Evaluation of airborne contaminant exposure in a single-bed isolation ward equipped with a protected occupied zone ventilation system

Abstract

Effective ventilation in general hospital wards is important for controlling the transmission of airborne infectious agents that may cause respiratory diseases. This study investigates the potential of protected occupied zone ventilation (POV) to reduce the risk of cross-infection in hospital isolation wards. Two life-size breathing thermal manikins were used to simulate an infected patient lying in a bed and a sitting, receiving health care worker. N2O was used as a tracer gas to simulate the droplet nuclei exhaled by patients. The contaminant exposure index [Formula: see text] was used to assess the risk of cross-infection for different configurations of the supply velocity, the patient’s lying position and the exhaust openings. The contaminant exposure index [Formula: see text] shows that the ventilation strategy is effective, but this is also highly dependent on the supply velocity and the location of the exhaust relative to the patient’s breathing zone. The patient’s posterior position does not affect the personal exposure of the receiving patient. Compared to traditional ventilation systems, the POV system can reduce the risk of cross-infection in hospital isolation rooms. The full potential of a POV system can be achieved in an isolation ward where movement between the infected and protected zones is restricted or prohibited.

Ventilation strategies and design impacts on indoor airborne transmission: A review

“…Indeed, MV systems should be designed considering ventilation rate, airflow pattern, and inlet and exhaust number and position to control airborne transmission [ 63 , 68 , 75 , 113 ]. The number and location of inlets and exhausts and the balance and distance between airflow rate, as well as the exhaust distance to the contamination source, can play a significant role in removing airborne contaminants from indoor areas [ 37 , 50 , 60 , [69] , [70] , [71] , 79 , 89 , 110 , [113] , [114] , [115] , [116] , [117] ]. MV performance in removing particles is affected by contaminations' size [ 110 ], so the literature suggests considering the expected type, size, and level of potential contaminants based on the function of indoor spaces to design MV systems.…”

HVAC systems for environmental control to minimize the COVID-19 infection

“…Exposure to these droplet particles within indoor spaces would provide a major route of infection of people to the virus. 2 The guidelines from the WHO 11,12 are to well ventilate the indoor spaces as well as keeping important personal hygiene practices such as regular washing of hands, wearing of face masks (or covering), disinfecting all touched surfaces, etc. Thus, ventilation control should meet the requirement of reducing the infection risk particularly in enclosed spaces such as homes, health-care facilities, offices, shopping centres, public vehicles, etc.…”

“…Equivalent efforts should be made to prevent healthy people from being infected by the virus. Physical isolation such as the isolation treatment for patients, 2 social distancing and lockdown for cities have been enforced with some success. 3 However, with the gradual resumption of normal life, work and production, there would be people visiting public facilities and services (e.g.…”

Exposure of Ophthalmologists to Patients' Exhaled Droplets in Clinical Practice: A Numerical Simulation of SARS-CoV-2 Exposure Risk

“…A comparison was made between the ophthalmologist's inhalation exposure in this study and the interpersonal exposure that has been reported in previous studies. As shown in Figure 3, the previous studies were classified as CFD (17)(18)(19)(20)(21)(22) or experimental studies, where the latter used tracer gas (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33) or particles (34) to simulate droplets or droplet nuclei. In addition, Ueki (35) compared the inhalation exposure to live SARS-CoV-2 particles when wearing no mask, a surgical mask or an N95 respirator.…”