Which component is essential to maintain negative pressure in a BE room?

• A. Dedicated exhaust system
• B. Weather sealing of doors with no exhaust
• C. Sealed windows and no ventilation
• D. Increase incoming air without exhaust

Answer: (A)

To keep a BE room under negative pressure, you must remove more air from the room than you supply. The dedicated exhaust system does exactly that by actively pulling air out, which lowers the internal pressure relative to surrounding spaces. This pressure difference ensures that air flows into the room through gaps rather than out of it, helping contain contaminants inside.

Simply weather sealing doors without any exhaust won’t remove air, so pressure can’t be reliably maintained. Sealed windows with no ventilation stop air exchange entirely and won’t create the inward flow needed for negative pressure. Increasing incoming air without an exhaust tends to raise the room’s pressure, potentially reversing the direction of airflow.

So, an active exhaust component is essential to sustain negative pressure.