Confined Space Risk Assessment for Australian Workplaces

A confined space risk assessment is a structured evaluation of the health and safety risks associated with entry into, work within, or exit from a confined space — an enclosed or partially enclosed space that is not intended or designed primarily as a place of work, that may have restricted means of entry or exit, and that has the potential to contain a hazardous or potentially hazardous atmosphere. The assessment identifies the specific hazards present in or associated with the confined space, evaluates the risk of harm from those hazards, and determines the controls necessary to ensure safe entry and work.

Confined space incidents are among the most lethal categories of workplace accident in Australia and internationally. Historical data consistently shows that a significant proportion of confined space fatalities are not the original entrant but the would-be rescuer — a worker who enters the space without atmospheric testing and without rescue equipment to assist an incapacitated colleague, and is overcome by the same atmosphere. This rescue fatality pattern is the reason that confined space entry requires a detailed risk assessment, a written entry permit, a trained standby person, and a tested rescue plan before any entry is made.

The definition of a confined space under Australian WHS law is broader than many workplaces appreciate. A confined space is not limited to storage tanks, sewers, and mine shafts. Under the WHS Regulation 2025, a confined space is an enclosed or partially enclosed space that is not designed or intended primarily to be occupied by a person; that is, or is designed or intended to be, at normal atmospheric pressure while a person is in it; and that is, or is likely to be, a risk to health and safety because of an atmosphere without a safe oxygen level, contaminants (airborne gases, vapours and dusts) that may cause injury from fire or explosion, harmful concentrations of any airborne contaminant, or engulfment. Size and restricted access alone do not make a space a confined space – the hazardous atmosphere or the engulfment risk does.

This definition can take in manholes, pits, tunnels, culverts, pipes, boilers, pressure vessels, ship holds, grain silos, furnaces, ovens, and any other enclosed space where a hazardous atmosphere or engulfment is possible. Workplaces routinely encounter confined spaces without recognising them as such — the underground communications pit, the sub-floor crawl space, the sealed water treatment tank — which is why a confined space identification audit is the first step of the risk assessment process.

Confined space entry in Australian workplaces is governed by the confined spaces provisions of the WHS Regulation 2025 and explained in the Code of Practice Confined spaces. AS 2865 Confined spaces is the Australian Standard on the subject; it is detailed guidance, and is not called up by the Regulation.

WHS Regulation 2025 — confined spaces: The Regulation requires PCBUs to:

• Identify all confined spaces at the workplace;
• Where it is not reasonably practicable to eliminate the need for entry, manage the risks of entry in accordance with the Regulation;
• Prepare a confined space entry permit for every entry, signed by a competent person;
• Test the atmosphere in the confined space before entry and at intervals during the work;
• Ensure a standby person is present outside the confined space whenever a worker is inside;
• Prepare and test a rescue plan before any entry is made;
• Provide appropriate atmospheric testing equipment, respiratory protective equipment, and rescue equipment;
• Ensure all persons involved in confined space work — entrants, standby persons, and rescue team members — are trained and competent.

AS 2865 Safe Work in a Confined Space: AS 2865 provides detailed technical guidance on confined space work including the classification of confined spaces, the hierarchy of controls for confined space entry, atmospheric testing methods and acceptance criteria, ventilation requirements, personal protective equipment specifications, and rescue procedures. Following the Code of Practice Confined spaces is the recognised way of showing compliance with the Regulation's confined space requirements. AS 2865 provides further technical detail.

Entry Permits: The confined space entry permit is the key document that links the risk assessment to the point-of-work control system. The permit must record: the identity and location of the confined space; the work to be performed; the duration of entry; the atmospheric test results; the controls to be implemented; the identity of the entrants and standby person; the rescue plan; and the signatures of the competent person approving entry and the entrants acknowledging the conditions of entry.

Penalties: Confined space fatalities are subject to intensive regulatory investigation and prosecution. In several Australian states, deaths in confined spaces have resulted in prosecutions under both WHS legislation and industrial manslaughter provisions, with sentences including substantial fines and imprisonment for responsible persons.

The atmospheric hazards present in or potentially present in a confined space are the primary risk factor that distinguishes confined space entry from other hazardous work. The atmosphere can be hazardous from three distinct mechanisms, each of which requires specific testing and control.

Oxygen deficiency. Normal atmospheric air contains approximately 20.9% oxygen. An oxygen-deficient atmosphere — defined as containing less than 19.5% oxygen — impairs judgment, causes disorientation and loss of fine motor control, and can lead to unconsciousness and death without warning in severe cases (below 10% oxygen). Oxygen deficiency occurs in confined spaces where oxygen has been displaced by inert gases (nitrogen purging, carbon dioxide from fermentation, argon welding gas), consumed by biological processes (decay, rusting of ferrous metals in a damp environment), or consumed by combustion or chemical reaction.

Oxygen enrichment. An oxygen-enriched atmosphere — containing more than 23.5% oxygen — dramatically increases the flammability and reactivity of materials within the space. Ordinary clothing can ignite; mild steel can burn. Oxygen enrichment occurs from oxygen leaks in welding gas supply lines or from oxygen-generating processes.

Toxic contaminants. Toxic gases and vapours may be present in confined spaces from residual contamination by the substance previously stored or processed in the space; from biological decomposition (hydrogen sulphide in sewers, carbon dioxide and methane in organic waste pits); from process operations conducted within the space (welding fumes, solvent vapour, hot work combustion products); and from external sources that migrate into the space through drains, pipes, or permeable walls.

Flammable and explosive atmospheres. Flammable or explosive atmospheres can develop in confined spaces that contain or have previously contained flammable liquids, gases, or dusts, or where biological decomposition generates methane. The WHS Regulation requires the concentration of any flammable gas, vapour or mist in a confined space to be kept below 5% of its lower explosive limit (LEL), so far as is reasonably practicable. At 5% or more but less than 10% of the LEL, people must be removed unless a suitably calibrated, continuous-monitoring flammable gas detector is in use. At 10% or more, everyone must be removed immediately.

Atmospheric testing requirements. AS 2865 requires that atmospheric testing be conducted: before every entry; after any period of absence from the space by the entrant; after any change in work activity within the space; and at regular intervals throughout the work. Testing must be performed with calibrated instruments appropriate for the specific contaminants present. Testing from outside the space using a remote probe before entry is essential.

Atmospheric conditions to confirm before entry:

• Oxygen: 19.5%–23.5%
• Flammable gas, vapour or mist: below 5% of the LEL
• Carbon monoxide, hydrogen sulphide and every other contaminant: below the current workplace exposure standard published by Safe Work Australia

A compliant confined space risk assessment follows a structured process that must be completed before the entry permit is issued and before any entry is made.

Step 1 — Identify and classify the confined space. Confirm that the space meets the regulatory definition of a confined space. Review the construction drawings, process flow diagrams, and operational history of the space to understand its configuration, the substances it has contained, and the work tasks that have previously been performed within it. Decide first whether entry is necessary at all: the Regulation requires the need to enter a confined space to be eliminated so far as is reasonably practicable.

Step 2 — Assess whether entry can be eliminated. The WHS Regulation requires that the PCBU first consider whether the work can be performed without entering the confined space — using remote inspection technologies, robotic cleaning systems, or extended-reach tools. If entry can be eliminated, no further confined space risk management is required. If entry cannot be eliminated, proceed to Step 3.

Step 3 — Identify all hazards in and associated with the confined space. Using the space classification, construction records, and operational history, identify all hazards that are present or potentially present: atmospheric hazards (oxygen deficiency, toxic contaminants, flammable atmosphere); physical hazards (moving machinery, flooding or liquid ingress risk, falling objects, unstable surfaces, engulfment by solid materials); thermal hazards (hot surfaces, steam, or extreme cold); radiation hazards (ionising radiation from process equipment); and biological hazards (legionella in water systems, mould, vermin).

Step 4 — Assess the risk for each hazard. For each identified hazard, assess the likelihood and consequence of harm using a risk matrix. The worst-case scenario in a confined space — acute atmospheric toxicity or oxygen deficiency — is potentially fatal, which drives the risk rating to extreme even at low probability of occurrence, justifying the comprehensive controls required.

Step 5 — Select controls. Apply the hierarchy of controls: eliminate the need for entry; use ventilation (forced or natural) to render the atmosphere safe before entry; use supplied air or self-contained breathing apparatus (SCBA) for entry where the atmosphere cannot be rendered safe; isolate energy sources (lock-out/tag-out) and blank off or disconnect pipe connections that could introduce hazardous substances or flooding; use a standby person and communication system; and prepare and test a rescue plan with appropriate rescue equipment.

Step 6 — Issue the entry permit. Prepare and sign the entry permit recording all steps above, the atmospheric test results, the identity of entrants and standby person, the controls to be implemented, and the maximum duration of the entry. The permit is a legal document and must be retained after the entry.

Step 7 — Monitor and review. Maintain continuous atmospheric monitoring during the entry (where feasible) or conduct periodic re-testing at intervals specified on the permit. Review the confined space risk assessment after every entry, after any incident or near-miss, and when the space or the work performed in it changes.

Rescue planning is the element of confined space management that most workplaces under-invest in, and it is the failure that contributes most directly to would-be rescuer fatalities. The WHS Regulation and AS 2865 are unambiguous: a rescue plan must be prepared and the means to execute it must be in place before any entry is made.

A compliant confined space rescue plan includes the following elements.

Rescue methods. The rescue plan must specify the primary rescue method for recovering an incapacitated entrant from this specific space — considering the geometry of the space, the entry and exit points, the depth of the space, and the nature of the most likely incapacitation scenario. Non-entry rescue (hauling the entrant out without a rescuer entering the space) is the preferred method and must be the primary rescue method where the space geometry permits. Entry rescue (a trained rescuer entering the space with appropriate respiratory protection) is the backup method when non-entry rescue is not feasible.

Rescue equipment. The rescue plan must specify the rescue equipment required — a tripod and mechanical winch, harnesses, lifelines, rescue breathing apparatus — and confirm that it is at the entry point before entry commences, in serviceable condition, and that the standby person knows how to use it.

Emergency services notification. The rescue plan must include the procedure for contacting emergency services — fire and rescue, ambulance — and the information to be communicated. Where the site is remote or access for emergency services is difficult, pre-notification of emergency services before entry is recommended.

Rescue drills. AS 2865 recommends that rescue procedures be practised at regular intervals to verify their effectiveness and ensure that the standby person is competent to execute the rescue. A rescue plan that has never been practised provides far less assurance than one that has been tested in the specific space.

Standby person competency. The standby person must be trained in recognising the signs of atmospheric contamination or incapacitation, operating the rescue equipment, communicating with the entrant, and executing the rescue plan without entering the space. The standby person must remain at the entry point throughout the duration of the entry — they cannot leave to perform other tasks.

The confined space entry permit is the document that authorises entry into a confined space under the conditions specified in the risk assessment. It is both an operational tool — a checklist that the competent person and entrants work through before entry — and a compliance record that documents that all required checks were completed.

A compliant confined space entry permit must include the following sections.

Space identification: The identity and location of the confined space, including a reference to the confined space register and any relevant drawings or diagrams.

Work description: A description of the work to be performed, the equipment to be used, and the estimated duration of the entry.

Atmospheric test results: The pre-entry atmospheric test results for oxygen, flammable gases, and identified toxic contaminants, with the instrument used, calibration date, and the name of the tester. Space for recording in-space test results during the entry.

Energy isolation verification: Confirmation that all energy sources and hazardous substance connections have been isolated and locked out in accordance with the isolation procedure.

Ventilation confirmation: Confirmation that ventilation is operating as specified and that the atmosphere is within the acceptable range for entry.

Personnel: The names of all authorised entrants, the standby person, and the competent person authorising the entry.

Rescue plan: A summary of the rescue procedure, the rescue equipment at the entry point, and the emergency contacts.

Entry conditions: The maximum duration of the permit, the conditions that require the permit to be cancelled and a new risk assessment conducted, and the procedure for cancellation.

Authorisation signatures: The signature of the competent person authorising entry, the signatures of the entrants confirming they have read the permit and understand the conditions, and the date and time of entry and exit.

We do not yet publish a stand-alone confined space risk assessment; the closest ready-made document is described at the end of this guide.

How do I know if a space is a confined space? A space is a confined space if it is enclosed or partially enclosed, is not designed or intended primarily to be occupied by a person, is at normal atmospheric pressure while someone is inside, and is or is likely to be a risk to health and safety because of an unsafe oxygen level, airborne contaminants, a fire or explosion risk from those contaminants, or engulfment. Restricted access on its own does not make a space a confined space. If any of these criteria apply, the space must be managed as a confined space. If in doubt, treat it as a confined space until a competent person has assessed it and determined otherwise.

Can I enter a confined space without a permit for a quick inspection? No. The WHS Regulation and AS 2865 require an entry permit for every entry into a confined space, regardless of the duration of the entry. An 'emergency' entry without a permit and without atmospheric testing is the scenario that most commonly results in multiple fatalities — when a worker enters without testing and is overcome, and a colleague follows without testing to assist.

What qualifications are needed for confined space entry? All persons entering a confined space must be trained in the specific hazards of the space and the controls to be used. The competent person responsible for the risk assessment and entry permit must have the knowledge and experience to assess the atmospheric and physical hazards and specify appropriate controls. Many Australian training organisations offer nationally recognised confined space entry units of competency (e.g., RIIWHS202E Enter and work in confined spaces) — completion of this training is typically required for workers who regularly perform confined space entry.

Is forced ventilation always required for confined space entry? Not always. The decision to use forced ventilation depends on the result of the atmospheric assessment. If the pre-entry atmospheric test confirms that the space contains an acceptable atmosphere and that there are no sources of atmospheric contamination that could cause the atmosphere to deteriorate during the entry, entry without forced ventilation may be acceptable. However, where any doubt exists about the stability of the atmosphere — for example, where biological decomposition is ongoing, where process operations could generate contaminants, or where the space has previously contained toxic substances — continuous forced ventilation and continuous atmospheric monitoring are required.

What happens if atmospheric conditions deteriorate while workers are in the space? If the atmospheric monitoring equipment alarms, or if the entrant notices symptoms consistent with atmospheric exposure (dizziness, nausea, difficulty breathing, confusion), all entrants must immediately leave the space. The entry permit must be cancelled. No re-entry is permitted until a new risk assessment has been conducted, the source of the atmospheric change has been identified and controlled, and the atmosphere has been re-tested and confirmed to be within acceptable limits.