Hazard Identification, Risk Assessment and Risk Management
Hazard versus risk
The single most examined distinction: a hazard is a source of potential harm (a rotating shaft, a solvent, a work-at-height edge); risk is the combination of the likelihood of harm and its severity. Candidates lose marks by calling a hazard 'high risk' without a scenario. Always attach the exposure - who, how often, how long, under what conditions.
Choosing a method
Know when each tool fits: JSA/task-based analysis for routine maintenance and procedural work; HAZID for early design; HAZOP for process plant with continuous flows; FMEA for equipment failure modes; bow-tie to link threats, top event, consequences and barriers; LOPA for quantified barrier adequacy. The trap is selecting a method that cannot deliver the output the question needs (e.g. using HAZOP for a manual handling task).
The hierarchy of control
Eliminate, substitute, engineer, administrate, PPE. Questions test whether you apply controls in order and recognise that PPE and training are the weakest, last-resort layers. ALARP means risk is reduced until further reduction is grossly disproportionate in cost and effort - not 'zero risk'.
Residual risk and review
Risk remaining after controls is the residual risk; it must be recorded, accepted by an accountable person, and reviewed when the task, equipment, people or legislation change.
Worked example
A team must clean a confined vessel. Identify the hazard (toxic atmosphere, engulfment, oxygen deficiency). Assess: likelihood of entry without testing is high, severity fatal - intolerable. Apply hierarchy: eliminate by remote cleaning if possible; engineer by isolation and ventilation; administrate by permit and standby; PPE as last layer. Residual risk: low but not nil - reclassify and review before each entry.