5.3 Hierarchy of Controls

5.3 Hierarchy of Controls

After you assess risk, HEMP Step 3 asks you to control it. The hierarchy of controls is the standard order for choosing measures from most effective to least effective. It appears throughout Nigerian HSE training, client standards, and the ISPON Level 1 syllabus. Memorise the order, know why the top levels are preferred, and practise applying Nigerian workplace examples.

The Hierarchy Order (Most Effective → Least Effective)

Memory phrase: "Eliminate, Substitute, Engineer, Administer, then PPE."

Level-by-Level Teaching with Nigerian Flavour

1. Elimination

Elimination means the hazard is no longer present.

Examples:

• Cancel a non-essential confined-space entry by redesigning the task so cleaning is done from outside
• Remove obsolete chemical drums from site instead of storing them near hot work
• Use pre-fabricated modules so workers spend fewer hours at height on a Lagos high-rise
• Reroute a cable so temporary trailing leads are not needed across a walkway

If you can not do the hazardous thing at all, you have eliminated exposure. Elimination is not always possible (you cannot eliminate hydrocarbons from a refinery), but when it is possible it is the gold standard.

2. Substitution

Substitution keeps the function but uses a less hazardous material, process, or method.

Examples:

• Replace a highly toxic solvent with a lower-toxicity cleaner for workshop degreasing
• Use water-based paint instead of high-VOC solvent paint where specification allows
• Choose a quieter compressor model to reduce noise at a fabrication yard
• Use a mobile elevating work platform with proper controls instead of an improvised ladder setup for repeated elevated access (method substitution)

Trap: substitution fails if the replacement introduces equal or worse risk (for example a "safer" chemical that is more flammable, or a method that creates new fall exposure). Always reassess after substitution.

3. Engineering Controls

Engineering controls reduce exposure through physical design, equipment, and barriers—without relying only on perfect human behaviour.

Examples:

• Machine guards on rotating equipment in a manufacturing plant in Ogun
• Local exhaust ventilation for welding fumes in a Port Harcourt fabrication shop
• Acoustic enclosures around noisy generators
• Gas detection with automatic alarms interlocked to ventilation or shutdown logic
• Bunds and drip trays under diesel tanks to contain spills
• Edge protection, hole covers, and scaffolding that meets design standards
• Interlocks that prevent opening a panel while equipment is energised

Engineering controls are powerful because they protect everyone nearby, not only the worker who remembered to put something on.

4. Administrative Controls

Administrative controls manage risk through systems, rules, and people processes:

• Safe work procedures and Job Safety Analysis (JSA)
• Permits to work (hot work, confined space, excavation—awareness at Level 1)
• Training, competence assurance, and toolbox talks
• Warning signs, barriers, and exclusion zones
• Shift limits and job rotation to reduce fatigue or noise dose
• Supervision and stop-work authority
• Housekeeping schedules and traffic management plans

Administrative controls are essential, but they fail when people are rushed, untrained, or pressured to skip steps. That is why they sit below elimination, substitution, and engineering.

5. PPE (Personal Protective Equipment)

PPE is equipment worn or held by a person to reduce exposure: hard hat, safety boots, eye protection, gloves, hearing protection, respirator, flame-resistant clothing, harness (as part of a fall system), and so on.

PPE is vital in Nigerian industry—but it is the last resort / final barrier because:

1. The hazard still exists; PPE only reduces the dose or injury severity if exposure happens.
2. Protection depends on correct selection, fit, training, use, and maintenance.
3. PPE can fail (torn gloves, wrong filter cartridge, poorly fitted respirator).
4. PPE usually protects only the wearer, not co-workers who may also be exposed.
5. Comfort and heat stress in Nigerian outdoor work can reduce compliance if PPE is the only strategy.

Correct mindset: Use PPE with higher controls, not instead of them. A welder still needs fume control and screens where practicable, plus welding PPE. A scaffolder needs proper scaffold design and fall protection systems as specified—not "hard hat only."

Hierarchy Table for Quick Revision

Combining Controls

Real jobs almost always need a bundle:

Example — Cement bag handling on a construction site in Abuja

• Substitution/engineering: use bulk bags and mechanical lifting aids where possible
• Administrative: manual handling training, team lifts, rest breaks in heat
• PPE: gloves, dust mask/respirator as specified, safety boots

Example — Potential H₂S exposure in oil and gas

• Engineering: fixed detection, ventilation, process design
• Administrative: permits, gas testing, buddy systems, emergency drills
• PPE: breathing apparatus as required by the task and atmosphere

Never treat one hard hat poster as a complete control strategy for a high-risk task.

Common Exam Traps (Choosing PPE First)

ISPON-style questions love these mistakes:

Linking Hierarchy to HEMP and Risk Matrices

• Identify hazards that need control.
• Assess which risks are high.
• Control using the hierarchy (stronger controls lower residual risk more reliably).
• Recover still needed because even good hierarchies can fail (detection, emergency response).

When a matrix shows high residual risk after "PPE only," the exam-correct answer is usually to move up the hierarchy, not to buy a second pair of gloves and hope.

Practical Decision Order for Level 1 Workers

When you face a hazard on site, ask in this order:

1. Can we remove this hazard or task element?
2. Can we replace it with something safer?
3. Can we guard, ventilate, contain, or interlock it?
4. What procedures, training, permits, and supervision are required?
5. What PPE is mandatory as the final layer?

If someone pressures you to jump straight to step 5 for a high-energy hazard, escalate. That pressure is a classic symptom of weak HSE culture.

Exam Focus

Drill the exact order, define each level in one sentence, and practise scenario questions where several options are "controls" but only one sits at the correct hierarchy level asked. Prefer answers that remove or engineer out risk over answers that only warn or kit-up the worker.