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A number of people are killed or seriously injured in confined spaces each year, in a wide range of industries.

Those killed include people working in the confined space and those who try to rescue them, often without proper training and equipment.

A confined space is any enclosed space with a risk of death or serious injury from hazardous substances or dangerous conditions (e.g. lack of oxygen). Some confined spaces are easy to identify (e.g. storage tanks, enclosed drains, sewers, etc.), while others may be less obvious but equally dangerous (e.g. open-topped chambers, vats, combustion chambers in furnaces and ductwork). Even large spaces which are poorly ventilated can be classed as confined spaces.

It’s not possible to give a comprehensive list of confined spaces. Some places may become confined spaces when particular work is carried out, during their construction or following modifications.

In addition to duties under a wide range of other health and safety regulations, the Confined Spaces Regulations apply where the risk assessment identifies a reasonably foreseeable risk of serious injury, either within a confined space or nearby, arising from:

  • fire or explosion;
  • loss of consciousness due to an increase in body temperature;
  • loss of consciousness due to asphyxiation, either because of the presence of gas, fumes, vapours or a lack of oxygen;
  • drowning due to an increase in the level of a liquid;
  • asphyxiation due to a free flowing solid; or
  • the inability to reach a respirable environment due to entrapment by a free flowing solid.
This page doesn’t cover the additional measures needed for working in mines, ships, docks, offshore work, nuclear or diving operations.
  • Carry out a suitable and sufficient assessment of the risks for all work activities, to decide what measures are necessary for safety (under the Management of Health and Safety at Work Regulations). For work in confined spaces, this means identifying the hazards present, assessing the risks and determining what precautions to take. In most cases, the assessment will include consideration of:

    - the task;

    - the working environment;

    - the suitability of those carrying out the task; and

    - arrangements for emergency rescue.

  • Investigate whether it’s reasonably practicable for work (including testing of the atmosphere) to be done safely from outside, without entering a confined space.

    - Employers and self-employed persons have to eliminate hazards as much as possible. This may be done, for example, by using long handled tools or probes, water jetting or steam cleaning, or using remotely operated equipment (like drones).
  • Make sure risk control measures are proportionate to the size and scope of the risks identified in the risk assessment, while still fulfilling the requirements of relevant health and safety legislation.
  • Confirm the training, competence, suitability, capability and fitness of everyone involved and make sure they’re all informed of the risks.
  • Appoint a competent person to supervise the work.
  • Lock off and isolate electrical and mechanical services and links to and from adjacent equipment.
  • Decontaminate and clean the confined space prior to entry.
  • Check the adequacy of the access for the entry of workers and rescuers and their equipment.
  • Provide mechanical ventilation or breathing apparatus where necessary.
  • Test the air to ensure it’s breathable and provide continuous air monitoring, so any change in the conditions can be identified.
  • Select suitable work equipment, tools, personal protective equipment, lighting and methods of use.
  • Provide appropriate lifting and rescue equipment.
  • Establish means of communication and emergency procedures prior to the work taking place.
  • Carry out emergency drills to ensure that the procedures are practical and will work.


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