The deaths follow a series of other confined space incidents in recent months. Three of the deaths, which occurred in two separate incidents, involved an oxygen-deficient atmosphere. The other death involved the use of a highly flammable liquid.
"It is believed the fatalities occurred soon after entering the confined spaces," said HSE Inspector Graham Watson. "This serves to emphasize that the dangers of confined spaces can be lethal no matter how brief the entry is expected to be."
The low oxygen levels were attributed separately to the process of rust formation within a previously sealed vessel, and the use of an inert gas in a welding process. As well as considering other possible causes of an oxygen-deficient atmosphere, employers must also consider all the other hazards associated with confined spaces, including:
- Flammable substances and oxygen enrichment;
- Toxic gases, fumes or vapor;
- The danger that people could be harmed by liquids getting into the space; The flow of solid materials such as grain.
Other recent confined space incidents included two employees of a construction firm being overcome by carbon monoxide fumes when using a gas-powered road cutter in a tented enclosure; and two painters who were overcome by paint fumes when applying a solvent-based paint by brush in a confined space.
"Recent incidents highlight the need to fully consider the impact that any work within a confined space may have on the atmosphere within that the space and the resulting risks to health and safety," added Watson.
Under the UK's Confined Spaces Regulations of 1997, employers must first try to avoid the need to enter a confined space. Where this is not possible, they must:
- Carry out an assessment of the risks associated with entering a confined space and draw up a safe system of work;
- Limit entry to the confined space to employees who are competent for confined space work and who have received suitable training;
- Verify, prior to entry, that the atmosphere in the confined space is safe to breathe;
- Provide any necessary ventilation; and
- Ensure suitable rescue arrangements are in place before anyone goes in to the confined space. These rescue arrangements should not involve risks to the safety of the people intended to carry out the rescue.
Guidance on the asphyxiation hazards in welding and allied processes is available on the HSE Web site at www.hse.gov.uk/fod/infodocs/288_6R.pdf.