P-B-3 Zone-wide Decontamination (S) is a Mechanic in SCP: Secret Laboratory that locks down Light Containment Zone after a set period, preventing players inside the zone from prolonging the round, while also making the overall playable area of Site-02 smaller.
The process is announced and initiated by C.A.S.S.I.E. as an emergency breach procedure.
C.A.S.S.I.E. will announce to everyone in Light Containment Zone about a decontamination procedure that is scheduled to occur in 15 minutes. A 15-minute timer will then display at both LCZ checkpoints and both elevator systems located in HCZ.
The timer is actually sped up, and the in-game time to decontamination is 11 minutes and 45 seconds. This is done to apply pressure to the players in LCZ.
As the round progresses, C.A.S.S.I.E. will announce the procedure's status to the Zone at the 10, 5, and 1-minute mark. At the 30-second mark, C.A.S.S.I.E. will announce a countdown. At this point, all doors in the zone will open. Elevator doors are not automatically called.
Once the timer stops, the process closes and locks all doors in the Zone. Vents in LCZ will begin to pour out lime, a corrosive gas that damages all players still in the Zone, including SCPs. This is announced to the entire facility.
The only method of escape at this point, is to teleport via the Remote Admin panel.
The LCZ Checkpoint Screens at the start of the round.
The Screens at the start of C.A.S.S.I.E. announcing decontamination.
The timer on the LCZ Checkpoint Screens, appears a couple seconds after C.A.S.S.I.E. says "in T-minus 15 minutes".
The timer as it appears on the screen above the elevators connecting Light and Heavy Containment Zone.
The timer during the last 30 seconds.
The checkpoint screens if the server uses Config or Remote Admin to disable the Decontamination Process.