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The transmission and deposition of pathogenic bioaerosols and the subsequent contamination of the air and surfaces is well recognized as a potential route of hospital cross-infection. A full-scale experiment using Bacillus subtilis and computational fluid dynamics were utilized to model the bioaerosol characteristics in a two-bed hospital ward with a constant air change rate (12 ACH). The results indicated that the bioaerosol removal efficiency of unilateral downward ventilation was 50% higher than that of bilateral downward ventilation. Additionally, health care workers (HCWs) and nearby patients had lower breathing zone concentrations in the ward with unilateral downward ventilation. Furthermore, a partition played a positive role in protecting patients by reducing the amount of bioaerosol exposure. However, no obvious protective effect was observed with respect to the HCWs. Only 10% of the bioaerosol was deposited on the surfaces in the ward with unilateral downward ventilation, while up to 35% of the bioaerosol was deposited on the surfaces in the ward with bilateral downward ventilation during the 900 s. The main deposition locations of the bioaerosols were near the wall on the same side of the room as the patient's head in all cases. This study could provide scientific evidence for controlling cross-infection in hospital wards, as well as several guidelines for the disinfection of hospital wards.

Laboratory-acquired infections (LAIs) are defined as infections of laboratory staff by exposure to pathogenic microorganisms during an experimental procedure. For a biosafety level-3 (BSL-3) laboratory with a high potential of exposure, reducing risks and threats relevant to LAIs has become a critical concern, especially after the recent outbreak of Novel Coronavirus causing COVID-19 in Wuhan, China. This study aimed to investigate the spatial-temporal characteristics of bioaerosol dispersion and deposition of two kinds of bioaerosols (Serratia marcescens and phage ΦX174). A combination of laboratory experiment and numerical simulation was adopted to explore bioaerosol removal. Three-dimensional concentration iso-surface mapping in conjunction with flow field analysis was employed to elucidate bioaerosol migration and deposition behavior. The total deposition number and unit area deposition ratio were calculated for different surfaces. The results indicate that bioaerosol concentration remains stable for up to 400 s after release, and that almost 70% of all bioaerosol particles become deposited on the surfaces of walls and equipment. Vortex flow regions and high-concentration regions were determined, and the most severely contaminated surfaces and locations were identified. Our results could provide the scientific basis for controlling the time interval between different experiments and also provide guidelines for a laboratory disinfection routine. Furthermore, future work regarding laboratory layout optimization and high efficiency air distribution for bioaerosol removal in a BSL-3 laboratory should be emphasized.

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