Ontario designated substances list

You need one before a construction project starts and before any work on it goes to tender or is contracted. The duty sits with the owner: under section 30 of Ontario's Occupational Health and Safety Act (OHSA), the owner must "determine whether any designated substances are present on the site" and "prepare a list of these substances" (Ministry guide to the OHSA, Part III). The Ministry's summary of section 30 doesn't use the term "designated substance survey". The survey is the usual way owners produce the list the Act requires.

Approach: The only Ontario workplace-safety law in the datasets I can search is O. Reg. 833, which doesn't deal with project surveys, so I used the Ministry of Labour's official guide to the OHSA. The e-Laws page for the Act wouldn't load, so I'm quoting the guide's summary of section 30, not the statute text.

When the list is needed under section 30 (all from the same Ministry page):

• Before the project begins: the owner identifies any of the 11 designated substances on the site and lists them.
• At tender: if the work is put out to bid, whoever issues the tenders (for example the owner or the constructor) "shall include the list of designated substances in the tendering information."
• Before the constructor's contract: the owner must make sure the constructor has a copy of the list before signing a contract with them.
• Before contractor and subcontractor contracts: the constructor must make sure every prospective contractor or subcontractor has a copy "before any binding contract for work on the project can be made."

If you skip it or get it wrong:

• The owner is liable to the constructor and every contractor and subcontractor for losses caused by designated substances that weren't on the list and "that the owner ought reasonably to have known of."
• A constructor who fails to pass the list on is liable for losses suffered by a contractor.

So a survey that misses substances the owner should reasonably have known about leaves the owner exposed to claims.

How this fits with the earlier answer: O. Reg. 490/09 governs ongoing exposure in workplaces generally and excludes construction employers. Section 30 is the construction-side rule: it is about telling the people who will do the work which designated substances are on site. Asbestos in construction is also covered by O. Reg. 278/05, as noted last time.

If you tell me what kind of project it is (renovation, demolition, or work on an occupied building), I can look at what O. Reg. 278/05 adds for asbestos on that work.

The survey and O. Reg. 833 do different jobs. Section 30 of the OHSA makes the owner find and list the designated substances on a project before work starts. O. Reg. 833 sets how workers must be protected from a hazardous chemical agent during the work: exposure limits, controls, air monitoring and respirators. They connect because O. Reg. 833 steps aside for a designated substance only where another designated-substance regulation actually covers that substance at that workplace.

Approach: I read the consolidated text of O. Reg. 833 in full. The section 30 duties and the scope of O. Reg. 490/09 come from the Ministry of Labour guidance cited in the earlier answers.

1. When O. Reg. 833 does not apply (section 2(2)) O. Reg. 833 does not apply to:

• (a) a chemical agent listed in Table 1 of O. Reg. 490/09, "in a workplace that is subject to that regulation with respect to that agent"
• (b) asbestos, in a workplace subject to O. Reg. 278/05 (asbestos on construction projects and in buildings and repair operations) ^[1]

The exclusion depends on the workplace, not just the substance. As covered earlier, the Ministry's guide says O. Reg. 490/09 does not cover construction employers. On that reading, the section 2(2)(a) exclusion would not be triggered on a construction project. The text of O. Reg. 833 contains no separate exclusion for construction. So for designated substances other than asbestos (for example lead, silica, mercury or isocyanates), O. Reg. 833 looks like the exposure-control rule that governs the work on site. Asbestos is the exception: it stays under O. Reg. 278/05. That conclusion is my reading of the two texts together. I haven't found a Ministry statement that says it directly.

2. The Ontario Table sets the limits for designated substances Table 1 of O. Reg. 833 (the "Ontario Table") marks the designated substances with an asterisk, with a note pointing to section 2(2)(a) ^[3]. Substances you're likely to find in a survey include:

Substance	TWA	STEL or ceiling (C)
Asbestos, all forms	0.1 f/cc	none listed
Benzene (Skin notation)	0.5 ppm	2.5 ppm
Lead and inorganic and organic compounds, as Pb (except tetraethyl lead)	0.05 mg/m³	none listed
Mercury, all forms except alkyl, as Hg	0.025 mg/m³	none listed
Crystalline silica, quartz (respirable)	0.10 mg/m³	none listed
Crystalline silica, cristobalite (respirable)	0.05 mg/m³	none listed
TDI, MDI and HDI (isocyanates)	0.005 ppm	C 0.02 ppm
Vinyl chloride	1 ppm	none listed

Sources: asbestos and benzene ^[4]; lead, mercury, silica and isocyanates ^[5]; vinyl chloride ^[3].

Where the table gives only a TWA, O. Reg. 833 normally adds default short-term limits: 3 times the TWA over any 30 minutes and 5 times the TWA at any time. Section 4, paragraph 4 says these defaults do not apply to designated substances, so the table values stand on their own ^[2].

3. What the employer has to do once the survey finds something Where O. Reg. 833 applies, the survey list becomes the starting point for these duties:

• Controls (s. 3): take all measures reasonably necessary, in this order: substitution, engineering controls, administrative controls and work practices, hygiene facilities, then PPE where section 7.2 allows it ^[6].
• Air monitoring (s. 6): use a recognised sampling method and the rules in Schedule 1. The work must be done by, or under the direction of, a person qualified in industrial hygiene ^[7].
• Skin notation (s. 7): where the table marks an agent "Skin" (for example benzene), take measures against skin absorption ^[8].
• Respirators (ss. 7.2 and 9 to 13): respirators are allowed only if substituting the agent and engineering controls aren't feasible or don't work ^[9]. The employer must then have a written program and give training ^[10]. Respirators must be NIOSH- or CSA-approved and meet the assigned protection factor in Schedule 2. For asbestos they need HEPA or 100-series filters ^[11]. Tight-fitting respirators need fit testing ^[12].
• Medical examinations (s. 8): if a worker's health may have been affected by exposure, the worker (if they agree) gets medical examinations and clinical tests at the employer's expense. The employer must give the physician any exposure records ^[13].

Which rule applies where

Setting	Finding the substances	Controlling exposure
Construction project, asbestos	OHSA s. 30 list	O. Reg. 278/05 (O. Reg. 833 excluded by s. 2(2)(b))
Construction project, other designated substances	OHSA s. 30 list	O. Reg. 833 (on the reading above)
Non-construction workplace covered by O. Reg. 490/09 for that substance	No s. 30 duty	O. Reg. 490/09 (O. Reg. 833 excluded by s. 2(2)(a))