Hazard Identification and Control
The hierarchy is a decision rule
The order is elimination, substitution, engineering controls, administrative controls, and personal protective equipment. Choose the highest level that is feasible and document why lower levels were used. PPE is the last line of defense and is almost never the correct stand-alone answer when the exposure can be designed or engineered out of the task.
Tools to know
A job hazard analysis breaks a task into steps, lists hazards for each step, and assigns controls; it is most credible when the workers who perform the job help build it. Inspections find conditions. Audits test systems. Industrial hygiene sampling quantifies exposure. Compare sampling results against OSHA PELs (enforceable limits), NIOSH RELs (recommended, frequently stricter), and ACGIH TLVs (guidance, not law).
Traps
- Mislabeling controls: ventilation and machine guards are engineering; job rotation, signage, and procedures are administrative; respirators and gloves are PPE.
- Treating a PEL as proof of safety. A PEL is a legal minimum, not a health-based goal.
- Forgetting the hierarchy applies to ergonomic, noise, heat, and chemical stressors, not only to machine hazards.
- Accepting "employee was trained" as a control for a hazard created by equipment or layout.
Worked example
An 8-hour noise TWA of 95 dBA against a 90 dBA PEL. Feasible engineering controls come first: enclosure, muffler, dampening, or process change. Hearing protection and a hearing conservation program are interim or supplemental. Remember the 3 dB exchange rate: each 3 dB increase halves allowable exposure time.
Rule of thumb: if the control depends on a person remembering to do something every time, keep looking for a control that does not.