How is the breathing zone best described?

• A. The region around a person's mouth and nose where inhaled air is drawn.
• B. The entire room volume.
• C. The outdoor air intake location.
• D. The ductwork near the supply diffusers.

Answer: (A)

The breath zone is the air right around a person’s face—the region from which inhaled air is drawn. It’s the part of the room air that actually enters the lungs, so it’s the focus for evaluating occupants’ exposure to contaminants. That’s why this description best fits the breathing zone: it centers on the air the person breathes, not the entire room, not external air intake locations, and not the ductwork itself, which are parts of the delivery system rather than the air the occupant inhales.