Hazard Identification, Assessment, and Control Measures
Domain 5 tests hazard identification, assessment, and control: the ISO's continuous size-up and ability to prioritize the hazard most likely to hurt someone now. The exam distinguishes a hazard from a risk.
Core rules
- A hazard is a condition with potential harm; risk is the likelihood and severity of that harm. Assess both, then control.
- Use a 360 size-up, reading smoke and fire behavior, building construction, occupancy, utilities, weather, and crew factors. Update the assessment as conditions change; a single initial size-up is not enough.
- Apply the hierarchy of controls: elimination, substitution, engineering controls, administrative controls, and PPE. PPE is the last line, not the first.
- Control measures must be specific and assigned: evacuation, defensive strategy, ventilation, shutoffs, exclusion zones, atmospheric monitoring, and rehab.
Worked example
A floor sags near a doorway, smoke is pulsing from gaps, and crews report heat. The ISO identifies lightweight truss construction, probable void-space fire, and collapse potential. Controls: withdraw interior crews, establish collapse zone, switch to defensive, and monitor exposures. The ISO does not simply order 'more PPE'.
Traps
Listing hazards without prioritizing; calling PPE a control when withdrawal is needed; missing construction cues; failing to reassess after ventilation or door control changes.