Confined spaces – No easy way out (updated)

Introduction

This publication complements the Canada Labour Code (the Code) and Part XI (Confined Spaces) of the Canada Occupational Health and Safety Regulations (COHSR).

It contains general information to:

  • help employers and employees interpret key changes to the amended regulations (in force October 1, 2021)
  • help assess if health and safety measures have been appropriately implemented prior to entering a:
    • confined space, or
    • hazardous confined space

Definitions of confined spaces and hazardous confined spaces

The amendments to Part XI of the COHSR defines 2 distinct types of spaces in a workplace, namely “confined spaces” and “hazardous confined spaces”.

"Confined space" means a space that meets all 3 of the following conditions:

  1. is enclosed or partially enclosed
  2. is not designed or intended for continuous human occupancy, and
  3. has a limited or restricted means of entry or exit or an internal configuration that could complicate provision of first aid, evacuation, rescue or other emergency response (espace clos)

Table 1 - Confined space assessment criteria

Table 1 - Confined space assessment criteria
Enclosed or partially enclosed Is not designed or intended for continuous human occupancy Has a limited or restricted means of entry or exit or an internal configuration that could complicate provision of first aid, evacuation, rescue or other emergency response Result:
Confined space
No No No No
No No Yes
No Yes No
No Yes Yes
Yes No No
Yes No Yes
Yes Yes No
Yes Yes Yes Yes

A confined space may then be further classified as “hazardous” if at least 1 of the following criteria applies to the space:

"Hazardous confined space" means a confined space that, when entered, occupied or exited by persons, presents hazards likely to cause injury, illness or other adverse health effects to persons entering, exiting or occupying it because of 1 of the following conditions:

  1. its design, construction, location or atmosphere
  2. the materials or substances in it, or
  3. any other conditions relating to it (espace clos dangereux)

Table 2 – Hazardous confined space assessment criteria

Table 2 should be used to assess if a space is considered hazardous. In summary, a space is hazardous if, when entered, occupied or exited by persons, presents hazards likely to cause injury, illness or other adverse health effects to persons entering, exiting or occupying it because of ...:

Table 2 – Hazardous confined space assessment criteria
... its design, construction, location or atmosphere ... the materials or substances in it ... any other conditions relating to it Result:
Hazardous confined space
No No No No
No No Yes Yes
No Yes No
No Yes Yes
Yes No No
Yes No Yes
Yes Yes No
Yes Yes Yes

Examples of confined spaces or hazardous confined spaces commonly identified in federal work places may include:

  • maintenance holes
  • sewers
  • boilers
  • tunnels
  • pipelines
  • wells
  • fuel tanks
  • ballast tanks
  • storage tanks
  • tank cars and tank trucks
  • vats
  • process vessels
  • septic tanks
  • sewage lift stations
  • silos
  • grain elevators
  • trenches
  • ventilation systems
  • utility vaults
  • aircraft wings
  • ship holds
  • other spaces

Class of confined spaces

In Part XI, a “class of confined spaces” means a group of at least 2 confined spaces that are likely to present the same hazards, due to their similarities, to persons entering, exiting or occupying them.

Use the following criteria to identify a class of confined spaces:

  1. the confined spaces may be of similar size or shape
  2. they may contain similar equipment or machinery, or
  3. similar entry and/or emergency procedures apply

Duties of the employer

Before permitting any person to enter a confined space or a hazardous confined space to inspect, clean or carry out maintenance work, employers are required to:

  • perform an investigation of the workplace to identify all confined spaces
  • establish and maintain a record of confined spaces, which would be accessible to those entering those spaces
  • appoint a qualified person to determine whether the confined space is a hazardous confined space
  • ensure there is a visible sign at the entrance to each confined space identifying it as a confined space, and informing that it is forbidden to enter without permission from the employer
  • monitor a person entering a hazardous confined space, and
  • maintain records of all employees who received instruction and training on emergency procedures and obligations when working in confined spaces

Hazard assessment

If it is likely that a person will enter a hazardous confined space in order to perform work for an employer, the employer must appoint 1 or more qualified persons to:

  • carry out an assessment of the hazards to which the person may to be exposed, and
  • specify the test(s) that are necessary to determine whether the person is likely to be exposed to any of the hazards identified

The employer must ensure that the qualified person or persons record the findings of the assessment in a signed and dated report to the employer that specifies:

  • the protection equipment referred to in Part XII that is to be used by every person granted access to the hazardous confined space by the employer
  • insulated protection equipment and tools referred to in Part VIII that a person may need in the hazardous confined space
  • the personal protective equipment and emergency equipment to be used by any person who takes part in a rescue operation
  • the requirement for a first aid attendant, if applicable
  • steps to control or mitigate hazards, and
  • entry permit system, if required by the report

The employer must make a copy of the report available to the policy committee, if any, and the workplace committee or the health and safety representative.

The employer must ensure that the report and the list are reviewed:

  • by a qualified person at least once every 3 years
  • however, if there is reason to believe that the conditions inside a confined space have changed, the employer must ensure that the space is reassessed and treated in accordance with the new findings

The assessment does not need to be carried out if:

  • a confined space has not been entered in the 3 years preceding the time when the assessment should have been carried out, and
  • no entry is scheduled

Specific hazards associated with hazardous confined spaces

Investigation reports indicate that the root cause of a majority of incidents related to hazardous confined spaces are due to:

  • lack of training
  • lack of information about the hazards prior to entry, or
  • attempted rescue

Examples of hazards that may be present in hazardous confined spaces may include:

Physical hazards
  • Noise
  • Engulfment
  • Flooding
  • Moving machinery
  • Heat or cold stress
  • Vibration
  • Radiation
  • Fire
  • Explosions
  • Poor lighting
  • Other
Biological hazards
  • Mould
  • Bacteria
  • Viruses
  • Bloodborne pathogens
  • Biological toxins
  • Other
Chemical hazards
  • Gases
  • Vapours
  • Fumes
  • Chemical asphyxiants
  • Lack of oxygen
  • Asbestos
  • Lead
  • Silica
  • Nanoparticles
  • Concentrations of airborne substances above occupational exposure limits
  • Other
Electrical hazards
  • Live wires
  • Electrical panels
  • Other
Ergonomic hazards
  • Maintaining difficult postures
  • Repetitive strain
  • Lifting
  • Awkward reaching
  • Use of hand tools
  • Other
Psychological hazards
  • Working alone
  • Claustrophobia
  • Fatigue
  • Other

Confined space and hazardous confined space entry

Every employer must establish procedures that are to be followed by a person:

  • entering
  • exiting, or
  • occupying a confined space or hazardous confined space

The procedures must take into account the report made by the qualified person, if applicable.

The procedures for each confined space must include:

  • safe entry and exit procedures
  • two-way communication and person check systems, and
  • emergency response measures

In addition to the previous requirements, the procedures for each hazardous confined space must also include:

  • all additional risk control measures that would ensure:
    • the health and safety of a person in the space, and
    • an entry permit system, if required under the report

Verification processes for hazardous confined spaces

The employer must ensure that no person is granted access to a hazardous confined space, unless:

  • they have appointed a qualified person to confirm compliance with the conditions specified in Subsections 11.05 (1) to (4).

Emergency procedures and equipment

The employer must ensure:

  • requirements are being followed at all times based on the conditions in a hazardous confined space, and
  • requirements are being followed at all times based on the nature of the work being performed in a hazardous confined space

If the requirements cannot be met when a person is in the hazardous confined space, the employer must:

  • in consultation with the policy committee or, if there is no policy committee, the work place committee or the health and safety representative, establish emergency procedures to be followed in the event:
    • of an accident, or
    • other emergency in or near the hazardous confined space that includes
      • a plan for reporting the emergency, and
      • a list of necessary resources, including the required numbers of persons, to carry out the emergency procedures
  • specify the date when the emergency procedures are established and provide a plan for the immediate evacuation of the hazardous confined space if:
    • an alarm is activated, or
    • there is a change in a concentration or percentage of an airborne hazard that would adversely affect the health or safety of a person in the hazardous confined space
  • provide the necessary personal protective equipment for each employee who is about to enter the hazardous confined space
  • ensure that a qualified person trained in the appropriate the emergency procedures is:
    • in attendance outside the hazardous confined space, and
    • in communication with the person inside the hazardous confined space
  • in consultation with the policy committee or, if there is no policy committee, the work place committee or the health and safety representative, provide the qualified person with:
    • a suitable communication device, or
    • alarm for summoning assistance, and
    • ensure that the required number of persons are available to assist in the event of an emergency and to carry out the emergency procedures

At least 1 of the persons in attendance outside of the hazardous confined space must:

  • be trained in the hazardous confined space emergency procedures (and receive annual refresher training)
  • possess at least a basic first aid and cardiopulmonary resuscitation (CPR) certificate, and
  • be provided with the necessary personal protective equipment and emergency equipment

Additionally, the employer must ensure that every person entering, exiting or occupying a hazardous confined space wears an appropriate safety harness that is securely attached to a lifeline that:

  • is attached to a secure anchor outside the hazardous confined space
  • is monitored by the qualified person
  • protects the person from the hazard for which it is provided, and does not in itself create a hazard, and
  • is, if feasible, equipped with a mechanical lifting device

Hot work

"Hot work" means any work where a flame is used or a source of ignition may be produced.

Unless a qualified person has determined that the work can be performed safely, the employer must ensure that hot work is not performed in a hazardous confined space that contains:

  • an explosive or flammable hazardous substance in a concentration in excess of 10% of its lower explosive limit, or
  • oxygen in a concentration in excess of 23%

If hot work is to be performed in a hazardous confined space that contains:

  • concentrations of flammable, or
  • explosive materials

In excess of the aforementioned concentrations, a qualified person must:

  • patrol the area surrounding the hazardous confined space
  • maintain a fire protection watch in that area until the fire hazard has passed
  • ensure that emergency equipment must be provided in the area

Where airborne hazards may be produced by hot work in the hazardous confined space, no person shall:

  • shall enter, or
  • occupy the confined space
  • unless
    • the appropriate ventilation requirements of Section 11.11 are met, and
    • the person uses respiratory protection in accordance with Sections 12.,04, 12.05, and 12.2

Ventilation equipment

When ventilation is used in a hazardous confined space, the employer shall not grant access to any person unless the ventilation equipment is:

  • equipped with an alarm that will, if the equipment fails:
    • be activated automatically, and
    • be audible or visible to every person in the hazardous confined space, or
    • be monitored by an employee who is in constant attendance and who is in communication with any person in the hazardous confined space

Oxygen deficiency and enrichment

An “oxygen deficient atmosphere” means an atmosphere in which there is less than 18% by volume of oxygen at a pressure of one atmosphere or in which the partial pressure of oxygen is less than 135 mm Hg.

There are 2 common causes of oxygen deficiency:

  1. oxygen is displaced by gases such as nitrogen, which is often used as an inert gas to displace flammable gases when purging vessels in preparation for hot work
  2. oxygen is “used up” by:
    • combustion of flammable substances such as in welding activities or other hot work
    • explosions or fires (oxygen levels may remain low after the fire has been extinguished because the oxygen is replaced by the products of combustion)
    • chemical reactions (for example: oxidation of a metal), or
    • people working in the space actively using up oxygen as they breathe

Note: Given the challenges associated with the emergency evacuation of a person from a confined space, and the risks associated with a potential rapid decrease in the oxygen level, the minimum concentration deemed safe when entering the confined space is set at 19.5%.

What are the effects of reduced oxygen levels?

Normal air has approximately 21% oxygen by volume at normal atmospheric pressure.

  • At approximately 16% oxygen, your judgment and breathing are impaired ,and you are quickly exhausted
  • At approximately 12% oxygen, you may lose consciousness and could die unless moved to fresh air

Reminder: The atmosphere within a hazardous confined space must be assessed and continuously monitored prior to and during entry, if deemed necessary as per the qualified person.

What happens when the level of oxygen is too high?

An oxygen-enriched atmosphere contains more than 23% oxygen by volume. This may cause flammable materials, such as clothing and hair, to burn violently when ignited. Never use pure oxygen to ventilate a confined space, since an oxygen-enriched atmosphere is a fire and explosion hazard.

Fires and explosions

Combustible gases have an explosive range with a:

  • lower explosive limit (LEL), and
  • an upper explosive limit (UEL)

When the fuel and air mixture is below the LEL, or above the UEL, ignition will not take place. A gas is combustible only between its LEL and UEL. For example, methane is combustible only when mixed with air in a concentration between 5% and 15%.

Other combustible gases have different characteristics. Some have a wider range between their upper and lower explosive limits. Fires and explosions are serious dangers in confined spaces.

The following may contribute to explosions or fires:

  • chemicals
  • poor ventilation
  • static electricity
  • machinery
  • other

Toxicity

Toxic gases present 2 primary types of health risks in a confined space:

  • chemical asphyxiation
  • irritation to:
    • respiratory system
    • skin, or
    • eyes

Examples of toxic gases that are commonly identified in hazardous confined spaces include:

Hydrogen sulphide (H2S)
  • By-product of sewage treatment, petroleum, and other industrial processes
  • May be encountered in mines, gas wells, sewers, and similar installations
  • Heavier than air (settles in low places)
  • In low concentrations, smells like rotten eggs, and
  • In high concentrations, may be fatal
Methane (CH4)
  • Highly explosive
  • Can leak from a gas line
  • By-product of sewage
  • May be present in coal mines, and
  • Displace oxygen and may cause asphyxiation
Sulphur dioxide (SO2)
  • Colourless gas with a strong smell (similar to burnt matches)
  • Toxic at very low concentrations
Carbon monoxide (CO)
  • Colourless
  • Odourless
  • Tasteless
  • By-product of incomplete combustion
  • Commonly generated from internal combustion engines
  • Overexposure may cause ringing in the ears, nausea, headache, and sleepiness, and
  • May be fatal in very low concentrations

Closing off a confined space

The employer must ensure that no person closes off a confined space unless a qualified person has verified that no person is inside it.

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