The Occupational Health and Safety Regulation provides that Occupational Exposure Limits (OELs) for hazardous chemical substances are generally determined with reference to the Threshold Limit Values (TLVs) set by the American Conference of Governmental Industrial Hygienists (ACGIH).

Each year, the ACGIH publishes a list of substances for which they have set new or revised TLVs.

When the new or revised TLVs for substances are adopted, WorkSafeBC refers to these TLVs as OELs.

An OEL is the maximum allowed airborne concentration for a particular substance from which nearly all workers are believed to experience no adverse health effects over a working lifetime. OELs may be set out as an 8-hour time-weighted average concentration, short-term exposure limit, or ceiling limit.

When the ACGIH publishes its annual list, WorkSafeBC identifies the substances with new or revised TLVs and adds these substances (together with their existing OELs) to the Table of Occupational Exposure Limits for Excluded Substances in OHS Policy R5.48-1. By doing so, WorkSafeBC ensures that the existing OELs for these substances continue to be in effect until WorkSafeBC’s Board of Directors makes a decision on adoption of the changes. This gives WorkSafeBC the opportunity to consult stakeholders prior to adopting new or revised ACGIH TLVs as OELs.

The ACGIH has published the 2019 new or revised TLVs. The following substances, for which there are new or revised TLVs, have been added to the Table of Occupational Exposure Limits for Excluded Substances in OHS Policy R5.48-1. The current BC OELs are maintained for these substances until the Board of Directors makes a decision on the adoption of their respective TLVs:

• Chlordane
• Chlordane, Inhalable fraction & vapour
• o-Chlorobenzylidene malononitrile
• Cobalt and inorganic compounds, as Co, Total
• Cobalt and inorganic compounds, as Co, Inhalable
• Cyanazine
• Cyclopentadiene
• Dicyclopentadiene
• Dicyclopentadiene, including Cyclopentadiene
• Dimethylphenol, all isomers
• Dinitrobenzene, all isomers
• Dinitro-o-cresol
• EPN, Inhalable
• EPN, Inhalable fraction & vapour
• Fluorine, as F
• Indium tin oxide, as In
• Isobutyl nitrite, Inhalable fraction & vapour
• 4,4’-Methylene bis(2-chloroaniline)
• Methyltetrahydrophthalic anhydride isomers
• Methyl vinyl ketone
• Monomethylformamide
• Nitrapyrin
• Nitrapyrin, Inhalable fraction & vapour
• 5-Nitro-o-toluidine, Inhalable
• 5-Nitro-o-toluidine, Inhalable fraction & vapour
• Pentachloronaphthalene
• Pentachloronaphthalene, Inhalable fraction & vapour
• o-Phthalaldehyde
• Propylene glycol ethyl ether
• Sulfometuron methyl
• Sulfometuron methyl, Inhalable fraction & vapour
• Sulfoxaflor
• Temephos, Total
• 1,1,2,2-Tetrabromoethane, Inhalable fraction & vapour
• Tetramethyl succinonitrile
• Thiacloprid
• Tin and inorganic compounds, excluding Tin hydride and Indium tin oxide, as Sn
• Tin and inorganic compounds, excluding Tin hydride, as Sn, Metal
• Tin and inorganic compounds, excluding Tin hydride, as Sn, Oxide and inorganic compounds
• 2,4,6-Trinitrotoluene (TNT), Total
• 2,4,6-Trinitrotoluene (TNT), Inhalable fraction & vapour
• m-Xylene alpha, alpha’-diamine

All WorkSafeBC OELs can be found in the updated Table of Exposure Limits for Chemical and Biological Substances.