Introduction to working in confined spaces

A confined space is one which is both enclosed or largely enclosed and has a reasonably foreseeable specified risk to workers of:

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.


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 you have to do

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

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


Do not


Crane compartment

Having identified a fault in a crane's hydraulics, 2 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 3 men were extracted by the emergency service but 2 of them died.

How it could 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.

Updated 2023-04-20