Skip to content

Safety in Design – Using the Hierarchy of Controls

Designing Safety into to your Projects

This article discussed how planning for projects or upgrades should include a process to work through a hierarchy of controls to reduce risk. The process of using the hierarchy of controls, when done correctly, will help to determine if the engineering and procurement of equipment (or components, ingredients etc) is safe for humans and the environment in the workplace. 

Risk of harm must always be reduced to as low as reasonably practicable.  


An Example - Process Sampling of Chemicals

A dangerous substance splashes a chemical plant operator who collects a sample. The worker was not seriously injured and the resulting investigation focused on training, personal protective equipment and the characteristics of the sampling station. 

Do we need this sample? If so, can a solution be engineered to eliminate the risk of being splashed?


hierarchy of controls

The objective of all health and safety professionals is to identify and mitigate occupational risks prior to commencing work. NIOSH provides basic insight in interpreting the hierarchy of controls. Project Engineers also need to understand this concept well. 

The hierarchy begins with controls that are perceived to be the most effective and shifts to those that are perceived to be the least effective. This article focuses on the first three steps of the Hierarchy of Controls, where safety is designed into the equipment and processes.  


NIOSH Hierarchy of Controls

The National Institute of Occupational Safety and Health describes the hierarchy of controls as a step by step method to reduce hazards to as low as reasonably practicable (ALARP). In other words, determining which actions will best control exposures.


Hierarchy of Controls

Key Takeaways from the Hierarchy of Controls Theory

  • NIOSH defines the Hierarchy of Controls in five descending steps: elimination, substitution, engineering controls, administrative controls and personal protective equipment. The hierarchy is arranged beginning with the most effective controls and proceeds to the least effective.
  • Although eliminating the hazard is the ultimate goal, it can be difficult and is not always possible.
  • NIOSH’s Prevention through Design Initiative comprises “all of the efforts to anticipate and design out hazards to workers in facilities, work methods and operations, processes, equipment, tools, products, new technologies, and the organization of work.”. 
  • Project Engineers that are designing new equipment and processes, should use the Hierarchy of Controls during the design phase and involve experts in Process and Occupational Safety. 
  • Design MUST take into consideration “how the human” will interact with and work safely around the equipment. Consider for example, the placement of valve wheels and control panels.  Valve wheels placed too low to the ground (or too high-up) can cause musculoskeletal injuries. 
  • Prepare your own Safety in Design Handbook. To read up on SID, check out this book. 




The Hierarchy of Control Steps

Elimination – Beginning at the top, identify if the hazard be physically eliminated? Removal eliminates the hazard at the source. This may include designing or modifying the work process to stop using a toxic chemical, a heavy object or a sharp tool. This is a preferred design solution to protect workers because there is no exposure.  If not, then move to the next step and consider substitution.

Substitution – Replacing the hazard. Substitution is using a safer alternative to the source of the hazard. An example is using plant-based printing inks as a substitute for solvent-based inks.

When considering a substitute, it’s important to compare the potential new risks of the substitute to the original risks. This review should consider how the substitute will combine with other agents in the workplace. Effective substitutes reduce the potential for harmful effects and do not create new risks.


Elimination and Substitution can be the most difficult and potentially costly actions to adopt in an existing process. 

These methods are best used when designing or developing a work process, location or tool. 


Hierarchy of Controls - substituting or eliminating

During the design phase, elimination and substitution can possibly be the simplest solution. However, it is highly recommended that project engineers should involve Process Safety and Occupational Safety & Health experts to advise and help with the risk assessments during this stage.  

The safety experts may see processes from a different angle than the project engineer and can help prevent costly errors in design that may be difficult to fix later. They can help engineers to design for safety with humans in mind. 


This is because Project Engineers may focus too much on the functional process and not have full comprehension of how their designs may affect people operating the equipment or working close to it. 

When working down the Hierarchy of Controls and the hazard cannot be eliminated or substituted, then the project engineer must move to the next phase in designing for safety.


Engineering Controls
Ergonomic Hazards

Engineering Controls – These are controls that isolate people from danger.

Engineering controls minimize or prevent hazards from coming into contact with workers. 

Engineering controls may include changes to equipment or work space, use of protective barriers, ventilation, etc. The NIOSH engineering controls database provides examples of published research results on engineering controls.


The most effective engineering controls:

  • Will form part of the original design of the equipment.
  • Eliminate or block the hazard at the source prior to contact with the worker.
  • Prevent users from changing or impeding the control.
  • Provide minimum user input required for controls to work.
  • Perform correctly without disrupting or making the work process more difficult.


Engineering controls can cost more upfront than administrative controls or PPE. However, long-term operating costs tend to be lower, especially for the protection of multiple workers. Furthermore, engineered controls can lead to savings in other areas of the work process or the operation of the plant.


Administrative Controls and PPE

Administrative Controls and PPE are your last line of defence. Although they should be designed into a safety program, the project engineers should always strive to design out the hazards as much as possible. These last two controls rely on humans to make the right decisions and take appropriate actions.


I call this the Human Error section of the Hierarchy of Controls. These controls are the hardest to manage and also the most frequent root cause of incidents involving injuries.



  • Involve the safety experts at the beginning and throughout the stages of design, build and commissioning.
  • Eliminate, Substitute or Engineer away the hazards as much as possible. 
  • Develop a Safety In Design Handbook for your site operations. This can be used as a guideline for engineering design.
  • Don’t let project budgets get in the way of safe design. It may come back to haunt you later.


3 1 vote
Article Rating

Don’t miss out on recent news and posts!

I don’t spam! Read my privacy policy for more info.

1 Comment
Newest Most Voted
Inline Feedbacks
View all comments

[…] is important to note that an ergonomist (if you have one) can make a contribution at the design stage of equipment and workplaces in order to try to prevent problems from occurring […]

%d bloggers like this: