Which feature helps ensure that clean air flows from the OR to surrounding spaces, reducing contamination risk?

• A. Positive-pressure ventilation
• B. Negative-pressure ventilation
• C. No filtration
• D. Ultraviolet-only lighting

Answer: (A)

Maintaining a higher air pressure in the operating room than in surrounding spaces makes clean air flow outward, from the OR to the adjacent areas. This outward flow helps push potential contaminants away and prevents unfiltered hallway air from entering the sterile field, especially when doors are opened. In practice, the OR is kept positive relative to the corridors, and the air is filtered (typically with HEPA filtration) and exchanged frequently to dilute any contaminants.

If the system were negative pressure, it would pull air from the surrounding spaces into the OR, increasing the risk of contaminants entering the sterile field. Filtration alone doesn’t control the direction of airflow, and ultraviolet lighting addresses disinfection of surfaces or air only to a limited extent without the airflow pattern in place. So, positive-pressure ventilation is the feature that best ensures clean air moves from the OR to surrounding spaces, reducing contamination risk.