A confined space sounds like something that is really easy to define, doesn’t it? But that’s not always the case.
When does an area that is enclosed become a ‘confined space’ and why are some areas that seem pretty big classified as confined spaces? In this article you will find guidance on how to identify a confined space, work out when a confined space isn’t a confined space, and perhaps make you think of some confined spaces that you might not have considered before. We’ll also look at why confined space accidents so often result in multiple casualties or fatalities and what you can do to help keep those who need to enter a confined space safe.
So, to start our journey we need to get a common understanding of what we mean by a confined space.
“confined space accidents so often result in multiple casualties or fatalities”
What exactly is a confined space?
One of the simplest definitions is provided by the Health and Safety Executive (HSE) in the UK.
“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.1“
The first part of this definition seems pretty obvious – an enclosed or largely enclosed space. You may be sitting in your home, office, or car with all the windows closed and thinking perhaps this is a confined space as it is enclosed, but, the key to identifying a confined space is also whether the risk of fire, explosion, loss of consciousness, asphyxiation or drowning is reasonably foreseeable.


If you have any dealings with confined spaces, you will probably have come across the term ‘Specified Risk’. These are a set of hazards which are detailed in the Confined Spaces Regulations in the UK and are included in guidance from the ERBD2. These are a good basis for understanding what harm could come to people. These hazards include noxious fumes such as carbon monoxide, carbon dioxide and hydrogen sulphide, reduced oxygen levels and the risk of a fire occurring. Other hazards include the risk of flooding, drowning or asphyxiation due to the possible presence of liquids or free flowing solids such as dust, grain, or other contaminants.
Again, as with everything there are certain phrases that are key to using the definition to assist in your risk assessment and controls and in this case the phrase is ‘Reasonably Foreseeable’.
How do we work out if something is reasonably foreseeable? Well, a good test is to ask, would a reasonable person (the man on the Clapham omnibus3) recognise the risk associated with the work by applying common sense and knowledge? In doing so we need to consider an undertaking of the activity taking place, previous experiences with carrying out the work, and local knowledge.


The ‘big’ risk with confined spaces
Now we know what we are looking for, but what is it about confined spaces that have led bodies such as the HSE in the UK4, the European Bank for Reconstruction and Development5, and industry specific bodies such as Water UK6 and Port Skills and Safety7 to publish guidance documents in recent years?
Whilst the number of fatalities that result from confined spaces can be difficult to quantify, because they are generally classified by the cause of death (such as asphyxiation) rather than the activity that was taking place at the time of the incident, the one constant that is true is the high proportion of multiple fatalities that occur as a result of confined space work. This often involves people attempting the rescue of an injured person or investigation of an incident in a confined space.
“70 investigations accounted for 109 deaths and 36% of these there were multiple fatalities”
This is not a new phenomenon
Until 1986, the canary was used as a form of early warning for noxious gases in British mines as they were particularly sensitive to gases such as carbon monoxide, which is colourless, odourless, and tasteless8.
More recently in 1994, the National Institute for Occupational Safety and Health (NIOSH) in the USA produced a paper following an investigation undertaken as part of the Fatality Assessment and Control Evaluation (FACE) programme.9 This research involved a review of 70 onsite FACE field investigations of fatal work-related incidents in confined spaces. In the period December 1983 to September 1993, these 70 investigations accounted for 109 deaths and 36% of these there were multiple fatalities. According to a NIOSH publication from January 1986, 60% of would-be rescuers died10.
Multiple deaths often occur because the hazard is not immediately visible in a confined space and the natural reaction of people is to go and help. Sadly, it is often not until one or two people have tried to rescue those overcome by the specified risk of the confined space that there is a realisation of what has happened.




Where are confined spaces found?
Each year a significant number of people are killed or seriously injured in confined spaces. These occur across a wide range of industries, from those involving complex plant and processes through to simple storage vessels and containers. The sewage industry, docks and ports, and mining are three of the primary industries for confined spaces due to the nature of the work carried out and the environment in which it is undertaken. Some of these areas you might expect to be on the list but perhaps some of them you would not. For example, an incident in the UK which involved a father and son who died pumping flood water from a Gloucestershire rugby club’s beer cellar and were overcome by carbon monoxide11.
These examples of confined spaces above are in no way exhaustive but are good indicators of where you may find specified risk in substantially or wholly enclosed areas.
Introducing additional risk and controlling it
When carrying out a confined space risk assessment it is essential that you include any additional hazards that may be present, and which could increase the risk to those entering the area such as falls from height and diesel-powered vehicles, etc.
It is also important that appropriate controls are put in place to mitigate these risks, such as the use of intrinsically safe equipment like torches and radios which are ATEX rated12.
Getting in and out – you need a plan!
One of the main requirements for working in a confined space is having everything planned in advance. Depending on the level of risk presented you may need a formal permit to work, or you might just need a documented system of work. You must also document a rescue plan. This will detail how you would extricate an individual from the confined space should they suffer an injury or ill health whilst in the confined space, or if the atmosphere becomes unsafe so that they must leave. Depending on the level of risk posed, your rescue plan might involve simple self-rescue where the individual can simply stand up or walk out of the confined space, you might need an inhouse team including a supervisor and top man ready to winch someone out, or you might need to have a dedicated external rescue team on site to provide support.


The Water UK Confined Spaces Occasional Guidance Note (3rd Revision)13 provides a classification for confined spaces which can be used to help assess the risk and the controls needed. This is summarised to the left.
“remote monitoring, in high risk confined space entry can mean help getting to people quicker”
Keep up with technology
It is possible now for management and others to remotely monitor the access to confined spaces with the use of Bluetooth personal gas monitors which send out readings. Remote monitoring, particularly in high risk confined space entry can mean help getting to people quicker in the event of an emergency.
The golden rules of confined spaces
The golden rules of confined spaces are set out below. Make sure you are aware of these and follow them when planning and carrying out confined space work.
- Do not enter the confined space if you don’t have to. If the work can be done from outside, then it should be.
- Be aware of the risks that may occur.
- Don’t rely on the emergency services, you must have your own plans in place for emergency rescue.
- Don’t ignore the risks, just because a confined space is safe one day doesn’t mean it will always be.
- Don’t let others enter a confined space until you are sure it is safe to do so.
- All confined space entry must be planned, this includes an emergency egress plan.
- Where possible, ventilate prior to entry.
- Anyone entering a confined space must be trained and capable to do the work they are carrying out and the use of any emergency equipment. This also includes the top man, supervisor, rescue team, and first aiders.
- Keep anything which could be a source of ignition or generate a spark away from confined spaces, e.g. tools, electrical items, torches, and radios which aren’t intrinsically safe, medical devices such as pacemakers, and anything with a combustion engine.
- Document, train, and communicate. Ensure everyone knows what is expected of them and what to do in an emergency.








“follow the plan, ‘do, check, act, cycle’ to ensure confined space entry goes to plan”
In conclusion
We have discussed what a confined space is and where you might find one, remember this isn’t always as obvious as it might sound. The essential take away from all of this is the foundation of planning the working activity and creating an emergency plan, documenting this so it is available for all parties to see, communicating this to all parties involved. Be responsive – if things change then your plans need to too, and keep everything under review.
Following the plan, ‘do, check, act, cycle’ will help you to ensure that every confined space entry goes to plan. Finally, don’t be afraid to ask for help. It’s OK to ask for help, confined spaces can be complex topics and you might need to seek advice from a competent advisor or rescue team to make sure you have all the necessary arrangements in place.
References
- www.hse.gov.uk/toolbox/confined.htm
- www.ebrd.com/documents/environment/safe-working-in-confined-spaces.pdf
- Hall v Brooklands Auto-Racing Club [1933] 1 KB 205
- www.hse.gov.uk/confinedspace/
- www.ebrd.com/documents/environment/safe-working-in-confined-spaces.pdf
- www.water.org.uk/guidance/the-classification-and-management-of-confined-space-entries-2019/
- www.portskillsandsafety.co.uk/staying-safe-ports-confined-spaces
- news.bbc.co.uk/onthisday/hi/dates/stories/december/30/newsid_2547000/2547587.stm
- www.cdc.gov/niosh/docs/94-103/pdfs/94-103.pdf?id=10.26616/NIOSHPUB94103
- www.cdc.gov/niosh/docs/86-110/default.html
- news.bbc.co.uk/1/hi/england/gloucestershire/7595243.stm
- en.wikipedia.org/wiki/Intrinsic_safety
- www.water.org.uk/guidance/the-classification-and-management-of-confined-space-entries-2019/
- www.water.org.uk/guidance/the-classification-and-management-of-confined-space-entries-2019/
- www.draeger.com/Products/Content/gas-detection-connect-pi-DMC-121-en-master.pdf