Every workplace has hazards, but not every hazard has to become an injury. The difference usually comes down to how well an organisation controls risk. The hierarchy of controls is the framework safety professionals use to decide which control measures to apply first, and understanding it properly can transform the way a business protects its people.

What the Hierarchy of Controls Actually Is

The hierarchy of controls is a ranked list of ways to reduce or remove a hazard, arranged from most effective to least effective. The idea is simple: rather than jumping straight to handing out gloves and hard hats, you first ask whether the hazard can be removed altogether. Only when the stronger options are exhausted do you rely on measures that depend on human behaviour.

Elimination: Remove the Hazard Completely

Elimination sits at the top because it is the only control that offers total protection. If a dangerous machine is no longer used, or a hazardous chemical is designed out of a process, the risk disappears entirely. It is often cheapest to eliminate a hazard during the design or planning stage, which is why safety should be considered long before work begins rather than bolted on afterwards.

Substitution: Swap for Something Safer

When you cannot remove a hazard, the next best thing is to replace it with something less dangerous. A common example is switching a toxic solvent for a water-based alternative. Substitution needs care, because a new material or method can introduce its own risks, so any swap should be assessed rather than assumed to be safer.

Engineering Controls: Isolate People From the Hazard

Engineering controls physically separate workers from the danger. Machine guarding, ventilation systems, sound enclosures, and barriers all fall into this category. Their strength is that they work without relying on a person remembering to do the right thing. Once a guard is fitted correctly, it keeps protecting everyone who works near the machine.

Administrative Controls: Change the Way People Work

Administrative controls include training, safe systems of work, job rotation, warning signs, and permits to work. They are useful and often necessary, but they are weaker because they depend on people following the rules consistently. A well-written procedure only protects someone if it is read, understood, and applied every single time.

Personal Protective Equipment: The Last Line of Defence

PPE sits at the bottom of the hierarchy, not because it is unimportant, but because it only protects the individual wearing it and does nothing to reduce the hazard itself. If PPE fails or is worn incorrectly, the person is directly exposed. It is best used to top up other controls rather than as a substitute for them.

Putting the Hierarchy Into Practice

In reality, most workplaces use a combination of controls at the same time. A welding operation might use extraction to remove fumes, screens to protect passers-by, training on safe technique, and a respirator as a final layer. The key habit is to always start at the top of the hierarchy and work down, rather than reaching for PPE first because it feels quick and cheap.

Frequently Asked Questions

Why is PPE ranked lowest in the hierarchy?

Because it does not remove the hazard and only protects the person wearing it. If it fails, is uncomfortable, or is worn incorrectly, the protection is lost, so it is treated as a last resort.

Can I use more than one control at once?

Yes, and you usually should. Combining controls from different levels provides layered protection, so that if one measure fails, others are still in place.

Where does the hierarchy of controls come from?

It is a long-established principle in occupational health and safety and appears in guidance from bodies such as OSHA and NIOSH, as well as in courses like IOSH Managing Safely.

Final Thoughts

The hierarchy of controls is one of the most practical tools in safety management because it forces a simple, powerful question: can we make the hazard less dangerous before we ask people to protect themselves from it? Applying it consistently leads to safer workplaces and fewer injuries, which is exactly what good safety training aims to achieve.