How is a stairway that prevents the entry of smoke known?

A stairway designed to prevent the entry of smoke is known as a smokeproof enclosure. This type of stairway is specifically engineered to maintain a clear path for evacuation during a fire situation while restricting smoke from entering the stairway, thereby enhancing the safety of building occupants as they exit.

Smokeproof enclosures are typically constructed with materials and design features that ensure they remain pressurized, which helps keep smoke at bay. This includes the use of sealed doors, proper ventilation systems, and possibly even fan systems that maintain the integrity of the enclosure against smoke infiltration.

In contrast, terms like fire ladder, protected stairway, and emergency stairway may relate to other features or functions within fire safety but do not specifically address the prevention of smoke entry in the way that smokeproof enclosures do. A fire ladder serves a different purpose, typically for rescue purposes. A protected stairway may allow for a safe escape but might not have the specific design elements to prevent smoke. An emergency stairway can refer to any stairway used in emergencies without specifying smoke prevention. Hence, the designation of smokeproof enclosure is the most accurate in this context.