The hierarchy of control

What is the hierarchy of control?

Workplace health and safety laws require duty holders to select the highest level of protection (control measure) against a hazard that is reasonably practicable in the circumstances.

The hierarchy of control is a system of selecting the most appropriate control measures for managing risks to health and safety using a step-by-step approach from the highest level of protection and reliability through to the lowest and least reliable protection.

The figure below shows the structure of the general hierarchy of control.

Applying the hierarchy of control

Working from the highest level through to the lowest in the hierarchy of control will help you to select the most appropriate control measure. Eliminating the hazard and risk is the highest level of protection and reliability in the hierarchy, followed by reducing the risk through substitution, isolation and engineering controls, then reducing the risk through administrative controls and the use of protective personal equipment (PPE) as the lowest level of control.

Level 1 - Eliminate the hazards

The most effective control measure is to eliminate the hazard and its associated risk. The best ways of eliminating hazards is to not introduce the hazards in the first place or to remove the hazards completely.

For example, you may be able to eliminate the risk of a fall by removing slip and trip hazards on a floor.

You need to aim to eliminate hazards and associated risks.  However, it may not be possible or reasonably practicable to eliminate a hazard or risk if doing so means you are unable to make the end product or deliver the service.If it is not reasonably practicable to eliminate a hazard or risk you will need to go to the next step to reduce the risk posed by the hazard.

Level 2 - Reduce the risk through substitution, isolation or engineering controls

If it is not reasonably practicable to eliminate the hazards and associated risks, minimise the risks by using one or more of the following approaches:

Substitution

This means substituting the hazard with something safer. For example:

• a cordless drill instead of an electric drill with a power cord could become damaged or cutwater-based paints instead of solvent-based paints
• water-based paints instead of solvent-based paints

Isolation

This means separating the source of harm from people by distance or barriers. For example:

• concrete barriers to separate people from powered mobile plant or vehicles
• use of remote control systems to operate machinery

Engineering controls

This means control measures that are physical in nature, including a mechanical device or process.  For example:

• use of an elevating work platform
• use of trolleys or hoists to move heavy loads
• use of RCDs (electrical safety switches)

If reducing the risk through substitution, isolation or engineering controls is not reasonably practicable, the next level of control measures may be used to reduce risks.

Level 3 - Administrative controls and personal protective equipment

These control measures rely on human behaviour and supervision for their effectiveness, and used on their own, tend to be the least effective in minimising risks.

Administrative controls

This means using work methods or procedures designed to minimize exposure to a hazard.  For example:

• procedures on how to operate machinery safely
• limiting the time to which a workers is exposed to a hazardous task
• using signs to warn people of a hazard

Personal protective equipment (PPE)

PPE is anything workers use or wear to minimize risks to their health and safety.  Examples of PPE include hard hats, face masks, ear muffs, earplugs, safety glasses, goggles, face shields gloves, high-visibility clothing, safety footwear.

PPE may reduce exposure to the harmful effects of a hazard but only if workers wear and use the PPE correctly.

Administrative controls and PPE should only be used:

• when there are no other practical control measures available (as a last resort)
• as an interim measure until a more effective way of controlling the risk can be used
• to supplement higher level control measures (as a back-up).

Reducing the risk may involve a single control measure or a combination of different controls that work together to provide the highest level of reasonably practicable protection.

Specific control measures for a task or hazard.

Some workplace health and safety laws prescribe specific control measures for managing risks to health and safety arising from particular hazards or activities.  Examples include asbestos, falls and confined spaces.

These specific control measures must be complied with regardless of where they may fit in the hierarchy of control.

To find out more, contact HIA's Building Services team.

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