What Is a Hierarchy of Controls? 5 Stages of Safety Controls

One method of managing occupational hazards, such as accidents, injuries and illnesses, is through implementing the hierarchy of controls. Organizational leaders use this globally recognized system in workplaces to manage hazards through five strategy tiers, from elimination to prevention. 

In this article, we define the hierarchy of controls and list the five stages of safety controls that can be used to protect employees.

Key takeaways:

• The hierarchy of controls is used to keep employees safe from injury and illness in the workplace.

• The five steps in the hierarchy of controls, from most effective to least effective, are elimination, substitution, engineering controls, administrative controls and personal protective equipment.

• The hierarchy of controls is especially vital in occupations where employees come into regular contact with hazardous chemicals, vehicle-related accidents and heavy machinery errors.

What is the hierarchy of controls?

The hierarchy of controls is a structural method for keeping employees safe from occupational hazards. It’s widely promoted as the best way to control occupational hazards by various worldwide safety organizations, including the National Institute for Occupational Safety and Health (NIOSH).

The hierarchy details five methods of varying effectiveness for controlling occupational hazards and emphasizes elimination or substitution of the hazardous object(s) first:. 

• Elimination: Physically remove the hazard(s)

• Substitution: Replace the hazard(s)

• Engineering controls: Isolate people from the hazard(s)

• Administrative controls: Change the way people work

• Personal protective equipment (PPE): Protect workers

Workplaces often combine all five methods of control to ensure thorough protection, even in the event that a single, high-level control mechanism fails.

Related: How To Obtain an Environmental Health and Safety Certification

5 stages of safety controls

Five key stages of safety controls are included within the hierarchy of controls. These stages are ranked by efficacy and are typically represented using an inverted triangle graph, which lists the most to least effective stages.

You can think of the five stages as defense mechanisms that prevent employees from interacting with or being impacted by occupational hazards:

1. Elimination

Elimination, or physically removing a hazard from a workplace, is the most effective stage of the hierarchy of controls. When hazards are eliminated or removed from a work environment, they no longer have the potential to negatively impact employees. 

Though it’s conceptualized as the most effective stage, elimination is also typically the most challenging to implement. Doing so can be costly and require major overhauls in preexisting workplace processes.

Examples:

• Redesign a process to eliminate the use of hazardous equipment or product

• Perform tasks at ground level rather than working high above ground

• Store goods at lower heights so workers don’t have to climb tall heights and risk fall injuries or fatalities

2. Substitution

Substitution, or replacing a hazardous item or activity with something less hazardous, is the second-most effective stage of safety control. Substitution serves a similar purpose to elimination, as it removes a hazard from the workplace or decreases the potential for the hazard to negatively affect employees. If a workplace process is still in its design or development phase, substitution can be an inexpensive and streamlined method for managing a hazard.

Examples:

• Replace a caustic cleaning agent with a non-toxic alternative

• Substitute a solvent-based paint with water-based paint

• Use a non-silica abrasive material instead of sandblasting

Related: How to Become a Safety Director

3. Engineering controls

Engineering controls, or designing purposeful solutions that physically separate employees from hazards, are the third-most effective stage of safety control. Many organizations favor engineering controls to remove the hazard at the source, rather than after an employee comes into contact with a hazard. It’s important to note that while engineering controls can sometimes be costly to implement, they typically result in lower overall operating costs due to the new safety features.

Examples:

• Place barriers around fans and other loud machinery

• Fence around dangerous high-voltage equipment

• Install guardrails at worksites that are high above ground

4. Administrative controls

Administrative controls, or changes to the way employees work and perform particular processes, are the fourth-most effective stage of safety control. Administrative controls are typically employed alongside other existing processes in which hazards are not totally controlled.

Organizations sometimes favor administrative controls due to their low-cost nature, but such initiatives are often somewhat ineffective and require significant effort on the part of affected employees.

Examples:

• Limit the time a worker is exposed to a hazard

• Create written formalized operating procedures

• Install signs, labels and alarms

5. Personal protective equipment

PPE, physical equipment worn or used by employees while they perform their work, are the fifth- or least-most effective stage of the hierarchy of controls. 

Like administrative controls, PPE is typically used alongside preexisting processes that haven't completely controlled the occupational hazard. Using PPE as a safety control is typically very costly in the long term and can be somewhat ineffective if worn or used improperly.

Examples:

• Eye and face protection (goggles and masks)

• Head protection (hard hats)

• Foot and leg protection (foundry shoes)

• Hand and arm protection (chemical-resistant gloves)

• Body protection (hazmat suits)

• Hearing protection (earplugs)

Related: 10 Workplace Safety Tips To Stay Productive and Protected

Why is the hierarchy of controls important?

The hierarchy of controls is especially vital in occupations where employees come into regular contact with hazards like toxic chemicals, air pollutants, diseases and illnesses, structural or vehicle-related accidents and heavy machinery errors.

The hierarchy of controls is an integral part of the NIOSH initiative prevention through design (PtD), which aims to prevent or reduce occupational injuries and illnesses by “designing out” hazards and risks. PtD employs the hierarchy of controls through these methods:

• Eliminating occupational hazards and risks at the start or early on their life cycle

• Designing, redesigning or retrofitting workspaces, tools and procedures to protect employees

• Including prevention methods within workflow design