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10 February, 2010

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Workplace safety - confined spaces

A confined space is any enclosed structure that has limited access and contains a potentially harmful atmosphere. Examples include tanks, pits, chimneys, silos, underground sewers, tunnels and wells. A confined space may contain dangerous vapours, reduced oxygen levels or stored substances that might collapse and engulf a person. Around 60 per cent of people killed in confined spaces were trying to rescue someone already overcome. Rescues should never be attempted without a proper rescue plan and appropriate safety equipment, such as self-contained breathing apparatus.

Examples of confined space hazards
Confined spaces are particularly dangerous because the hazards may not be immediately apparent. The dangers of confined spaces can include:

Biological hazards, such as bacteria
Exhaust gases
Flammable gases
Low oxygen levels
Risk of engulfment if stored substances collapse
Toxic gases
Solids, such as wheat.

Assessing the risk
Preventing injury and death in the workplace requires identifying confined spaces and the type of work performed inside them. A health and safety officer from the Victorian WorkCover Authority can offer information and advice. To reduce the risks:

Whenever possible, eliminate the need for anyone to go inside the confined space - for example, use mechanical aids instead.
Find out what is in the confined space before planning entry.
Assess the air in the confined space. This should be done if you don’t know for certain what’s been in there in the past. Do not assume it is safe.
Devise safety procedures for working inside the confined space.
Make sure that any cleaning compounds or equipment used in the confined space are properly assessed.
Make sure anyone going into a confined space has appropriate protection.
Devise emergency and rescue procedures.
Rehearse emergency and rescue procedures regularly.
Thoroughly train the people who work inside the confined space.

Signposts and permits
All confined spaces should be clearly signposted. Safety regulations demand that only workers with valid entry permits may go inside a confined space. Those workers should be thoroughly trained and familiar with emergency procedures.

Making safer design changes
Suggestions on improving the safety of a confined space include:

Ensure entrances and exits are large enough to permit free access of people, protective clothing and rescue equipment.
Make sure that any structures leading to the confined space, such as ladders and walkways, are safe.
Include sufficient entry and exit openings in long confined spaces, such as tunnels or pipelines.
Make sure the confined space is well lit and properly ventilated.

Ventilation
The risks of confined spaces include low oxygen levels or harmful vapours. It is impossible to smell oxygen or some lethal gases, so the human nose is an unreliable indicator of safe or unsafe atmospheres. Instead, the air in confined spaces needs to be regularly tested for oxygen and contaminants using the proper equipment. Mechanical ventilation, such as fresh air blowers or extractors, should always be used. Safety suggestions include:

Make sure any mechanical or other types of equipment are suitable, especially equipment being used in flammable areas, which should be non spark generating and flameproof.
Make sure the ventilation system is powerful enough to be effective.
Operate the ventilation system before anyone enters the confined space to make sure the atmosphere is safe.
Ventilation should be operating continuously while anyone is inside the confined space.
The ventilation line should be close to the working face.
Any exhaust from machinery should be vented straight out of the confined space.
When using vaporous chemicals such as solvents, refer to Material Safety Data Sheets (MSDS) for their safe use.

Safety equipment
If a safe atmosphere can’t be guaranteed, the use of appropriate safety equipment, such as air-supplied respiratory protective equipment, is paramount. If the confined space contains chemicals or dangerous substances, other protective equipment required may include gloves, goggles and overalls.

Harnesses and winches, when attached to the person entering the confined space, are an excellent backup, but they must be properly organised.

Observation and communication
Make sure the people inside the confined space are monitored from the outside. There should be a person trained in initiating emergency procedures observing them from a safe vantage point. Practical communication methods include:

Mobile telephones
Two-way radios
Closed circuit television
Hand signals
Rope signals.

Emergency procedures
It is vital to devise proper emergency procedures and to rehearse them often. Suggestions include:

Contact the Victorian WorkCover Authority for advice and information.
Train workers in first aid.
Keep a suitable first aid kit in an accessible place.
Buy rescue equipment - such as lifelines, lifting equipment, stretchers, and air-supplied, escape-type or self-rescue respiratory protective equipment.
Install emergency equipment, such as fire extinguishers.
Ensure easy access to medical treatment and emergency services.

Where to get help

Your doctor
Victorian WorkCover Authority Tel. (03) 9641 1555 (head office)
In an emergency, always call 000 for an ambulance

Things to remember

A confined space is any enclosed structure that has limited access and contains a potentially harmful atmosphere.
It is vital to understand the specific risks involved and devise suitable emergency procedures and rehearse them often.
Contact the Victorian WorkCover Authority for advice and information on safety issues for working in confined spaces.

You might also be interested in:
Farm safety - confined spaces.
Work-related fatalities.
Work issues - infection control.
Workplace health - coping with a critical incident.
Workplace safety - hazardous substances.

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