Confined spaces are enclosed or partially enclosed structures that pose a danger because they are not designed or intended to be areas occupied by people. Confined spaces are commonly found in:
- storage tanks
- wet and dry wells
- manure and silage pits
- ducts, flues and chimneys
Confined spaces are high-risk work environments. You must be trained and competent in confined spaces before you are allowed to work in them. The hazards are not always obvious and may change in the same space from one day to the next. Often they have poor ventilation which allows hazardous atmospheres to quickly develop, especially if the space is small.
The Confined spaces - Code of Practice provides practical guidance on compliance with our work health and safety laws. The code applies to persons conducting a business or undertaking who have management or control of a confined space, and to designers, manufacturers or suppliers of plant or structures that include, or are intended to include, a confined space.
High-risk work environments
The inherent hazards of working in confined spaces include:
- loss of consciousness, impairment, injury or death due to the immediate effects of airborne contaminants
- fire or explosion from the ignition of flammable vapours, gases or dusts that come into contact with an ignition source such as a flame, hot surface or spark
- asphyxiation from oxygen deficiency or immersion in free-flowing materials such as grain, sand, water or other liquids.
Other hazards may include, but are not limited to:
- infectious diseases, dermatitis or lung conditions resulting from contact with micro-organisms such as viruses, bacteria or fungi – sewers and grain silos are examples of where biological hazards may be present
- extremes in temperature
- noise from reverberations inside the space
- restricted access in rescuing and treating an injured or unconscious person.
Exhaust fumes from diesel or petrol-powered appliances, for example when using a pump to clean out an in-ground water tank, can result in a potentially lethal build-up of carbon monoxide. These fumes are heavier than air. They can gradually seep into a confined space and fill up to a dangerous level, leading to loss of consciousness of anyone inside the space. Use alternative power sources such as battery-powered electrical appliances.
Before starting any work that might involve entry into a confined space, a confined space risk assessment must be conducted by a competent person who must also complete a confined space entry permit.
Control measures should be implemented to deal with hazards introduced by the tasks to be carried out in and around the vicinity of the space. Some possible safety solutions include:
- eliminating the risk by carrying out the work from outside the space
- substituting or isolating the risk, or applying engineering controls
- suitably locating the fresh air intake and exhaust, especially during the purging of hazardous or flammable airborne contaminants from the space
- getting trained professionals to do the work instead
- reviewing any safety information such as technical standards or other information and, if relevant, finding out about previous uses for the space
- placing restricted access signs that show you must have a signed entry permit to enter
- implementing confined space safe work practices
- developing an emergency response procedure, including a safe recovery process.
You must follow certain safety procedures:
- ensure the space is well ventilated before entry
- place a competent stand-by person outside for support and in case of an emergency
- ensure workers are trained in safe working in confined spaces, emergency rescue and the use of safety harnesses and safety or rescue lines where there is a risk of falling
- provide personal protective equipment that is suitable for the nature of the work and the hazard, and that is used or worn by workers who have been trained in its use and care
- provide rescue, first aid and suitable fire suppression equipment.