Determine if any of your confined spaces have hazards that make them permit spaces. Do not allow any employees to enter a confined space until it has been fully evaluated. At workplaces where confined spaces are being built, host employers or controlling contractors do not need to evaluate confined spaces unless:

• One of their employees will enter the space
• An employee of an employer responsible to the host employer or controlling contractor will enter the space
• A host employer or controlling contractor assumes control over the space If your workplace has a permit space, your employees must know where it is located, that it is hazardous, and that it is a permit space.
• Allow employees to observe the evaluation of the space.
• Identify the space as a permit space. You can use signs, labels, or tags to identify the space.
• When conditions within the space change, re-evaluate it.
• Prevent unauthorized employees from entering the space. If someone else will enter a permit space under your control (employees of another employer, for example), inform them: • About all hazards or potential hazards in the spaces
• If the spaces have been evaluated before and what that evaluation discovered
• What your precautions or procedures are for entering the spaces If your employees will enter a permit space, they must follow the requirements of your written permit-space program.

If you have mobile employees, you must determine whether there are confined spaces at the sites where they will be working.

If confined spaces are present, the space must be evaluated to identify any physical or atmospheric hazards that make it a permit space. 



HUMAN OCCUPANCY

To determine if a space is designed and constructed for human occupancy, we must look at the intent and construction of the space – what is the purpose of the space, or in other words, what was it intended for, and to what standards has it been designed and constructed to allow people to occupy it?

Workspaces such as offices, arenas, maintenance rooms, control rooms, etc., are obvious places that are designed for humans to occupy for long periods of time (continuously). These spaces are not considered a confined space, regardless of the atmospheric hazards that may occur in them. However, occupational health and safety legislation and regulations apply and must be complied with to protect workers.

Although the regulations do not define human occupancy, the Ministry of Labour uses the term ‘continuous human occupancy’ to refer to a space that has been designed and constructed in accordance with recognized codes and standards that contain provisions to make the space suitable for humans to occupy, such as provisions for structural adequacy, access and egress, ventilation and lighting such that a human could continually occupy that space.

Other spaces, such as parts of a tunnelling operation or an underground mine (stopes, drifts, ramps, shafts, raises), are designed and constructed specifically for people to carry out work within them. Specific codes and standards and requirements are intended to make the space adequate for the health and safety of workers. However, parts of a tunnel or mine could be confined spaces. Tunnels and mines could also include confined spaces within them, such as bins and tanks.

Some examples of spaces that would not be considered as “both designed and constructed for human occupancy” are:

• storage tanks, tank cars, process vessels, boilers, pressure vessels, vats, bins, silos, bag-houses and other tank like compartments usually having only a manhole for entry;
• 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, inside of a skip hanging in a shaft, crusher jaws; and
• flues, chimneys, ovens or furnaces. 



Structures such as vessels, sewers and tank cars are designed and constructed to play a role in part of a process. Their primary purpose is to contain, transport, move or manipulate materials or equipment and they are not primarily designed for people to occupy them. They may have structures such as ladders or platforms where workers can perform work within the space on occasion. However, these spaces were not designed for human occupancy.

A construction project space that is intended for human occupancy but not yet completed in its construction is not considered a confined space if its stage of construction is suitable for continuous human occupancy. Some construction spaces such as sumps and tanks and projects within these spaces will be confined spaces, but not projects in general.

A chamber or vault may have cooling ventilation for equipment purposes and have a temporary access space, designed to allow workers to access pipes and equipment (perhaps by using ladders or a door). However, this does not mean that it has been designed to meet codes and standards that would allow workers to safely perform their duties on a regular basis within the chamber or vault. 

Therefore, these spaces are considered NOT to be both designed and constructed for human occupancy.

What are examples of spaces that are both designed and constructed for continuous human occupancy?

Some examples include offices, service rooms (such as mechanical rooms, elevator rooms), shops, walk-in freezers and refrigerators, laboratories, flammable liquid storage and dispensing rooms, and rooms equipped with approved fire suppression systems.

Trenches that are under construction and that are in compliance with the requirements (which cover access and egress, stability of the trench walls and adequate ventilation in the trench) would have been designed for continuous human occupancy during the construction phase.

What if I cannot determine if a space is not designed and constructed for human occupancy?

Where it is not obvious and your evaluation does not determine whether a workspace is or is not designed for human occupancy, consider whether or not there may be an atmospheric hazard present because of its design, construction or location and the work to be performed.

If it is determined that no atmospheric hazard may occur, then the confined space provisions would not apply in any case, and the human occupancy question need not be considered.

Where an atmospheric hazard may exist and you are still uncertain as to whether the space is designed for human occupancy, it may then be a reasonable precaution to comply with the confined space provisions. 

What are examples of means of entry or exit?

Also known as ‘access and egress’, the purpose of this section is to ensure that employers provide for safe exit and entry as per the plan. For example: openings into confined spaces must be large enough to permit the entry of workers wearing safety equipment; a manhole should be at least 61 cm in diameter; hinged covers, doors, etc., should be provided with a means whereby they can be locked in the open position. Ladders or other suitable means should be provided where necessary to give ready access and egress. Ladders should be well secured.

The size of access and egress areas should be considered when choosing personal protective equipment to be used by the workers entering the confined space. The same considerations should be made when setting up rescue procedures and choosing rescue workers’ personal protective equipment and rescue equipment.