What Counts as a Confined Space

Defining whether a space is confined or not is still something that tends to cause some confusion in the workplace. So, let’s simplify what can sometimes be a grueling task.

In Ontario, Regulation 632/05 defines confined spaces as: 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;

It’s important to note that we need both (a) AND (b) in order for a space to meet the definition. We need to evaluate the space and each part of the definition separately.

When evaluating part (a) we must look at criteria for human occupancy. In other words, what is the purpose and intent of the space and to what standards has the space been designed and constructed to allow people to occupy it?

The Ministry of Labour refers to the term continuous human occupancy as “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, entry and exit, ventilation and lighting such that a human could continually occupy that space.” Some aspects to focus on include: ventilation, lighting, and structural adequacy.

Does the space conform to the Ontario Building or Fire Code? If it doesn’t, chances are high that it is not both designed and constructed for continuous human occupancy.

If you cannot determine if the space is designed for human occupancy, consider part (b), is there an atmospheric hazard because of the design, construction, location or work to be performed? If there is not an atmospheric hazard, then the question of human occupancy doesn’t need to be considered as the space must meet both parts of the definition to be confined, therefore it is not confined.

Part (b) of the definition is where it can get tricky as it gets into whether an atmospheric hazard “may” occur because of its construction, location or contents or because of work that is done in it. It is this “may” term that causes some deliberation. First let’s look at how O. Reg 632/05 defines atmospheric hazards. An atmospheric hazard means:

(a) the accumulation of flammable, combustible or explosive agents

(b)  an oxygen content in the atmosphere that is less than 19.5 per cent or more than 23 per cent by volume, or

(c)  the accumulation of atmospheric contaminants, including gases, vapours, fumes, dusts or mists, that could,

(i) result in acute health effects that pose an immediate threat to life, or

(ii) interfere with a person’s ability to escape unaided from a confined space.

Based on the space, ask yourself the following: Is there currently an atmospheric hazard? Can one be created based on what we are doing in or around the space? If it is determined that an atmospheric hazard may be present, take it one step further and consider if the atmospheric hazard may accumulate and cause harm to the entrants or attendants.

To determine if the atmospheric hazards can accumulate, look at past air sampling data. Consider the construction of the space, size, design, and areas for pocketing of gases or other contaminants.

In short, if your space is not built to codes or standards that support human occupancy, lack lighting and ventilation AND there is an atmospheric hazard present or one can be created based on processes in or around the space and that atmospheric hazard can accumulate, there is a good chance the space meets the definition of a confined space.

Remember, always assess your spaces for all potential and foreseeable hazards, follow your entry plan, and make a safe entry.

Written by Jeff Thorne | Manager of Training & Consulting


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