Confined space: Risk assessment

Control Measure Knowledge

Because of the nature and severity of the risks faced while working in confined spaces, it is essential that fire and rescue services, taking into account their risk management plan, establish policies on their response to confined space incidents. Policies should define what type and complexity of confined space incidents can be dealt with by initial non-specialist personnel. Policies should also define how more complex confined space incidents will be handled, including details of the specialist resources and equipment that may be required.

Incident commanders should obtain as much information as possible before determining whether to deploy personnel.

All potential hazards within the confined space, as detailed in this guidance, should be identified and evaluated in accordance with the Confined Space Regulations, to assess whether the benefit of entering outweighs the associated risks.

If the decision is made to deploy personnel, the risk assessment and safe system of work should be shared with all those deployed.

The incident commander may be able to seek advice from a competent confined space supervisor or specialist rescue teams; they can provide assistance for dealing with the hazards of working in confined spaces.

Where it is not reasonably practicable to avoid entering a confined space to undertake work, incident commanders or confined space supervisors are responsible for ensuring that a safe system of work is used. Any safe system of work should give priority to eliminating the source of any hazards before deciding what precautions are needed for entry.

A safe system of work will depend on the nature of the confined space and the results of the risk assessment. For example, the risks involved and the precautions needed for accessing a lift machine room will be relatively straightforward compared to performing a rescue from an underground petrol storage tank or sewer. For further information refer to Rescue from confined space (awaiting publication)


Incident commanders must assess the risks connected with entering or working in the confined space, taking into consideration their service’s policy on confined space work. The assessment should identify the risks to people entering or working there, emergency responders and anyone else in the vicinity who could be affected by the work to be undertaken. The risk assessment needs be carried out by someone competent to do so.

Incident commanders should assess the general condition of the confined space to identify the presence of anything that may present a hazard, such as the concentration of oxygen or evidence of damage or corrosion. Any records relating to the confined space should be checked for relevant information.

The following list provides some of the most common essential elements to consider when preparing a safe system of work. Consideration should be given to:

Previous contents – even if held briefly, can indicate what kind hazard may be expected such as toxic or flammable gases

Residues – chemical residues or scale, rust, sludge or other deposits, such as animal slurry, which can release toxic or flammable gases if disturbed

Contamination – can be from adjacent sites, processes, gas mains or surrounding land, soil or within the rock layers, which can leak liquids or gases

Oxygen levels – atmospheres that are deficient in oxygen, also known as hypoxic environments, are often caused by replacement of another gas; this can lead to unconsciousness or death. Enriched atmospheres pose a high risk of fire; for further information refer to Hazardous materials – Physical: Oxygen-enriched atmosphere.

Physical dimensions – can personnel wearing all the necessary equipment enter, exit, and traverse easily, and provide ready access and egress in an emergency

Hazards arising from work to be carried out – hazards that arise directly from the work to be undertaken in the confined space should be assessed. The work itself may produce the hazard, such as battery-operated rescue equipment can be a source of ignition or increased noise.

Hazards from outside the space – there may be a risk of substances from nearby processes and services entering the confined space. This could be caused by the inadvertent operation of machinery. There may also be a risk of carbon monoxide, carbon dioxide and nitrogen dioxide entering the confined space from the exhaust of nearby combustion engines.

Emergency arrangements – possible emergencies should be anticipated, and appropriate emergency rescue arrangements put in place. The likely risks, and therefore the equipment and measures needed for a rescue by emergency teams, must be identified and the equipment made available for use. For further information refer to:

Strategic Actions

Tactical Actions