Influence of Surgical Staff Movement on Airborne Particle Concentrations in Operating Rooms with Laminar and Mixing Ventilation

Operating rooms (ORs) are critical environments where airborne contamination control is essential for reducing the risk of surgical site infections. Ventilation strategies typically rely on either laminar air flow (LAF) systems or mixed ventilation (MV). For several decades, the effectiveness of these approaches, particularly the ability of LAF to minimize particle concentrations near the surgical wound has been widely debated. Numerous experimental studies with stationary mannequins have concluded that LAF provides superior protection by establishing a clean air zone around the operating field. However, recent findings suggest that the situation becomes more complex once healthcare personnel are moving within the room, disturbing the airflow patterns and potentially transporting contaminants into the critical zone. This study presents detailed measurement results from a newly established full-scale operating room laboratory, specifically designed to evaluate airflow performance under realistic surgical conditions. The laboratory setup allows for controlled experiments with both LAF and MV configurations, including scenarios with surgical staff activity. Particle concentrations and flow structures were measured in critical zones close to the operating site. The experimental results provide new insights into the limitations of steady-state mannequin-based studies, highlighting the importance of movement in assessing OR air quality. The findings contribute to the ongoing discussion of optimal OR ventilation design and operation and suggest that strategies for controlling and mitigating airborne pollutants must account not only for the ventilation principle itself, but also for realistic workflow conditions. This research is supported by the Norwegian Research Council.