Managing the risks associated with confined spaces

The first step in the risk management is identifying all hazards associated with confined spaces. This involves finding things and situations which could potentially cause harm to people.

Hazards may be identified by looking at the workplace and how work is carried out. It is also useful to talk to workers, manufacturers, suppliers and health and safety specialists and review relevant information, records and incident reports.

The types of substances previously stored in a confined space (however briefly) will indicate the sorts of hazards that may be present. Substances stored in a confined space may result in a lack of oxygen, airborne contaminants or a flammable atmosphere within the confined space.

Other hazards may arise from work activities, products or by-products in or around the confined space.

Hazards associated with a confined space

• Restricted entry or exit
• Harmful airborne contaminants
• Unsafe oxygen level
• Fire and explosion
• Engulfment
• Uncontrolled introduction of substances
• Biological hazards
• Mechanical hazards
• Electrical hazards
• Skin contact with hazardous substances
• Noise
• Manual tasks
• Radiation
• Environmental hazards
• Hazards outside the confined space

A risk assessment is mandatory for confined spaces under the Work Health and Safety (General) Regulations 2022 and the Work Health and Safety (Mines) Regulations 2022. The PCBU must ensure that a competent person conducts a risk assessment and is recorded in writing. A risk assessment will determine the measures that should be implemented to control risks. It will help to:  

• Identify which workers are at risk of exposure;
• Determine what sources and processes are causing that risk;
• Identify if and what kind of control measures should be implemented; and
• Check the effectiveness of existing control measures.

A competent person must review and revise the risk assessment whenever any risks change.

A copy must be kept until at least 28 days after the work it relates to is completed, or if a notifiable incident occurs in connection with the work to which the assessment relates, for at least two years after the incident occurs.

A copy of the risk assessment must be available to any relevant worker on request.

Further guidance on the risk management process and the hierarchy of control measures is available in the How to manage work health and safety risks: Code of practice.

A confined space entry permit may be used as a risk assessment record.

Atmospheric testing and monitoring

Testing and monitoring the atmosphere in a confined space are routine parts of determining appropriate control measures for confined spaces.

Air monitoring in a confined space should be carried out by a competent person using a suitable, correctly calibrated gas detector.

You must ensure that while work is being carried out in a confined space to test the atmosphere for:

• oxygen content
• airborne concentration of flammable contaminants
• airborne concentration of potentially harmful contaminants (for example, hydrogen sulphide and carbon monoxide).

Look at the assessed risks and decide what needs to be done to eliminate or reduce the risks and how quickly these control measures need to be implemented. The hierarchy of control guides you to choose a solution that most effectively eliminates or minimises the risk. There are different types of control strategies to eliminate or reduce the risks. These are listed below in order of their effectiveness.

Eliminate the risks

You must always aim to eliminate the risk. Therefore, the first question is: Can the work be carried out without entering a confined space?

Work could be carried out from outside the confined space, for example, by:

• installing fixed or temporary cleaning devices, for example, spray balls using high-pressure hoses inserted through an access hatch to clean the inside of a tank;
• using remote cameras or a mirror attached to a probe for internal inspection of vessels;
• using remotely operated rotating flail devices, vibrators or air purgers to clear blockages in silos;
• using a hook, long-handled clasp or magnet on a string to retrieve an object dropped into a confined space.  

If entering a confined space cannot be avoided, then a safe system for working inside the space must be implemented by one or more of the following.

Substitution 

Minimise the risk by substituting or replacing a hazard or hazardous work practice with something that gives rise to a lesser risk. For example, changing work methods to minimise time inside the confined space reduces the likelihood of heat stress.

Isolation 

Minimise the risk by isolating or separating the hazard or hazardous work practice from any person exposed to it, for example, by isolating moving or electric parts. All potentially hazardous plants and services should be isolated before any person entering the confined space. Refer to AS 2865:2009 Confined spaces for further information on isolation requirements.

Engineering controls 

Engineering controls are physical measures to minimise risk, such as forced extraction ventilation for large spaces, tanks, and vessels.

A safe atmosphere can be achieved within the confined space using cleaning, purging and ventilation methods.

Administrative controls 

If risk remains, it must be minimised by implementing administrative controls so far as is reasonably practicable. For example, providing training relevant to working in confined spaces.

Entry permits

A confined space entry permit provides a formal check to ensure all elements of a safe system of work are in place before people are allowed to enter the confined space. It also provides communication between site management, supervisors and those carrying out the work. It ensures that the PCBU has checked and authorised the entry to the confined space and it is safe to proceed.

A PCBU must not allow or direct a worker to enter a confined space to carry out work unless the worker has been issued a confined space entry permit.

A copy of the permit must be kept until the work is completed or, if a notifiable incident occurs, for at least two years after the confined space work to which the permit relates is completed.

Communication and safety monitoring

A communication system is needed to communicate between people inside and outside the confined space and to summon help in an emergency.

Depending on the conditions in the confined space, communication can be achieved by voice, radio, hand signals or other suitable methods.

Before a worker enters a confined space, a standby person must be assigned to continuously monitor the wellbeing of those inside the space, if practicable, observe the work being carried out, and initiate appropriate emergency procedures when necessary. The standby person should:

• understand the nature of the hazards inside the confined space and be able to recognise signs and symptoms that workers in the confined space may experience
• remain outside the confined space and do no other work which may interfere with their primary role of monitoring the workers inside the space
• have all required rescue equipment (for example, safety harnesses, lifting equipment, and a lifeline) immediately available
• have the authority to order workers to exit the space if any hazardous situation arises
• never enter the space to attempt a rescue.

Entry and exit procedures 

For the entire period for which the confined space entry permit is valid, procedures should be in place to indicate when any worker is in the space, for example, by using tags, a system of signing in and out on the entry permit or having a standby person record who is in the space.

Signs and barricades 

Before any work in a confined space starts, signs must be erected to prevent entry of persons not involved.

Signs must warn against entry by people other than those listed on the confined space entry permit and must be placed at each entrance to the confined space. Signs must be in place while the confined space is accessible, including when preparing to work in the space, during work in the space, and when packing up on completion.

Signposting alone should not be relied on to prevent unauthorised entry to a potential confined space. Security devices, for example, locks and fixed barriers, should be installed.

Personal protective clothing and equipment (PPE)

Any remaining risk must be minimised with suitable PPE. For example, respiratory protective equipment (RPE) when oxygen levels are outside the safe range.

Suppose it is not reasonably practicable to ensure the confined space contains a safe oxygen level or safe levels of airborne contaminants. In that case, appropriate air-supplied RPE must be provided. Further guidance is available in AS/NZS 1715:2009 Selection, use and maintenance of respiratory protective equipment.

Control measures must be maintained to remain fit for purpose, suitable for the nature and duration of the work and be installed, set up and used correctly.

The control measures put in place should be regularly reviewed to make sure they are effective. If the control measure is not working effectively, it must be revised to ensure it effectively controls the risk. Common review methods include workplace inspection, consultation, testing and analysing records and data.

Emergency procedures

There must be documented first aid and rescue procedures to be followed in an emergency, and ensure that workers practise those procedures to ensure they are efficient and effective. In an emergency, first aid and rescue procedures must be initiated from outside the confined space.

The openings for entry and exit must be sufficient to allow emergency access, openings must not be obstructed, and any plant, equipment and personal protective equipment (PPE) provided for first aid or emergency rescue must be maintained in good working order.

First aid and rescue procedures should be rehearsed with workers to ensure they are effective.