Confined spaces

Information on the common hazards of working in confined spaces

Common confined space hazards

Work in confined spaces can create a risk of death or serious injury. This could be from exposure to hazardous substances or dangerous conditions such as lack of oxygen or a build-up of water.

Examples include:

  • pits and trenches
  • sewers and drains
  • vats, silos and tanks
  • chambers and ducting
  • unventilated or poorly ventilated rooms

People are killed and seriously injured working in confined spaces. This includes people trying to conduct rescues without proper training or equipment. Where possible, avoid the need to work in confined spaces by using remote access methods.

Hazards when working in confined spaces include:

  • lack of oxygen
  • lack of natural light
  • dust in high concentrations, such as flour
  • liquids and solids suddenly filling the space
  • hot working conditions increasing body heat

There is a risk with gas, fumes or vapours filling the space as these can be flammable or poisonous.

Before you conduct any work

Before conducting any work in potentially confined spaces, you should read and understand the Health and Safety Executive's regulations and guidance (external site). If you are uncertain, seek professional help.

You may need to appoint competent people to help manage the risks, and ensure that employees are adequately trained and instructed.​

Carry out a risk assessment

Where entry to a confined space is unavoidable, a thorough risk assessment should be carried out to devise a safe system of work. You should consider the:

  • duration
  • task being performed
  • training requirements
  • physical effort required
  • suitability of those carrying out the task including their health
  • number of those involved, inside and outside the confined space, and rescue teams

You should also consider the working environment, including:

  • access
  • lighting
  • lack of oxygen
  • by-products of the task being undertaken, for example welding fumes
  • communication methods for raising an alarm and any evacuation difficulties

Working materials also need to be considered. This includes:

  • fire or spark risk
  • waste removal
  • fume ventilation
  • tools needed and their access

Method statement

Where the work being carried out is considered to be complex, you should provide more detail to those involved in the form of a method statement. This includes how the job is to be carried out and how the risks are managed.​

Although not a legal requirement, a method statement describes, in a logical way, exactly how a job is to be carried out to ensure safety for all involved. You should also consider the application of a permit to work system (external site).

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