Personnel exposure studies to multi-source diffusion of bioaerosols under biosafety laboratory - Level 2 plus operating conditions.

Biosafety Laboratories are utilized for the handling of hazardous samples and pathogenic agents. However, the accidental bioaerosol dissemination has triggered many laboratory-acquired infections. Thus, this study elucidated the diffusion of leaked bioaerosols in the laboratory. Three operational conditions and three bioaerosol sources were considered. Firstly, bioaerosol experiments were conducted to measure the spatial concentration of bioaerosols. Subsequently, the visualized airflow and real-time distribution of bioaerosol were obtained using Euler-Lagrange model. Furthermore, the infection risk of laboratory technicians (LTs) was quantitatively assessed using an improved Wells-Riley equation. The results indicate that the usage of biosafety cabinets and the influence of LTs on the airflow organization are significant factors. Released bioaerosols preferentially deposited on surfaces near the release source, with over 50 % of bioaerosol settling on the biosafety cabinet, central worktop, and ceiling. The initiation of the biosafety cabinet can reduce the deposition on LT surfaces by 5-20 times. The LT-3, located downstream of the airflow, consistently posed the highest risk, with infection probabilities reaching up to 19.9 %, even when protective devices were considered. This study serves as a reference for controlling the bioaerosols in biosafety laboratories and for identifying critical steps in the disinfection and sterilization processes.