What is the primary purpose of smoke control systems that use opposed air flow in open floor plan buildings?

• A. Keep smoke from migrating into unaffected areas.
• B. Dilute the contaminants.
• C. Collect smoke at its highest point in a large space.
• D. Maximize the movement of smoke from one building to another.

Answer: (A)

Opposed air flow smoke control creates two air streams moving in opposite directions to form a boundary that confines smoke to a designated area. In open floor plan buildings, where there are few barriers, this setup pushes or contains the smoke away from spaces that must remain tenable, such as stairwells, exits, and occupied zones, thereby preventing smoke migration into those unaffected areas. The goal is to preserve safe paths of egress and maintain visibility and air quality where people are evacuating. Dilution is not the primary aim of this system—the focus is containment by a pressure barrier. Collecting smoke at the highest point or intentionally moving smoke between buildings would undermine safety and are not the intended purpose of opposed air flow systems.