Understanding the hierarchy of controls

The goal of any hazard control program is to eliminate the risk to workers in the workplace. If elimination is not possible, reasonable measures must be taken to reduce the risk to an acceptable level. The hierarchy of controls is essential to any safety and health program and provides a framework for deciding how to protect workers.

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How do I know when a control is needed? 

Workplaces should always aim to eliminate risks or remove hazards. If that’s not possible, the hierarchy of controls is used—starting with the most effective measures and working down to the least reliable. In some cases, a combination of controls is needed to reduce risk to a reasonably practical level.

For more information, see Part 2 of the Workplace Safety and Health Regulation. 

What are the hierarchy of controls?

The hierarchy of controls is a method for controlling hazards. A control measure is an action, process, material or equipment that can be used to reduce or eliminate the risk of a hazard. The hierarchy of controls includes elimination, substitution, engineering, administrative and personal protective equipment.

The best prevention plan is to eliminate hazards completely by removing them from the workplace. For example, eliminating a machine that creates a level of noise exposure beyond the threshold limit value removes the need for hearing protection because the hazard is eliminated. When elimination is not possible, a key safety principle is to invest in reducing the risk to the lowest possible level.

How can workplaces use the hierarchy of controls to reduce risk?

• Substitution
  Substitution means replacing a hazardous process or substance with one that poses less risk. For example, using a less toxic chemical instead of a toxic one. Be careful when substituting substances to ensure you are not introducing a new hazard.
• Engineering controls
  Engineering controls do not remove hazards but modify processes, materials or equipment to reduce risk. Engineering controls are reliable because they are often built into the design of the equipment, such as emergency stop buttons on machines or protective guards and barriers.
• Administrative controls
  Administrative controls include policies, safe work procedures, training, shift schedules, emergency plans, housekeeping and work practices that guide how tasks are performed. These controls do not eliminate hazards but limit worker exposure. For example, a procedure requiring drivers to use their smart phones only when parked helps reduce the risk of distracted driving.
• Personal protective equipment (PPE)
  PPE is the last line of defense against hazards. Examples include high-visibility clothing, safety footwear, hearing protection, gloves and masks. For example, if noise levels remain hazardous after other controls have been applied, workers must wear hearing protection and follow a hearing conservation program. Proper training on how to wear, use and maintain PPE is essential.

It is important to understand that a workplace may also use a combination of these controls to reduce the risk to workers. Depending on the situation, a workplace may use a more natural product, but still have a SWP for handling the product. It is also important to understand that another hazard or risk is not created, when a hazard or risk is eliminated.

Where are controls placed?

Generally speaking, there are three areas to place controls:

• Remove or control the hazard at the source: These are measures in the work environment designed to prevent contact with a hazard through elimination or substitution. 
• Control the hazard along the path: When a hazard cannot be eliminated, automated, isolated or replaced, we look to minimize the risk of the hazard before it reaches a worker. 
• Limit harm at the worker: Sometimes, it is not possible to remove risk or control it along the path, so we place a control at the worker. These controls involve education, training and controlling the degree or amount of exposure a worker has to a hazard. They may be administrative or may involve personal protective equipment (PPE). 

How can the committee use the hierarchy of controls when reviewing processes and making recommendations?

The committee can be instrumental in ensuring that the hierarchy of controls is used when providing recommendations. By understanding these controls, the committee can propose a range of options to the employer. Short-term measures may be recommended to reduce the hazard to an acceptable level until a permanent solution is in place.

Hierarchy of controls resources for committee members  

• Bulletin 249
• Driving
• Controlling risks 
• Hazard and risk

Top tips

• Understand the hierarchy of controls. 
• The most effective method of controlling hazards is to eliminate the hazard. 
• Understand where hazards can be placed to be the most effective and reliable. 
• Provide recommendations that will follow the hierarchy of controls. 
• Be aware that eliminating one hazard could create another. Monitor the control method implemented to ensure it is working effectively and the hazard has been eliminated or reduced.
• PPE should be the last resort to protect against a hazard.