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.

Historical limits

Historical occupational exposure limits for Ontario workplaces under Regulation 833:

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 ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneAcetaldehyde [75-07-0]noneC 25 ppmnone
noneAcetamide [60-35-5]1 ppm (IFV)nonenone
noneAcetic acid [64-19-7]10 ppm15 ppmnone
noneAcetic anhydride [108-24-7]1 ppm3 ppmnone
noneAcetone [67-64-1]250 ppm500 ppmnone
noneAcetone cyanohydrin [75-86-5], as CNnoneC 5 mg/m3Skin
noneAcetonitrile [75-05-8]20 ppmnoneSkin
noneAcetophenone [98-86-2]10 ppmnonenone
noneAcetylene [74-86-2](EX), Simple asphyxiant (D); section 7.1 Regulation 833 applies(EX), Simple asphyxiant (D); section 7.1 Regulation 833 appliesnone
noneAcetylsalicylic acid (Aspirin) [50-78-2]5 mg/m3nonenone
noneAcrolein [107-02-8]noneC 0.1 ppmSkin
noneAcrylamide [79-06-1]0.03 mg/m3 (IFV)noneSkin
noneAcrylic acid [79-10-7]2 ppmnoneSkin
Ontario Table, designated substanceAcrylonitrile [107-13-1]2 ppmC 10 ppmSkin
noneAdipic acid [124-04-9]5 mg/m3nonenone
noneAdiponitrile [111-69-3]2 ppmnoneSkin
noneAlachlor [15972-60-8]1 mg/m3 (IFV)nonenone
noneAldrin [309-00-2]0.05 mg/m3 (IFV)noneSkin
noneAllyl alcohol [107-18-6]0.5 ppmnoneSkin
noneAllyl bromide [106-95-6]0.1 ppm0.2 ppmSkin
noneAllyl chloride [107-05-1]1 ppm2 ppmSkin
noneAllyl glycidyl ether (AGE) [106-92-3]1 ppmnonenone
noneAllyl propyl disulfide [2179-59-1]0.5 ppmnonenone
noneAluminum metal [7429-90-5] and insoluble compounds1 mg/m3 (R)nonenone
none4-Aminodiphenyl [92-67-1](L)noneSkin
none2-Aminopyridine [504-29-0]0.5 ppmnonenone
noneAmitrole [61-82-5]0.2 mg/m3nonenone
noneAmmonia [7664-41-7]25 ppm35 ppmnone
noneAmmonium chloride, fume [12125-02-9]10 mg/m320 mg/m3none
noneAmmonium perfluorooctanoate [3825-26-1]0.01 mg/m3noneSkin
noneAmmonium sulfamate [7773-06-0]10 mg/m3nonenone
nonetert-Amyl methyl ether (TAME) [994-05-8]20 ppmnonenone
noneAniline [62-53-3]2 ppmnoneSkin
noneo-Anisidine [90-04-0]0.5 mg/m3noneSkin
nonep-Anisidine [104-94-9]0.5 mg/m3noneSkin
noneAntimony [7440-36-0] and compounds, as Sb0.5 mg/m3nonenone
noneAntimony hydride [7803-52-3]0.1 ppmnonenone
noneAntimony trioxide [1309-64-4] production(L)nonenone
noneANTU [86-88-4]0.3 mg/m3noneSkin
noneArgon [7440-37-1]

Simple asphyxiant (D); section 7.1 Regulation 833 applies

Simple asphyxiant (D); section 7.1 Regulation 833 appliesnone
Ontario Table, designated substanceArsenic, 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/m30.05 mg/m3none
noneArsine [7784-42-1]0.005 ppmnonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4]0.1 f/cc (F)nonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4] –
Actinolite [77536-66-4]
0.1 f/cc (F)nonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4] –
Amosite [12172-73-5]
0.1 f/cc (F)nonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4] –
Anthophyllite [77536-67-5]
0.1 f/cc (F)nonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4] –
Chrysotile [132207-32-0]
0.1 f/cc (F)nonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4] –
Crocidolite [12001-28-4]
0.1 f/cc (F)nonenone
Ontario Table, designated substanceAsbestos – All forms [1332-21-4] –
Tremolite [77536-68-6]
0.1 f/cc (F)nonenone
noneAsphalt (Bitumen) fume [8052-42-4],
as benzene-soluble aerosol
0.5 mg/m3 (I)nonenone
noneAtrazine [1912-24-9] (and related symmetrical triazines)2 mg/m3 (I)nonenone
noneAzinphos-methyl [86-50-0]0.2 mg/m3 (IFV)noneSkin

Occupational exposure limits for Ontario workplaces: B

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneBarium [7440-39-3] and soluble compounds,
as Ba
0.5 mg/m3nonenone
noneBarium sulfate [7727-43-7]5 mg/m3 (I)(E)nonenone
noneBenomyl [17804-35-2]1 mg/m3 (I)nonenone
noneBenz[a]anthracene [56-55-3](L)nonenone
Ontario TableBenzaldehyde [100-52-7]none4 ppm
17 mg/m3
none
Ontario Table, designated substanceBenzene [71-43-2]0.5 ppm2.5 ppmSkin
noneBenzidine [92-87-5](L)noneSkin
noneBenzo[b]fluoranthene [205-99-2](L)nonenone
noneBenzo[a]pyrene [50-32-8](L)nonenone
noneBenzotrichloride [98-07-7]noneC 0.1 ppmSkin
noneBenzoyl chloride [98-88-4]noneC 0.5 ppmnone
noneBenzoyl peroxide [94-36-0]5 mg/m3nonenone
noneBenzyl acetate [140-11-4]10 ppmnonenone
noneBenzyl chloride [100-44-7]1 ppmnonenone
noneBeryllium and compounds, as Be [7440-41-7]0.00005 mg/m3 (I)noneSkin (Soluble compounds only)
noneBiphenyl [92-52-4]0.2 ppmnonenone
noneBismuth telluride [1304-82-1] –
Undoped, as Bi2Te3
10 mg/m3nonenone
noneBismuth telluride [1304-82-1] –
Se-doped, as Bi2Te3
5 mg/m3nonenone
noneBorate compounds, Inorganic [1303-96-4;1330-43-4;10043-35-3; 12179-04-3]2 mg/m3 (I)6 mg/m3 (I)none
noneBoron oxide [1303-86-2]10 mg/m3nonenone
noneBoron trichloride [10294-33-4]noneC 0.7 ppmnone
noneBoron tribromide [10294-34-5]noneC 0.7 ppmnone
noneBoron trifluoride [7637-07-2]0.1 ppmC 0.7 ppmnone
noneBromacil [314-40-9]10 mg/m3nonenone
noneBromine [7726-95-6]0.1 ppm0.2 ppmnone
noneBromine pentafluoride [7789-30-2]0.1 ppmnonenone
noneBromoform [75-25-2]0.5 ppmnonenone
none1-Bromopropane [106-94-5]0.1 ppmnonenone
none1,3-Butadiene [106-99-0]2 ppmnonenone
noneButane, All isomers [75-28-5;106-97-8]none1000 ppm (EX)none
nonen-Butanol [71-36-3]20 ppmnonenone
nonesec-Butanol [78-92-2]100 ppmnonenone
nonetert-Butanol [75-65-0]100 ppmnonenone
noneButenes, All isomers [106-98-9; 107-01-7; 590-18-1; 624-64-6; 25167-67-3]250 ppmnonenone
noneButenes, All isomers [106-98-9; 107-01-7; 590-18-1; 624-64-6; 25167-67-3] –
Isobutene [115-11-7]
250 ppmnonenone
none2-Butoxyethanol (EGBE) [111-76-2]20 ppmnonenone
none2-Butoxyethyl acetate (EGBEA) [112-07-2]20 ppmnonenone
noneButyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5]50 ppm150 ppmnone
nonen-Butyl acrylate [141-32-2]2 ppmnonenone
nonen-Butylamine [109-73-9]noneC 5 ppmSkin
noneButylated hydroxytoluene (BHT) [128-37-0]2 mg/m3 (IFV)nonenone
nonetert-Butyl chromate, as CrO3 [1189-85-1]noneC 0.1 mg/m3Skin
nonen-Butyl glycidyl ether (BGE) [2426-08-6]3 ppmnoneSkin
nonen-Butyl lactate [138-22-7]5 ppmnonenone
nonen-Butyl mercaptan [109-79-5]0.5 ppmnonenone
noneo-sec-Butylphenol [89-72-5]5 ppmnoneSkin
nonep-tert-Butyl toluene [98-51-1]1 ppmnonenone

Occupational exposure limits for Ontario workplaces: C

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

 
Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneCadmium [7440-43-9]0.01 mg/m3nonenone
noneCadmium [7440-43-9] –
Cadmium compounds, as Cd
0.002 mg/m3 (R)nonenone
noneCadusafos [95465-99-9]0.001 mg/m3 (IFV)noneSkin
Ontario TableCalcium chloride [10043-52-4]5 mg/m3nonenone
noneCalcium chromate [13765-19-0], as Cr0.001 mg/m3nonenone
noneCalcium cyanamide [156-62-7]0.5 mg/m3nonenone
noneCalcium hydroxide [1305-62-0]5 mg/m3nonenone
noneCalcium oxide [1305-78-8]2 mg/m3nonenone
noneCalcium silicate, naturally occurring as Wollastonite [13983-17-0]1 mg/m3 (I)(E)nonenone
noneCalcium sulfate [7778-18-9; 10034-76-1; 10101-41-4; 13397-24-5)]10 mg/m3 (I)nonenone
noneCamphor, synthetic [76-22-2]2 ppm3 ppmnone
noneCaprolactam [105-60-2]5 mg/m3 (IFV)nonenone
noneCaptafol [2425-06-1]0.1 mg/m3 (IFV)noneSkin
noneCaptan [133-06-2]5 mg/m3 (I)nonenone
noneCarbaryl [63-25-2]0.5 mg/m3 (IFV)noneSkin
noneCarbofuran [1563-66-2]0.1 mg/m3 (IFV)nonenone
noneCarbon black [1333-86-4]3 mg/m3 (I)nonenone
noneCarbon dioxide [124-38-9]5,000 ppm30,000 ppmnone
noneCarbon disulfide [75-15-0]1 ppmnoneSkin
 Carbon monoxide [630-08-0]25 ppmnonenone
noneCarbon tetrabromide [558-13-4]0.1 ppm0.3 ppmnone
Ontario TableCarbon tetrachloride [56-23-5]2 ppm3 ppmSkin
noneCarbonyl fluoride [353-50-4]2 ppm5 ppmnone
noneCarbonyl sulfide [463-58-1]5 ppmnonenone
noneCatechol [120-80-9]5 ppmnoneSkin
noneCellulose [9004-34-6]10 mg/m3nonenone
noneCesium hydroxide [21351-79-1]2 mg/m3nonenone
Ontario TableCharcoal, except activated [16291-96-6]10 mg/m3nonenone
noneChlordane [57-74-9]0.5 mg/m3noneSkin
noneChlorinated camphene [8001-35-2]0.5 mg/m31 mg/m3Skin
Ontario TableChlorinated diphenyl oxides [55720-99-5]0.5 mg/m32 mg/m3none
noneChlorine [7782-50-5]0.5 ppm1 ppmnone
noneChlorine dioxide [10049-04-4]0.1 ppm0.3 ppmnone
noneChlorine trifluoride [7790-91-2]noneC 0.1 ppmnone
noneChloroacetaldehyde [107-20-0]noneC 1 ppmnone
noneChloroacetone [78-95-5]noneC 1 ppmSkin
none2-Chloroacetophenone [532-27-4]0.05 ppmnonenone
noneChloroacetyl chloride [79-04-9]0.05 ppm0.15 ppmSkin
noneChlorobenzene [108-90-7]10 ppmnonenone
Ontario Tableo-Chlorobenzaldehyde [89-98-5]none4 ppm
23 mg/m3
none
noneo-Chlorobenzylidene malononitrile [2698-41-1]noneC 0.05 ppmSkin
noneChlorobromomethane [74-97-5]200 ppmnonenone
noneChlorodifluoromethane [75-45-6]1,000 ppmnonenone
Ontario TableChlorodiphenyl (42% chlorine) [53469-21-9]
Chlorodiphenyl (54% chlorine) [11097-69-1]
See Polychlorinated Biphenyls (PCBs)See Polychlorinated Biphenyls (PCBs)none
noneChloroform [67-66-3]10 ppmnonenone
nonebis(Chloromethyl) ether [542-88-1]0.001 ppmnonenone
noneChloromethyl methyl ether [107-30-2](L)nonenone
none1-Chloro-1-nitropropane [600-25-9]2 ppmnonenone
noneChloropentafluoroethane [76-15-3]1,000 ppmnonenone
noneChloropicrin [76-06-2]0.1 ppmnonenone
none1-Chloro-2-propanol [127-00-4] and
2-Chloro-1-propanol [78-89-7]
1 ppmnoneSkin
noneβ-Chloroprene [126-99-8]1 ppmnoneSkin
none2-Chloropropionic acid [598-78-7]0.1 ppmnoneSkin
noneo-Chlorostyrene [2039-87-4]50 ppm75 ppmnone
noneo-Chlorotoluene [95-49-8]50 ppmnonenone
noneChlorpyrifos [2921-88-2]0.1 mg/m3 (IFV)noneSkin
noneChromite ore processing (Chromate), as Cr0.05 mg/m3nonenone
noneChromium [7440-47-3] and inorganic compounds, as Cr –
Metal and Cr III compounds
0.5 mg/m3nonenone
noneChromium [7440-47-3] and inorganic compounds, as Cr –
Water-soluble Cr VI compounds
0.05 mg/m3nonenone
noneChromium [7440-47-3] and inorganic compounds, as Cr –
Insoluble Cr VI compounds
0.01 mg/m3nonenone
noneChromyl chloride [14977-61-8]0.025 ppmnonenone
noneChrysene [218-01-9](L)nonenone
noneCitral [5392-40-5]5 ppm (IFV)noneSkin
noneClopidol [2971-90-6]3 mg/m3 (IFV)nonenone
noneCoal dust –
Anthracite
0.4 mg/m3 (R)nonenone
noneCoal dust –
Bituminous
0.9 mg/m3 (R)nonenone
noneCoal tar pitch volatiles [65996-93-2],
as benzene soluble aerosol
0.2 mg/m3nonenone
noneCobalt [7440-48-4] and inorganic compounds, as Co0.02 mg/m3nonenone
noneCobalt carbonyl [10210-68-1], as Co0.1 mg/m3nonenone
noneCobalt hydrocarbonyl [16842-03-8], as Co0.1 mg/m3nonenone
Ontario TableN-Cocomorpholine [1541-81-7]5 ppm
52 mg/m3
noneSkin
Ontario Table, designated substanceCoke Oven Emissions10.15 mg/m3nonenone
noneCopper –
Fume, as Cu
0.2 mg/m3nonenone
noneCopper –
Dusts and mists, as Cu
1 mg/m3nonenone
noneCotton dust, raw, untreated0.1 mg/m3 (T)nonenone
noneCoumaphos [56-72-4]0.05 mg/m3 (IFV)noneSkin
Ontario TableCoumarone-Indene Resins (total dust) [63393-89-5]5 mg/m3nonenone
noneCresol, All isomers [1319-77-3; 95-48-7; 108-39-4; 106-44-5]20 mg/m3 (IFV)noneSkin
noneCrotonaldehyde [4170-30-3]noneC 0.3 ppmSkin
noneCrufomate [299-86-5]5 mg/m3nonenone
noneCumene [98-82-8]50 ppmnonenone
noneCyanamide [420-04-2]2 mg/m3nonenone
noneCyanogen [460-19-5]noneC 5 ppmnone
noneCyanogen bromide [506-68-3]noneC 0.3 ppmnone
noneCyanogen chloride [506-77-4]noneC 0.3 ppmnone
noneCyclohexane [110-82-7]100 ppmnonenone
noneCyclohexanol [108-93-0]50 ppmnoneSkin
noneCyclohexanone [108-94-1]20 ppm50 ppmSkin
noneCyclohexene [110-83-8]300 ppmnonenone
noneCyclohexylamine [108-91-8]10 ppmnonenone
noneCyclonite [121-82-4]0.5 mg/m3noneSkin
noneCyclopentadiene [542-92-7]75 ppmnonenone
noneCyclopentane [287-92-3]600 ppmnonenone
noneCyhexatin [13121-70-5]5 mg/m3nonenone
Ontario TableCymene (sum of o-,m-and p-isomers) [25155-15-1]50 ppm
274 mg/m3
noneSkin


Occupational exposure limits for Ontario workplaces: D

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
none2,4-D [94-75-7]10 mg/m3 (I)nonenone
noneDDT [50-29-3]1 mg/m3nonenone
noneDecaborane [17702-41-9]0.05 ppm0.15 ppmSkin
noneDemeton [8065-48-3]0.05 mg/m3 (IFV)noneSkin
noneDemeton-S-methyl [919-86-8]0.05 mg/m3 (IFV)noneSkin
noneDiacetone alcohol [123-42-2]50 ppmnonenone
noneDiacetyl [431-03-8]0.01 ppm0.02 ppmnone
noneDiazinon [333-41-5]0.01 mg/m3 (IFV)noneSkin
noneDiazomethane [334-88-3]0.2 ppmnonenone
noneDiborane [19287-45-7]0.1 ppmnonenone
none2-N-Dibutylaminoethanol [102-81-8]0.5 ppmnoneSkin
noneDibutyl phenyl phosphate [2528-36-1]0.3 ppmnoneSkin
noneDibutyl phosphate [107-66-4]5 mg/m3 (IFV)noneSkin
noneDibutyl phthalate [84-74-2]5 mg/m3nonenone
noneDichloroacetic acid [79-43-6]0.5 ppmnoneSkin
noneDichloroacetylene [7572-29-4]noneC 0.1 ppmnone
noneo-Dichlorobenzene [95-50-1]25 ppm50 ppmnone
nonep-Dichlorobenzene [106-46-7]10 ppmnonenone
none3,3'-Dichlorobenzidine [91-94-1](L)noneSkin
none1,4-Dichloro-2-butene [764-41-0]0.005 ppmnoneSkin
noneDichlorodifluoromethane [75-71-8]1,000 ppmnonenone
none1,3-Dichloro-5,5-dimethyl hydantoin [118-52-5]0.2 mg/m30.4 mg/m3none
none1,1-Dichloroethane [75-34-3]100 ppmnonenone
Ontario Table1,1 Dichloroethene [75-35-4]1 ppm
4 mg/m3
20 ppm
80 mg/m3
none
none1,2-Dichloroethylene, All isomers [540-59-0; 156-59-2; 156-60-5]200 ppmnonenone
noneDichloroethyl ether [111-44-4]5 ppm10 ppmSkin
noneDichlorofluoromethane [75-43-4]10 ppmnonenone
noneDichloromethane [75-09-2]50 ppmnonenone
none1,1-Dichloro-1-nitroethane [594-72-9]2 ppmnonenone
Ontario Table1,3-Dichloro-2-Propanol [96-23-1]none1 ppm
5 mg/m3
Skin
none1,3-Dichloropropene [542-75-6]1 ppmnoneSkin
none2,2-Dichloropropionic acid [75-99-0]5 mg/m3(I)nonenone
noneDichlorotetrafluoroethane [76-14-2]1,000 ppmnonenone
noneDichlorvos (DDVP) [62-73-7]0.1 mg/m3 (IFV)noneSkin
noneDicrotophos [141-66-2]0.05 mg/m3 (IFV)noneSkin
noneDicyclopentadiene [77-73-6]5 ppmnonenone
noneDicyclopentadienyl iron, as Fe [102-54-5]10 mg/m3nonenone
noneDieldrin [60-57-1]0.1 mg/m3 (IFV)noneSkin
noneDiesel fuel [68334-30-5; 68476-30-2; 68476-31-3; 68476-34-6; 77650-28-3],
as total hydrocarbons
100 mg/m3 (IFV)noneSkin
noneDiethanolamine [111-42-2]1 mg/m3 (IFV)noneSkin
noneDiethylamine [109-89-7]5 ppm15 ppmSkin
none2-Diethylaminoethanol [100-37-8]2 ppmnoneSkin
noneDiethylene glycol monobutyl ether [112- 34-5]10 ppm (IFV)nonenone
Ontario TableDiethylene glycol monoethyl ether [111- 90-0]30 ppm
165 mg/m3
nonenone
noneDiethylene triamine [111-40-0]1 ppmnoneSkin
Ontario TableDi(2-ethylhexyl)phthalate (DEHP) [117-81-7]3 mg/m35 mg/m3none
noneN,N-Diethylhydroxylamine [3710-84-7]2 ppmnonenone
noneDiethyl ketone [96-22-0]200 ppm300 ppmnone
noneDiethyl phthalate [84-66-2]5 mg/m3nonenone
noneDifluorodibromomethane [75-61-6]100 ppmnonenone
noneDiglycidyl ether (DGE) [2238-07-5]0.01 ppmnonenone
Ontario TableDiisodecyl phthalate [26761-40-0]5 mg/m3nonenone
noneDiisobutyl ketone [108-83-8]25 ppmnonenone
noneDiisopropylamine [108-18-9]5 ppmnoneSkin
noneN,N-Dimethyl acetamide [127-19-5]10 ppmnoneSkin
noneDimethylamine [124-40-3]5 ppm15 ppmnone
noneBis(2-Dimethylaminoethyl)ether [3033-62-3]0.05 ppm0.15 ppmSkin
Ontario Table3-(Dimethylamino) propylamine [109-55-7]0.5 ppm
2 mg/m3
noneSkin
noneDimethylaniline [121-69-7]5 ppm10 ppmSkin
noneDimethyl carbamoyl chloride [79-44-7]0.005 ppmnoneSkin
Ontario TableN, N-Dimethyl-cyclohexylamine [98-94-2]none5 ppm
26 mg/m3
none
noneDimethyl disulfide [624-92-0]0.5 ppmnoneSkin
noneDimethylethoxysilane [14857-34-2]0.5 ppm1.5 ppmnone
Ontario TableN, N-Dimethyl-ethanolamine [108-01-0]3 ppm
11 mg/m3
6 ppm
22 mg/m3
none
noneDimethylformamide [68-12-2]10 ppmnoneSkin
none1,1-Dimethylhydrazine [57-14-7]0.01 ppmnoneSkin
noneDimethyl phthalate [131-11-3]5 mg/m3nonenone
noneDimethyl sulfate [77-78-1]0.1 ppmnoneSkin
noneDimethyl sulfide [75-18-3]10 ppmnonenone
Ontario TableDimethyl terephthalate [120-61-6]5 mg/m3nonenone
Ontario TableDimethyl 2,3,5,6-tetracholoroterephthalate [1861-32-1]5 mg/m3nonenone
noneDinitrobenzene, All isomers [528-29-0; 99-65-0; 100-25-4; 25154-54-5]0.15 ppmnoneSkin
noneDinitro-o-cresol [534-52-1]0.2 mg/m3noneSkin
none3,5-Dinitro-o-toluamide [148-01-6]1 mg/m3nonenone
noneDinitrotoluene [25321-14-6]0.2 mg/m3noneSkin
none1,4-Dioxane [123-91-1]20 ppmnoneSkin
noneDioxathion [78-34-2]0.1 mg/m3 (IFV)noneSkin
none1,3-Dioxolane [646-06-0]20 ppmnonenone
noneDiphenylamine [122-39-4]10 mg/m3nonenone
noneDipropyl ketone [123-19-3]50 ppmnonenone
Ontario TableDipropylene glycol monomethyl ether acetate [88917-22-0]100 ppm
776 mg/m3
150 ppm
1,164 mg/m3
none
Ontario TableDiquat [2764-72-9; 85-00-7; 6385-62-2]0.5 mg/m3
0.1 mg/m3 (R)
noneSkin
noneDisulfiram [97-77-8]2 mg/m3nonenone
noneDisulfoton [298-04-4]0.05 mg/m3 (IFV)noneSkin
noneDiuron [330-54-1]10 mg/m3nonenone
noneDivinyl benzene [1321-74-0]10 ppmnonenone
noneDodecyl mercaptan [112-55-0]0.1 ppmnonenone


Occupational exposure limits for Ontario workplaces: E

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneEndosulfan [115-29-7]0.1 mg/m3 (IFV)noneSkin
noneEndrin [72-20-8]0.1 mg/m3noneSkin
Ontario TableEnflurane [13838-16-9]2 ppm
16 mg/m3
nonenone
noneEpichlorohydrin [106-89-8]0.5 ppmnoneSkin
noneEPN [2104-64-5]0.1 mg/m3 (I)noneSkin
noneEthane [74-84-0](EX), Simple asphyxiant (D); section 7.1 of Regulation 833 applies(EX), Simple asphyxiant (D); section 7.1 of Regulation 833 appliesnone
noneEthanol [64-17-5]none1,000 ppmnone
noneEthanolamine [141-43-5]3 ppm6 ppmnone
noneEthion [563-12-2]0.05 mg/m3 (IFV)noneSkin
none2-Ethoxyethanol (EGEE) [110-80-5]5 ppmnoneSkin
none2-Ethoxyethyl acetate (EGEEA) [111-15-9]5 ppmnoneSkin
noneEthyl acetate [141-78-6]400 ppmnonenone
noneEthyl acrylate [140-88-5]5 ppm15 ppmnone
noneEthylamine [75-04-7]5 ppm15 ppmSkin
noneEthyl amyl ketone [541-85-5]10 ppmnonenone
noneEthyl benzene [100-41-4]20 ppmnonenone
noneEthyl bromide [74-96-4]5 ppmnoneSkin
noneEthyl tert-butyl ether (ETBE) [637-92-3]25 ppmnonenone
noneEthyl butyl ketone [106-35-4]50 ppm75 ppmnone
noneEthyl chloride [75-00-3]100 ppmnoneSkin
noneEthyl cyanoacrylate [7085-85-0]0.2 ppmnonenone
Ontario TableEthyl-3-ethoxy propionate [763-69-9]50 ppm
300 mg/m3
nonenone
noneEthylene [74-85-1]200 ppmnonenone
noneEthylene chlorohydrin [107-07-3]noneC 1 ppmSkin
noneEthylenediamine [107-15-3]10 ppmnoneSkin
Ontario TableEthylene dibromide [106-93-4](L)noneSkin
noneEthylene dichloride [107-06-2]10 ppmnonenone
noneEthylene glycol [107-21-1]25 ppm (V)

50 ppm (V)

C 10 mg/m3 (I)(H)

none
Ontario TableEthylene glycol dimethyl ether [110-71-4]5 ppm
18 mg/m3
noneSkin
noneEthylene glycol dinitrate (EGDN) [628-96-6]0.05 ppmnoneSkin
Ontario TableEthylene glycol mono-n-propyl ether [2807-30-9]25 ppm
110 mg/m3
noneSkin
Ontario TableEthylene glycol mononitrate [16051-48-2]0.05 ppm
0.22 mg/m3
noneSkin
Ontario Table, designated substanceEthylene oxide [75-21-8]1 ppm
1.8 mg/m3
10 ppm
18 mg/m3
none
noneEthyleneimine [151-56-4]0.05 ppm0.1 ppmSkin
noneEthyl ether [60-29-7]400 ppm500 ppmnone
noneEthyl formate [109-94-4]none100 ppmnone
none2-Ethylhexanoic acid [149-57-5]5 mg/m3 (IFV)nonenone
noneEthylidene norbornene [16219-75-3]2 ppm4 ppmnone
Ontario Table, designated substanceEthyl isocyanate [109-90-0]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
noneEthyl mercaptan [75-08-1]0.5 ppmnonenone
Ontario TableEthyl methacrylate [97-63-2]50 ppm100 ppmnone
noneN-Ethylmorpholine [100-74-3]5 ppmnoneSkin
noneEthyl silicate [78-10-4]10 ppmnonenone


Occupational exposure limits for Ontario workplaces: F

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneFenamiphos [22224-92-6]0.05 mg/m3 (IFV)noneSkin
noneFensulfothion [115-90-2]0.01 mg/m3 (IFV)noneSkin
noneFenthion [55-38-9]0.05 mg/m3 (IFV)noneSkin
noneFerbam [14484-64-1]5 mg/m3 (I)nonenone
noneFerrovanadium dust [12604-58-9]1 mg/m33 mg/m3none
Ontario TableFlour dustSee Wheat Flour Dust (total dust)See Wheat Flour Dust (total dust)none
noneFluorides, as F2.5 mg/m3nonenone
noneFluorine [7782-41-4]1 ppm2 ppmnone
noneFolpet [133-07-3]1 mg/m3 (I)nonenone
noneFonofos [944-22-9]0.01 mg/m3 (IFV)noneSkin
Ontario TableForane [26675-46-7]2 ppm
15 mg/m3
nonenone
Ontario TableFormaldehyde [50-00-0]noneSTEL 1 ppm
C 1.5 ppm
none
noneFormamide [75-12-7]10 ppmnoneSkin
noneFormic acid [64-18-6]5 ppm10 ppmnone
noneFurfural [98-01-1]0.2 ppmnoneSkin
noneFurfuryl alcohol [98-00-0]0.2 ppmnoneSkin


Occupational exposure limits for Ontario workplaces: G

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneGallium arsenide [1303-00-0]0.0003 mg/m3 (R)nonenone
noneGasoline [86290-81-5]300 ppm500 ppmnone
noneGermanium tetrahydride [7782-65-2]0.2 ppmnonenone
noneGlutaraldehyde [111-30-8], activated and inactivatednoneC 0.05 ppmnone
noneGlycidol [556-52-5]2 ppmnonenone
noneGlyoxal [107-22-2]0.1 mg/m3 (IFV)nonenone
noneGrain dust (oat, wheat, barley)4 mg/m3nonenone
noneGraphite (all forms except graphite fibers) [7782-42-5]2 mg/m3 (R)nonenone


Occupational exposure limits for Ontario workplaces: H

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneHafnium [7440-58-6] and compounds, as Hf0.5 mg/m3nonenone
Ontario TableHalothane [151-67-7]2 ppm
16 mg/m3
nonenone
noneHard metals containing Cobalt [7440-48-4] and Tungsten carbide [12070-12-1], as Co0.005 mg/m3 (T)nonenone
noneHelium [7440-59-7]Simple asphyxiant (D); section 7.1 of Regulation 833 appliesSimple asphyxiant (D); section 7.1 of Regulation 833 appliesnone
noneHeptachlor [76-44-8] and
Heptachlor epoxide [1024-57-3]
0.05 mg/m3noneSkin
noneHeptane, All isomers [142-82-5; 590-35-2; 565-59-3; 108-08-7; 591-76-4; 589-34-4]400 ppm500 ppmnone
Ontario TableHeptyl acetate [112-06-1]50 ppm
320 mg/m3
nonenone
noneHexachlorobenzene [118-74-1]0.002 mg/m3noneSkin
noneHexachlorobutadiene [87-68-3]0.02 ppmnoneSkin
noneHexachlorocyclopentadiene [77-47-4]0.01 ppmnonenone
noneHexachloroethane [67-72-1]1 ppmnoneSkin
noneHexachloronaphthalene [1335-87-1]0.2 mg/m3noneSkin
noneHexafluoroacetone [684-16-2]0.1 ppmnoneSkin
noneHexafluoropropylene [116-15-4]0.1 ppmnonenone
noneHexahydrophthalic anhydride, All isomers [85-42-7; 13149-00-3; 14166-21-3]noneC 0.005 mg/m3 (IFV)none
Ontario Table, designated substanceHexamethylene diisocyanate [822-06-0]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
Ontario TableHexamethylenetetramine (HMT) [100-97-0]none0.35 ppm
2 mg/m3
none
Ontario TableHexamethyl phosphoramide [680-31-9](L)noneSkin
nonen-Hexane [110-54-3]50 ppmnoneSkin
noneHexane isomers, other than n-Hexane [75-83-2;79-29-8;96-14-0;107-83-5]500 ppm1,000 ppmnone
none1,6-Hexanediamine [124-09-4]0.5 ppmnonenone
none1-Hexene [592-41-6]50 ppmnonenone
nonesec-Hexyl acetate [108-84-9]50 ppmnonenone
Ontario TableHexyl acetate (isomeric mixture) [88230-35-7]50 ppm
294 mg/m3
nonenone
noneHexylene glycol [107-41-5]25 ppm (V)

50 ppm (V)

10 mg/m3 (I) (H)

none
noneHydrazine [302-01-2]0.01 ppmnoneSkin
noneHydrogen [1333-74-0](EX),Simple asphyxiant (D); section 7.1 of Regulation 833 applies(EX),Simple asphyxiant (D); section 7.1 of Regulation 833 appliesnone
Ontario TableHydrogenated terphenyls2 [61788-32-7]0.5 ppmnonenone
noneHydrogen bromide [10035-10-6]noneC 2 ppmnone
noneHydrogen chloride [7647-01-0]noneC 2 ppmnone
noneHydrogen cyanide and cyanide salts, as CN
Hydrogen cyanide [74-90-8]
noneC 4.7 ppmSkin
noneHydrogen cyanide and cyanide salts, as CN
Cyanide salts [143-33-9; 151-50-8; 592-01-8]
noneC 5 mg/m3Skin
noneHydrogen fluoride [7664-39-3], as F0.5ppmC 2 ppmSkin
noneHydrogen peroxide [7722-84-1]1 ppmnonenone
noneHydrogen selenide [7783-07-5], as Se0.05 ppmnonenone
Ontario TableHydrogen sulfide [7783-06-4]10 ppm15 ppmnone
noneHydroquinone [123-31-9]1 mg/m3nonenone
none2-Hydroxypropyl acrylate [999-61-1]0.5 ppmnoneSkin


Occupational exposure limits for Ontario workplaces: I

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneIndene [95-13-6]5 ppmnonenone
noneIndium [7440-74-6] and compounds, as In0.1 mg/m3nonenone
noneIodine and Iodides –
Iodine [7553-56-2]
0.01 ppm (IFV)0.1 ppm (V)none
noneIodine and Iodides –
Iodides
0.01 ppm (IFV)nonenone
noneIodoform [75-47-8]0.6 ppmnonenone
noneIron oxide (Fe2 O3) [1309-37-1]5 mg/m3 (R)nonenone
noneIron pentacarbonyl [13463-40-6], as Fe0.1 ppm0.2 ppmnone
noneIron salts, soluble, as Fe1 mg/m3nonenone
noneIsoamyl alcohol [123-51-3]100 ppm125 ppmnone
noneIsobutanol [78-83-1]50 ppmnonenone
noneIsobutyl nitrite [542-56-3]noneC 1 ppm (IFV)none
Reg. 833 O. Reg. 490/09Isocyanates, organic compounds –
Toluene diisocyanate (TDI) [584-84-9] [91-08-7]
0.005 ppmC 0.02 ppmnone
Ontario Table, designated substanceIsocyanates, organic compounds –
Methylene bisphenyl isocyanate (MDI) [101-68-8]
0.005 ppmC 0.02 ppmnone
Ontario Table, designated substanceIsocyanates, organic compounds –
Hexamethylene diisocyanate (HDI) [822-06-0]
0.005 ppmC 0.02 ppmnone
Ontario Table, designated substanceIsocyanates, organic compounds –
Isophorone diisocyanate (IPDI) [4098-71-9]
0.005 ppmC 0.02 ppmnone
Ontario Table, designated substanceIsocyanates, organic compounds –
Methylene bis (4-cyclohexylisocyanate) [5124-30-1]
0.005 ppmC 0.02 ppmnone
Ontario Table, designated substanceIsocyanates, organic compounds –
Methyl isocyanate [624-83-9]
0.02 ppm0.06 ppmSkin
Ontario Table, designated substanceIsocyanates, organic compounds –
Ethyl isocyanate [109-90-1]
0.02 ppm0.06 ppmSkin
Ontario Table, designated substanceIsocyanates, organic compounds –
Phenyl isocyanate [103-71-9]
0.005 ppm0.015 ppmSkin
noneIsooctyl alcohol [26952-21-6]50 ppmnoneSkin
noneIsophorone [78-59-1]noneC 5 ppmnone
Ontario Table, designated substanceIsophorone diisocyanate [4098-71-9]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
none2-Isopropoxyethanol [109-59-1]25 ppmnoneSkin
noneIsopropyl acetate [108-21-4]100 ppm200 ppmnone
noneIsopropylamine [75-31-0]5 ppm10 ppmnone
Ontario TableIsopropylaminoethanols [109-56-8; 121-93-7]none400 ppm
1,900 mg/m3
none
noneN-Isopropylaniline [768-52-5]2 ppmnoneSkin
Ontario TableIsosorbide dinitrate [87-33-2]0.2 mg/m3noneSkin
noneIsopropyl ether [108-20-3]250 ppm310 ppmnone
noneIsopropyl glycidyl ether (IGE) [4016-14-2]50 ppm75 ppmnone


Occupational exposure limits for Ontario workplaces: K-L

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneKaolin [1332-58-7]2 mg/m3 (E)(R)nonenone
noneKerosene [8008-20-6; 64742-81-0] / Jet fuels, as total hydrocarbon vapour200 mg/m3 (P)noneSkin
noneKetene [463-51-4]0.5 ppm1.5 ppmnone
Ontario Table, designated substanceLead [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/m3noneSkin (organic compounds)
Ontario Table, designated substanceLead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pb –
Tetraethyl lead, as Pb [78-00-2]
0.10 mg/m30.30 mg/m3Skin
Ontario Table, designated substanceLead chromate [7758-97-6] –
as Pb (see listing for Lead [7439-92-1])
0.05 mg/m3nonenone
Ontario Table, designated substanceLead chromate [7758-97-6] –
as Cr
0.012 mg/m3nonenone
Ontario TableLincomycin [154-21-2]0.1 mg/m3nonenone
noneLindane [58-89-9]0.5 mg/m3noneSkin
noneLithium hydride [7580-67-8]noneC 0.05 mg/m3 (I)none
Ontario TableLithium hydroxide –
Anhydrous [1310-65-2]
none1 mg/m3none
Ontario TableLithium hydroxide –
Monohydrate [1310-66-3]
none1 mg/m3none
noneL.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 appliesnone


Occupational exposure limits for Ontario workplaces: M

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneMagnesium oxide [1309-48-4]10 mg/m3 (I)nonenone
noneMalathion [121-75-5]1 mg/m3 (IFV)noneSkin
noneMaleic anhydride [108-31-6]0.01 mg/m3 (IFV)nonenone
Ontario TableManganese [7439-96-5] elemental and inorganic compounds, as Mn0.2 mg/m3nonenone
noneManganese cyclopentadienyl tricarbonyl
[12079-65-1], as Mn
0.1 mg/m3noneSkin
Ontario Table, designated substanceMercury [7439-97-6], elemental mercury, inorganic and organic compounds of mercury, as Hg –
All forms of except alkyl, as Hg
0.025 mg/m3noneSkin
Ontario Table, designated substanceMercury [7439-97-6], elemental mercury, inorganic and organic compounds of mercury, as Hg –
Alkyl compounds of, as Hg
0.01 mg/m30.03 mg/m3Skin
noneMesityl oxide [141-79-7]15 ppm25 ppmnone
noneMethacrylic acid [79-41-4]20 ppmnonenone
noneMethane [74-82-8]Section 7.1 of Regulation 833 appliesSection 7.1 of Regulation 833 appliesnone
noneMethanol [67-56-1]200 ppm250 ppmSkin
noneMethomyl [16752-77-5]0.2 mg/m3 (IFV)noneSkin
noneMethoxychlor [72-43-5]10 mg/m3nonenone
none2-Methoxyethanol (EGME) [109-86-4]0.1 ppmnoneSkin
none2-Methoxyethyl acetate (EGMEA) [110-49-6]0.1 ppmnoneSkin
Ontario TableMethoxyflurane [76-38-0]2 ppm
13 mg/m3
nonenone
none(2-Methoxymethylethoxy) propanol (DPGME) [34590-94-8]100 ppm150 ppmSkin
none4-Methoxyphenol [150-76-5]5 mg/m3nonenone
none1-Methoxy-2-propanol (PGME) [107-98-2]50 ppm100 ppmnone
noneMethyl acetate [79-20-9]200 ppm250 ppmnone
noneMethylacetylene [74-99-7]1,000 ppm (EX)nonenone
noneMethylacetylene-propadiene mixture (MAPP) [59355-75-8]1,000 ppm (EX)1,250 ppm (EX)none
noneMethyl acrylate [96-33-3]2 ppmnoneSkin
noneMethylacrylonitrile [126-98-7]1 ppmnoneSkin
noneMethylal [109-87-5]1,000 ppmnonenone
noneMethylamine [74-89-5]5 ppm15 ppmnone
Ontario TableMethyl n-amyl ketone [110-43-0]25 ppm
115 mg/m3
nonenone
noneN-Methyl aniline [100-61-8]0.5 ppmnoneSkin
noneMethyl bromide [74-83-9]1 ppmnoneSkin
Ontario TableMethyl tert-butyl ether (MTBE) [1634-04-4]40 ppmnonenone
Ontario TableMethyl n-butyl ketone [591-78-6]1 ppm
4 mg/m3
noneSkin
noneMethyl chloride [74-87-3]50 ppm100 ppmSkin
noneMethyl chloroform [71-55-6]350 ppm450 ppmnone
noneMethyl 2-cyanoacrylate [137-05-3]0.2 ppmnonenone
noneMethylcyclohexane [108-87-2]400 ppmnonenone
noneMethylcyclohexanol [25639-42-3]50 ppmnonenone
noneo-Methylcyclohexanone [583-60-8]50 ppm75 ppmSkin
none2-Methylcyclopentadienyl manganese tricarbonyl [12108-13-3], as Mn0.2 mg/m3noneSkin
noneMethyl demeton [8022-00-2]0.05 mg/m3 (IFV)noneSkin
Ontario Table, designated substanceMethylene bisphenyl isocyanate [101-68-8]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
Ontario Table4,4'-Methylene bis(2-chloroaniline) (MBOCA; MOCA®) [101-14-4]0.0005 ppm
0.005 mg/m3
noneSkin
Ontario Table, designated substanceMethylene bis(4-cyclohexylisocyanate [5124-30-1]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
Ontario Table4,4'-Methylene dianiline [101-77-9]0.04 mg/m3noneSkin
noneMethyl ethyl ketone (MEK) [78-93-3]200 ppm300 ppmnone
noneMethyl ethyl ketone peroxide [1338-23-4]noneC 0.2 ppmnone
noneMethyl formate [107-31-3]50 ppm100 ppmSkin
noneMethyl hydrazine [60-34-4]0.01 ppmnoneSkin
noneMethyl iodide [74-88-4]2 ppmnoneSkin
noneMethyl isoamyl ketone [110-12-3]20 ppm50 ppmnone
noneMethyl isobutyl carbinol [108-11-2]25 ppm40 ppmSkin
noneMethyl isobutyl ketone [108-10-1]20 ppm75 ppmnone
Ontario Table, designated substanceMethyl isocyanate [624-83-9]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
noneMethyl isopropyl ketone [563-80-4]20 ppmnonenone
noneMethyl mercaptan [74-93-1]0.5 ppmnonenone
noneMethyl methacrylate [80-62-6]50 ppm100 ppmnone
none1-Methyl naphthalene [90-12-0] and
2-Methyl naphthalene [91-57-6]
0.5 ppmnoneSkin
noneMethyl parathion [298-00-0]0.02 mg/m3 (IFV)noneSkin
noneMethyl propyl ketone [107-87-9]none150 ppmnone
Ontario TableN-Methyl-2-pyrrolidone [872-50-4]400 mg/m3nonenone
noneMethyl silicate [681-84-5]1 ppmnonenone
noneα-Methyl styrene [98-83-9]10 ppmnonenone
noneMethyl vinyl ketone [78-94-4]noneC 0.2 ppmSkin
noneMetribuzin [21087-64-9]5 mg/m3nonenone
noneMevinphos [7786-34-7]0.01 mg/m3 (IFV)noneSkin
noneMica [12001-26-2]3 mg/m3 (R)nonenone
Ontario TableMineral Spirits525 mg/m3nonenone
noneMineral oil [8012-95-1], excluding metal working fluids –
Pure, highly and severely refined
5 mg/m3 (I)nonenone
noneMineral oil [8012-95-1], excluding metal working fluids –
Poorly and mildly refined
(L)nonenone
noneMolybdenum [7439-98-7], as Mo –
Soluble compounds
0.5 mg/m3 (R)nonenone
noneMolybdenum [7439-98-7], as Mo –
Metal and insoluble compounds
10 mg/m3 (I)
3 mg/m3 (R)
nonenone
noneMonochloroacetic acid [79-11-8]0.5 ppm (IFV)noneSkin
noneMonocrotophos [6923-22-4]0.05 mg/m3 (IFV)noneSkin
noneMorpholine [110-91-8]20 ppmnoneSkin


Occupational exposure limits for Ontario workplaces: N

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneNaled [300-76-5]0.1 mg/m3 (IFV)noneSkin
noneNaphthalene [91-20-3]10 ppmnoneSkin
noneβ-Naphthylamine [91-59-8](L)nonenone
noneNatural gas [8006-14-2]Section 7.1 of Regulation 833 appliesSection 7.1 of Regulation 833 appliesnone
noneNatural rubber latex [9006-04-6],
as inhalable allergenic proteins
0.0001 mg/m3 (I)noneSkin
noneNeon [7440-01-9]Simple asphyxiant; section 7.1 of Regulation 833 appliesSimple asphyxiant; section 7.1 of Regulation 833 appliesnone
Ontario TableNepheline syenite (total dust) [37244-96-5]10 mg/m3nonenone
Ontario TableNickel –
Elemental/metal [7440-02-0]
1 mg/m3 (I)nonenone
Ontario TableNickel –
Insoluble compounds, as Ni [7440-02-0]
0.2 mg/m3 (I)nonenone
Ontario TableNickel –
Soluble compounds, as Ni [7440-02-0]
0.1 mg/m3 (I)nonenone
Ontario TableNickel –
Nickel subsulfide, as Ni [12035-72-2]
0.1 mg/m3 (I)nonenone
noneNickel carbonyl [13463-39-3], as NinoneC 0.05 ppmnone
noneNicotine [54-11-5]0.5 mg/m3noneSkin
noneNitrapyrin [1929-82-4]10 mg/m320 mg/m3none
noneNitric acid [7697-37-2]2 ppm4 ppmnone
noneNitric oxide [10102-43-9]25 ppmnonenone
nonep-Nitroaniline [100-01-6]3 mg/m3noneSkin
noneNitrobenzene [98-95-3]1 ppmnoneSkin
nonep-Nitrochlorobenzene [100-00-5]0.1 ppmnoneSkin
none4-Nitrodiphenyl [92-93-3](L)noneSkin
noneNitroethane [79-24-3]100 ppmnonenone
noneNitrogen [7727-37-9]Simple asphyxiant; section 7.1 of Regulation 833 appliesSimple asphyxiant; section 7.1 of Regulation 833 applies 
Ontario TableNitrogen dioxide [10102-44-0]3 ppm5 ppmnone
noneNitrogen trifluoride [7783-54-2]10 ppmnonenone
noneNitroglycerin (NG) [55-63-0]0.05 ppmnoneSkin
noneNitromethane [75-52-5]20 ppmnonenone
none1-Nitropropane [108-03-2]25 ppmnonenone
none2-Nitropropane [79-46-9]10 ppmnonenone
Ontario TableN-Nitrosamines, including
n-Nitrosodimethylamine [62-75-9]
(L)noneSkin
noneNitrotoluene, All isomers [88-72-2; 99-08-1; 99-99-0]2 ppmnoneSkin
none5-Nitro-o-toluidine [99-55-8]1 mg/m3 (I)nonenone
Ontario TableNitrous oxide [10024-97-2]25 ppm
45 mg/m3
nonenone
noneNonane [111-84-2]
All isomers
200 ppmnonenone


Occupational exposure limits for Ontario workplaces: O

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneOctachloronaphthalene [2234-13-1]0.1 mg/m30.3 mg/m3Skin
noneOctane, All isomers [111-65-9]300 ppmnonenone
noneOsmium tetroxide [20816-12-0], as Os0.0002 ppm0.0006 ppmnone
noneOxalic acid, anhydrous [144-62-7] and dehydrate [6153-56-6]1 mg/m32 mg/m3none
nonep,p'-Oxybis(benzenesulfonyl hydrazide) [80-51-3]0.1 mg/m3 (I)nonenone
noneOxygen difluoride [7783-41-7]noneC 0.05 ppmnone
Ontario TableOzone [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 ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneParaffin wax fume [8002-74-2]2 mg/m3nonenone
Ontario TableParaquat [4685-14-7]0.1 mg/m3nonenone
noneParathion [56-38-2]0.05 mg/m3 (IFV)noneSkin
Ontario TableParticles (Insoluble or Poorly Soluble) Not Otherwise Specified (PNOS)10 mg/m3 (I)
3 mg/m3(R)
nonenone
Ontario TablePenicillin (total dust) [1406-05-9]0.1 mg/m3nonenone
nonePentaborane [19624-22-7]0.005 ppm0.015 ppmnone
nonePentachloronaphthalene [1321-64-8]0.5 mg/m3noneSkin
nonePentachloronitrobenzene [82-68-8]0.5 mg/m3nonenone
nonePentachlorophenol [87-86-5]0.5 mg/m3 (IFV)1 mg/m3 (IFV)Skin
nonePentaerythritol [115-77-5]10 mg/m3nonenone
Ontario TablePentaerythritol tetrabenzoate [4196-86-5]none2 mg/m3none
nonePentane, All isomers [78-78-4; 109-66-0; 463-82-1]1000 ppmnonenone
none2,4-Pentanedione [123-54-6]25 ppmnoneSkin
nonePentyl acetate, All isomers [628-63-7; 626-38-0; 123-92-2; 625-16-1; 624-41-9; 620-11-1]50 ppm100 ppmnone
nonePeracetic acid [79-21-0]none0.4 ppm (IFV)none
nonePerchloromethyl mercaptan [594-42-3]0.1 ppmnonenone
nonePerchloryl fluoride [7616-94-6]3 ppm6 ppmnone
nonePerfluorobutyl ethylene [19430-93-4]100 ppmnonenone
nonePerfluoroisobutylene [382-21-8]noneC 0.01 ppmnone
nonePersulfates, as persulfate0.1 mg/m3nonenone
Ontario TablePetroleum coke (total dust) [64741-79-3]3.5 mg/m3 (a)nonenone
nonePetroleum ether(d)nonenone
nonePhenol [108-95-2]5 ppmnoneSkin
nonePhenothiazine [92-84-2]5 mg/m3noneSkin
Ontario Table2-Phenoxyethanol [122-99-6]25 ppm
141 mg/m3
noneSkin
noneN-Phenyl-β-naphthylamine [135-88-6](L)nonenone
noneo-Phenylenediamine [95-54-5]0.1 mg/m3nonenone
nonem-Phenylenediamine [108-45-2]0.1 mg/m3nonenone
nonep-Phenylenediamine [106-50-3]0.1 mg/m3nonenone
nonePhenyl ether [101-84-8], vapor1 ppm2 ppmnone
nonePhenyl glycidyl ether (PGE) [122-60-1]0.1 ppmnoneSkin
nonePhenylhydrazine [100-63-0]0.1 ppmnoneSkin
Ontario Table, designated substancePhenyl isocyanate [103-71-9]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
nonePhenyl mercaptan [108-98-5]0.1 ppmnoneSkin
nonePhenylphosphine [638-21-1]noneC 0.05 ppmnone
nonePhorate [298-02-2]0.05 mg/m3 (IFV)noneSkin
nonePhosgene [75-44-5]0.1 ppmnonenone
nonePhosphine [7803-51-2]0.3 ppm1 ppmnone
nonePhosphoric acid [7664-38-2]1 mg/m33 mg/m3none
nonePhosphorus (yellow) [12185-10-3]0.1 mg/m3nonenone
nonePhosphorus oxychloride [10025-87-3]0.1 ppmnonenone
nonePhosphorus pentachloride [10026-13-8]0.1 ppmnonenone
nonePhosphorus pentasulfide [1314-80-3]1 mg/m33 mg/m3none
nonePhosphorus trichloride [7719-12-2]0.2 ppm0.5 ppmnone
nonePhthalic anhydride [85-44-9]0.002 mg/m3 (IFV)0.005 mg/m3 (IFV)Skin
nonem-Phthalodinitrile [626-17-5]5 mg/m3 (IFV)nonenone
noneo-Phthalodinitrile [91-15-6]1 mg/m3 (IFV)nonenone
nonePicloram [1918-02-1]10 mg/m3nonenone
nonePicric acid [88-89-1]0.1 mg/m3nonenone
nonePindone [83-26-1]0.1 mg/m3nonenone
nonePiperazine [110-85-0] and salts, as piperazine0.03 ppm (IFV)nonenone
Ontario TablePlatinum [7440-06-4] –
Metal
1 mg/m3nonenone
Ontario TablePlatinum [7440-06-4] –
Water-soluble compounds of, including chloroplatinates (as Pt)
0.002 mg/m3nonenone
nonePolyvinyl chloride (PVC) [9002-86-2]1 mg/m3 (R)nonenone
Ontario TablePolychlorinated biphenyls (PCBs)20.05 mg/m3nonenone
nonePortland cement [65997-15-1]1 mg/m3 (E)(R)nonenone
nonePotassium hydroxide [1310-58-3]noneC 2 mg/m3none
Ontario TablePoultry dust (total dust)5 mg/m3nonenone
nonePropane [74-98-6](EX),Simple asphyxiant (D) ; section 7.1 of Regulation 833 applies(EX),Simple asphyxiant (D) ; section 7.1 of Regulation 833 appliesnone
nonePropane sultone [1120-71-4](L)nonenone
nonen-Propanol (n-Propyl alcohol) [71-23-8]100 ppmnonenone
none2-Propanol [67-63-0]200 ppm400 ppmnone
nonePropargyl alcohol [107-19-7]1 ppmnoneSkin
noneβ-Propiolactone [57-57-8]0.5 ppmnonenone
nonePropionaldehyde [123-38-6]20 ppmnonenone
nonePropionic acid [79-09-4]10 ppmnonenone
nonePropoxur [114-26-1]0.5 mg/m3 (IFV)nonenone
nonen-Propyl acetate [109-60-4]200 ppm250 ppmnone
nonePropylene [115-07-1]500 ppmnonenone
nonePropylene dichloride [78-87-5]10 ppmnonenone
nonePropylene glycol dinitrate [6423-43-4]0.05 ppmnoneSkin
Ontario Table1,2-Propylene glycol [57-55-6]50 ppm (V)
155 mg/m3 (V)
10 mg/m3 (H)(b)
nonenone
Ontario TablePropylene glycol monomethyl ether acetate [108-65-6]50 ppm
270 mg/m3
nonenone
nonePropylene oxide [75-56-9]2 ppmnonenone
nonePropyleneimine [75-55-8]0.2 ppm0.4 ppmSkin
nonen-Propyl nitrate [627-13-4]25 ppm40 ppmnone
nonePyrethrum [8003-34-7]5 mg/m3nonenone
nonePyridine [110-86-1]1 ppmnonenone

Occupational exposure limits for Ontario workplaces: Q-R

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

Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneQuinone [106-51-4]0.1 ppmnonenone
noneResorcinol [108-46-3]10 ppm20 ppmnone
noneRhodium [7440-16-6], as Rh –
Metal and Insoluble compounds
1 mg/m3nonenone
noneRhodium [7440-16-6], as Rh –
Soluble compounds
0.01 mg/m3nonenone
noneRonnel [299-84-3]5 mg/m3 (IFV)nonenone
noneRosin core solder thermal decomposition products (colophony) [8050-09-7](L)nonenone
noneRotenone (commercial) [83-79-4]5 mg/m3nonenone
noneRubber Solvent (Naphtha) [8030-30-6](d)nonenone


Occupational exposure limits for Ontario workplaces: S

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Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneSelenium [7782-49-2] and compounds, as Se0.2 mg/m3nonenone
Ontario TableSelenium hexafluoride [7783-79-1], as Se0.025 ppm
0.1 mg/m3
nonenone
noneSesone [136-78-7]10 mg/m3nonenone
Ontario TableShellac dust (total dust) [9000-59-3]10 mg/m3nonenone
Ontario Table, designated substanceSilica, Crystalline –
Quartz/Tripoli [14808-60-7; 1317-95-9]
0.10 mg/m3 (R)nonenone
Ontario Table, designated substanceSilica, Crystalline –
Cristobalite [14464-46-1]
0.05 mg/m3 (R)nonenone
Ontario TableSilica fume [69012-64-2]2 mg/m3 (R)nonenone
Ontario TableSilica fused [60676-86-0]0.1 mg/m3 (R)nonenone
Ontario TableSilicon carbide [409-21-2] –
Non-fibrous
10 mg/m3 (I)(E)
3 mg/m3 (R)(E)
nonenone
Ontario TableSilicon carbide [409-21-2] –
Fibrous (including whiskers)
0.1 f/cc(R)(F)nonenone
noneSilicon tetrahydride [7803-62-5]5 ppmnonenone
noneSilver [7440-22-4] and compounds –
Metal, dust and fume
0.1 mg/m3nonenone
noneSilver [7440-22-4] and compounds –
Soluble Compounds, as Ag
0.01 mg/m3nonenone
noneSimazine [122-34-9]0.5 mg/m3 (I)nonenone
Ontario TableSisal dust (total dust)2 mg/m3nonenone
Ontario TableSoap dust [68918-36-5]5 mg/m3nonenone
noneSodium azide [26628-22-8] –
as Sodium azide
noneC 0.29 mg/m3none
noneSodium azide [26628-22-8] –
as Hydrazoic acid vapour
noneC 0.11 ppmnone
noneSodium bisulfite [7631-90-5]5 mg/m3nonenone
noneSodium fluoroacetate [62-74-8]0.05 mg/m3noneSkin
noneSodium hydroxide [1310-73-2]noneC 2 mg/m3none
noneSodium metabisulfite [7681-57-4]5 mg/m3nonenone
Ontario TableSpectinomycin [1695-77-8]2 mg/m3nonenone
noneStarch [9005-25-8]10 mg/m3nonenone
noneStearates (J) [57-11-4; 557-04-0; 557-05-1;822-16-2]

10 mg/m3 (I)

3 mg/m3 (R)

nonenone
noneStoddard solvent [8052-41-3]100 ppmnonenone
Ontario Table140 Degree F Flash Aliphatic Solvent, Type of Stoddard Solvent525 mg/m3nonenone
noneStrontium chromate [7789-06-2], as Cr0.0005 mg/m3nonenone
noneStrychnine [57-24-9]0.15 mg/m3nonenone
Ontario TableStyrene - monomer [100-42-5]35 ppm100 ppmnone
noneSubtilisins [1395-21-7; 9014-01-1], as 100%
crystalline pure active enzyme
noneC 0.00006 mg/m3none
noneSucrose [57-50-1]10 mg/m3nonenone
noneSulfometuron methyl [74222-97-2]5 mg/m3nonenone
noneSulfotepp (TEDP) [3689-24-5]0.1 mg/m3 (IFV)noneSkin
Ontario TableSulfur dioxide [7446-09-5]2 ppm
5.2 mg/m3
5 ppm
10.4 mg/m3
none
noneSulfur hexafluoride [2551-62-4]1,000 ppmnonenone
noneSulfuric acid [7664-93-9]0.2 mg/m3 (T)nonenone
noneSulfur monochloride [10025-67-9]noneC 1 ppmnone
noneSulfur pentafluoride [5714-22-7]noneC 0.01 ppmnone
noneSulfur tetrafluoride [7783-60-0]noneC 0.1 ppmnone
noneSulfuryl fluoride [2699-79-8]5 ppm10 ppmnone
noneSulprofos [35400-43-2]0.1 mg/m3 (IFV)noneSkin
Ontario TableSynthetic Vitreous Fibres (Man Made Mineral Fibres) –
Continuous filament glass fibres
5 mg/m3 (I)
1 f/cc (F)
nonenone
Ontario TableSynthetic Vitreous Fibres (Man Made Mineral Fibres) –
Glass wool fibres
1 f/cc (F)nonenone
Ontario TableSynthetic Vitreous Fibres (Man Made Mineral Fibres) –
Refractory ceramic fibres
0.5 f/cc (F)nonenone
Ontario TableSynthetic Vitreous Fibres (Man Made Mineral Fibres) –
Rock wool fibres
1 f/cc (F)nonenone
Ontario TableSynthetic Vitreous Fibres (Man Made Mineral Fibres) –
Slag wool fibres
1 f/cc (F)nonenone
Ontario TableSynthetic Vitreous Fibres (Man Made Mineral Fibres) –
Special purpose glass fibres
1 f/cc (F)nonenone
Ontario TableSynthetic 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)nonenone


Occupational exposure limits for Ontario workplaces: T

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Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
none2,4,5-T [93-76-5]10 mg/m3nonenone
Ontario TableTalc [14807-96-6], containing no asbestos2 mg/m3 (R)(E)
2 f/cc (K)
nonenone
noneTellurium [13494-80-9] and compounds (NOS), as Te, excluding hydrogen telluride0.1 mg/m3nonenone
Ontario TableTellurium hexafluoride [7783-80-4], as Te0.01 ppm
0.1 mg/m3
nonenone
noneTemephos [3383-96-8]1 mg/m3 (IFV)noneSkin
noneTerbufos [13071-79-9]0.01 mg/m3 (IFV)noneSkin
noneTerephthalic acid [100-21-0]10 mg/m3nonenone
noneTerphenyls (o-, m-, p-isomers) [26140-60-3]noneC 5 mg/m3none
none1,1,2,2-Tetrabromoethane [79-27-6]0.1 ppm (IFV)nonenone
none1,1,1,2-Tetrachloro-2,2-difluoroethane [76-11-9]100 ppmnonenone
none1,1,2,2-Tetrachloro-1,2-difluoroethane [76-12-0]50 ppmnonenone
none1,1,2,2-Tetrachloroethane [79-34-5]1 ppmnoneSkin
noneTetrachloroethylene [127-18-4]25 ppm100 ppmnone
Ontario TableTetrachlorophathalic anhydride [117-08-8]0.1 mg/m3nonenone
Ontario TableTetrachlorophenol [25167-83-3]0.5 mg/m3noneSkin
noneTetrachloronaphthalene [1335-88-2]2 mg/m3nonenone
Ontario Table, designated substanceTetraethyl lead [78-00-2], as PbSee Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as PbSee Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pbnone
noneTetraethyl pyrophosphate (TEPP) [107-49-3]0.01 mg/m3 (IFV)noneSkin
noneTetrafluoroethylene [116-14-3]2 ppmnonenone
noneTetrahydrofuran [109-99-9]50 ppm100 ppmSkin
noneTetrakis (hydroxymethyl) phosphonium salts –
Tetrakis (hydroxymethyl) phosphonium chloride [124-64-1]
2 mg/m3nonenone
noneTetrakis (hydroxymethyl) phosphonium salts –
Tetrakis (hydroxymethyl) phosphonium sulfate [55566-30-8]
2 mg/m3nonenone
Ontario Table, designated substanceTetramethyl lead [75-74-1], as PbSee Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as PbSee Lead [7439-92-1] elemental lead, inorganic and organic compounds of lead, as Pbnone
noneTetramethyl succinonitrile [3333-52-6]0.5 ppmnoneSkin
noneTetranitromethane [509-14-8]0.005 ppmnonenone
Ontario TableTetrasodium pyrophosphate [7722-88-5]5 mg/m3nonenone
noneTetryl [479-45-8]1.5 mg/m3nonenone
noneThallium [7440-28-0] and
compounds, as Tl
0.02 mg/m3 (I)noneSkin
none4,4' Thiobis (6-tert-butyl-m-cresol) [96-69-5]1 mg/m3 (I)nonenone
noneThioglycolic acid [68-11-1]1 ppmnoneSkin
noneThionyl chloride [7719-09-7]noneC 0.2 ppmnone
noneThiram [137-26-8]0.05 mg/m3 (IFV)nonenone
Ontario TableTin [7440-31-5], as Sn –
Metal
2 mg/m3nonenone
Ontario TableTin [7440-31-5], as Sn –
Oxide and inorganic compounds, as Sn, except tin hydride
2 mg/m3nonenone
Ontario TableTin [7440-31-5], as Sn –
Organic compounds, as Sn
0.1 mg/m3noneSkin (organic compounds)
noneTitanium dioxide [13463-67-7]10 mg/m3nonenone
Ontario Tableo-Tolidine [119-93-7](L)noneSkin
noneToluene [108-88-3]20 ppmnonenone
Ontario Table, designated substanceToluene-2,4-or 2,6-diisocyanate (or as a mixture) [584-84-9][91-08-7]See Isocyanates, organic compoundsSee Isocyanates, organic compoundsnone
noneo-Toluidine [95-53-4]2 ppmnoneSkin
nonem-Toluidine [108-44-1]2 ppmnoneSkin
nonep-Toluidine [106-49-0]2 ppmnoneSkin
noneTributyl phosphate [126-73-8]5 mg/m3 (IFV)nonenone
noneTrichloroacetic acid [76-03-9]0.5 ppmnonenone
none1,2,4-Trichlorobenzene [120-82-1]noneC 5 ppmnone
none1,1,2-Trichloroethane [79-00-5]10 ppmnoneSkin
noneTrichloroethylene [79-01-6]10 ppm25 ppmnone
noneTrichlorofluoromethane [75-69-4]noneC 1,000 ppmnone
noneTrichloronaphthalene [1321-65-9]5 mg/m3noneSkin
none1,2,3-Trichloropropane [96-18-4]0.005 ppmnonenone
none1,1,2-Trichloro-1,2,2-trifluoroethane [76-13-1]1,000 ppm1,250 ppmnone
noneTrichlorphon [52-68-6]1 mg/m3 (I)nonenone
Ontario TableTriethanolamine [102-71-6]0.5 ppm
3.1 mg/m3
nonenone
noneTriethylamine [121-44-8]0.5 ppm1 ppmSkin
Ontario TableTriethylenediamine [280-57-9]1 ppm
4.6 mg/m3
noneSkin
Ontario TableTriethylenetetramine [112-24-3]0.5 ppm
3 mg/m3
noneSkin
noneTrifluorobromomethane [75-63-8]1,000 ppmnonenone
none1,3,5-Triglycidyl-s-triazinetrione [2451-62-9]0.05 mg/m3nonenone
noneTrimellitic anhydride [552-30-7]0.0005 mg/m3 (IFV)0.002 mg/m3 (IFV)Skin
Ontario TableTrimethoxyvinylsilane [2768-02-7]none10 ppm
60 mg/m3
none
noneTrimethylamine [75-50-3]5 ppm15 ppmnone
noneTrimethyl benzene (mixed isomers) [25551-13-7]25 ppmnonenone
noneTrimethyl phosphite [121-45-9]2 ppmnonenone
none2,4,6-Trinitrotoluene (TNT) [118-96-7]0.1 mg/m3noneSkin
noneTriorthocresyl phosphate [78-30-8]0.02 mg/m3 (IFV)noneSkin
noneTriphenyl phosphate [115-86-6]3 mg/m3nonenone
Ontario TableTrixylylphosphate [25155-23-1]0.1 mg/m3nonenone
noneTungsten [7440-33-7], and compounds, in the absence of Cobalt, as W3 mg/m3 (R)nonenone
noneTurpentine [8006-64-2] and selected monoterpenes [80-56-8; 127-91-3; 13466-78-9]20 ppmnonenone


Occupational exposure limits for Ontario workplaces: U-V

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Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneUranium (natural) [7440-61-1]
Soluble and insoluble compounds, as U
0.2 mg/m30.6 mg/m3none
nonen-Valeraldehyde [110-62-3]50 ppmnonenone
noneVanadium pentoxide [1314-62-1] as V0.05 mg/m3 (I)nonenone
noneVinyl acetate [108-05-4]10 ppm15 ppmnone
noneVinyl bromide [593-60-2]0.5 ppmnonenone
Ontario Table, designated substanceVinyl chloride [75-01-04]1 ppmnonenone
none4-Vinyl cyclohexene [100-40-3]0.1 ppmnonenone
noneVinyl cyclohexene dioxide [106-87-6]0.1 ppmnoneSkin
noneVinyl fluoride [75-02-5]1 ppmnonenone
noneN-Vinyl-2-pyrrolidone [88-12-0]0.05 ppmnonenone
Ontario TableVinylidene chloride [75-35-4]See 1,1-Dichloroethene [75-35-4]See 1,1-Dichloroethene [75-35-4]none
noneVinylidene fluoride [75-38-7]500 ppmnonenone
noneVinyl toluene [25013-15-4]50 ppm100 ppmnone
noneVM & P Naphtha [8032-32-4](d)nonenone


Occupational exposure limits for Ontario workplaces: W-X-Y-Z

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Ontario Table ListingsAgent [CAS No.]Time-Weighted Average Limit (TWA)Short-Term Exposure Limit (STEL) / Ceiling Limit (C)Notations
noneWarfarin [81-81-2]0.01 mg/m3 (I)noneSkin
Ontario TableWheat flour dust (total dust)3 mg/m3nonenone
Ontario TableWood dust –
Certain hardwoods as beech and oak
1 mg/m3nonenone
Ontario TableWood dust –
Softwood
5 mg/m310 mg/m3none
noneXylene [1330-20-7] (o, m & p isomers) [95-47-6; 108-38-3; 106-42-3]100 ppm150 ppmnone
nonem-Xylene α,α'- diamine [1477-55-0]noneC 0.1 mg/m3Skin
noneXylidine (mixed isomers) [1300-73-8]0.5 ppm (IFV)noneSkin
noneYttrium [7440-65-5] and compounds, as Y1 mg/m3nonenone
noneZinc chloride fume [7646-85-7]1 mg/m32 mg/m3none
noneZinc chromates [13530-65-9; 11103-86-9; 37300-23-5], as Cr0.01 mg/m3nonenone
noneZinc oxide [1314-13-2]2 mg/m3 (R)10 mg/m3 (R)none
noneZirconium [7440-67-7] and compounds, as Zr5 mg/m310 mg/m3none

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.