What does “Hierarchy of controls” mean?
Short answer
The hierarchy of controls ranks ways to reduce a hazard, from strongest to weakest. NIOSH puts removing the hazard first and protective gear last.
Also known as: control hierarchy, hierarchy of hazard controls
The five levels
| Level | What it does (NIOSH) | Example |
|---|---|---|
| 1. Elimination | Removes the hazard at the source | Stop using the hazardous task or chemical |
| 2. Substitution | Uses a safer alternative to the source of the hazard | Replace a solvent with a water-based product |
| 3. Engineering controls | Reduce or prevent hazards from contacting workers | Machine guards, interlocks, ventilation |
| 4. Administrative controls | Set work practices that cut the time, frequency or strength of exposure | Rotation, procedures, signs |
| 5. PPE (personal protective equipment) | Equipment worn to reduce exposure to hazards | Gloves, respirators, hearing protection |
NIOSH says the top three work better because they control exposure without much human effort. The lower levels need workers to comply every time.
Choosing actions
Work from the top. Ask if you can remove the hazard, then swap it out. Record why a higher level is not possible before you settle for a lower one.
The VA's action ranking for root cause analysis follows the same idea, with stronger, middle and weaker actions. Training and new policies are weaker.
Example: after a pinch-point injury, a warning label and retraining are administrative. A fixed guard is engineering. A corrective action plan of only training and signs sits at the bottom.
Mix-up: PPE is not wrong, just the weakest alone. You often need it on top of higher controls. Also, the hierarchy is NIOSH's framework. Specific OSHA standards set their own rules.
Frequently asked questions
Which level of the hierarchy of controls is most effective?
Elimination, which removes the hazard at its source. Then substitution, engineering, administrative controls and PPE. NIOSH says the top three work without much human effort.
Is PPE a bad control?
No. It is the last line of defense and weakest alone, since it needs right choice, fit and use every time. It works best with higher controls.
Is the hierarchy of controls an OSHA requirement?
It is a NIOSH framework used across industries. Some OSHA standards set their own control rules, so check yours. It is still a sound way to rank corrective actions.
Sources
- CDC NIOSH: Hierarchy of controls
- VHA National Center for Patient Safety: Root cause analysis (page and Guide to Performing a Root Cause Analysis, rev. 02/05/2021)
- VHA National Center for Patient Safety: Proactive risk assessment (HFMEA, fault tree analysis, hierarchy of actions)
Reviewed against the sources above on Oct 5, 2026. Rules change: confirm current requirements with the issuing body or your counsel before relying on any summary.
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