What Is the Hierarchy of Controls?

It’s important to work through a logical progression when you’re considering controls for a hazard. That logical progression, from first to last, is represented by the hierarchy of controls.

Look at the diagram below. The hazard controls are listed in order. At the top is elimination. This is what you should try to do first. If elimination isn’t possible or feasible, then you continue down the list, trying substitution, then engineering controls, then administrative controls, and then finally (and only as a last resort) personal protective equipment.

Note: We’ve “collapsed” work practice controls into the administrative controls category here, but don’t forget about it.

Why are the controls in the hierarchy of controls ordered in the way they are?

The most effective controls are the ones ranked at the top. Think about it–you can’t do much better than completely eliminate a hazard, can you?

Likewise, using an engineering control (such as enclosing a noisy machine inside a sound-proof barrier) is going to be better than limiting the number of hours a worker can work in the room with the noisy machine, right?

You’ll notice that the use of personal protective equipment is at the bottom of the pyramid. That means it’s the control that should be tried last. And that’s because it’s the least effective.

Using More than One Control to Control a Hazard

Many times, you’ll find you can’t completely control a hazard by using just one of the controls.

What should you do? Use more than one control.

For example, you could use Substitution to remove a very hazardous chemical with a less hazardous chemical. But it may still be necessary to create Administrative Controls that limit the time a worker is near the chemical, and even then it may still be necessary to provide the worker with personal protective equipment (PPE).

Use PPE ONLY as a Last Resort

Although PPE may be one of the first things that springs to mind when you’re thinking of controlling a hazard, it should never be the first control you turn to. In fact, you should only turn to PPE as a possible control when all other controls have been exhausted and there’s still an unacceptable level of hazard.