What is a stairway designed to limit heat, smoke, and toxic gases called?

A stairway designed to limit heat, smoke, and toxic gases is referred to as a smokeproof enclosure. This design is crucial in enhancing the safety of evacuation routes during a fire. Smokeproof enclosures are specifically constructed to resist the infiltration of smoke and heat, allowing individuals to move safely through the stairway without being exposed to hazardous conditions.

These enclosures typically feature sealed doorways and ventilation systems that help manage smoke movement, ensuring that occupants can escape effectively even in heavily smoke-laden environments. The goal is to provide a viable exit path for building occupants while also protecting the staircase as a critical route for firefighters and emergency responders.

In contrast, other options like fire escapes are external structures that allow occupants to exit a building, but they do not provide the same level of protection against smoke and toxic gases as a smokeproof enclosure. Smoke barriers are intended to limit the movement of smoke within a building, but they do not specifically pertain to stairways. Lastly, emergency exits refer to the designated pathways or doors for evacuation, but again, they lack the specialized features required to qualify as smokeproof enclosures.