2.3 Hierarchy of Controls Implementation

Introduction to the Hierarchy of Controls

Once a hazard has been identified and its risk assessed as unacceptable, the Safety Management Professional must determine how to mitigate that risk. The Hierarchy of Controls is the universally accepted framework used to select the most effective and feasible risk reduction measures. Developed by organizations like NIOSH (National Institute for Occupational Safety and Health), this inverted pyramid ranks hazard control strategies from the most reliable and effective at the top, down to the least effective at the bottom.

The core philosophy of the hierarchy is that controlling the hazard at the source is vastly superior to relying on human behavior or protective gear. The levels, in descending order of effectiveness, are: Elimination, Substitution, Engineering Controls, Administrative Controls, and Personal Protective Equipment (PPE).

1. Elimination: Removing the Hazard entirely

Elimination is the pinnacle of the hierarchy. It involves physically removing the hazard from the workplace entirely. If the hazard no longer exists, the risk is reduced to zero.

Because it requires fundamental changes to processes or facility design, Elimination is most effectively implemented during the initial design phase of a project (Prevention through Design). For example, if workers must perform maintenance on equipment located 30 feet in the air, the fall hazard can be eliminated by redesigning the facility so that the equipment is mounted at ground level. Another example is eliminating the need for manual lifting by completely automating a material handling process.

2. Substitution: Replacing the Hazard

When elimination is not feasible, the next best option is Substitution. This involves replacing a hazardous material, process, or piece of equipment with a less hazardous one. The goal is to perform the same task but with lower inherent risk.

Common examples of substitution include replacing toxic, solvent-based paints with water-based alternatives, or swapping out highly abrasive blasting materials (like silica sand, which causes silicosis) for less hazardous media like walnut shells or steel grit. A critical consideration for SMPs when implementing substitution is avoiding "regrettable substitutions"—where the new material introduces a different, poorly understood, or equally dangerous hazard.

3. Engineering Controls: Isolating People from the Hazard

If the hazard cannot be eliminated or substituted, Engineering Controls are the next line of defense. These controls involve making physical changes to the workplace, equipment, or environment to isolate workers from the hazard. Crucially, well-designed engineering controls work independently of worker interactions—they protect the worker passively.

Examples are abundant in industrial settings:

• Machine Guarding: Installing physical barriers around moving parts (like flywheels, belts, and blades) to prevent physical contact.
• Local Exhaust Ventilation (LEV): Installing fume hoods or extraction arms that capture toxic fumes or dust at the source before they can reach the worker's breathing zone.
• Noise Enclosures: Building sound-dampening acoustic enclosures around loud generators or compressors to reduce ambient noise levels.

Engineering controls often require a significant upfront capital investment, but they provide reliable, long-term protection and generally result in lower long-term operating costs compared to managing complex administrative rules or continually purchasing PPE.

4. Administrative Controls: Changing the Way People Work

When engineering controls cannot sufficiently reduce the risk, Administrative Controls are implemented. Unlike the top three tiers which address the hazard physically, administrative controls address the human element. They establish rules, procedures, and scheduling to limit exposure.

Because they rely entirely on human compliance, supervision, and consistent behavior, they are inherently less reliable. Examples include:

• Standard Operating Procedures (SOPs): Written, step-by-step instructions for safely performing hazardous tasks (like Lockout/Tagout).
• Job Rotation: Limiting the amount of time any single worker is exposed to a hazard (e.g., rotating workers out of a high-noise or high-vibration area every two hours).
• Training and Signage: Conducting extensive safety training and posting warning signs or floor markings to designate hazardous areas.

While necessary in almost all safety programs, administrative controls are prone to failure if supervision lapses, if production pressure increases, or if safety culture degrades.

5. Personal Protective Equipment (PPE): The Last Resort

At the very bottom of the hierarchy lies Personal Protective Equipment (PPE). PPE includes gear such as hard hats, safety glasses, respirators, fall protection harnesses, and cut-resistant gloves.

PPE is considered the least effective control method for several critical reasons:

• It does nothing to eliminate or reduce the hazard itself; the hazard is still present in the environment.
• If the PPE fails (e.g., a respirator cartridge is saturated, or safety glasses shatter), the worker is immediately exposed to the full force of the hazard.
• PPE is highly dependent on human factors: workers must wear it correctly, ensure it fits properly, and maintain it diligently. Discomfort often leads to non-compliance.

Therefore, PPE should never be the first choice for hazard control. It should be used as a last resort when higher-level controls are not feasible, as an interim measure while higher-level controls are being installed, or as a secondary backup to provide an extra layer of defense.

Implementing a Combined Approach

In reality, safety professionals rarely rely on a single control. Effective risk management typically involves deploying multiple controls across different levels of the hierarchy to create "defense in depth."

For example, to protect workers from a hazardous chemical process, an organization might substitute the chemical for a less volatile one (Substitution), install an enclosed, automated mixing system with ventilation (Engineering), implement strict handling procedures and training (Administrative), and require operators to wear chemical splash goggles and gloves (PPE). This layered approach ensures that if one control fails, others remain to protect the worker.