Canada workplace carbon monoxide limits
What are the workplace carbon monoxide exposure limits in Canada?
Canada has no single national carbon monoxide limit. Each province or territory sets its own, and federally regulated workplaces use the American Conference of Governmental Industrial Hygienists (ACGIH) values. For carbon monoxide (CAS 630-08-0), the 8-hour limit is 25 ppm wherever I could check, except Québec, where it is 35 ppm.
| Jurisdiction | 8-hour limit (TWA) | Short-term or ceiling limit | Source |
|---|---|---|---|
| Federal (workplaces regulated under the Canada Labour Code) | The ACGIH value. The CCOHS profile, adapted from the 2022 ACGIH booklet, shows 25 ppm | Not shown in the CCOHS profile | Canada Occupational Health and Safety Regulations (SOR/86-304), s. 10.19(1)(a) |
| Alberta | 25 ppm (29 mg/m³) | None ("-") | OHS Code Schedule 1, Table 2 (consolidation in force March 31, 2025) [1] |
| Ontario | 25 ppm | None listed | Regulation 833 |
| British Columbia | 25 ppm | 100 ppm (15-minute STEL); notation "R" (harmful to reproduction) | WorkSafeBC table of exposure limits |
| Québec | 35 ppm (40 mg/m³) | 200 ppm (230 mg/m³), 15-minute average | GESTIS international limit-value database (IFA/DGUV) [2][3][4][5] |
Federal. Section 10.19(1)(a) says an employee "shall be kept free from exposure" to an airborne chemical agent above the value adopted by ACGIH in its TLVs and BEIs publication, "as amended from time to time". So the federal limit moves with each new ACGIH edition. The CCOHS profile also lists a Biological Exposure Index (BEI) for CO [6]. When levels are likely to exceed the limit, s. 10.19(3)-(5) require air sampling by the methods listed there, and the test records "shall be kept" for three years. The consolidation is current to 2026-10-19 (Justice Laws, s. 10.19).
Ontario. The Ministry's table (updated June 26, 2025) says it should not be relied on alone. Excursion limits for substances without a short-term limit are in the official Regulation 833, which I did not open, so I give no excursion figure (Ontario.ca).
British Columbia. The table is updated 2026/09/03. WorkSafeBC says it is published for information only. The official limits are the ACGIH TLV documentation plus the exceptions in Policy R5.48-1, applied through OHS Regulation s. 5.48. The "R" notation means s. 5.57 applies: substitute where possible and keep exposure as low as reasonably achievable (WorkSafeBC table). WorkSafeBC's E-Limit page gives the same 25 ppm and 100 ppm, but that page is marked as draft (E-Limit).
Québec. These figures are from the GESTIS database, not the regulation itself. I couldn't open Schedule I of Québec's workplace health and safety regulation (RSST, S-2.1, r. 13) on LégisQuébec, so they are not confirmed against the official text. A search-engine summary gave different numbers ("35 and 175"), so treat the Québec values as unconfirmed until checked against the official text (LégisQuébec, S-2.1, r. 13).
Not covered: Saskatchewan, Manitoba, the Atlantic provinces and the territories. If one of them applies to you, I can look it up.
Approach: I searched the Alberta OHS Code exposure-limit table, the CCOHS chemical profiles and the GESTIS international limit-value database. I then opened the federal regulation on Justice Laws, Ontario's Regulation 833 table and WorkSafeBC's exposure-limit table.