Print This Page

Review of Occupational Exposure Limits in Ontario:
Current and Proposed Exposure Limits


On this page:

Proposed changes based on the 2016 ACGIH recommendations

Proposed Changes to Occupational Exposure Limits for Substances Regulated Under Regulation 833, Control of Exposure to Biological or Chemical Agents and O. Reg. 490/09 - Designated Substances
Current Substance Current
TWA
Current
STEL/C
Proposed Substance Proposed
TWA
Proposed
STEL/C
Change
Boron tribromide [10294-33-4]   C 1 ppm Boron tribromide [10294-33-4]   C 0.7 ppm C reduced
Boron trichloride [10294-34-5] No listing No listing Boron trichloride [10294-34-5]   C 0.7 ppm Substance added to regulation
Boron trifluoride [7637-07-2]   C 1 ppm Boron trifluoride [7637-07-2] 0.1 ppm C 0.7 ppm TWA added. C reduced
Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5] No specific listing No specific listing Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5] 50 ppm 150 ppm Listings for isomers combined into single listing.
TWAs for all isomers reduced.
STEL for n- Butyl acetate reduced.
STEL added for other isomers.
n- Butyl acetate [123-86-4] 150 ppm 200 ppm No listing     Listing and OELs withdrawn.
Regulated under general listing for Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5]
sec- Butyl acetate [105-46-4] 200 ppm   No listing     Listing and OEL withdrawn.
Regulated under listing for Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5]
tert-Butyl acetate [540-88-5] 200 ppm   No listing     Listing and OEL withdrawn.
Regulated under listing for Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5]
Isobutyl acetate [110-19-0] 150 ppm   No listing     Listing and OEL withdrawn.
Regulated under listing for Butyl acetates, all isomers [105-46-4; 110-19-0; 123-86-4; 540-88-5]
Calcium silicate, naturally occurring as Wollastonite [13983-17-0] No listing No listing Calcium silicate, naturally occurring as Wollastonite [13983-17-0] 1 mg/m3(I,E)   Substance added to regulation.
Calcium silicate, synthetic nonfibrous [1344-95-2] 10 mg/m3 (E)   No listing     Listing withdrawn.
Insufficient data to support OEL.
Cyanogen [460-19-5] 10 ppm   Cyanogen [460-19-5]   C 5 ppm TWA removed. C added.
Hard metals, containing Cobalt [7440-48-4] and Tungsten carbide [12070-12-1], as Co No listing No listing Hard metals, containing Cobalt [ 7440-48-4] and Tungsten carbide [12070-12-1], as Co 0.005 mg/m3 (T)   Substance added to regulation.
Propoxur [114-26-1] 0.5 mg/m3   Propoxur [114-26-1] 0.5 mg/m3(IFV)   OEL developed for inhalable fraction and vapour.
Simazine [122-34-9] No listing No listing Simazine [122-34-9] 0.5 mg/m3 (I)   Substance added to regulation.
Toluene diisocyanate (TDI) [584-84-9] [91-08-7] 0.005 ppm C 0.02 ppm Toluene diisocyanate, 2,4- or 2,6- (or as a mixture) [584-84-9; 91-08-7] - Skin 0.001 ppm(IFV) 0.005 ppm(IFV) Change in listing.
OELs developed for inhalable fraction and vapour.
Skin notation added.
Triorthocresyl phosphate [78-30-8] - Skin 0.1 mg/m3   Triorthocresyl phosphate [78-30-8] - Skin 0.02 mg/m3(IFV)   OEL developed for inhalable fraction and vapour.
Warfarin [81-81-2] 0.1 mg/m3   Warfarin [81-81-2] - Skin 0.01 mg/m3 (I)   OEL developed for inhalable particulate matter.
Skin notation added.

Proposed changes based on the 2017 ACGIH recommendations

Proposed Changes to Occupational Exposure Limits for Substances Regulated Under Regulation 833, Control of Exposure to Biological or Chemical Agents and O. Reg. 490/09 - Designated Substances
Current Substance Current
TWA
Current
STEL/C
Proposed Substance Proposed
TWA
Proposed
STEL/C
Change
Acetamide [60-35-5] No listing No listing Acetamide [60-35-5] 1 ppm (IFV)   Substance added to regulation.
Acetylene [74-86-2] See Appendix F: Minimal Oxygen Content (D).
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content (D).
Note: section 7.1 of Regulation 833 applies
Acetylene [74-86-2] See Appendix F: Minimal Oxygen Content (D) (EX).
Note: section 7.1 of Regulation 833 applies
  Addition of notation for explosion hazard (EX).
Butane, isomers [75-28-5; 106-97-8]   1000 ppm Butane, isomers [75-28-5; 106-97-8]   1000 ppm (EX) Addition of explosion hazard notation.
Cadusafos [95465-99-9] No listing No listing Cadusafos [95465-99-9] - Skin 0.001 mg/m3(IFV)   Substance added to regulation.
Captafol [2425-06-1] - Skin 0.1 mg/m3   Captafol [2425-06-1] - Skin 0.1 mg/m3(IFV)   OEL developed for inhalable fraction and vapour.
ß-Chloroprene [126-99-8] - Skin 10 ppm   ß-Chloroprene [126-99-8] - Skin 1 ppm   TWA reduced.
2,4-D [94-75-7] - Skin 10 mg/m3 (I)   2,4-D [94-75-7] 10 mg/m3 (I)   Skin notation removed.
Ethane [74-84-0] See Appendix F: Minimal Oxygen Content.
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content.
Note: section 7.1 of Regulation 833 applies
  See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies.
See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies.
Addition of notations for simple asphyxiant (D) and explosion hazard (EX).
Ethylene glycol [107-21-1]   C 100 mg/m3 (H) Ethylene glycol [107-21-1] 25 ppm (V) 50 ppm (V)
10 mg/m3 (I, H)
TWA and STEL added for vapour fraction. C removed for aerosol only. STEL added for inhalable particulate matter and aerosol only.
Folpet [133-07-3] No listing No listing Folpet [133-07-3] 1 mg/m3 (I)   Substance added to regulation
Formaldehyde [50-00-0]   STEL 1 ppm C 1.5 ppm Formaldehyde [50-00-0] 0.1 ppm 0.3 ppm TWA added. STEL reduced. C removed.
Furfural [98-01-1] – Skin 2 ppm   Furfural [98-01-1] – Skin 0.2 ppm   TWA reduced.
Furfuryl alcohol [98-00-0] - Skin 10 ppm 15 ppm Furfuryl alcohol [98-00-0] – Skin 0.2 ppm   TWA reduced. STEL removed.
Hexylene glycol [107-41-5]   C 25 ppm Hexylene glycol [107-41-5] 25 ppm (V) 50 ppm (V)
10 mg/m3 (I, H)
TWA and STEL added for vapour fraction. C removed.
STEL
added for inhalable particulate matter and aerosol only.
Hydrogen [1333-74-0] See Appendix F: Minimal Oxygen Content (D).
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content (D).
Note: section 7.1 of Regulation 833 applies
Hydrogen [1333-74-0] See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies
Addition of notation explosion hazard (EX).
L.P.G. (liquefied petroleum gas) [68476-85-7] See Appendix F: Minimal Oxygen Content.
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content.
Note: section 7.1 of Regulation 833 applies
L.P.G. (liquefied petroleum gas) [68476-85-7] See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies
Addition of notations for simple asphyxiant (D) and explosion hazard (EX).
Methyl acetylene [74-99-7] 1000 ppm   Methylacetylene [74-99-7] 1000 ppm (EX)   Minor change in listing. Addition of notation for explosion hazard (EX).
Methyl acetylene-propadiene mixture [59355-75-8] 1000 ppm 1250 ppm Methylacetylene-propadiene mixture [56960-91-9] 1000 ppm (EX) 1250 ppm (EX) Change in listing (including CAS number).
Addition of notation for explosion hazard (EX).
Phthalic anhydride [85-44-9] 1 ppm   Phthalic anhydride [85-44-9] – Skin 0.002 mg/m3(IFV) 0.005 mg/m3(IFV) TWA and STEL developed for inhalable fraction and vapour.
Skin notation added.
Propane [74-98-6] See Appendix F: Minimal Oxygen Content.
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content.
Note: section 7.1 of Regulation 833 applies
Propane [74-98-6] See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies
See Appendix F: Minimal Oxygen Content (D, EX).
Note: section 7.1 of Regulation 833 applies
Addition of notations for simple asphyxiant (D) and explosion hazard (EX).
Stearates (J) 10 mg/m3   Stearates (J) [57-11-4; 557-04-0; 557-05-1;822-16-2] 10 mg/m3 (I)
3 mg/m3 (R)
  Addition of CAS numbers. OELs developed for inhalable particulate matter and respirable particulate matter.

Tungsten [7440-33-7], as W

    Tungsten [7440-33-7] and compounds, in the absence of Cobalt, as W. 3 mg/m3 (R)   Single listing and OELs for all compounds of Tungsten.
OEL developed for respirable particulate matter.

Metal and insoluble compounds

mg/m3 10 mg/m3        

Soluble compounds

mg/m3 mg/m3        

Endnotes and Abbreviations

TWA or time-weighted average limit means the time-weighted average airborne concentration of a biological or chemical agent to which a worker may be exposed in a work day or work week.

STEL or short-term exposure limit means the maximum airborne concentration of a biological or chemical agent to which a worker may be exposed in any 15-minute period;

C or ceiling limit means the maximum airborne concentration of a biological or chemical agent to which a worker may be exposed at any time;

(D) Simple asphyxiant

(E) The value is for particulate matter containing no asbestos and < 1% crystalline silica.

(EX) Explosion hazard: The substance is a flammable asphyxiant or excursions above the OEL could approach 10% of the lower explosive limit.

(H) Aerosol only

(I) Inhalable particulate matter (Note: changed from “inhalable fraction”)

(J) Does not include stearates of toxic metals

(IFV) Inhalable fraction and vapour

(R) Respirable particulate matter (Note: changed from “respirable fraction”)

(T) Thoracic particulate matter (Note: changed from “thoracic fraction”)

(V) Vapour fraction (Note: changed from “vapour and aerosol”)