The definition
A "confined space" means a fully or partially enclosed space:
- (a) that is not both designed and constructed for continuous human occupancy, and
- (b) in which atmospheric hazards may occur because of its construction, location or contents or because of work that is done in it.
For a fully or partially enclosed space, both conditions (a) and (b) must apply before it is a confined space.
Do you have a confined space?
Ask three questions:
- Is the space fully or partially enclosed?
- Is the space not both designed and constructed for continuous human occupancy?
- Might an atmospheric hazard occur?
The only way to know is to evaluate the space, and how you do the evaluation is up to you as the employer. For a fully or partially enclosed space: if it is designed and constructed for continuous human occupancy, it is not a confined space, whether or not an atmospheric hazard might occur. If it is not designed for continuous human occupancy and an atmospheric hazard might occur, it is a confined space. If it is not designed for continuous human occupancy but no atmospheric hazard might occur, it is not a confined space.
If you have properly evaluated a space and found it is not a confined space, you don't need a confined space program for it, even if you choose to do air sampling before entering as a precaution. You still need to meet any other regulatory requirements that apply.
Designed and constructed for continuous human occupancy
To decide whether a space is designed and constructed for human occupancy, look at its intent and construction: what it was intended for, and what standards it was designed and built to so that people can occupy it.
The regulation doesn't define human occupancy. The Ministry of Labour uses "continuous human occupancy" to mean a space designed and constructed under recognized codes and standards that make it suitable for people to occupy continually, with provisions for structural adequacy, entry and exit, ventilation and lighting. Examples are the Ontario Building Code, the Ontario Fire Code and CSA B52 (Mechanical Refrigeration Code).
Offices, arenas, maintenance rooms and control rooms are obviously designed for people to occupy for long periods. They are not confined spaces, whatever atmospheric hazards may occur in them, although occupational health and safety law still applies. Parts of a tunnel or underground mine are designed for people to work in, but parts of them could be confined spaces, and they can contain confined spaces such as bins, tanks, sumps and water storage dams.
Spaces that are not both designed and constructed for continuous human occupancy include:
- storage tanks, tank cars, process vessels, boilers, pressure vessels, vats, bins, silos, bag-houses and other tank-like compartments usually entered only through a manhole
- open-topped spaces such as pump wells, augured caissons, pits or degreasers
- pipes, sewers, ducts and similar structures
- cargo tanks, cellular double bottom tanks, duct keels, ballast and oil tanks and void spaces
- chutes, mill holes, ore bins, the inside of a skip hanging in a shaft, crusher jaws
- flues, chimneys, ovens or furnaces
Vessels, sewers and tank cars are built to play a role in a process: to contain, transport, move or handle materials or equipment, not for people to occupy. They may have ladders or platforms for occasional work inside, but they are not designed for continuous human occupancy. Likewise, a chamber or vault with cooling ventilation for equipment and a temporary access space for workers is not designed to codes and standards that let workers safely work inside on a regular basis.
Spaces that are both designed and constructed for continuous human occupancy include offices, service rooms (such as mechanical and elevator rooms), shops, walk-in freezers and refrigerators, laboratories, flammable liquid storage and dispensing rooms, and rooms with approved fire suppression systems.
A construction project space intended for human occupancy but not yet finished is not a confined space if its stage of construction is suitable for continuous human occupancy. Some construction spaces, such as sumps and tanks, may be confined spaces, but not projects in general. Trenches under construction that comply with O. Reg. 213/91 (Construction Projects) requirements for access and egress, wall stability and ventilation are designed for continuous human occupancy during the construction phase.
Openings too small to enter
A confined space is one a person can occupy. The Ministry's position is that the opening must be large enough for a person's body to pass through. Entry happens as soon as any part of the entrant's body breaks the plane of the opening, whether or not the work, such as atmospheric testing, needs whole-body entry, and the Confined Spaces Regulation then applies.
If the opening is too small for a person's body to pass through, the regulation doesn't apply, even if a hand breaks the plane of the opening to do the work. You must still comply with the OHSA, including taking every precaution reasonable in the circumstances to protect workers on or near the space, for example from explosive gases.
Restricted space or confined space?
Only the Regulation for Health Care and Residential Facilities (O. Reg. 67/93) uses the term "restricted space", in section 42. It refers, in part, to a "space from which the egress of a worker is restricted, limited, or impeded". A restricted space may also be a confined space, so an evaluation may find that an area is a confined space, a restricted space, or both.