Contamination characteristics and airflow regulated transport of microbial aerosols in a hospital respiratory ward

Airborne transmission of microbial aerosols in hospital environments has been increasingly recognized as an important factor in healthcare-associated infections. However, their distribution and transmission mechanisms in hospital wards remain unclear. To address this gap, this study investigated a respiratory ward in a hospital in Beijing. An integrated approach combining air impactor sampling, high-throughput sequencing, and computational fluid dynamics modeling was employed to systematically examine microbial concentrations, particle size distributions, community composition, and dispersion behavior under indoor airflow conditions. The results showed that corridors functioned as hotspots for microbial aerosol contamination. More than 50% of culturable particles were smaller than 3.3 μm, indicating the potential for penetration into the alveolar region and subsequent inhalation exposure. Distinct differences were observed between airborne and surface associated microbial communities. Air samples were predominantly characterized by Staphylococcus and Aspergillus, including genera with potential pathogenic relevance, and exhibited concentrated high relative abundance patterns. Numerical simulations further demonstrated that airflow organization critically governs the transport and deposition of aerosols. A health risk assessment based on infection probability revealed that the infection risk exceeds 80% in high‑risk zones, such as the area between the patient bed and the washbasin. Both bacterial and fungal communities displayed pronounced spatial heterogeneity, closely associated with airflow pathways. By integrating field measurements with numerical simulations, this study not only characterizes spatial distributions but also elucidates airflow-driven transport pathways, thereby advancing the mechanistic understanding of microbial aerosol transmission and providing a scientific basis and practical insights for ventilation optimization and infection control.