To limit the probability that fire will spread into an exit by means of a plenum, which could lead to delays in the evacuation or movement of persons to a safe place, which could lead to harm to persons.
To limit the probability that fire will spread into an exit by means of a plenum, which could lead to emergency responders being delayed in gaining access to floor areas, which could lead to delays or ineffectiveness in fire emergency response operations, which could lead to:
To limit the probability that fire will spread into an exit by means of a plenum, which could lead to the spread of fire from one floor area to another floor area, which could lead to harm to persons in the other floor area.