Glossary

Look up definitions here!

To find out definitions and more information, please click on the letters below.

Please note that these definitions are based on the Canada Labour Code and Part XI of Canada's Occupational Health and Safety Regulations. Although some organisations are covered by these regulations, most will be governed by their respective provincial or territorial Occupational Health and Safety Regulations. For a list of all provincial and territorial Occupational Health and Safety Regulations, please click here.

Please remember: before entering a confined space, check with your supervisor that you are abiding by the correct regulations.

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Acceptable entry conditions
These are conditions that must exist in a confined space to allow someone to enter it. Acceptable entry conditions ensure that the authorized entrant can safely enter into and work within the confined space.

Atmospheric monitor
An atmospheric monitor is a device that detects the presence of different gaseous chemicals in the air.

Attendant
This is the person who may be stationed outside a designated confined space and who will monitor the authorized entrants, under certain conditions.

Authorized entrant
This is the employee who is authorized by the employer to enter a confined space.

Canada Labour Code
The Canada Labour Code is a federal regulation that describes the measures your employer must take to protect your health and safety at work.

Canada Occupational Safety and Health Regulations
Part XI of the Canada Occupational Safety and Health Regulations sets the standards for working in confined spaces.

Carbon monoxide
Also known as CO.
Carbon monoxide is a colourless, odourless and tasteless gas that is usually produced by incomplete combustion of organic material, such as gasoline-fueled combustion engines.

Confined space
According to the Canada Occupational Health and Safety Regulations, a confined space is an enclosed or partially enclosed area that:

Is occupied by people only for the purpose of completing work.
Has restricted entry/exit points.
Could be hazardous to people entering due to:
1. its design, construction, location or atmosphere
2. the materials or substances in it, or
3. any other conditions

Emergency
An event that occurs in or around a confined space that could endanger the entrants and/or the attendants. An emergency includes the failure of hazard control or monitoring equipment.

Engulfment
This occurs when a person becomes surrounded and captured by a liquid or fine solid substance that can be breathed in to cause death by filling or plugging the respiratory system. It can also exert enough force on the body to cause death by strangulation, constriction or crushing.

Entry
This occurs as soon as any part of the body of the person entering the confined space breaks the plane of the opening into the confined space. It includes working within the confined space.

Entry permit
This is a written or printed document provided by the employer to allow and control entry into a confined space. It should contain the following information:

name of the entrant and attendant
date and time of entry
personal protective equipment (PPE) and safety equipment to be used by all employees (entrant and attendant)

Hazard
Anything that is considered to be a potential source of danger or harm to a worker, for example:

physical hazards, such as ledges
mechanical hazards, such as moving machinery
electrical hazards, such as exposed electrical conduits

Hazardous atmosphere
This is an atmosphere that may expose a worker to the risk of death or incapacitation, or prevent a worker from getting out of the confined space because of an injury or critical illness.

Hot work
These are operations that can provide a source of fire, such as:

riveting
welding
cutting
burning
heating

Hot work permit
This type of permit is required if you must complete hot work in a confined space.

Hydrogen chloride
Also known as chlorhydric acid, muriatic acid and hydrochloric acid.
Hydrogen chloride gas reacts with most metals in the presence of moisture. This reaction liberates hydrogen, an extremely flammable gas.

Hydrogen sulfide
Also known as sewer gas, hepatic acid, stink damp and sulfur hydride.
Hydrogen sulfide is a colourless gas with a strong odour of rotten eggs. This toxic gas is highly flammable and may form an explosive mixture with air.

Immediately dangerous to life or health (IDLH)
Any immediate or delayed life threatening working condition. It also includes any condition that may:

Cause irreversible adverse health effects.
Interfere with the worker's ability to get out of a confined space in case of injury or severe illness.

Inerting
This is the process undertaken when the atmosphere within a confined space is made non-combustible by adding a non-combustible gas (such as nitrogen). This procedure creates an IDLH oxygen-deficient atmosphere.

Lock out
A lock out is the placement of a lock out device (locks, blank flanges, bolted slip blinds) on a piece of equipment to ensure that the machine cannot start-up unexpectedly or release a hazardous energy source. Hazardous energy sources must be controlled before entry into any confined space. Placing a lock out is only the first step: you also must tag out and try the energy sources.

Monitoring
Continuous monitoring of the atmosphere in the confined space is essential for worker health and safety. Before entering any confined space, you must have access to appropriate monitoring equipment to test for atmospheric hazards.

Nitrogen oxide
Also known as laughing gas, nitrous oxide and factitious air.
Nitrogen oxide may cause flammable materials to catch on fire or explode upon contact. As an oxidizing agent, nitrogen oxide can also accelerate combustion.

Oxygen
Oxygen is a major component of air and is necessary for respiration. Normal air contains approximately 21% oxygen. Given the nature of confined spaces, you need to monitor the oxygen levels in the air while working. You may encounter two extremes:

Oxygen deficient atmosphere: the air contains less than 18% oxygen.
Oxygen enriched atmosphere: the air contains more than 23% oxygen.

Ozone
Also known as triatomic oxygen.
Ozone is an unstable gas that decomposes to diatomic oxygen - the form of oxygen found in the air we breathe. Fires that involve ozone can start at a lower temperature and will produce more heat.

Personal Protective Equipment
Also known as PPE, this includes any safety device or safeguard worn by workers to protect themselves against environmental hazards. Standard PPE includes:

Hard hat
Earplugs or earmuffs
Safety goggles
Gloves
Steel-toed rubber boots

Prohibited condition
Based on the permit issued for the confined space, a condition that is not allowed to occur during the period when entry is authorized.

Rescue service
The personnel designated to rescue workers from a confined space. This may include industry emergency personnel, an outside rescue service, or a combination of both.

Retrieval system
This is the equipment that is used to remove a worker from a confined space without having to enter the space. It may include:

retrieval line (life line)
chest or full-body harness
approved retrieval units, such as tripod, davit arm or manhole frame and winch

Solvents
Solvents/compounds are often used in the communication industry.. If you are exposed to solvents/compounds, you may lose consciousness as this class of chemicals depresses the central nervous system.

Tag out
A tag out is the placement of a tag out device (an attached warning) on a piece of equipment to show that the machine or hazardous energy source may not be operated until the tag out device is removed.

Testing
This is the process for identifying and evaluating the hazards within a confined space . It enables employers to develop and implement appropriate measures to control or eliminate the hazards.

Try
A try is the process of physically testing the lock out device to confirm that it has in fact rendered the equipment inoperable/unenergized. Failure to test lock out procedures is a common cause of accidents.

Ventilation
This is the process for mechanically circulating the air in a confined space to create or maintain a safe atmosphere.

Vinyl chloride monomer
Also known as vinyl chloride, monochlorethylene and ethylene monochloride.
Vinyl chloride monomer is a highly flammable gas that is practically inextinguishable once ignited.