The impact of air change rate on the air quality of surgical microenvironment in an operating room with mixing ventilation

Abstract

Transmission of airborne microbe-carrying particles (MCPs) is one of the key factors causing surgical site infection during surgical procedures. In operating rooms (ORs) with mixing ventilation, air change rate may determine the MCPs transmission and indoor air quality in the surgical microenvironment. This study focuses on the impact of the air change rate on the air quality in the surgical microenvironment in ORs. Experimental measurements of MCPs were carried out in a full-scale operating room laboratory (OR Lab) with different air change rates: 10 air changes per hour (ACH), 15 ACH, 20 ACH, and 26 ACH. Nitrous oxide, N2O, was used as tracer gas to simulate MCPs from five surgical staff. The N2O concentration (Cr) in the OR under fully mixed condition and local ventilation index (εv) were used to evaluate the ventilation efficiency of the OR Lab. The experiment results verified that the air change rate is a key factor influencing the concentration of MCPs. The higher exposure risks of surgical incision in the surgical microenvironment may be mitigated with increasing ACH. The current most commonly recommended air change rate should be modified to improve the air quality of surgical microenvironment in ORs with mixing ventilation. Significant difference of contaminant concentration among the air-exhaust outlets indicates the location of medical equipment may affect the efficiency of exhaust. This study clarifies the impact of the air change rate on the air quality in the surgical microenvironment in ORs and contributes to developing new ventilation guidelines for ORs.