Hazard Prevention and Control
The hierarchy is the answer key
Elimination → substitution → engineering controls → administrative controls → PPE. Questions frequently ask you to pick the best control, and the best control is always the highest feasible one, not the most familiar one. Prevention through design - removing the hazard at the concept or procurement stage - outranks everything applied after the fact.
Concepts to know cold
- Engineering controls change the physical environment: guarding, interlocks, local exhaust ventilation, enclosure, automation, noise dampening.
- Administrative controls depend on people: procedures, rotation, permits, training, signage, housekeeping schedules.
- PPE is the last line of defense; it requires a written hazard assessment, correct selection, fit testing where applicable, training, maintenance, and replacement.
- LOTO is a control sequence - notify, shut down, isolate, apply locks and tags, release stored energy, verify zero energy - and verification is the step most often skipped.
Traps
Items that select PPE or "additional training" as the primary fix. Items that call a warning sign or a written procedure an engineering control. Items that assume a control remains effective forever - controls degrade and need periodic verification and effectiveness checks. Also expect distractors that confuse isolation with de-energization; both are steps, not the whole procedure.
Rule of thumb
Rank every control by how much it depends on human behavior. The more it depends on someone remembering to do something correctly every time, the weaker it is. If the control fails when a worker is tired or rushed, it is administrative.
Worked example
Operators are exposed to solvent vapor. "Train operators to work quickly" and "issue respirators" are weak answers; "enclose the process and add local exhaust ventilation" is the engineering answer and ranks above both.