Negative Pressure to Prevent Cross-Contaminantion

Negative Room Pressure to Prevent Cross-Contaminantion A negative pressure room includes a ventilation system designed so that air flows from the corridors, or any adjacent area, into the negative pressure room, ensuring that contaminated air cannot escape from the negative pressure room to other parts of the facility.

Negative Pressure Room

Air naturally moves from areas of higher pressure to areas of lower pressure. When negative pressure exists, a continuous air current enters the room under the door, which prevents airborne particles generated in the room from escaping into the corridor. A common example of negative pressure is a bathroom with an exhaust fan. When operating correctly, and with the door closed, the fan prevents unwanted odors and moisture from escaping.

Negative pressure is created by balancing the room’s ventilation system so that more air is mechanically exhausted from a room than is mechanically supplied. This creates a ventilation imbalance, which the room ventilation makes up by continually drawing in air from outside the room. In a well-designed negative pressure room, this air is pulled in under the door through a gap (typically abot one half-inch high) for that purpose. Other than this gap, the room should be as airtight as possible to prevent air from being pulled in through cracks and gaps, such as those around windows, light fixtures, and electrical outlets. Leakage from these sources can compromise or eliminate room negative pressure, even if the system is balanced to achieve it.