Confined Spaces – a discussion and memoir of an experienced health and safety practitioner part 2
The history of confined spaces
Earlier in this article, the definition from the Confined Spaces Regulations was quoted, This was however not a new definition but taken from the Factories Act 1961. A confined spaces incident in 1996, in Crymlyn Burrows, near Swansea was the catalyst for the 1997 regulations to be written.
“Ryan Preece was 27 when he was killed along with colleague Robert Simpson as they entered an underground chamber at a sewage pumping station near Swansea and were overcome by toxic fumes on October 10, 1996.”.
The two sewerage workers, were experienced workers, employed by the local authority. They had entered the sewage network, as they often did as part of their role. Unbeknown to them, an adjacent chemical factory had suffered a ‘loss’ of 300 Kg of a refrigerant chemical which had leaked into the sewer. Refrigerant gas is heavier than air and the level of oxygen was displaced to the point where the atmosphere was not sufficient to sustain life.
For many of us, who are used to confined spaces, the thought of entering a sewer system with no apparent controls is unthinkable, and this incident perhaps demonstrates how far confined space controls and awareness have come following this incident. However, whilst a sewer is clearly a confined space, we must always be cognisant of the words of HSE in their short guidance document ‘Confined spaces A brief guide to working safely; INDG 258’, which states:
“It is not possible to provide a comprehensive list of confined spaces. Some places may become confined spaces when work is carried out, or during their construction, fabrication or subsequent modification.”
So how do we decide if something is a confined space?
To do this, we must always go back to the regulations and their definitions. To be a confined space, the space must be enclosed or largely enclosed and one/a combination of the significant hazards at (a) to (d) must be present (my emphasis). We must always be aware of creating a temporary confined space by the work that we are undertaking.
Principles of prevention or the hierarchy of control
The Management of Health and Safety at Work Regulations 1999, at Schedule 1, provide a hierarchy of control which should be applied when risk assessing. The first control in the General Principles of Prevention is “avoiding risks,” which readers may recognise as ‘eliminating’ (the hazard) from NEBOSH studies they may have undertaken. L101 guidance document states:
“[para] 48 If it is not reasonably practicable to avoid the need to work in a confined space the duty holder must assess the risks connected with entering or working in the space. The assessment should identify the risks to those entering or working there, and any others, for example, other workers including contractors and the general public in the vicinity who could be affected by the work to be undertaken. The risk assessment must be carried out by someone competent to do so.”
I often witness confined space control being applied at the enter the space stage, and I rarely see evidence of discussions of avoidance. Below I have detailed some techniques which I have used to avoid, or control entry:
- The use of long-handled tools – this is a simple, but often overlooked control which can effectively prevent the need to enter a confined space, or minimise it
- The use of technology. Endoscopes can provide high-resolution images, which may provide sufficient detail for engineers to avoid the need to enter a confined space. I have similarly used an underwater robot in a fire water sprinkler tank. This was not strictly a confined space but did minimise the time a diving team had to enter the water tank. Diving operations are not considered confined spaces and are not covered by the Confined Space Regulations 1997 (stated in Regulation 2), but rather by the ‘Diving at Work Regulations 1997’.
- The use of process equipment which automates work processes and removes the need for entry. Often these can be used in farming grain silos, and tanks containing liquids or sludges to name a few. Some examples I have seen involve flails which move the grain and prevent blockage and piped systems which can spray high-pressure water to maintain tank cleanliness.
- Using gas detection equipment which allows the meter to be inserted remotely. I have seen many confined space teams sending someone in with the gas tester, not realising that this person may be exposed to an atmosphere which cannot sustain life. The very act of assessing the environment may expose that assessor to unacceptable risk. This is particularly true of exposure to hydrogen sulphide (H2S) which at high concentrations would not provide enough time for escape once detected. There are many ways in which this can be done remotely – I recommend discussion with gas detection device companies to explore options to avoid entry. Solutions can be simply a plastic tube, which can be attached to the gas meter and inserted remotely.
The HSE indicate the following H2S concentrations in parts per million with the associated effects on the human body:
- 0.0047 ppm is the recognition threshold of human smell, the concentration at which 50% of humans can detect the characteristic odour of hydrogen sulphide.
- 10-20 ppm is the borderline concentration for eye irritation.
- 50-100 ppm leads to eye damage.
- At 150-250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with an awareness of danger.
- 320-530 ppm leads to pulmonary edema with the possibility of death.
- 530-1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing.
- Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
Look out for part 3 coming soon where Richard gives his final anecdote.
For any more information on confined spaces or anything else you’ve read here please contact [email protected].
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