What the Regulation Actually Says
Ontario Regulation 632/05 Section 6 governs hazard assessments for confined spaces. The relevant subsection is Section 6(9):
"The employer shall ensure that the assessment is reviewed as often as is necessary to ensure that the relevant plan remains adequate."
That is the entirety of the review frequency requirement. There is no number, no timeline, and no fixed review interval in the regulation. The requirement is that the assessment must remain adequate, and the employer must review it whenever necessary to ensure that adequacy.
What "Adequate" Means
The regulation defines "adequate" in Section 1 to mean:
- (a) sufficient for both its intended and its actual use, and
- (b) sufficient to protect a worker from occupational illness or occupational injury.
This definition is performance-based. An assessment is adequate if it currently protects workers, given the current state of the confined space, the current hazards, and the current planned work. If anything about those conditions has changed in a way that affects the adequacy of the plan, the assessment requires review.
When a Review Is Triggered
While the regulation does not name specific triggers, the practical interpretation by competent persons and Ontario inspectors generally identifies the following situations as requiring assessment review:
- Physical changes to the confined space (modifications, repairs, equipment installations)
- Changes to materials or substances stored in or routed through the space
- Changes to adjacent processes that could introduce new hazards
- New work activities planned in the confined space
- Incidents, near-misses, or rescue events at the space or similar spaces
- Changes to the workforce structure, training, or competency of entrants and attendants
- Changes to applicable regulations or standards (such as O. Reg. 632/05 amendments)
- Discovery of previously unidentified hazards through routine inspections or audits
- Changes in equipment used (atmospheric testing devices, ventilation equipment, rescue equipment)
When any of these triggers occur, the assessment must be reviewed before further entry, and the plan updated as needed.
The 3-Year Industry Practice
Despite the regulation not specifying a fixed interval, a 3-year review cycle is widely used as industry practice in Ontario. The 3-year practice comes from several sources:
- Federal Part XI of the Canada Occupational Health and Safety Regulations and the National Joint Council directive reference a 3-year review of the qualified person's report. Many Ontario employers and consultants apply this same standard to provincial assessments for consistency.
- CSA standards and good practice guides for confined space programs typically recommend a maximum review interval, with 3 years being the most common.
- Most Ontario employers manage multiple confined spaces and find that periodic comprehensive reviews are easier to coordinate on a fixed cycle than purely event-driven reviews.
- Inspectors and auditors looking at a confined space program will often ask when the last comprehensive review was conducted. A 3-year cycle is recognized as conservative practice that demonstrates due diligence.
The 3-year cycle is a complement to event-driven reviews, not a replacement. An adequate program should include both: comprehensive periodic reviews on a fixed schedule, plus immediate review whenever a trigger occurs.
What a Review Actually Involves
A review of a confined space assessment is not a formality. It involves:
- Re-evaluating the physical condition of the space
- Re-checking the hazards from design, construction, location, contents, and adjacent processes
- Verifying the plan still addresses each identified hazard
- Confirming that the procedures, equipment, and rescue planning remain appropriate
- Updating documentation with the review date, who performed the review, and any changes made
A review may conclude that the assessment remains accurate and adequate, or it may result in updates to the assessment and plan. Either way, the review itself must be documented.
Common Mistakes Ontario Employers Make
In CCL's practice, the most common mistakes related to assessment reviews include:
- Treating the 3-year cycle as the only review trigger and missing event-driven reviews
- Performing reviews on the calendar but not actually re-evaluating the space (a calendar check rather than a substantive review)
- Failing to document that a review was performed, even when the review concluded no changes were needed
- Reviewing the assessment but not updating the plan or the entry permit when changes are needed
- Conducting the review without a competent person, particularly when the original assessment was carried out by someone with specific expertise that the reviewer lacks
- Letting the cycle slip when staff turn over and tracking responsibility is not formally assigned
Each of these mistakes creates a compliance gap that becomes visible during inspection or, more seriously, after an incident.
How CCL Health & Safety Helps
CCL builds confined space programs that include both event-driven and periodic review structures. We carry out the original hazard assessment, document the plan, and structure the program so review triggers are explicit and tracked. For ongoing engagements, we conduct comprehensive periodic reviews on the schedule appropriate for each workplace.
For more detail on our confined space program development services, see Confined Space Program Development. For workplaces under federal jurisdiction, see our guide to Provincial vs Federal Confined Space Regulations. For the underlying regulation that the Section 6(9) review requirement comes from, see Ontario Regulation 632/05 Explained. For how the assessment review obligation interacts with the Ontario general duty clause, see OHSA Section 25(2)(h) and Due Diligence Explained.