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There are a wide range of hazards you’re likely to come across when operating in a confined space. It’s important to know what they are, how to identify them and how to manage them safely.

According to Safe Work Australia’s “Confined Spaces: Code of Practice”, there are 16 major hazards associated with a confined space. Here are the top five!

Too Little or Too Much Oxygen

If oxygen in a confined space is either used up or replaced by another gas, this can result in an oxygen-deficient atmosphere. This can lead to a number of health problems, including a lack of coordination, tiredness, poor judgement, dizziness, fainting, changes in behaviour, asphyxiation and, in some cases, death.

There are a number of situations in which the amount of oxygen in a confined space might fall below safe levels. As mentioned above, oxygen can sometimes be used up or replaced by another gas during either biological processes or purging.

In addition to this, when metal rusts it can remove oxygen from the atmosphere, as can “bacterial action” – that is, processes such as fermentation. The “Confined Spaces: Code of Practice” also reveals that oxygen can be consumed during the combustion of flammable substances, as well as during activities such as welding and cutting. It might also be “grains, wood chips, soil or chemicals in sealed silos”.

The other side of the coin is also true. A confined space that contains too much oxygen can also be hazardous and put workers’ lives at risk. One of the major concerns associated with an oxygen-enriched atmosphere is the increased likelihood of fire or explosion it presents.

It’s much easier for a fire to start in air that contains a lot of oxygen. The Zenith – a company that specialises in Workers’ Compensation – also claims that “oil in the presence of pure oxygen will ignite”.

You may find yourself faced with an oxygen-enriched atmosphere if particular chemical reactions take place in the confined space you’re working in. For example, the decomposition of hydrogen peroxide will produce water and oxygen. Safe Work Australia also suggests a leak from an oxygen tank or piece of a equipment could boost oxygen to unsafe levels.

Under normal circumstances, air is made up of about 79 per cent nitrogen and various other gases, such as argon and carbon dioxide. The remaining 21 per cent is oxygen. Safe Work Australia states that oxygen levels of between 19.5 per cent and 23.5 per cent are considered safe – anything below or above that, however, is dangerous to workers.


In some confined spaces, workers run the risk of being engulfed – that is, swallowed or immersed in a stored material. Work Safe Victoria puts forward grain, sand, flour and fertiliser as substances that could potentially engulf someone. Other examples include coal and coal products, sewage, plastics and many types of liquid.

If a person is engulfed by any of the above materials, they could be crushed or suffocate, which may result in serious injuries or death.

Fires and Explosions

Fires and explosions are another hazard that workers operating in confined spaces might have to contend with. These can occur if you’re performing tasks in a flammable atmosphere.

The Health and Safety Authority states that such an atmosphere can arise if and when flammable gases and liquids are present, or there’s a “suspension of combustible dust in the air”. These alone are not enough to cause fires and explosions, though. They must also combine with an ignition source and the air in order to ignite.

Safe Work Australia’s “Confined Spaces: Code of Practice” states that, officially, a flammable atmosphere is “one in which a flammable gas, vapour or mist is likely to exceed 5 per cent of its lower explosive limit (LEL)”. To put it simply, the LEL is the smallest amount of gas mixed with air that will either burn or explode.

According to the Department of Commerce, the LEL for natural gas is 5 per cent gas to 95 per cent air, while the LEL for LPG is 9.5 per cent gas to 90.5 per cent air.

In addition to flammable gases, the presence of flammable liquids also poses a hazard in confined spaces. Such liquids include petrol, methylated spirits, kerosene and paint thinners, to name just a few. There’s also the “combustible dust” referred to earlier, which refers to substances such as wood, floor and grain dust.

To prevent these gases, liquids and dust from causing fires or explosions, it’s important that any and all ignition sources are removed from the confined space. A number of objects and activities can act as ignition sources, such as flames, hot surfaces, electrical equipment, metal tools (which can cause sparks when they strike metal surfaces), internal combustion engines and even static electricity.

Limited Entry and Exit

Many confined spaces are difficult to get into and get out of because their entrances and exits are either small or hard to access. For example, some confined spaces can only be entered or exited using ladders or hoists. While this wouldn’t usually be an issue, it can mean the difference between life and death if someone has a medical emergency while operating in the confined space.

Work Safe Victoria encourages all workers to consider how difficult it would be for an injured person to either exit the confined space themselves or have first aid brought to them in the event of a medical emergency. You should also take precautions such as never working alone in a confined space and having a coworker nearby who can jump to your rescue if need be.

Hazardous Substances

There are many airborne contaminants that can build up in confined spaces and be harmful to workers. For instance, any substances that are or have been stored in a confined space that are toxic, such as hydrogen sulfide, can be inhaled by workers, leading to unconsciousness and sometimes death if the situation is not managed correctly.

The kinds of tasks workers are performing in a confined space can also result in the release of hazardous substances and airborne contaminants. A worker that’s painting in a confined space without the proper ventilation systems or respiratory protective equipment (RPE), for example, risks being overwhelmed by the fumes and becoming dizzy and uncoordinated.

In addition to this, if “sludge, slurry or other deposits” are disturbed while workers are operating in a confined space, this could unleash materials such as asbestos or silica, which are known to cause cancer and respiratory illnesses.

Safe Work Australia adds that a confined space’s location can also determine whether or not its workers could be exposed to hazardous substances. If it’s situated near a plant, installation, service or process that’s producing gases or liquids, these could enter and accumulate in the confined space and put workers in real danger.

One example the “Confined Spaces: Code of Practice” provides to illustrate this is the build up of carbon monoxide in a confined space due to its close vicinity to LPG-powered forklifts.

The presence of such hazardous substances, or the likelihood of them becoming present in a confined space, must be determined before any work commences and steps taken to either remove or reduce the risk they pose to workers.

If you want to learn how to not only identify but also manage such hazards, a confined spaces training course could be the answer.

For more information, get in touch with the AlertForce team today!

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