What type of system may be provided for fire emergency use in enclosed stairs in lieu of smoke shafts?

A system of pressurization is designed specifically to protect enclosed stairways during a fire emergency by preventing smoke infiltration. When a fire occurs, maintaining a smoke-free environment in stairwells is critical for safe evacuation as well as access for firefighters.

Pressurization systems work by creating a higher air pressure within the stairwell compared to the surrounding areas. This is often achieved by using fans to force air into the stairwell, which effectively keeps smoke from entering the space. The system is particularly beneficial in high-rise buildings where smoke can spread rapidly.

While other systems may be used in various contexts, such as purging systems that clear smoke after a fire or decontamination systems that clean harmful substances, they do not provide the same level of ongoing protection for evacuating occupants as pressurization does. This makes pressurization the appropriate and effective choice for enhancing safety in enclosed stairs during fire emergencies.