Hazard Identification, Risk Assessment, and Control
This domain rewards systematic thinking. Know the difference between a hazard (potential source of harm) and a risk (combination of likelihood and severity). Be fluent in the hierarchy of controls: elimination, substitution, engineering controls, administrative controls, and personal protective equipment, applied in that order of preference. Understand common assessment methods: task-based job hazard analysis, checklists, fault tree and bow-tie analysis, and qualitative risk matrices. Recognize that a risk matrix is a prioritization tool with known subjectivity, not a precise measurement.
Traps include selecting PPE as the primary control when an engineering option exists; treating training as an engineering control; forgetting that residual risk must be evaluated after controls; and confusing hazard identification (finding hazards) with risk assessment (rating them). Another trap is failing to consider routine versus non-routine tasks such as maintenance, startup, and shutdown.
Rule of thumb: controls should be as close to the hazard source as possible, and should not rely on human behavior where a physical barrier works. Worked example: workers are exposed to noise at 95 dBA. Earplugs (PPE) are the last resort. The preferred sequence is to eliminate the noisy process, substitute quieter equipment, enclose or isolate the source, then rotate workers, and finally issue hearing protection with fit testing and audiometric surveillance.