Hazard Identification, Risk Assessment, and Control
This domain tests whether you can find hazards systematically, judge risk with a defensible method, and select controls in the correct order. Items often present a scenario and ask what should happen next: identify, assess, control, verify, or reassess.
Hazard versus risk
A hazard is a potential source of harm: energy, a substance, a condition. Risk is the combination of likelihood and severity of harm given exposure. A hazard exists whether or not anyone is exposed; risk changes with exposure, duration, and controls. Answers that swap the two terms are usually wrong.
Identification tools matched to the situation
- JSA/JHA for task-level work, especially maintenance and high-turnover jobs.
- HAZOP guide words for process deviations in chemical and continuous-flow systems.
- FMEA for failure modes, effects, and detection gaps in equipment and systems.
- What-if analysis, checklists, walkthroughs, worker interviews, and trend review of incidents and near misses.
- Prevention through Design (ANSI/ASSP Z590.3) at the specification and layout stage, where risk can be eliminated cheapest.
Hierarchy of controls
Elimination, substitution, engineering controls, administrative controls, then PPE. PPE is the last line and depends on human behavior every shift.
Worked example
A press task scores likelihood 4 (daily exposure) and severity 4 (permanent disability) on a 4x4 matrix: 16, high risk. An interlocked barrier guard reduces likelihood to 1 while severity stays 3 if the guard fails: score 3, low. Residual risk is documented and the guarding is verified by test. Had the team only added a warning sign and toolbox talk, likelihood might fall to 3 for a score of 12, still high. That comparison is the exam's point: administrative controls rarely move a high risk into the tolerable band.
Traps that cost marks
- Selecting training or PPE first when engineering is feasible.
- Multiplying ordinal ranks and claiming 16 is 'four times' worse than 4; treat scores as bands.
- Ignoring non-routine tasks: startup, shutdown, maintenance, upset conditions, and changes.
- Treating a low score as permission to skip controls rather than as residual risk requiring monitoring.