Confined Spaces in Canada: Definition, Hazards & the Law

A confined space is an enclosed or partially enclosed area that is not designed for continuous human occupancy and that has limited or restricted entry or exit. Tanks, silos, sewers, vaults and pits are everyday examples — and they are among the most dangerous places to work in Canada.

Many workers are injured or killed in confined spaces each year, and the Canadian Centre for Occupational Health and Safety reports an estimate that 60% of the fatalities are would-be rescuers. 1 This guide to confined space safety covers the legal definition, the hazards, and the rules in every Canadian jurisdiction.

What is a confined space?

Under the federal definition, a space is a confined space when it meets all three conditions:

• it is fully or partially enclosed;
• it is not designed or intended for continuous human occupancy;
• it has a limited or restricted means of entry or exit, or an internal configuration that could complicate first aid, evacuation, rescue or other emergency response. 6,3

The provincial definitions differ, and the one that binds you is your own jurisdiction's. Ontario has no entry-or-exit condition at all, asking instead whether atmospheric hazards may occur in the space. 11 British Columbia adds a fourth condition: the space must be large enough and so configured that a worker could enter to perform the work. 13

Canada's federal rules, in Part XI of the Canada Occupational Health and Safety Regulations, define two distinct kinds of space: a confined space, as defined above, and a hazardous confined space.

A hazardous confined space is a confined space that presents hazards likely to cause injury, illness or other adverse health effects to the people entering, exiting or occupying it because of its design, construction, location or atmosphere, because of the materials or substances in it, or because of any other condition relating to it.

The distinction carries real weight. Every hazardous confined space is a confined space, but not every confined space is hazardous, and the hazardous ones attract the additional requirements Part XI sets out. Note that this is federal terminology. Provinces and territories reach comparable outcomes through their own definitions and their own hazard assessment requirements, and several do not use the phrase hazardous confined space at all.

Because all three conditions have to be met at once, a space that fails even one of them is not a confined space under the federal definition. The table below shows every possible combination. 3

Table 1 — Confined space assessment criteria. Source: Employment and Social Development Canada, Confined spaces — No easy way out (updated).

What are the types of confined spaces, and what is a restricted space?

There is no national set of three types of confined spaces in Canada, and no single national list of types. Federally, the split is between a confined space and a hazardous confined space. Alberta uses its own pair of terms, restricted space and confined space, and inverts the usual meaning. British Columbia classifies the atmosphere inside the space as low, moderate or high hazard. Which set of terms applies to you depends on your jurisdiction. 6,14,13

One word causes more confusion than any other here. Federally, a class of confined spaces means a group of at least two confined spaces that are likely, because of their similarity, to present the same hazards to the people entering, exiting or occupying them — grouped so that one assessment and one set of procedures can cover them all. It is a grouping device for administering an entry program. It is not a hazard rating, and there is no national system of Class 1, Class 2 and Class 3 confined spaces. 6

Alberta is the jurisdiction worth reading closely, because it uses the same two words in the opposite order to everyone else. Under Alberta's Occupational Health and Safety Code, a restricted space is "an enclosed or partially enclosed space, not designed or intended for continuous human occupancy that has a restricted, limited, or impeded means of entry or exit because of its construction."

A confined space in Alberta is a restricted space that may become hazardous to a worker entering it because of its atmosphere, because of a condition or changing set of circumstances inside it, or because of the activity being carried out in it. 14

So in Alberta, a space that everyone else would call a confined space may legally be a restricted space, and the term confined space is reserved for the hazardous ones. Part 5 of the Code covers both, and the distinction changes what the Code requires.

British Columbia takes a different approach again, classifying the atmosphere rather than the space. Part 9 of the Occupational Health and Safety Regulation sorts the atmosphere inside a confined space into three categories, and the controls required scale with the category. 13

Table 2 — British Columbia's atmospheric hazard categories under OHSR Part 9. These categories are British Columbia's; they are not a national classification.

What are examples of confined spaces?

Five common examples are storage tanks, silos, sewers, manholes and pits. Confined spaces are far more varied than that, and they turn up in almost every industry. The everyday ones group into three families.

Storage and containment

• Tanks and storage vessels
• Silos and grain bins
• Hoppers and bins
• Vats and reactors
• Tank cars and tanker trailers

Access and underground structures

• Sewers and storm drains
• Manholes and access chambers
• Tunnels and utility vaults
• Pits, sumps and trenches
• Crawl spaces, wells and cisterns

Process equipment

• Boilers and furnaces
• Pipelines and large-diameter piping
• Flues, stacks and ductwork
• Degreasers and process vessels
• Ship holds and machinery compartments

Being small is not part of the test. A space can be large enough to walk around in and still be a confined space, and a space can be open at the top and still be one. British Columbia goes the other way and requires the space to be large enough for a worker to enter and do the work. If it meets the definition that applies where you work, it counts.

What are the main hazards of confined spaces?

Confined space hazards fall into six groups: physical, chemical, biological, electrical, ergonomic and psychological. The ones that kill most often are atmospheric — oxygen deficiency and toxic or flammable gases — which is why the atmosphere is tested before anyone enters and monitored while they are inside. 1

What oxygen level makes a confined space unsafe?

Normal air is about 20.9% oxygen. Below 19.5% an atmosphere is oxygen deficient and is no longer safe to enter without supplied air. Alberta's OHS Code sets the acceptable range at 19.5% to 23.0% oxygen by volume, and Nova Scotia's regulations require not less than 19.5% and not more than 22.5%. 14,23

Oxygen disappears quietly: rust forming inside a steel tank, fermenting grain, curing concrete, welding, or an inert gas purge can all pull it down with no smell and nothing visible to warn the worker. Above the upper limit the opposite problem starts, because an oxygen-enriched atmosphere makes materials that normally burn slowly ignite easily and burn violently.

Physical hazards

• Entrapment and suffocation. Workers can be trapped by a collapsed structure or an equipment failure, or engulfed by grain, sand, sludge or liquid that behaves like quicksand once it starts moving.
• Explosions and fires. Flammable gases, vapours, liquids or combustible dust can be ignited by a spark from electrical equipment, static, or hot work such as welding and cutting.
• Falls and trips. Limited room, poor lighting, wet or uneven surfaces, ladders and vertical entries all make falls more likely and rescue after a fall much harder.
• Heat stress and cold. Confined spaces trap heat, and protective clothing makes it worse. Workers can suffer heat exhaustion and dehydration, or in unheated outdoor spaces, hypothermia and frostbite.
• Noise and moving equipment. Sound reflects off hard interior surfaces and amplifies, and agitators, augers and mixers can start unexpectedly if hazardous energy is not isolated and locked out.

Chemical hazards

• Toxic gases and vapours. These can come from the product stored in the space, from residue in the walls or sludge, from a connected supply line, or from the work itself. Most corrosive substances give some warning by irritating the eyes and airways, which produces coughing and watering eyes. Many poisonous substances give little or no warning at all. Carbon monoxide has no odour and blocks the blood from carrying oxygen.
• Hydrogen sulphide. Hydrogen sulphide gives a rotten-egg odour at low concentrations, but it quickly dulls the sense of smell — and at high concentrations it can cause sudden collapse ("knockdown"), unconsciousness and death within minutes. 2
• Flammable liquids and gases. Fuels, solvents and process chemicals can build a flammable atmosphere inside an enclosed space very quickly. Testing measures this as a percentage of the lower explosive limit.
• Corrosive substances. Acids, bases and corrosive gases cause chemical burns, severe eye and skin injury and respiratory damage, and residue left in a supposedly empty vessel is a common cause.

Biological hazards

• Mould and fungi
• Bacteria and viruses, including those in sewage and standing water
• Biological toxins
• Animal droppings, insects and vermin

Electrical hazards

• Live wiring and exposed conductors
• Electrical panels and equipment inside the space
• Wet surfaces and conductive enclosures, which make shock more severe
• Stored energy in capacitors, springs and pressurized lines

Ergonomic hazards

• Holding awkward or difficult postures
• Repetitive strain
• Lifting in a restricted position
• Awkward reaching
• Extended use of hand tools in a cramped space

Psychological hazards

• Working alone
• Claustrophobia and panic
• Fatigue and reduced alertness
• Communication breakdown between the entrant, the attendant and the rescue team

What are the roles in a confined space entry?

Common confined space entry roles include the entrant, an attendant or standby worker, and a person responsible for supervising or authorizing the entry. Exact roles and separation of duties depend on the applicable jurisdiction and entry procedure, so build the role assignments from your own regulation and entry program rather than from a generic model.

A confined space attendant, where one is assigned, stays outside the space for the whole entry, keeps continuous communication with everyone inside, keeps an accurate count of who has gone in and who has come out, watches for changing conditions, orders an evacuation if anything goes wrong, and summons rescue. An attendant should not leave the post or enter the space to attempt a rescue, because unplanned rescue attempts are how confined space incidents claim a second life. 11,1

Entrant

The entrant is the worker who goes into the space. The entrant needs to know the hazards identified in the assessment, understand the signs and symptoms of exposure, use the assigned protective and respiratory equipment correctly, stay in communication with the person outside, and leave the space immediately when told to or as soon as anything feels wrong.

Attendant or standby worker

A confined space attendant, also called the standby worker, is the person posted outside the space for the whole entry; the attendant keeps contact with everyone inside, counts who is in and out, and summons rescue. Requirements differ by jurisdiction. Ontario expressly requires an attendant whenever a worker is to enter a confined space (O. Reg. 632/05, s. 15). 11

Manitoba's Workplace Safety and Health Regulation requires a standby worker for every hazardous confined space, present at the entrance the whole time anyone is inside (s. 15.8(1)). New Brunswick's General Regulation 91-191 defines the attendant and the air supply system attendant in its confined space Part. 17,21

Federally, the Canada Occupational Health and Safety Regulations require two-way communication and person-check systems in the written procedures for every confined space. 6

Supervisor or authorizing person

The supervisor or authorizing person is the competent or qualified person who supervises or authorizes the entry under the employer's program. That person typically confirms the hazard assessment applies, checks that isolation, lockout, ventilation and testing have been done, verifies that rescue arrangements are in place, authorizes the entry and any permit that goes with it, and closes it out when the work is finished or conditions change. The title and the exact duties are set by the applicable regulation.

What do confined space entry programs and entry permits require?

A confined space entry needs a written system from the employer, not just a trained worker. Federally, section 11.04 of the Canada Occupational Health and Safety Regulations requires written confined space procedures for every confined space. They cover safe entry and exit, two-way communication and person-check systems, and emergency response measures. For every hazardous confined space, they also cover all the risk control measures needed to protect the people inside, and an entry permit system where the hazard assessment calls for one. 6

Those procedures apply to everyone who enters, including contractors, and the hazard assessment report, the procedures and the emergency procedures are kept for ten years (s. 11.13). 6

British Columbia names the document outright. Part 9 of the Occupational Health and Safety Regulation requires a written confined space entry program before any worker enters. The program has to assign responsibilities and identify and assess every confined space at the workplace. It also has to set written procedures for isolation and lockout, atmospheric testing, ventilation and purging, standby persons, rescue, lifelines and harnesses, personal protective equipment, and coordination between employers working on the same site. 13

Where an entry permit is required, it is the per-entry record that proves those procedures were followed on the day: the space, the tests and their results, the controls in place, the people assigned to each role, and the period the entry is authorized for. Whether a permit is required, and what triggers one, differs by jurisdiction and by the conditions of the entry.

For what a permit must confirm and contain, who signs it and where each province puts the requirement, see our full guide to confined space entry permits.

What are the federal confined space regulations?

The Canada Labour Code, Part II sets the occupational health and safety requirements for federally regulated workplaces: banks, telecommunications and broadcasting, interprovincial road, rail, air and marine transport, ports, pipelines, and the federal public service. The confined space rules themselves sit in the regulations made under it, at Part XI (sections 11.01 to 11.13) of the Canada Occupational Health and Safety Regulations (SOR/86-304). 5,6

Part XI was substantially amended by SOR/2021-143, in force October 1, 2021, and the assessment, procedure and training requirements were rebuilt around the distinction between a confined space and a hazardous confined space. 7,6

Under Part XI the work is split. The employer, in consultation with the work place committee or health and safety representative, surveys the workplace, identifies every confined space, and appoints a qualified person to decide which of them are hazardous (s. 11.02(1)). Where someone is likely to enter a hazardous confined space, the employer appoints one or more qualified persons to assess the hazards and specify the tests needed, and records their findings in a signed and dated report (s. 11.03(1) and (2)). 6,4

That report specifies six things: the protection equipment for everyone granted access, any insulated equipment and tools, the equipment for rescuers, any requirement for a first aid attendant, the steps to control or mitigate each hazard, and any situation in which an entry permit system is required. The report and the list of confined spaces are reviewed by a qualified person at least once every three years, and sooner if the conditions inside a space have changed (s. 11.03(4)). 6

The employer then has to establish written confined space procedures, provide training on them, keep the record of confined spaces up to date and readily accessible to anyone before they enter (s. 11.02(4)), and keep the hazard assessment report, the procedures and the emergency procedures for ten years (s. 11.13). 6

Two CSA standards fill in the technical detail the regulations leave open: CSA Z1006:23, Management of work in confined spaces, and CAN/CSA-Z94.4-18 (R2023), Selection, use, and care of respirators. They cover hazard assessment, ventilation, communication, rescue procedures and respiratory protection in far more depth than any regulation does. Saskatchewan's current approved standards and practices for confined space entry reference CSA Z1006:23 directly. 8,9,16

Most workplaces in Canada are not federally regulated, so for the great majority of employers the rules that actually apply are provincial or territorial. The table below sets them out.

What are the confined space regulations by province and territory?

Every province and territory regulates confined space work, and the broad shape is similar: identify the spaces, assess the hazards, write procedures, test the atmosphere, post someone outside, and have rescue arranged. The definitions, the triggers and the details differ enough to matter, so work from the instrument that applies to your workplace. The instrument name links to the legislation text and the authority name links to the regulator.

A few jurisdictions carry requirements the others do not, and they are worth knowing if you work across provincial lines. British Columbia requires pre-entry atmospheric testing to be completed no more than 20 minutes before a worker enters (s. 9.25). Manitoba builds a statutory entry permit system into Part 15. 13,17

Nova Scotia limits the written certification for an entry to 24 hours after the tests were performed. Newfoundland and Labrador requires a WorkplaceNL-approved 16-hour certification course for entrants. Yukon requires an entry permit for specified high-hazard conditions (s. 2.09). Quebec added section 297.1 to the RSST in 2023: a new or renovated confined space must be laid out with equipment and installations that allow the work to be done from outside; only where that is not possible must the layout control the risks and make entry, exit and rescue easier. 23,26,27,19

Which part of the training can be done online?

It depends on what you actually do, and the employer remains responsible either way. Online training can carry the theory: the regulations, how to recognize a confined space, what the hazards are, and how an entry program and permit system work. It cannot carry practical competency. Workers who enter need hands-on practice with the equipment they will actually use, which means gas detectors, ventilation, harnesses, tripods and retrieval gear, and rescue procedures rehearsed under supervision.

Whatever the role, training has to be adequate for the duties the worker actually performs, in the workplace where they perform them. Ontario, for example, requires that every worker who enters a confined space or performs related work receives adequate training in accordance with the relevant plan. That is a competency test, not a course-length test, and it is the employer who has to be satisfied it has been met. 11

The workable answer for most employers is blended training. The online portion covers the theory. The on-site portion covers the practical skills, using your own equipment, in your own spaces, with workplace-specific checklists completed under the guidance of a competent person. That combination usually beats generic classroom training, where the equipment on the table often is not the equipment you will be using at work.

Regulators accept the online component on those terms. Ontario's official guideline for working in confined spaces states that web-based training could be part of your training, that it may need to be supplemented with plan-specific training, and that the employer has the duty to ensure the training is adequate. 12

Newfoundland and Labrador is stricter, and it is the one province where the answer for entrants is a flat no. WorkplaceNL's Confined Space Entry certification training standard requires a minimum 16-hour course delivered by a WorkplaceNL-approved provider, with eight hours of individualized practical training, and recertification every three years. If you work in Newfoundland and Labrador and you enter confined spaces, you need an approved provider. 26

One thing to be wary of anywhere: a provider offering full confined space entry certification with no hands-on component at all. For entry roles requiring practical competence with monitoring equipment, personal protective equipment, retrieval or rescue equipment, online theory alone should not be treated as proof of practical competency.

Who must be trained to work in or around a confined space?

Anyone who enters a confined space needs confined space training, and so does anyone whose work is connected to the entry: attendants and standby workers, supervisors, rescue personnel, and workers whose job puts them next to an open manhole, tank or pit. Confined space safety training teaches workers to recognize the hazards of working in and around confined spaces and to work safely in them. Federally, the content is written into the regulation: every employee likely to enter a confined space must be instructed and trained in the employer's confined space procedures and emergency procedures and in the use of the protection equipment (COHSR s. 11.12). 6

Employers are responsible for providing it. The duty to identify confined spaces, assess the hazards, write the procedures, train the workers and supply the required equipment sits with the employer in every Canadian jurisdiction, and it cannot be transferred to the worker. 5,6

The industries where confined space work is routine:

• Construction
• Manufacturing and food processing
• Oil and gas
• Mining
• Agriculture
• Utilities, water and wastewater
• Transportation and marine
• Municipal services and maintenance trades

When does the law require confined space retraining?

There is no single Canada-wide expiry period for confined space training. Most legislation fixes no certificate term at all, and where a term does exist it is set by that jurisdiction rather than by a national rule. Where a jurisdiction does set a term, it governs: Nova Scotia requires anyone who enters a confined space to be retrained at least once every 2 years, and anyone who undertakes rescue operations at least once every year (Occupational Safety General Regulations, s. 130(5)). 23

A three-year certificate does not satisfy Nova Scotia. In practice, confined space training certificates in Canada are commonly renewed every three years as industry and contractual practice. Treat three years as practice, not as a legal expiry date, and check your own jurisdiction first.

Newfoundland and Labrador is the clearest case. Entrants need Confined Space Entry certification from a WorkplaceNL-approved provider, delivered as a minimum 16-hour course with eight hours of individualized practical training, and that certification expires three years after it is issued. 26

Ontario has no certificate scheme at all. British Columbia, for example, sets no certificate term in Part 9 of its regulation 13. What it requires is adequate training for every worker who enters a confined space or performs related work, and at non-project workplaces the training is reviewed whenever circumstances change and in any case at least once a year (O. Reg. 632/05, s. 8(4)). New Brunswick requires yearly practice, or practice before entry, for rescue roles (General Regulation 91-191, s. 262.031(c)). Other jurisdictions set their own retraining triggers. 11,21,22

Everywhere, retraining is driven by change rather than by the calendar. If the space, the hazards, the equipment or the procedures change, the training is out of date regardless of the year printed on the certificate. Two practical consequences follow.

First, a certificate still inside its renewal window is not automatically current: if the space, the equipment or the procedure has changed since the training, retraining is due now. Second, a certificate is not a licence to enter. It shows the worker has been trained. The entry itself still depends on a current hazard assessment, a valid entry permit where one is required, and an atmosphere tested on the day. Check what your employer, your client and your compensation board require.

Key takeaways

Under the federal definition, a confined space is any space that is fully or partially enclosed, is not designed for continuous human occupancy, and has restricted entry or exit or a shape that would make rescue difficult; the provincial tests differ, as the definition section above sets out. Once a space meets the definition that applies where you work, the employer must follow the identification, assessment and entry requirements imposed by that jurisdiction.

The additional controls, from atmospheric testing and ventilation through to attendants, entry permits and standby rescue, depend on the hazards found in the assessment and on the conditions of the particular entry. Check your own jurisdiction in the table above, because the details differ from province to province.