Working in confined spaces

A confined space is one which is both enclosed, or largely enclosed, and which also has a reasonably foreseeable risk to workers of fire, explosion, loss of consciousness, asphyxiation or drowning.

It may be small and restrictive for the worker or it could be far larger such as a grain storage silo with hundreds of cubic metre capacity.

Case study

Having identified a fault in a crane's hydraulics, two men accessed a closed compartment. Within a minute of entering the compartment, one had passed out and the other was feeling lightheaded but managed to escape. Two others entered and tried to save the first man but were both overcome.

The three men were extracted by the emergency service but two of them died.

How could it have been avoided?

Water had got into the compartment causing rusting, which depleted the oxygen levels. Had the oxygen levels been checked, the space could have been ventilated and the deaths could have been avoided.

What are the hazards?

Working in a confined space is dangerous because of the risks from noxious fumes, reduced oxygen levels, or a risk of fire.

Other dangers may include flooding/drowning or asphyxiation from some other source such as dust, grain or other contaminant.

What do I have to do?

Wherever possible, you should avoid carrying out tasks in confined spaces. Where this is not possible, you must assess the risks of the particular confined space and plan how you will control those risks. For example:

You should have emergency arrangements where necessary. If someone is working in a confined space, think about the following:

Dos and don'ts of working in confined spaces



Find out more

The law

Confined Spaces Regulations 1997

Other legislation may apply, depending on where the confined space is situated or on the task being carried out, for example:

Confined spaces within machinery

Provision and Use of Work Equipment Regulations 1998 (PUWER)

Workplace (Health, Safety and Welfare) Regulations 1992 

Equipment required before entering a confined space

Personal Protective Equipment Regulations 2002

Personal Protective Equipment at Work Regulations 1992 (as amended)

Updated 2022-09-06