What Is Hierarchy of Controls
The hierarchy of controls is a five-tier system that ranks hazard reduction methods by effectiveness. OSHA and the CDC use this framework to guide safety decisions across industries. The five levels, from most to least effective, are: elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE). Most workplaces and homes need to use multiple tiers together, not just one.
The Five Levels in Order
- Elimination: Remove the hazard entirely. Example: Replace a chemical cleaning process with a non-toxic alternative, or remove an old lead-based paint from a home rather than encapsulating it.
- Substitution: Replace a hazardous substance or process with a less dangerous one. Example: Swap out silica dust-producing tools for water-suppression systems on job sites.
- Engineering Controls: Design physical changes to isolate workers from the hazard. Examples include ventilation systems for chemical handling, guardrails for fall protection, and fire suppression systems in homes and workplaces.
- Administrative Controls: Establish work practices, training, and scheduling to reduce exposure. Examples: rotating workers to limit chemical exposure duration, lockout-tagout procedures, emergency evacuation drills, and safety signage.
- PPE: Provide personal protective equipment as a last resort. Examples: respirators, gloves, safety glasses, and hearing protection. PPE alone does not eliminate hazards and should never be the only control method.
OSHA Requirements and Compliance
OSHA standards require employers to follow the hierarchy when developing safety programs. Under 29 CFR 1910.1450 and similar standards, organizations must document which controls they have selected and why. During safety audits, OSHA inspectors verify that companies have evaluated higher-tier controls before relying on lower ones. For example, if a workplace uses only respirators to manage chemical exposure, OSHA may cite violations if engineering controls (ventilation) or substitution (safer chemicals) were feasible but not attempted.
Practical Applications in Workplaces and Homes
- Fire Safety: Elimination (removing ignition sources), substitution (fireproof materials), engineering (fire alarms and sprinklers), administrative (evacuation procedures), and PPE (hard hats during evacuation) work together to reduce fire risk.
- Chemical Handling: Use non-toxic cleaners if possible (elimination), upgrade to safer formulations (substitution), install local exhaust ventilation (engineering), limit worker shift length (administrative), and provide gloves and respirators (PPE).
- Emergency Preparedness: Administrative controls like evacuation plans and regular drills reduce injury during emergencies. Engineering controls like backup generators and reinforced safe rooms provide physical protection.
- Home Safety: Homeowners can eliminate fall hazards by removing clutter, substitute steep ladders for safer step stools, install handrails on stairs (engineering), establish rules about not running (administrative), and wear appropriate footwear (PPE).
Why the Order Matters
The hierarchy ranks controls by how reliably they prevent injury. Elimination and substitution remove the root cause. Engineering controls separate people from hazards without changing behavior. Administrative controls depend on human compliance and can fail if workers are tired or distracted. PPE only works if fitted correctly, maintained, and worn consistently. A safety audit should trace through each level and document why lower-tier controls were chosen when higher ones were not feasible.
Common Questions
- Can I use only PPE to meet safety requirements? No. OSHA and other regulatory bodies require you to evaluate and use higher-tier controls first. PPE is required only after you have exhausted feasible engineering and administrative measures.
- How do I document my hierarchy decisions for a safety audit? Create a written assessment for each major hazard. List which control tier you selected, why you selected it, what alternatives you considered, and why they were not feasible. This documentation demonstrates due diligence if an inspector or insurer questions your approach.
- What if multiple controls are needed? Most real-world safety plans combine controls from all five levels. A chemical storage area might eliminate excess inventory (elimination), substitute safer products (substitution), use ventilation hoods (engineering), require training and inspection schedules (administrative), and provide respirators and gloves (PPE).
Related Concepts
- Engineering Controls details the physical design solutions that isolate hazards.
- Administrative Controls covers the policies, training, and procedures that reduce exposure.