CBRN FM 3-11 / ATP 3-11.32

CBRN Operations

Chemical, Biological, Radiological, and Nuclear defense, protective equipment, and decontamination.

MOPP Levels

  • Mission Oriented Protective Posture (MOPP) levels dictate how much protective equipment is worn:
  • MOPP 0: Protective gear available within arm's reach. Mask carried.
  • MOPP 1: Overgarment worn (trousers and jacket). Mask carried.
  • MOPP 2: Overgarment AND overboots worn. Mask carried.
  • MOPP 3: Overgarment, overboots, AND mask with hood worn. Gloves carried.
  • MOPP 4: Full protective ensemble — all items worn including gloves.

M50 Protective Mask

The M50 Joint Service General Purpose Mask (JSGPM) replaced the M40 series. It provides protection against chemical and biological agents and radioactive particles.

  • The standard is to don, clear, and seal the mask within 9 seconds. You have an additional 6 seconds to pull the hood over and zip the overgarment (15 seconds total).
  • The mask utilizes twin M61 filters (NOT C2A1 canisters).
  • Perform a positive and negative pressure check immediately after donning to ensure a proper seal.

Alarms and Signals

  • Vocal Signal: 'GAS GAS GAS' repeated three times.
  • Visual Signal: Extend both arms horizontally, bend at the elbows, and tap the top of your helmet with closed fists three times.
  • Audible Signal: Banging two metal objects together rapidly, or a continuous ringing of a siren/bell.
  • All Clear Signal: Given ONLY by the commander after proper testing indicates the area is safe.

Decontamination

There are three levels of decontamination:
1. Immediate Decontamination: Performed by the individual Soldier to save lives and minimize casualties (skin decon, personal wipedown, operator's wipe down).
2. Operational Decontamination: Vehicle washdown and MOPP gear exchange conducted by the unit to sustain operations.
3. Thorough Decontamination: Detailed equipment and personnel decontamination. Conducted at a dedicated site to reduce contamination to negligible risk levels.

Board Tips

DO NOT say the M50 mask uses C2A1 canisters — it uses M61 filters. Know all 5 MOPP levels and what gear is added at each stage. Know the 9-second masking standard (and the 15-second total time for the hood). The vocal alarm 'GAS GAS GAS' and the visual hand-and-arm signal are classic board questions. Be able to walk the board through the exact steps of donning, clearing, and sealing your mask.