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Confined spaces

The Confined Spaces Regulations and the Confined Spaces Regulations (Northern Ireland) sets out the legal definition of what constitutes a confined space. However, identifying environments that fall within the legal definition is not always that easy, especially when confronted with a rapidly escalating or complex incident.

This guidance seeks to identify the common hazards found at incidents that may be considered confined spaces or incidents that have similar operational and environmental characteristics requiring the same control measures to be applied by attending crews. It deals with the environment rather than the specific risks described in the legal definition, though some headings will be similar.

Summary of a legal definition of a confined space

A confined space must have both of the following defining features:

  1. It must be a space that is substantially (though not always entirely) enclosed
  2. One or more of the specified risks must be present or reasonably foreseeable

The specified risks are:

  • Serious injury through fire or explosion
  • Loss of consciousness arising from increased body temperature
  • Loss of consciousness or asphyxiation arising from gas, fume, vapour or lack of oxygen
  • Drowning from an increase in the level of a liquid
  • Asphyxiation arising from a free-flowing solid or being unable to reach a respirable environment due to entrapment by a free-flowing solid

A confined space could be any space in which the above defining features are present.

Some confined spaces are fairly easy to identify, such as enclosures with limited openings, for example:

  • Storage tanks and silos
  • Drains and sewers

Others may be less obvious but can be equally dangerous, for example:

  • Open-topped chambers and vats
  • Ducting
  • Trenches
  • Unventilated or poorly ventilated compartments

It is not possible to provide an exhaustive list of confined spaces.

It is very important to recognise that some locations that are not considered confined spaces in normal use will become, and must be treated as, confined spaces if conditions worsen during an emergency. These include:

  • Ship compartments
  • Basements
  • Tunnels

Utilities and fuel

Fire and rescue service personnel attending incidents at utility or fuel sites may need to enter confined spaces.

This could include

  • Tanks
  • Pump rooms
  • Subsurface sewerage systems
  • Culverts

While at least one of the above five specified risks must be present or reasonably foreseeable for a space to be classified as confined, there are other associated hazards that may be encountered when working in confined spaces.