Working in confined spaces without the appropriate risk mitigation measures can lead to multiple fatalities.

The definition of a confined space is a space which is substantially (although not always entirely) enclosed and one or more of the specified risks must be present.

  • storage tanks
  • silos
  • reaction vessels
  • enclosed drains
  • Sewers.

Then those that are less obvious:

  • open-topped chambers
  • vats
  • combustion chambers in furnaces etc
  • ductwork
  • unventilated or poorly ventilated rooms.

(Please note the above list is not exhaustive).

Legislation & Guidance
Confined Spaces Regulations 1997

If your risk assessment identifies risks of serious injury from work in confined spaces, these regulations apply and require you to:

  • prohibit entry into a confined space to carry out work unless there is no other reasonably practicable method to carry out the work
  • modify the confined space if possible so that entry is not necessary
    e.g. have the work done from outside
  • ensure any such work in a confined space is carried out in accordance with a Safe System of Work
  • ensure adequate arrangements are made for the rescue of any person in the event of an emergency (see below)
  • ensure confined space entry is controlled via a permit to work system.

The following hazard types (the specified risks) should be addressed in the risk assessment with the control measures then detailed in the permit to work:

  • Fire or explosion
  • Loss of consciousness from increase in body temperature/lack of oxygen
  • Asphyxiation from gas/fume/vapour/lack of oxygen
  • Drowning from an increased level of fluid
  • Asphyxiation from a free flowing solid
  • Entrapment by a free flowing solid
  • Working at height
  • Biological/chemical contamination
  • Slips/trips/falls
  • Restricted space/low ceiling height
  • Needlestick injuries
  • Contact with electricity/electrical cables
  • Poor lighting
  • Unsafe access/egress

Authoritative guidance on methods by which compliance with the Confined Spaces Regulations may be achieved is given in the form of an Approved Code of Practice (ACoP) and Guidance published by the Health and Safety Executive (HSE ACoP L101) – Safe Working in Confined Spaces.

Competent Person

Only a competent person can enter a confined space and all other personnel should be trained in emergency rescue procedures. The ‘top man’ should never enter the confined space to perform a rescue.

Workers should have adequate training and experience appropriate to the task and their expected roles and responsibilities.

Are there ‘classes’ of confined spaces?

It is noticeable that some training organisations are providing certificates for different classes of confined space. In reality, according to the Regulations, a space is either ‘confined’ as per the regulations, or not.

Care should be taken if such certificates are offered, as full training as required by the Regulations may not have taken place.

Some organisations offer on-line courses, however, the acceptability of such training should be carefully considered in line with the risk assessment process previously highlighted.

Emergency Procedures

The following emergency arrangements should be considered in the risk assessment and detailed in the permit to work:

  • How the alarm would be raised e.g. communication methods
  • Equipment required e.g. life lines/first aid equipment/breathing apparatus
  • Number of competent persons required
  • Identification of plant in the area that may need to be shut down
  • Fire precautions/extinguishing equipment
  • Precautions to protect nominated rescuers
  • Emergency means of access/egress
  • First aid/medical assistance to be available including resuscitation equipment
  • Means of contacting emergency services
  • Training/refresher training for rescue personnel.

Key Points to Note

  • Work in confined spaces should only occur if it is not practicable to do the work by another method
  • Carefully consider the level of supervision required
  • Consider what communications equipment may be require
  • Oxygen levels below 16% can lead to fatalities
  • A practice that has often been used known as ‘sweetening’ should not be considered due to increased flammability of the atmosphere (this is a deliberate addition of oxygen)
  • Gas meters should be appropriate for the type of atmosphere and routinely calibrated
  • Fitness levels required for staff to enter confined spaces should be determined
  • The possibility of purging/ventilating the space and options to isolate the space require consideration.

At William Martin Compliance we have a nationwide team of experts who offer a comprehensive range of health and safety compliance services to property management professionals.

For all enquiries please contact us: or call our team on 0203 819 8829

Click this link to download the Confined Spaces – Briefing Note – 01.09.21