The mass-casualty decontamination exercise — throughput under pressure

Why decontamination fails at scale

Individual decontamination is procedure; mass decontamination is logistics under fear. The corridor that processes one compliant casualty flawlessly jams when thirty arrive in ten minutes, a third of them stretcher-bound, several non-compliant, and most of them uncontaminated but convinced otherwise. The exercise exists to find the jam points — undressing bottlenecks, water-supply limits, re-dress and tracking failures, triage decisions made in the wrong zone — while they are still rehearsal problems.

Design parameters

• Arrival rate above plan — the corridor must be stressed past its design throughput, because real casualty flows do not respect planning assumptions
• Mixed casualty profile — ambulatory, stretcher, non-compliant, paediatric, and worried-well roleplayers, each stressing a different corridor function
• Contamination tracking — simulated contaminant (UV marker or equivalent) on roleplayers so clean-side transfer is measured, not guessed
• Weather and duration realism — decon in rain, cold, or darkness changes throughput and safety calculus; daylight-only programmes train a fair-weather capability
• Triage integration — medical priority and decontamination priority conflict by design; the exercise must force the sequencing decision

Metrics that separate pass from fail

Casualties per hour through each corridor stage against the stated design rate; clean-side contamination events (the single most important number of the exercise); time-to-first-decon for the highest-priority casualty; tracking integrity — can the organisation say, afterwards, who went through and where they went; and responder safety violations during doffing at the end of a long, wet, tiring serial. The recurring failure mode: the corridor works until the first non-compliant casualty, and then zone discipline collapses around the exception. Sequencing decisions of this kind are best rehearsed first in a command-level tabletop.

This exercise pairs naturally with the chemical-release exercise as its upstream event, inside the progressive formats described in the scenario design overview. Mission Support delivers mass-decontamination exercises with structured evaluation against throughput criteria within its CBRN training programme.