To limit the probability of the spread of smoke from one part of a walkway to another part of the walkway in a fire situation, which could lead to delays in evacuation or movement to a safe place, which could lead to harm to persons.
To limit the probability of the spread of smoke from one part of a walkway to another part of the walkway in a fire situation, which could lead to delays or ineffectiveness in emergency response operations, which could lead to the spread of fire, which could lead to harm to persons.