Hierarchy of Controls

The hierarchy of controls is the ranked order of effectiveness for controlling a workplace hazard, recognised by NIOSH and ISO 45001. From most to least effective the five levels are elimination (remove the hazard entirely), substitution (replace it with a less hazardous alternative), engineering controls (isolate the worker from the hazard), administrative controls (change the way people work), and personal protective equipment (protect the individual worker). The order is the point: a control higher on the list is more reliable than one below it because it does not depend on the worker doing the right thing.

PPE is the last resort, not a primary control, because it fails when the worker takes it off, wears it wrong, or the equipment degrades — and the consequence of that failure is the full, uncontrolled hazard. A program that controls a high-energy hazard with PPE and procedure alone has accepted the hazard at the bottom of the hierarchy, and an incident at that hazard is a predictable outcome. The defensible position is to walk up the list as far as the process allows: substitute before you guard, guard before you instruct, instruct before you issue PPE. See PPE, hazard, and risk.