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Managing Hazards in Confined Spaces

Best Practice

Confined spaces are responsible for a disproportionate number of serious injuries and fatalities on Australian worksites.

What makes them particularly dangerous is that conditions can change rapidly, leaving workers with very little time to respond. Understanding the hazards, implementing the right controls, and selecting appropriate equipment are the foundations of confined space safety.

What Qualifies as a Confined Space?

Under Australian standard AS 2865 and state WHS regulations, a confined space is an enclosed or partially enclosed space that is not designed for continuous human occupancy, has restricted means of entry or exit, and has the potential to contain a hazardous atmosphere or engulfment hazard.

Common examples on construction and industrial sites include:

Storage tanks and silos
Excavated pits and trenches
Sewers, culverts, and pipelines
Shafts, tunnels, wet and dry wells
Ducts and service voids
Inspection chambers

If your worksite includes any of the above, confined space regulations apply, regardless of how briefly your workers are in the confined space.

The Hazards You Need to Account For

Working in confined spaces requires strict safety measures because the risks are highly concentrated. Vigilance is critical, as understanding and mitigating these common hazards can prevent serious injury or fatality.

1. Oxygen Deficiency

When oxygen levels drop below 19.5%, a confined space is considered oxygen-deficient, as classified by AS 2865-2009. This presents a serious danger, as workers can lose consciousness within minutes. Oxygen depletion is often caused by factors such as biological activity, chemical reactions, or the use of combustion equipment inside the space.

2. Toxic Gases

The most common toxic gases found in confined spaces on Australian work sites are carbon monoxide, hydrogen sulphide, and methane, all resulting from chemical reactions. Hydrogen sulphide poses a unique danger: in high concentrations, it disables the olfactory nerve, meaning workers lose the ability to smell it before it reaches lethal levels.

3. Flammable Atmospheres

When ignition sources are present, certain solvent vapours and methane can build up to concentrations that pose an explosion risk.

4. Engulfment

Engulfment poses an immediate fatality risk, often within minutes, if a worker cannot be rescued. This danger occurs without warning when workers become submerged in materials such as grain, sand, slurry, or other liquids. The highest risk of engulfment is found in excavated areas with unstable walls, as well as in silos and hoppers.

5. Heat

Confined spaces can trap heat generated by workers, machinery, and chemical processes. Without adequate ventilation, temperatures inside these spaces can reach dangerous levels, leading to heat exhaustion or heat stroke. This risk is heightened for workers wearing Personal Protective Equipment (PPE), which can hinder the body’s natural ability to cool itself.

6. Physical Hazard

Confined spaces can present various physical hazards that may lead to injury. The most common physical hazards encountered when working in a confined space include:

Moving machinery
Low ceilings
Sharp edges and exposed metals

How to Minimise Confined Space Hazards

Identifying hazards is only part of the job. For every hazard present in a confined space, you need a control measure in place before entry begins. Australian WHS legislation sets out clear requirements, and meeting them protects your workers and your business. Here is what you need to have covered before entry begins:-

Atmospheric Testing and Monitoring

Before entering a confined space, test the atmosphere and continue monitoring it throughout the work period. Use calibrated gas detection equipment to measure oxygen levels, flammable gas concentrations, and the presence of toxic gases specific to your environment. Do not rely on a single pre-entry test as your only control.

Ventilation

Ventilation is the primary control measure for atmospheric hazards in confined spaces. There are two approaches:

Dilution ventilation uses fans and ducting to introduce fresh air into the space and reduce the concentration of contaminants. Portable axial or centrifugal fans with flexible ducting are commonly used for this purpose.
Local exhaust ventilation (LEV) extracts contaminants at the point of generation before they disperse into the space. This is the correct approach when workers inside are producing specific hazardous substances, such as welding fumes or solvent vapours.

The ideal ventilation system for a confined space depends entirely on the dimensions, identified hazards, and the specific nature of the work. Often, both supply and extraction ventilation are necessary. By choosing to hire ventilation equipment from specialists such as RVT Group, you gain access to the exact and industry-current tools for the job without the cost of ownership. Additionally, you benefit from expert support, including advice on optimal configuration and placement.

Isolation

Before entry begins, isolate the confined space from connected systems wherever possible. This includes isolating mechanical equipment that could be activated during entry, blanking off pipelines that could introduce gases or liquids, and locking out electrical systems. When hazards are isolated at the source, the risk inside the space is significantly reduced.

PPE and Rescue Equipment

PPE for confined spaces must match the specific hazards identified in your risk assessment. Standard construction PPE is rarely sufficient on its own. Depending on your environment, workers may require:

Self-contained breathing apparatus (SCBA) or supplied air respirators
Gas detection equipment worn on the body
Harnesses and retrieval systems for emergency extraction
Hearing protection rated for the noise levels inside the space

Ensure all equipment is inspected before every entry and that workers are trained in its use.

Standby Person

Australian WHS regulations and AS 2865 require a trained standby person to remain outside the confined space for the duration of the entry. The standby person monitors workers inside, maintains communication, tracks atmospheric monitoring data, and initiates the emergency response if conditions deteriorate. The standby person must not enter the space to attempt a rescue without the appropriate equipment and backup.

Emergency Planning

Every confined space entry requires a documented emergency and rescue plan. This plan must be in place before the entry permit is issued, and all workers involved in the entry must be familiar with it.

Your plan should cover

How workers will communicate from inside the space
The procedure for emergency extraction, including the equipment to be used
Who is responsible for initiating emergency services
The location of rescue equipment relative to the entry point

Rescue attempts without the correct equipment and training are a leading cause of secondary fatalities in confined space incidents. Your emergency plan must account for the reality that untrained bystanders entering a space to help a collapsed worker is a known and preventable cause of multiple fatalities in a single incident.

Getting Confined Space Safety Right

Safety in confined space comes down to preparation and the right controls for your specific environment. Atmospheric monitoring, isolation, a trained standby person, and a ventilation system configured for the space are all required, and each one depends on the others working correctly.

RVT Group provides ventilation equipment hire for confined space entries across construction, mining, oil and gas, and infrastructure projects in Australia. Every hire starts with an assessment to ensure your system is configured for your environment and meets your compliance requirements.