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Hierarchy of Control - Quick Reference

Overview​

The Hierarchy of Control is a systematic approach to eliminating or minimizing risks, ordered from most effective to least effective.

[!important] Legal Requirement (WHS Reg 36) When controlling risks, must implement controls in accordance with hierarchy:

  1. Eliminate the hazard
  2. If elimination not reasonably practicable, minimize risk by:
    • Substitution
    • Isolation
    • Engineering controls
  3. If risk remains, minimize by:
    • Administrative controls
    • PPE

Start at top, work down. Higher levels more effective.

The Six Levels​

Level 1: Elimination ✅ MOST EFFECTIVE​

Remove the hazard entirely.

Examples:

  • Design out fall hazard (prefabricate at ground level instead of working at heights)
  • Don't do hazardous work (use alternative construction method)
  • Remove asbestos before other work

Why most effective: No hazard = no risk

Details: Elimination

Level 2: Substitution​

Replace with something less hazardous.

Examples:

  • Water-based paint instead of solvent-based (reduced flammability, vapor exposure)
  • Electric saw instead of petrol saw (lower noise, no exhaust fumes)
  • Non-silica abrasive instead of silica sand for blasting

Why effective: Reduces hazard at source

Details: Substitution

Level 2: Isolation​

Separate people from hazard.

Examples:

  • Guardrails at edges (physical barrier prevents falls)
  • Barricade around excavation (prevents approach)
  • Noisy equipment in acoustic enclosure or remote location
  • Separate flammable storage from ignition sources

Why effective: People can't reach hazard, can't be harmed

Details: Isolation

Level 2: Engineering Controls​

Control hazard through physical means.

Examples:

  • Local exhaust ventilation (captures silica dust at source)
  • Water suppression for concrete cutting (binds dust)
  • Machine guards (prevents contact with moving parts)
  • RCDs on electrical equipment (cuts power if fault)
  • Rollover protection on excavators

Why effective: Controls hazard at source, doesn't rely on human behavior

Details: Engineering Controls

Level 3: Administrative Controls ⚠️ LESS EFFECTIVE​

Procedures, training, work practices to reduce exposure.

Examples:

  • Safe Work Method Statements (SWMS)
  • Training in safe work procedures
  • Job rotation (reduces exposure duration)
  • Permits to work (hot work permit)
  • Signage and warnings

Why less effective: Relies on human behavior (people forget, take shortcuts, may not understand importance)

Details: Administrative Controls

Level 3: Personal Protective Equipment (PPE) ❌ LEAST EFFECTIVE​

Barrier between worker and hazard.

Examples:

  • Hard hats (falling objects)
  • Safety glasses (flying particles)
  • Hearing protection (noise)
  • Respirators (dust, fumes)
  • Safety harness (fall arrest)

Why least effective:

  • Doesn't remove hazard (if PPE fails, full exposure)
  • Relies on correct, consistent use
  • Protects only individual wearing it
  • Requires maintenance

PPE only used:

  • After higher controls implemented
  • As additional protection (supplement)
  • For residual risks

Details: Personal Protective Equipment

Applying the Hierarchy - Construction Example​

Task: Concrete grinding (silica dust, noise, flying particles)

Hierarchy Application:​

Level 1 - Eliminate:

  • ❌ Can't eliminate grinding (required for surface preparation)

Level 2 - Substitution:

  • ✅ Use diamond grinding wheel (produces less dust than abrasive wheel)

Level 2 - Isolation:

  • ✅ Perform grinding in designated area, away from other workers
  • ✅ Barricade area (prevents other workers entering dust cloud)

Level 2 - Engineering:

  • ✅ Wet grinding (water suppression binds silica dust)
  • ✅ On-tool vacuum extraction (HEPA filter captures dust at source)
  • ✅ Grinder with low vibration handles

Level 3 - Administrative:

  • ✅ SWMS prepared and followed
  • ✅ Trained, competent operator
  • ✅ Time limits (1-hour blocks, rotation between operators)
  • ✅ Air monitoring to verify dust control effectiveness

Level 3 - PPE:

  • ✅ P2 respirator (fit-tested) - additional protection for silica dust
  • ✅ Earmuffs (Class 4, 28dB attenuation) - noise (grinder 100dB)
  • ✅ Safety glasses with side shields - flying particles
  • ✅ Gloves - vibration reduction
  • ✅ Hard hat, safety boots, high-vis - general site PPE

Result: Multiple layers of control. Engineering controls substantially reduce silica and noise. PPE provides additional protection if engineering controls not 100% effective.

Key Principles​

1. Start at top: Always consider elimination first. If not reasonably practicable, work down hierarchy.

2. Combination of controls: Often most effective approach uses multiple levels (engineering + administrative + PPE).

3. PPE is last resort: Never rely on PPE alone where higher-level controls reasonably practicable.

4. Review regularly: As technology advances, higher-level controls may become available.

5. Worker consultation: Workers often have practical insights on most effective controls.

Quick Decision Tree​

Can the hazard be eliminated?
├─ YES → Eliminate (Level 1) ✅
└─ NO → Can we substitute with less hazardous?
    ├─ YES → Substitute (Level 2)
    └─ NO → Can we isolate people from hazard?
        ├─ YES → Isolate (Level 2)
        └─ NO → Can we use engineering controls?
            ├─ YES → Engineering (Level 2)
            └─ NO → Risk still not adequately controlled?
                └─ YES → Add administrative + PPE (Level 3)

At each step: "Is risk now adequately controlled?"

  • If YES: May still add lower-level controls as extra protection
  • If NO: Continue down hierarchy and/or combine controls

Common Mistakes​

❌ Starting with PPE: "We'll just wear respirators" → Should first try elimination, substitution, engineering controls

❌ Administrative controls alone for serious risks: "We'll have a procedure and training" → Serious risks need engineering controls, not just procedures

❌ Assuming elimination impossible without investigation: "We've always done it this way" → May be alternative methods that eliminate hazard

❌ Using lower level when higher level reasonably practicable: "PPE is cheaper than engineering controls" → Cost alone doesn't determine reasonably practicable

Detailed Information​

For comprehensive guidance on each level:

Full process: Step 3: Control Risks