Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems

Abstract

As one of the major potential sources for infectious droplet nuclei in a hospital environment, exhalation flows of an infected patient can interact with the respiratory activities of other close individuals and with the room ventilation systems. Our latest results provide information on the penetration of exhalation jets into the ambient environment in different ventilation systems. This work is useful in identifying an appropriate and effective ventilation method for removing droplet nuclei more effectively, and thus minimizing the risk of cross-infections in hospital wards with multiple beds.

Bioaerosol deposition in single and two-bed hospital rooms: A numerical and experimental study

“…This finding concurs with tracer gas and simulation based studies evaluating airborne infection risk [13,26] …”

“…Smaller particles, while remaining airborne for longer, may still deposit out onto surfaces creating a possible contact transmission risk. While very large particles (>100µm) will clearly deposit quickly, mid-range (5-100µm) particles will be influenced by the air, initially through evaporation and then subsequently by ventilation flow patterns [12,13]. As a result, the final destination of an airborne pathogen may be many meters away from its original source.…”

“…Recommended bed spacing in multi-bed environments is often cited as being based on droplet transmission risk [21], and studies have recognised the relevance for pathogens such as Staphylococcus aureus as well as respiratory diseases [22]. Tracer gas and simulation studies have shown that ventilation design [13,23] and the presence of partitions between beds [23] influences airborne crossinfection risk between two patients. Several studies advocate the benefits of single patient rooms in reducing infection risk [24][25][26], although it is difficult to ascertain whether benefits can be directly attributed to room design or resulting change in nursing and hygiene practice.…”

Dispersion of Expiratory Droplets in a General Hospital Ward with Ceiling Mixing Type Mechanical Ventilation System

“…Studies such as Wan and Chao (2005) showed that the thermal plumes could create temperature and also density gradients in the air. They could also significantly affect the contaminant dispersions, as reported by Qian et al (2006). Qian et al (2006) also showed that contaminants injected laterally from the patient had dispersion patterns different from those injected vertically upward.…”

“…They could also significantly affect the contaminant dispersions, as reported by Qian et al (2006). Qian et al (2006) also showed that contaminants injected laterally from the patient had dispersion patterns different from those injected vertically upward. The injection could be affected by the heat plume generated by the real patient/thermal manikin, which implies that the effects of injection orientation should be investigated in conjunction with heat plumes.…”