Hazmat
Hazardous materials incidents involve substances that are toxic, flammable, corrosive, explosive, radioactive or infectious. Know the Hazmat emergency action principles: isolate, deny entry, and notify - establish an exclusion zone, keep people out, and call for specialist resources. The initial isolation distance depends on the substance and conditions; the Emergency Response Guidebook (ERG) provides isolation and protective action distances based on the UN number and guide page.
Understand PPE levels: Level A (fully encapsulating, highest), Level B (splash protection with SCBA), Level C (air-purifying respirator), Level D (work clothing). Know placards and UN numbers identify hazards and substances, and that wind direction determines the downwind hazard area - approach from upwind and uphill. Decontamination of people and equipment is essential; gross decontamination removes most contamination quickly.
Traps: questions often test whether to rescue casualties without PPE - never enter without appropriate protection. Another trap: approaching from downwind. Do not assume a substance is safe because it has no smell.
Rule of thumb: Approach from upwind, uphill and upstream; isolate the area; do not touch or inhale unknown substances.
Worked example: A tanker leaks an unknown liquid. The correct first actions are to isolate the area, keep people upwind, note the UN number and placard, and call specialist hazmat resources - not to plug the leak.