What is the function of a smoke curtain in stairwell countermeasures?

• A. To seal stairwells permanently.
• B. To increase airflow into stairwells.
• C. To provide decorative appearance.
• D. To restrict smoke from entering stairwells and maintain a tenable egress path for occupants and firefighters.

Answer: (D)

Smoke control in stairwells aims to keep the exit route usable during a fire. A smoke curtain acts as a deployed barrier that slows or stops smoke from moving into the stairwell, creating a protected path for people to evacuate and for firefighters to reach the scene. By limiting smoke infiltration, it helps maintain visibility, lowers smoke concentration, and reduces heat buildup, extending the time occupants have to get out and responders have to operate. It is not meant to seal stairs permanently, nor to increase airflow into the stairwell, nor to be decorative. Its real purpose is to restrict smoke from entering the stairwell and maintain a tenable egress path for occupants and firefighters.