Hierarchy of Controls

A Hierarchy of Controls provides a means of determining ways to implement systems or controls (from most effective to least effective) that protect workers from injuries, illnesses, and fatalities [National Institute for Occupational Safety and Health (NIOSH), 2021].

As identified in the graphic, the primary exposure control methods are hazard elimination or substitution by a less hazardous process or toxic substance. Workplaces should systematically implement exposure controls in the following order of effectiveness:

  1. Elimination
  2. Substitution
  3. Engineering Controls
  4. Administrative Controls
  5. Personal Protective Equipment (PPE)
Diagram of Hierarchy Controls

In some cases, a combination of controls may be necessary (e.g., ventilated containment hoods and PPE when compounding chemotherapy drugs).