The Hierarchy of Controls

When engineers encounter a hazard, they cannot simply hand a worker a hard hat and consider the problem solved. The safety industry uses a universal framework called the Hierarchy of Controls to determine the most effective way to protect people.

Controls are ranked from most effective to least effective. Engineers must always attempt to implement controls at the highest possible level first.

1. Elimination (Most Effective)

Physically remove the hazard entirely.

• Example: Instead of requiring a worker to climb a dangerous 50-meter tower to read a gauge, install a sensor to transmit the reading to the ground. The fall hazard is completely eliminated.

2. Substitution

Replace the hazard with something less hazardous.

• Example: Replacing a highly toxic chemical cleaning solvent with a water-based, non-toxic alternative. The job still gets done, but the severe hazard is gone.

3. Engineering Controls

Isolate people from the hazard by redesigning the physical environment. The hazard is still present, but a physical barrier protects the worker.

• Example: Installing a heavy steel guard over a spinning saw blade, or installing an exhaust hood to suck away toxic fumes before they reach a worker's face.

4. Administrative Controls

Change the way people work through rules, procedures, and warning signs.

• Example: Limiting the time a worker is allowed in a noisy room, requiring safety training, or posting a "Caution: Hot Surface" sign. This is less effective because it relies on human behavior and compliance.

5. Personal Protective Equipment (PPE - Least Effective)

Protect the worker with equipment worn on the body.

• Example: Hard hats, safety glasses, respirators, and earplugs.
• Why is it least effective? PPE does not eliminate or reduce the hazard itself. If the PPE fails, breaks, or is worn incorrectly, the worker is immediately exposed to the full force of the hazard. PPE is the last line of defense.