What Is the Hierarchy of Controls?


What is the Hierarchy of Controls image

What's the best way to protect your workers from hazards at the workplace?

One common and effective method is to use the hierarchy of controls. To which you may ask-but what is the hierarchy of controls? That's the focus on this article, and we'll explain it in full detail.

First, though, we'll set the scene, by explaining what a hazard is, how to identify hazards, how to assess and prioritize hazards for controls--using the hierarchy of controls, of course.

What Is a Hazard?

The hierarchy of controls is intended to control hazards, so let's start with this issue.

In general terms, a hazard is something that has the potential to cause harm. To be less abstract, a hazard is something that can cause an injury or illness (or cause damage to a machine or equipment - but we'll focus on the things that can cause injuries and illness right now).

There are several different kinds of hazards. We've listed some categories of hazards below.

Type of Hazard Description Example
Safety Hazards Common hazards that cause immediate injuries and illnesses, and may lead to death Slip, trip, and fall hazards; working from heights; electrical hazards; moving machines; mobile equipment
Biological Hazards Other life forms that can cause injury or illnesses Viruses, bacteria, mold, fungi, animal bites/stings, toxic plants, blood and other bodily fluids
Chemical and other Exposure Hazards Things that can cause harm to you when you are exposed Radiation, temperature (high or low), noise, chemicals
Ergonomic Hazards Strains and stresses on the body caused by workplace motions and body positions Poorly designed work areas, repeated motions, lifting heavy weights
Psychological or Societal Hazards Hazards caused by interacting with people and social conditions at the workplace Workplace violence, sexual harassment, stress, depression, alcohol and drug addiction

Notice that we said a hazard is something that has the potential to cause harm. While it's important to remember that potential for harm, it's also worth pointing out these three facts:

  • A hazard is not the same thing as the injury or illness itself
  • A hazard may never cause an injury or illness (even though it has the potential to)
  • Identifying hazards before they cause harm gives you a chance to remove or reduce the potential for harm

How to Identify Hazards

It's important to try to identify hazards before they cause harm. If you do this, you can then eliminate or otherwise control the hazard so that the hazard never does cause harm.

There are many ways to identify hazards at the workplace. Here are a few:

You may find OSHA's Hazard Identification Training Tool helpful here.

Assessing and Ranking Hazards

In a perfect world, you'd eliminate or control every hazard identified at your work place.

But as you know, the world's not perfect. So it makes sense to assess the hazards you've identified and then rank them in the order in which you should address them.

These are the kind of hazards you should address first:

  • Hazards that are very likely to cause harm
  • Hazards that would lead to very severe consequences
  • Hazards that are both very likely to cause harm and would lead to severe consequences (these would be the highest priority of all)

These kind of issues are typically addressed under the topics of risk management and risk assessment. Click to read more about this in our article on risk management and safety.

Controlling Hazards

Now that we've explained what a hazard is, learned some general categories of hazards, listed some ways to identify hazards at the workplace, and touched on the assessment and ranking of hazards, let's turn our attention to different ways to control safety hazards.

What does it mean to control a hazard?

"Controlling a hazard" is the way that safety people talk about taking a hazard and either:

  • Removing its ability to cause harm
  • Reducing its ability to cause harm

So, in everyday language, controlling a hazard is a way to make the workplace safer by making a hazardous situation less dangerous.

Are there different types of hazard controls?

Just as their are different categories of hazards, there are also different categories of hazard controls. Those hazard controls are listed in the table below.

Hazard Control Description Example
Elimination Remove a hazard from the workplace Changing a production process so that a chemical known to cause cancer is no longer used
Substitution Replace a hazard with something less hazardous Changing a formula so that instead of working with a highly explosive fluid, workers work with a fluid that's less explosive
Engineering Control(s) Design a solution that controls the hazard at its source (requires a physical change at the workplace) Encasing a noisy machine inside a sound-proof barrier
Safe Work Practice(s) Develop specific rules and procedures for all workers to follow when working in the presence of or potentially exposed to a hazard Placing warning labels on hazardous chemicals
Administrative Control(s) Developing other work practices to protect workers from hazards Limiting the amount of time workers can work in a noisy area
Personal Protective Equipment (PPE) Protective clothing or equipment that protects a worker from a hazard Providing hearing protection to people who work in a noisy area

Now that you've seen the table with the various hazard controls, let's discuss a few finer points.

Elimination and Substitution of Hazards:

You'll sometimes see these two lumped together within the Engineering Controls.

Safe Work Practices:

Some examples of safe work practices include:

  • Lockout tagout (energy control programs)
  • Confined space entry programs
  • Hazard communication

Safe Work Practices and Administrative Controls:

You'll sometimes see these grouped in as forms of Administrative Controls. However, OSHA specifically says "OSHA uses the term administrative controls to mean other measures aimed at reducing employee exposure to hazards" (other than safe work practices, that is).

Which hazard controls should you use? Which should you try first?

You shouldn't just try any random hazard control, and you shouldn't try them in just an order. Instead, there's a logical progression to work through.

Here's where the title of our article--the Hierarchy of Controls--comes into play.

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.


Hierarchy of Controls Image

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.

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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.

Conclusion: Use the Hierarchy of Controls to Create a Safer, Healthier, Better Workplace

Hope you found this article helpful. Let us know if you have any questions about what the hierarchy of controls is and/or how to use it to create a safer, healthier workplace.

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