m3 |
none |
| Ontario Table | Hexamethyl phosphoramide [680-31-9] | (L) | none | Skin |
| none | n-Hexane [110-54-3] | 50 ppm | none | Skin |
| none | Hexane isomers, other than n-Hexane [75-83-2;79-29-8;96-14-0;107-83-5] | 500 ppm | 1,000 ppm | none |
| none | 1,6-Hexanediamine [124-09-4] | 0.5 ppm | none | none |
| none | 1-Hexene [592-41-6] | 50 ppm | none | none |
| none | sec-Hexyl acetate [108-84-9] | 50 ppm | none | none |
| Ontario Table | Hexyl acetate (isomeric mixture) [88230-35-7] | 50 ppm 294 mg/m3 |
none | none |
| none | Hexylene glycol [107-41-5] | 25 ppm (V) |
50 ppm (V) 10 mg/m3 (I) (H) |
none |
| none | Hydrazine [302-01-2] | 0.01 ppm | none | Skin |
| none | Hydrogen [1333-74-0] | (EX),Simple asphyxiant (D); section 7.1 of Regulation 833 applies | (EX),Simple asphyxiant (D); section 7.1 of Regulation 833 applies | none |
| Ontario Table | Hydrogenated terphenyls2 [61788-32-7] | 0.5 ppm | none | none |
| none | Hydrogen bromide [10035-10-6] | none | C 2 ppm | none |
| none | Hydrogen chloride [7647-01-0] | none | C 2 ppm | none |
| none | Hydrogen cyanide and cyanide salts, as CN Hydrogen cyanide [74-90-8] |
none | C 4.7 ppm | Skin |
| none | Hydrogen cyanide and cyanide salts, as CN Cyanide salts [143-33-9; 151-50-8; 592-01-8] |
none | C 5 mg/m3 | Skin |
| none | Hydrogen fluoride [7664-39-3], as F | 0.5ppm | C 2 ppm | Skin |
| none | Hydrogen peroxide [7722-84-1] | 1 ppm | none | none |
| none | Hydrogen selenide [7783-07-5], as Se | 0.05 ppm | none | none |
| Ontario Table | Hydrogen sulfide [7783-06-4] | 10 ppm | 15 ppm | none |
| none | Hydroquinone [123-31-9] | 1 mg/m3 | none | none |
| none | 2-Hydroxypropyl acrylate [999-61-1] | 0.5 ppm | none | Skin |
Occupational exposure limits for Ontario workplaces: I
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Indene [95-13-6] | 5 ppm | none | none |
| none | Indium [7440-74-6] and compounds, as In | 0.1 mg/m3 | none | none |
| none | Iodine and Iodides – Iodine [7553-56-2] |
0.01 ppm (IFV) | 0.1 ppm (V) | none |
| none | Iodine and Iodides – Iodides |
0.01 ppm (IFV) | none | none |
| none | Iodoform [75-47-8] | 0.6 ppm | none | none |
| none | Iron oxide (Fe2 O3) [1309-37-1] | 5 mg/m3 (R) | none | none |
| none | Iron pentacarbonyl [13463-40-6], as Fe | 0.1 ppm | 0.2 ppm | none |
| none | Iron salts, soluble, as Fe | 1 mg/m3 | none | none |
| none | Isoamyl alcohol [123-51-3] | 100 ppm | 125 ppm | none |
| none | Isobutanol [78-83-1] | 50 ppm | none | none |
| none | Isobutyl nitrite [542-56-3] | none | C 1 ppm (IFV) | none |
| Reg. 833 O. Reg. 490/09 | Isocyanates, organic compounds – Toluene diisocyanate (TDI) [584-84-9] [91-08-7] |
0.005 ppm | C 0.02 ppm | none |
| Ontario Table, designated substance | Isocyanates, organic compounds – Methylene bisphenyl isocyanate (MDI) [101-68-8] |
0.005 ppm | C 0.02 ppm | none |
| Ontario Table, designated substance | Isocyanates, organic compounds – Hexamethylene diisocyanate (HDI) [822-06-0] |
0.005 ppm | C 0.02 ppm | none |
| Ontario Table, designated substance | Isocyanates, organic compounds – Isophorone diisocyanate (IPDI) [4098-71-9] |
0.005 ppm | C 0.02 ppm | none |
| Ontario Table, designated substance | Isocyanates, organic compounds – Methylene bis (4-cyclohexylisocyanate) [5124-30-1] |
0.005 ppm | C 0.02 ppm | none |
| Ontario Table, designated substance | Isocyanates, organic compounds – Methyl isocyanate [624-83-9] |
0.02 ppm | 0.06 ppm | Skin |
| Ontario Table, designated substance | Isocyanates, organic compounds – Ethyl isocyanate [109-90-1] |
0.02 ppm | 0.06 ppm | Skin |
| Ontario Table, designated substance | Isocyanates, organic compounds – Phenyl isocyanate [103-71-9] |
0.005 ppm | 0.015 ppm | Skin |
| none | Isooctyl alcohol [26952-21-6] | 50 ppm | none | Skin |
| none | Isophorone [78-59-1] | none | C 5 ppm | none |
| Ontario Table, designated substance | Isophorone diisocyanate [4098-71-9] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| none | 2-Isopropoxyethanol [109-59-1] | 25 ppm | none | Skin |
| none | Isopropyl acetate [108-21-4] | 100 ppm | 200 ppm | none |
| none | Isopropylamine [75-31-0] | 5 ppm | 10 ppm | none |
| Ontario Table | Isopropylaminoethanols [109-56-8; 121-93-7] | none | 400 ppm 1,900 mg/m3 |
none |
| none | N-Isopropylaniline [768-52-5] | 2 ppm | none | Skin |
| Ontario Table | Isosorbide dinitrate [87-33-2] | 0.2 mg/m3 | none | Skin |
| none | Isopropyl ether [108-20-3] | 250 ppm | 310 ppm | none |
| none | Isopropyl glycidyl ether (IGE) [4016-14-2] | 50 ppm | 75 ppm | none |
Occupational exposure limits for Ontario workplaces: K-L
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Kaolin [1332-58-7] | 2 mg/m3 (E)(R) | none | none |
| none | Kerosene [8008-20-6; 64742-81-0] / Jet fuels, as total hydrocarbon vapour | 200 mg/m3 (P) | none | Skin |
| none | Ketene [463-51-4] | 0.5 ppm | 1.5 ppm | none |
| Ontario Table, designated substance | 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 | none | Skin (organic compounds) |
| Ontario Table, designated substance | Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb – Tetraethyl lead, as Pb [78-00-2] |
0.10 mg/m3 | 0.30 mg/m3 | Skin |
| Ontario Table, designated substance | Lead chromate [7758-97-6] – as Pb (see listing for Lead [7439-92-1]) |
0.05 mg/m3 | none | none |
| Ontario Table, designated substance | Lead chromate [7758-97-6] – as Cr |
0.012 mg/m3 | none | none |
| Ontario Table | Lincomycin [154-21-2] | 0.1 mg/m3 | none | none |
| none | Lindane [58-89-9] | 0.5 mg/m3 | none | Skin |
| none | Lithium hydride [7580-67-8] | none | C 0.05 mg/m3 (I) | none |
| Ontario Table | Lithium hydroxide – Anhydrous [1310-65-2] |
none | 1 mg/m3 | none |
| Ontario Table | Lithium hydroxide – Monohydrate [1310-66-3] |
none | 1 mg/m3 | none |
| none | L.P.G. (Liquefied petroleum gas) [68476-85-7] | (EX),Simple asphyxiant (D) ; section 7.1 of Regulation 833 applies | (EX),Simple asphyxiant (D) ; section 7.1 of Regulation 833 applies | none |
Occupational exposure limits for Ontario workplaces: M
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Magnesium oxide [1309-48-4] | 10 mg/m3 (I) | none | none |
| none | Malathion [121-75-5] | 1 mg/m3 (IFV) | none | Skin |
| none | Maleic anhydride [108-31-6] | 0.01 mg/m3 (IFV) | none | none |
| Ontario Table | Manganese [7439-96-5] elemental and inorganic compounds, as Mn | 0.2 mg/m3 | none | none |
| none | Manganese cyclopentadienyl tricarbonyl [12079-65-1], as Mn |
0.1 mg/m3 | none | Skin |
| Ontario Table, designated substance | 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 | none | Skin |
| Ontario Table, designated substance | Mercury [7439-97-6], elemental mercury, inorganic and organic compounds of mercury, as Hg – Alkyl compounds of, as Hg |
0.01 mg/m3 | 0.03 mg/m3 | Skin |
| none | Mesityl oxide [141-79-7] | 15 ppm | 25 ppm | none |
| none | Methacrylic acid [79-41-4] | 20 ppm | none | none |
| none | Methane [74-82-8] | Section 7.1 of Regulation 833 applies | Section 7.1 of Regulation 833 applies | none |
| none | Methanol [67-56-1] | 200 ppm | 250 ppm | Skin |
| none | Methomyl [16752-77-5] | 0.2 mg/m3 (IFV) | none | Skin |
| none | Methoxychlor [72-43-5] | 10 mg/m3 | none | none |
| none | 2-Methoxyethanol (EGME) [109-86-4] | 0.1 ppm | none | Skin |
| none | 2-Methoxyethyl acetate (EGMEA) [110-49-6] | 0.1 ppm | none | Skin |
| Ontario Table | Methoxyflurane [76-38-0] | 2 ppm 13 mg/m3 |
none | none |
| none | (2-Methoxymethylethoxy) propanol (DPGME) [34590-94-8] | 100 ppm | 150 ppm | Skin |
| none | 4-Methoxyphenol [150-76-5] | 5 mg/m3 | none | none |
| none | 1-Methoxy-2-propanol (PGME) [107-98-2] | 50 ppm | 100 ppm | none |
| none | Methyl acetate [79-20-9] | 200 ppm | 250 ppm | none |
| none | Methylacetylene [74-99-7] | 1,000 ppm (EX) | none | none |
| none | Methylacetylene-propadiene mixture (MAPP) [59355-75-8] | 1,000 ppm (EX) | 1,250 ppm (EX) | none |
| none | Methyl acrylate [96-33-3] | 2 ppm | none | Skin |
| none | Methylacrylonitrile [126-98-7] | 1 ppm | none | Skin |
| none | Methylal [109-87-5] | 1,000 ppm | none | none |
| none | Methylamine [74-89-5] | 5 ppm | 15 ppm | none |
| Ontario Table | Methyl n-amyl ketone [110-43-0] | 25 ppm 115 mg/m3 |
none | none |
| none | N-Methyl aniline [100-61-8] | 0.5 ppm | none | Skin |
| none | Methyl bromide [74-83-9] | 1 ppm | none | Skin |
| Ontario Table | Methyl tert-butyl ether (MTBE) [1634-04-4] | 40 ppm | none | none |
| Ontario Table | Methyl n-butyl ketone [591-78-6] | 1 ppm 4 mg/m3 |
none | Skin |
| none | Methyl chloride [74-87-3] | 50 ppm | 100 ppm | Skin |
| none | Methyl chloroform [71-55-6] | 350 ppm | 450 ppm | none |
| none | Methyl 2-cyanoacrylate [137-05-3] | 0.2 ppm | none | none |
| none | Methylcyclohexane [108-87-2] | 400 ppm | none | none |
| none | Methylcyclohexanol [25639-42-3] | 50 ppm | none | none |
| none | o-Methylcyclohexanone [583-60-8] | 50 ppm | 75 ppm | Skin |
| none | 2-Methylcyclopentadienyl manganese tricarbonyl [12108-13-3], as Mn | 0.2 mg/m3 | none | Skin |
| none | Methyl demeton [8022-00-2] | 0.05 mg/m3 (IFV) | none | Skin |
| Ontario Table, designated substance | Methylene bisphenyl isocyanate [101-68-8] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| Ontario Table | 4,4'-Methylene bis(2-chloroaniline) (MBOCA; MOCA®) [101-14-4] | 0.0005 ppm 0.005 mg/m3 |
none | Skin |
| Ontario Table, designated substance | Methylene bis(4-cyclohexylisocyanate [5124-30-1] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| Ontario Table | 4,4'-Methylene dianiline [101-77-9] | 0.04 mg/m3 | none | Skin |
| none | Methyl ethyl ketone (MEK) [78-93-3] | 200 ppm | 300 ppm | none |
| none | Methyl ethyl ketone peroxide [1338-23-4] | none | C 0.2 ppm | none |
| none | Methyl formate [107-31-3] | 50 ppm | 100 ppm | Skin |
| none | Methyl hydrazine [60-34-4] | 0.01 ppm | none | Skin |
| none | Methyl iodide [74-88-4] | 2 ppm | none | Skin |
| none | Methyl isoamyl ketone [110-12-3] | 20 ppm | 50 ppm | none |
| none | Methyl isobutyl carbinol [108-11-2] | 25 ppm | 40 ppm | Skin |
| none | Methyl isobutyl ketone [108-10-1] | 20 ppm | 75 ppm | none |
| Ontario Table, designated substance | Methyl isocyanate [624-83-9] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| none | Methyl isopropyl ketone [563-80-4] | 20 ppm | none | none |
| none | Methyl mercaptan [74-93-1] | 0.5 ppm | none | none |
| none | Methyl methacrylate [80-62-6] | 50 ppm | 100 ppm | none |
| none | 1-Methyl naphthalene [90-12-0] and 2-Methyl naphthalene [91-57-6] |
0.5 ppm | none | Skin |
| none | Methyl parathion [298-00-0] | 0.02 mg/m3 (IFV) | none | Skin |
| none | Methyl propyl ketone [107-87-9] | none | 150 ppm | none |
| Ontario Table | N-Methyl-2-pyrrolidone [872-50-4] | 400 mg/m3 | none | none |
| none | Methyl silicate [681-84-5] | 1 ppm | none | none |
| none | α-Methyl styrene [98-83-9] | 10 ppm | none | none |
| none | Methyl vinyl ketone [78-94-4] | none | C 0.2 ppm | Skin |
| none | Metribuzin [21087-64-9] | 5 mg/m3 | none | none |
| none | Mevinphos [7786-34-7] | 0.01 mg/m3 (IFV) | none | Skin |
| none | Mica [12001-26-2] | 3 mg/m3 (R) | none | none |
| Ontario Table | Mineral Spirits | 525 mg/m3 | none | none |
| none | Mineral oil [8012-95-1], excluding metal working fluids – Pure, highly and severely refined |
5 mg/m3 (I) | none | none |
| none | Mineral oil [8012-95-1], excluding metal working fluids – Poorly and mildly refined |
(L) | none | none |
| none | Molybdenum [7439-98-7], as Mo – Soluble compounds |
0.5 mg/m3 (R) | none | none |
| none | Molybdenum [7439-98-7], as Mo – Metal and insoluble compounds |
10 mg/m3 (I) 3 mg/m3 (R) |
none | none |
| none | Monochloroacetic acid [79-11-8] | 0.5 ppm (IFV) | none | Skin |
| none | Monocrotophos [6923-22-4] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Morpholine [110-91-8] | 20 ppm | none | Skin |
Occupational exposure limits for Ontario workplaces: N
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Naled [300-76-5] | 0.1 mg/m3 (IFV) | none | Skin |
| none | Naphthalene [91-20-3] | 10 ppm | none | Skin |
| none | β-Naphthylamine [91-59-8] | (L) | none | none |
| none | Natural gas [8006-14-2] | Section 7.1 of Regulation 833 applies | Section 7.1 of Regulation 833 applies | none |
| none | Natural rubber latex [9006-04-6], as inhalable allergenic proteins |
0.0001 mg/m3 (I) | none | Skin |
| none | Neon [7440-01-9] | Simple asphyxiant; section 7.1 of Regulation 833 applies | Simple asphyxiant; section 7.1 of Regulation 833 applies | none |
| Ontario Table | Nepheline syenite (total dust) [37244-96-5] | 10 mg/m3 | none | none |
| Ontario Table | Nickel – Elemental/metal [7440-02-0] |
1 mg/m3 (I) | none | none |
| Ontario Table | Nickel – Insoluble compounds, as Ni [7440-02-0] |
0.2 mg/m3 (I) | none | none |
| Ontario Table | Nickel – Soluble compounds, as Ni [7440-02-0] |
0.1 mg/m3 (I) | none | none |
| Ontario Table | Nickel – Nickel subsulfide, as Ni [12035-72-2] |
0.1 mg/m3 (I) | none | none |
| none | Nickel carbonyl [13463-39-3], as Ni | none | C 0.05 ppm | none |
| none | Nicotine [54-11-5] | 0.5 mg/m3 | none | Skin |
| none | Nitrapyrin [1929-82-4] | 10 mg/m3 | 20 mg/m3 | none |
| none | Nitric acid [7697-37-2] | 2 ppm | 4 ppm | none |
| none | Nitric oxide [10102-43-9] | 25 ppm | none | none |
| none | p-Nitroaniline [100-01-6] | 3 mg/m3 | none | Skin |
| none | Nitrobenzene [98-95-3] | 1 ppm | none | Skin |
| none | p-Nitrochlorobenzene [100-00-5] | 0.1 ppm | none | Skin |
| none | 4-Nitrodiphenyl [92-93-3] | (L) | none | Skin |
| none | Nitroethane [79-24-3] | 100 ppm | none | none |
| none | Nitrogen [7727-37-9] | Simple asphyxiant; section 7.1 of Regulation 833 applies | Simple asphyxiant; section 7.1 of Regulation 833 applies | |
| Ontario Table | Nitrogen dioxide [10102-44-0] | 3 ppm | 5 ppm | none |
| none | Nitrogen trifluoride [7783-54-2] | 10 ppm | none | none |
| none | Nitroglycerin (NG) [55-63-0] | 0.05 ppm | none | Skin |
| none | Nitromethane [75-52-5] | 20 ppm | none | none |
| none | 1-Nitropropane [108-03-2] | 25 ppm | none | none |
| none | 2-Nitropropane [79-46-9] | 10 ppm | none | none |
| Ontario Table | N-Nitrosamines, including n-Nitrosodimethylamine [62-75-9] |
(L) | none | Skin |
| none | Nitrotoluene, All isomers [88-72-2; 99-08-1; 99-99-0] | 2 ppm | none | Skin |
| none | 5-Nitro-o-toluidine [99-55-8] | 1 mg/m3 (I) | none | none |
| Ontario Table | Nitrous oxide [10024-97-2] | 25 ppm 45 mg/m3 |
none | none |
| none | Nonane [111-84-2] All isomers |
200 ppm | none | none |
Occupational exposure limits for Ontario workplaces: O
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Octachloronaphthalene [2234-13-1] | 0.1 mg/m3 | 0.3 mg/m3 | Skin |
| none | Octane, All isomers [111-65-9] | 300 ppm | none | none |
| none | Osmium tetroxide [20816-12-0], as Os | 0.0002 ppm | 0.0006 ppm | none |
| none | Oxalic acid, anhydrous [144-62-7] and dehydrate [6153-56-6] | 1 mg/m3 | 2 mg/m3 | none |
| none | p,p'-Oxybis(benzenesulfonyl hydrazide) [80-51-3] | 0.1 mg/m3 (I) | none | none |
| none | Oxygen difluoride [7783-41-7] | none | C 0.05 ppm | none |
| Ontario Table | Ozone [10028-15-6] | 0.1 ppm 0.2 mg/m3 |
0.3 ppm 0.6 mg/m3 |
none |
Occupational exposure limits for Ontario workplaces: P
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Paraffin wax fume [8002-74-2] | 2 mg/m3 | none | none |
| Ontario Table | Paraquat [4685-14-7] | 0.1 mg/m3 | none | none |
| none | Parathion [56-38-2] | 0.05 mg/m3 (IFV) | none | Skin |
| Ontario Table | Particles (Insoluble or Poorly Soluble) Not Otherwise Specified (PNOS) | 10 mg/m3 (I) 3 mg/m3(R) |
none | none |
| Ontario Table | Penicillin (total dust) [1406-05-9] | 0.1 mg/m3 | none | none |
| none | Pentaborane [19624-22-7] | 0.005 ppm | 0.015 ppm | none |
| none | Pentachloronaphthalene [1321-64-8] | 0.5 mg/m3 | none | Skin |
| none | Pentachloronitrobenzene [82-68-8] | 0.5 mg/m3 | none | none |
| none | Pentachlorophenol [87-86-5] | 0.5 mg/m3 (IFV) | 1 mg/m3 (IFV) | Skin |
| none | Pentaerythritol [115-77-5] | 10 mg/m3 | none | none |
| Ontario Table | Pentaerythritol tetrabenzoate [4196-86-5] | none | 2 mg/m3 | none |
| none | Pentane, All isomers [78-78-4; 109-66-0; 463-82-1] | 1000 ppm | none | none |
| none | 2,4-Pentanedione [123-54-6] | 25 ppm | none | Skin |
| none | 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 | none |
| none | Peracetic acid [79-21-0] | none | 0.4 ppm (IFV) | none |
| none | Perchloromethyl mercaptan [594-42-3] | 0.1 ppm | none | none |
| none | Perchloryl fluoride [7616-94-6] | 3 ppm | 6 ppm | none |
| none | Perfluorobutyl ethylene [19430-93-4] | 100 ppm | none | none |
| none | Perfluoroisobutylene [382-21-8] | none | C 0.01 ppm | none |
| none | Persulfates, as persulfate | 0.1 mg/m3 | none | none |
| Ontario Table | Petroleum coke (total dust) [64741-79-3] | 3.5 mg/m3 (a) | none | none |
| none | Petroleum ether | (d) | none | none |
| none | Phenol [108-95-2] | 5 ppm | none | Skin |
| none | Phenothiazine [92-84-2] | 5 mg/m3 | none | Skin |
| Ontario Table | 2-Phenoxyethanol [122-99-6] | 25 ppm 141 mg/m3 |
none | Skin |
| none | N-Phenyl-β-naphthylamine [135-88-6] | (L) | none | none |
| none | o-Phenylenediamine [95-54-5] | 0.1 mg/m3 | none | none |
| none | m-Phenylenediamine [108-45-2] | 0.1 mg/m3 | none | none |
| none | p-Phenylenediamine [106-50-3] | 0.1 mg/m3 | none | none |
| none | Phenyl ether [101-84-8], vapor | 1 ppm | 2 ppm | none |
| none | Phenyl glycidyl ether (PGE) [122-60-1] | 0.1 ppm | none | Skin |
| none | Phenylhydrazine [100-63-0] | 0.1 ppm | none | Skin |
| Ontario Table, designated substance | Phenyl isocyanate [103-71-9] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| none | Phenyl mercaptan [108-98-5] | 0.1 ppm | none | Skin |
| none | Phenylphosphine [638-21-1] | none | C 0.05 ppm | none |
| none | Phorate [298-02-2] | 0.05 mg/m3 (IFV) | none | Skin |
| none | Phosgene [75-44-5] | 0.1 ppm | none | none |
| none | Phosphine [7803-51-2] | 0.3 ppm | 1 ppm | none |
| none | Phosphoric acid [7664-38-2] | 1 mg/m3 | 3 mg/m3 | none |
| none | Phosphorus (yellow) [12185-10-3] | 0.1 mg/m3 | none | none |
| none | Phosphorus oxychloride [10025-87-3] | 0.1 ppm | none | none |
| none | Phosphorus pentachloride [10026-13-8] | 0.1 ppm | none | none |
| none | Phosphorus pentasulfide [1314-80-3] | 1 mg/m3 | 3 mg/m3 | none |
| none | Phosphorus trichloride [7719-12-2] | 0.2 ppm | 0.5 ppm | none |
| none | Phthalic anhydride [85-44-9] | 0.002 mg/m3 (IFV) | 0.005 mg/m3 (IFV) | |
| none | m-Phthalodinitrile [626-17-5] | 5 mg/m3 (IFV) | none | none |
| none | o-Phthalodinitrile [91-15-6] | 1 mg/m3 (IFV) | none | none |
| none | Picloram [1918-02-1] | 10 mg/m3 | none | none |
| none | Picric acid [88-89-1] | 0.1 mg/m3 | none | none |
| none | Pindone [83-26-1] | 0.1 mg/m3 | none | none |
| none | Piperazine [110-85-0] and salts, as piperazine | 0.03 ppm (IFV) | none | none |
| Ontario Table | Platinum [7440-06-4] – Metal |
1 mg/m3 | none | none |
| Ontario Table | Platinum [7440-06-4] – Water-soluble compounds of, including chloroplatinates (as Pt) |
0.002 mg/m3 | none | none |
| none | Polyvinyl chloride (PVC) [9002-86-2] | 1 mg/m3 (R) | none | none |
| Ontario Table | Polychlorinated biphenyls (PCBs)2 | 0.05 mg/m3 | none | none |
| none | Portland cement [65997-15-1] | 1 mg/m3 (E)(R) | none | none |
| none | Potassium hydroxide [1310-58-3] | none | C 2 mg/m3 | none |
| Ontario Table | Poultry dust (total dust) | 5 mg/m3 | none | none |
| none | Propane [74-98-6] | (EX),Simple asphyxiant (D) ; section 7.1 of Regulation 833 applies | (EX),Simple asphyxiant (D) ; section 7.1 of Regulation 833 applies | none |
| none | Propane sultone [1120-71-4] | (L) | none | none |
| none | n-Propanol (n-Propyl alcohol) [71-23-8] | 100 ppm | none | none |
| none | 2-Propanol [67-63-0] | 200 ppm | 400 ppm | none |
| none | Propargyl alcohol [107-19-7] | 1 ppm | none | Skin |
| none | β-Propiolactone [57-57-8] | 0.5 ppm | none | none |
| none | Propionaldehyde [123-38-6] | 20 ppm | none | none |
| none | Propionic acid [79-09-4] | 10 ppm | none | none |
| none | Propoxur [114-26-1] | 0.5 mg/m3 (IFV) | none | none |
| none | n-Propyl acetate [109-60-4] | 200 ppm | 250 ppm | none |
| none | Propylene [115-07-1] | 500 ppm | none | none |
| none | Propylene dichloride [78-87-5] | 10 ppm | none | none |
| none | Propylene glycol dinitrate [6423-43-4] | 0.05 ppm | none | Skin |
| Ontario Table | 1,2-Propylene glycol [57-55-6] | 50 ppm (V) 155 mg/m3 (V) 10 mg/m3 (H)(b) |
none | none |
| Ontario Table | Propylene glycol monomethyl ether acetate [108-65-6] | 50 ppm 270 mg/m3 |
none | none |
| none | Propylene oxide [75-56-9] | 2 ppm | none | none |
| none | Propyleneimine [75-55-8] | 0.2 ppm | 0.4 ppm | Skin |
| none | n-Propyl nitrate [627-13-4] | 25 ppm | 40 ppm | none |
| none | Pyrethrum [8003-34-7] | 5 mg/m3 | none | none |
| none | Pyridine [110-86-1] | 1 ppm | none | none |
Occupational exposure limits for Ontario workplaces: Q-R
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Quinone [106-51-4] | 0.1 ppm | none | none |
| none | Resorcinol [108-46-3] | 10 ppm | 20 ppm | none |
| none | Rhodium [7440-16-6], as Rh – Metal and Insoluble compounds |
1 mg/m3 | none | none |
| none | Rhodium [7440-16-6], as Rh – Soluble compounds |
0.01 mg/m3 | none | none |
| none | Ronnel [299-84-3] | 5 mg/m3 (IFV) | none | none |
| none | Rosin core solder thermal decomposition products (colophony) [8050-09-7] | (L) | none | none |
| none | Rotenone (commercial) [83-79-4] | 5 mg/m3 | none | none |
| none | Rubber Solvent (Naphtha) [8030-30-6] | (d) | none | none |
Occupational exposure limits for Ontario workplaces: S
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Selenium [7782-49-2] and compounds, as Se | 0.2 mg/m3 | none | none |
| Ontario Table | Selenium hexafluoride [7783-79-1], as Se | 0.025 ppm 0.1 mg/m3 |
none | none |
| none | Sesone [136-78-7] | 10 mg/m3 | none | none |
| Ontario Table | Shellac dust (total dust) [9000-59-3] | 10 mg/m3 | none | none |
| Ontario Table, designated substance | Silica, Crystalline – Quartz/Tripoli [14808-60-7; 1317-95-9] |
0.10 mg/m3 (R) | none | none |
| Ontario Table, designated substance | Silica, Crystalline – Cristobalite [14464-46-1] |
0.05 mg/m3 (R) | none | none |
| Ontario Table | Silica fume [69012-64-2] | 2 mg/m3 (R) | none | none |
| Ontario Table | Silica fused [60676-86-0] | 0.1 mg/m3 (R) | none | none |
| Ontario Table | Silicon carbide [409-21-2] – Non-fibrous |
10 mg/m3 (I)(E) 3 mg/m3 (R)(E) |
none | none |
| Ontario Table | Silicon carbide [409-21-2] – Fibrous (including whiskers) |
0.1 f/cc(R)(F) | none | none |
| none | Silicon tetrahydride [7803-62-5] | 5 ppm | none | none |
| none | Silver [7440-22-4] and compounds – Metal, dust and fume |
0.1 mg/m3 | none | none |
| none | Silver [7440-22-4] and compounds – Soluble Compounds, as Ag |
0.01 mg/m3 | none | none |
| none | Simazine [122-34-9] | none | none | |
| Ontario Table | Sisal dust (total dust) | 2 mg/m3 | none | none |
| Ontario Table | Soap dust [68918-36-5] | 5 mg/m3 | none | none |
| none | Sodium azide [26628-22-8] – as Sodium azide |
none | C 0.29 mg/m3 | none |
| none | Sodium azide [26628-22-8] – as Hydrazoic acid vapour |
none | C 0.11 ppm | none |
| none | Sodium bisulfite [7631-90-5] | 5 mg/m3 | none | none |
| none | Sodium fluoroacetate [62-74-8] | 0.05 mg/m3 | none | Skin |
| none | Sodium hydroxide [1310-73-2] | none | C 2 mg/m3 | none |
| none | Sodium metabisulfite [7681-57-4] | 5 mg/m3 | none | none |
| Ontario Table | Spectinomycin [1695-77-8] | 2 mg/m3 | none | none |
| none | Starch [9005-25-8] | 10 mg/m3 | none | none |
| none | Stearates (J) [57-11-4; 557-04-0; 557-05-1;822-16-2] |
10 mg/m3 (I) 3 mg/m3 (R) |
none | none |
| none | Stoddard solvent [8052-41-3] | 100 ppm | none | none |
| Ontario Table | 140 Degree F Flash Aliphatic Solvent, Type of Stoddard Solvent | 525 mg/m3 | none | none |
| none | Strontium chromate [7789-06-2], as Cr | 0.0005 mg/m3 | none | none |
| none | Strychnine [57-24-9] | 0.15 mg/m3 | none | none |
| Ontario Table | Styrene - monomer [100-42-5] | 35 ppm | 100 ppm | none |
| none | Subtilisins [1395-21-7; 9014-01-1], as 100% crystalline pure active enzyme |
none | C 0.00006 mg/m3 | none |
| none | Sucrose [57-50-1] | 10 mg/m3 | none | none |
| none | Sulfometuron methyl [74222-97-2] | 5 mg/m3 | none | none |
| none | Sulfotepp (TEDP) [3689-24-5] | 0.1 mg/m3 (IFV) | none | Skin |
| Ontario Table | Sulfur dioxide [7446-09-5] | 2 ppm 5.2 mg/m3 |
5 ppm 10.4 mg/m3 |
none |
| none | Sulfur hexafluoride [2551-62-4] | 1,000 ppm | none | none |
| none | Sulfuric acid [7664-93-9] | 0.2 mg/m3 (T) | none | none |
| none | Sulfur monochloride [10025-67-9] | none | C 1 ppm | none |
| none | Sulfur pentafluoride [5714-22-7] | none | C 0.01 ppm | none |
| none | Sulfur tetrafluoride [7783-60-0] | none | C 0.1 ppm | none |
| none | Sulfuryl fluoride [2699-79-8] | 5 ppm | 10 ppm | none |
| none | Sulprofos [35400-43-2] | 0.1 mg/m3 (IFV) | none | Skin |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Continuous filament glass fibres |
5 mg/m3 (I) 1 f/cc (F) |
none | none |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Glass wool fibres |
1 f/cc (F) | none | none |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Refractory ceramic fibres |
0.5 f/cc (F) | none | none |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Rock wool fibres |
1 f/cc (F) | none | none |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Slag wool fibres |
1 f/cc (F) | none | none |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Special purpose glass fibres |
1 f/cc (F) | none | none |
| Ontario Table | Synthetic Vitreous Fibres (Man Made Mineral Fibres) – Synthetic Vitreous Fibres, not otherwise classified (excluding fibrous glass dust and mineral wool fibre) |
1 f/cc (F) (c) | none | none |
Occupational exposure limits for Ontario workplaces: T
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | 2,4,5-T [93-76-5] | 10 mg/m3 | none | none |
| Ontario Table | Talc [14807-96-6], containing no asbestos | 2 mg/m3 (R)(E) 2 f/cc (K) |
none | none |
| none | Tellurium [13494-80-9] and compounds (NOS), as Te, excluding hydrogen telluride | 0.1 mg/m3 | none | none |
| Ontario Table | Tellurium hexafluoride [7783-80-4], as Te | 0.01 ppm 0.1 mg/m3 |
none | none |
| none | Temephos [3383-96-8] | 1 mg/m3 (IFV) | none | Skin |
| none | Terbufos [13071-79-9] | 0.01 mg/m3 (IFV) | none | Skin |
| none | Terephthalic acid [100-21-0] | 10 mg/m3 | none | none |
| none | Terphenyls (o-, m-, p-isomers) [26140-60-3] | none | C 5 mg/m3 | none |
| none | 1,1,2,2-Tetrabromoethane [79-27-6] | 0.1 ppm (IFV) | none | none |
| none | 1,1,1,2-Tetrachloro-2,2-difluoroethane [76-11-9] | 100 ppm | none | none |
| none | 1,1,2,2-Tetrachloro-1,2-difluoroethane [76-12-0] | 50 ppm | none | none |
| none | 1,1,2,2-Tetrachloroethane [79-34-5] | 1 ppm | none | Skin |
| none | Tetrachloroethylene [127-18-4] | 25 ppm | 100 ppm | none |
| Ontario Table | Tetrachlorophathalic anhydride [117-08-8] | 0.1 mg/m3 | none | none |
| Ontario Table | Tetrachlorophenol [25167-83-3] | 0.5 mg/m3 | none | Skin |
| none | Tetrachloronaphthalene [1335-88-2] | 2 mg/m3 | none | none |
| Ontario Table, designated substance | Tetraethyl lead [78-00-2], as Pb | See Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb | See Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb | none |
| none | Tetraethyl pyrophosphate (TEPP) [107-49-3] | 0.01 mg/m3 (IFV) | none | Skin |
| none | Tetrafluoroethylene [116-14-3] | 2 ppm | none | none |
| none | Tetrahydrofuran [109-99-9] | 50 ppm | 100 ppm | Skin |
| none | Tetrakis (hydroxymethyl) phosphonium salts – Tetrakis (hydroxymethyl) phosphonium chloride [124-64-1] |
2 mg/m3 | none | none |
| none | Tetrakis (hydroxymethyl) phosphonium salts – Tetrakis (hydroxymethyl) phosphonium sulfate [55566-30-8] |
2 mg/m3 | none | none |
| Ontario Table, designated substance | Tetramethyl lead [75-74-1], as Pb | See Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb | See Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb | none |
| none | Tetramethyl succinonitrile [3333-52-6] | 0.5 ppm | none | Skin |
| none | Tetranitromethane [509-14-8] | 0.005 ppm | none | none |
| Ontario Table | Tetrasodium pyrophosphate [7722-88-5] | 5 mg/m3 | none | none |
| none | Tetryl [479-45-8] | 1.5 mg/m3 | none | none |
| none | Thallium [7440-28-0] and compounds, as Tl |
0.02 mg/m3 (I) | none | Skin |
| none | 4,4' Thiobis (6-tert-butyl-m-cresol) [96-69-5] | 1 mg/m3 (I) | none | none |
| none | Thioglycolic acid [68-11-1] | 1 ppm | none | Skin |
| none | Thionyl chloride [7719-09-7] | none | C 0.2 ppm | none |
| none | Thiram [137-26-8] | 0.05 mg/m3 (IFV) | none | none |
| Ontario Table | Tin [7440-31-5], as Sn – Metal |
2 mg/m3 | none | none |
| Ontario Table | Tin [7440-31-5], as Sn – Oxide and inorganic compounds, as Sn, except tin hydride |
2 mg/m3 | none | none |
| Ontario Table | Tin [7440-31-5], as Sn – Organic compounds, as Sn |
0.1 mg/m3 | none | Skin (organic compounds) |
| none | Titanium dioxide [13463-67-7] | 10 mg/m3 | none | none |
| Ontario Table | o-Tolidine [119-93-7] | (L) | none | Skin |
| none | Toluene [108-88-3] | 20 ppm | none | none |
| Ontario Table, designated substance | Toluene-2,4-or 2,6-diisocyanate (or as a mixture) [584-84-9][91-08-7] | See Isocyanates, organic compounds | See Isocyanates, organic compounds | none |
| none | o-Toluidine [95-53-4] | 2 ppm | none | Skin |
| none | m-Toluidine [108-44-1] | 2 ppm | none | Skin |
| none | p-Toluidine [106-49-0] | 2 ppm | none | Skin |
| none | Tributyl phosphate [126-73-8] | 5 mg/m3 (IFV) | none | none |
| none | Trichloroacetic acid [76-03-9] | 0.5 ppm | none | none |
| none | 1,2,4-Trichlorobenzene [120-82-1] | none | C 5 ppm | none |
| none | 1,1,2-Trichloroethane [79-00-5] | 10 ppm | none | Skin |
| none | Trichloroethylene [79-01-6] | 10 ppm | 25 ppm | none |
| none | Trichlorofluoromethane [75-69-4] | none | C 1,000 ppm | none |
| none | Trichloronaphthalene [1321-65-9] | 5 mg/m3 | none | Skin |
| none | 1,2,3-Trichloropropane [96-18-4] | 0.005 ppm | none | none |
| none | 1,1,2-Trichloro-1,2,2-trifluoroethane [76-13-1] | 1,000 ppm | 1,250 ppm | none |
| none | Trichlorphon [52-68-6] | 1 mg/m3 (I) | none | none |
| Ontario Table | Triethanolamine [102-71-6] | 0.5 ppm 3.1 mg/m3 |
none | none |
| none | Triethylamine [121-44-8] | 0.5 ppm | 1 ppm | Skin |
| Ontario Table | Triethylenediamine [280-57-9] | 1 ppm 4.6 mg/m3 |
none | Skin |
| Ontario Table | Triethylenetetramine [112-24-3] | 0.5 ppm 3 mg/m3 |
none | Skin |
| none | Trifluorobromomethane [75-63-8] | 1,000 ppm | none | none |
| none | 1,3,5-Triglycidyl-s-triazinetrione [2451-62-9] | 0.05 mg/m3 | none | none |
| none | Trimellitic anhydride [552-30-7] | 0.0005 mg/m3 (IFV) | 0.002 mg/m3 (IFV) | Skin |
| Ontario Table | Trimethoxyvinylsilane [2768-02-7] | none | 10 ppm 60 mg/m3 |
none |
| none | Trimethylamine [75-50-3] | 5 ppm | 15 ppm | none |
| none | Trimethyl benzene (mixed isomers) [25551-13-7] | 25 ppm | none | none |
| none | Trimethyl phosphite [121-45-9] | 2 ppm | none | none |
| none | 2,4,6-Trinitrotoluene (TNT) [118-96-7] | 0.1 mg/m3 | none | Skin |
| none | Triorthocresyl phosphate [78-30-8] | 0.02 mg/m3 (IFV) | none | Skin |
| none | Triphenyl phosphate [115-86-6] | 3 mg/m3 | none | none |
| Ontario Table | Trixylylphosphate [25155-23-1] | 0.1 mg/m3 | none | none |
| none | Tungsten [7440-33-7], and compounds, in the absence of Cobalt, as W | 3 mg/m3 (R) | none | none |
| none | Turpentine [8006-64-2] and selected monoterpenes [80-56-8; 127-91-3; 13466-78-9] | 20 ppm | none | none |
Occupational exposure limits for Ontario workplaces: U-V
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Uranium (natural) [7440-61-1] Soluble and insoluble compounds, as U |
0.2 mg/m3 | 0.6 mg/m3 | none |
| none | n-Valeraldehyde [110-62-3] | 50 ppm | none | none |
| none | Vanadium pentoxide [1314-62-1] as V | 0.05 mg/m3 (I) | none | none |
| none | Vinyl acetate [108-05-4] | 10 ppm | 15 ppm | none |
| none | Vinyl bromide [593-60-2] | 0.5 ppm | none | none |
| Ontario Table, designated substance | Vinyl chloride [75-01-04] | 1 ppm | none | none |
| none | 4-Vinyl cyclohexene [100-40-3] | 0.1 ppm | none | none |
| none | Vinyl cyclohexene dioxide [106-87-6] | 0.1 ppm | none | Skin |
| none | Vinyl fluoride [75-02-5] | 1 ppm | none | none |
| none | N-Vinyl-2-pyrrolidone [88-12-0] | 0.05 ppm | none | none |
| Ontario Table | Vinylidene chloride [75-35-4] | See 1,1-Dichloroethene [75-35-4] | See 1,1-Dichloroethene [75-35-4] | none |
| none | Vinylidene fluoride [75-38-7] | 500 ppm | none | none |
| none | Vinyl toluene [25013-15-4] | 50 ppm | 100 ppm | none |
| none | VM & P Naphtha [8032-32-4] | (d) | none | none |
Occupational exposure limits for Ontario workplaces: W-X-Y-Z
Go to endnotes and abbreviations at the bottom of the page.
| Ontario Table Listings | Agent [CAS No.] | Time-Weighted Average Limit (TWA) | Short-Term Exposure Limit (STEL) / Ceiling Limit (C) | Notations |
|---|---|---|---|---|
| none | Warfarin [81-81-2] | 0.01 mg/m3 (I) | none | Skin |
| Ontario Table | Wheat flour dust (total dust) | 3 mg/m3 | none | none |
| Ontario Table | Wood dust – Certain hardwoods as beech and oak |
1 mg/m3 | none | none |
| Ontario Table | Wood dust – Softwood |
5 mg/m3 | 10 mg/m3 | none |
| none | Xylene [1330-20-7] (o, m & p isomers) [95-47-6; 108-38-3; 106-42-3] | 100 ppm | 150 ppm | none |
| none | m-Xylene α,α'- diamine [1477-55-0] | none | C 0.1 mg/m3 | Skin |
| none | Xylidine (mixed isomers) [1300-73-8] | 0.5 ppm (IFV) | none | Skin |
| none | Yttrium [7440-65-5] and compounds, as Y | 1 mg/m3 | none | none |
| none | Zinc chloride fume [7646-85-7] | 1 mg/m3 | 2 mg/m3 | none |
| none | Zinc chromates [13530-65-9; 11103-86-9; 37300-23-5], as Cr | 0.01 mg/m3 | none | none |
| none | Zinc oxide [1314-13-2] | 2 mg/m3 (R) | 10 mg/m3 (R) | none |
| none | Zirconium [7440-67-7] and compounds, as Zr | 5 mg/m3 | 10 mg/m3 | none |
Endnotes and abbreviations
- Ontario Table – Denotes agents listed in Ontario Table in Regulation 833
- Designated substance – 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.
- (D) Simple asphyxiant
- (E) The value is for particulate matter containing no asbestos and < 1 per cent crystalline silica.
- (EX) Explosion hazard: The substance is a flammable asphyxiant or excursions above the occupational exposure limit could approach 10% of the lower explosive limit.
- (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 particulate matter.
- (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 particulate matter.
- (T) Thoracic particulate matter.
- (V) Vapour fraction.
- (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 MLTSD document determining occupational exposure limits for certain refined hydrocarbon solvent vapour mixtures.
Updated: June 01, 2023
Published: March 30, 2022