The Hierarchy of Controls

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

The controls are ranked from most effective to least effective. Engineers must always attempt the highest level of control first.

1. Elimination (Most Effective)

Physically remove the hazard entirely.

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

2. Substitution

Replace the hazard with something less dangerous.

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

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

4. Administrative Controls

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

• Example: Limiting the time a worker is allowed to spend in a loud room, requiring safety training, or putting up 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 remove 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.