What’s a “confined space”?

I recently received the following query regarding the application of the Confined Space Regulations 1997:

“is the intent that any room that has a hazard in it is considered a Confined Space?  Let’s say we have a room with 2 doors, some general dilution and exhaust ventilation, and has a CO2 line running through it with several flanged connections.  The line has never leaked, but I suppose it could if something breaks.  Is that a confined space according to the regs?”

The term “confined space” has a particular legal meaning. Once a space is defined as such then the requirements of the “Confined Spaces Regulations 1997” become applicable and employers are required to

  • avoid work in the confined space “as far as reasonably practicable”
  • where work is necessary, ensure that there is a safe system of work
  • make arrangements to safely rescue anyone who becomes incapacitated within the confined space.

It isn’t true that any room containing a hazard would be considered as a “confined space”. However, I would probably categorise the situation described in the query as such.  I once had to deal with a similar situation – a pub cellar where there are CO2 cylinders. There was a risk of a cylinder “bursting” which could release gas into the room. HSE does include “unventilated or poorly ventilated rooms” as an example of a confined space in their guidance on the Regulations in their guidance leaflet, indg258 .

Our British approach is a little woolly, but allows flexibility.  The crucial questions to answer when deciding on whether something is a “confined space” are

  1. Is the room “substantially” enclosed? i.e. is access / egress limited?
  2. Is a potential hazard present in the room ( or one is “reasonably foreseeable”)?
  3. In the case of a hazardous gas/vapour/fume/dust, is ventilation limited so that a dangerous concentration is possible?

If the answer to each of these is “yes”, particularly if access/egress limited, then I’d classify it as a confined space and the Confined Spaces Regulations would apply.

In the example given in the query, it appears that there is limited access/egress and there is a reasonably foreseeable risk (albeit small) of a leak. If the concentration could build up to a dangerous level than I’d  definitely classify it as a confined space under the Regulations. So the crucial test is whether a leak would lead to a dangerous concentration.

Detailed guidance on the Regulations are available here


Published by ms6282

I'm a consultant and trainer specialising in the recognition, evaluation and control of health hazards in the workplace. I'm based in the North West of England, but am willing to travel (almost) anywhere

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