The effect of door opening on air-mixing in a positively pressurized room: Implications for operating room air management during the COVID outbreak

Airborne infection risk assessment of COVID-19 in an inpatient department through on-site occupant behavior surveys

“…Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has had a significant effect on public health and economic development globally [ [1] , [2] , [3] ]. Scientists have highlighted the likelihood of airborne transmission of SARS-CoV-2 in enclosed spaces [ 4 , 5 ]. Hospitals are recognized as places with a considerable risk of infectious disease transmission, and there have been numerous reports of cross-infection between patients and hospital staff [ 6 ].…”

A review of facilities management interventions to mitigate respiratory infections in existing buildings

“…As assumed in the Wells-Riley equation and its extensions used by ten studies, mixing ventilation is supposed to mix air equally over an area. However, Computational Fluid Dynamics (CFD) simulations indicate that the air in rooms with a mixing ventilation system is often partially mixed, resulting in an atypical distribution of micro-organisms [ 97 , 103 ]. For this reason, some studies included “air distribution effectiveness” as a factor in their models instead of assuming a well-mixed air to estimate the infection risk more accurately.…”

“…For instance, Sun & Zhai adopted air distribution configurations based on the ASHRAE standard [ 73 ]. Moreover, indoor airflows are found to be very ‘turbulent’ and closely related to transient events such as the occupant behaviour and movement [ 12 ], door opening and closing [ 103 ], and changes in external conditions [ 12 ]. Therefore, further study on indoor air mixing and airflow patterns is required to understand virus transmission patterns better.…”

“…Since indoor airflow patterns significantly impact airborne virus transmission in buildings, air pressure created by HVAC systems has been widely used in sensitive settings to reduce virus transmission from contaminated spaces to other areas. In our review, ten articles discussed air pressure as an intervention measure, and they validated the effectiveness of air pressured facilities in various clinical settings, such as negative air ionisation [ 95 ], positively pressured operating rooms [ 103 ], negative pressure hoods [ 87 , 105 ], negative pressure isolation stretcher [ 104 ]. For example, Kim et al conducted a before-and-after intervention study at a South Korean hospital and discovered that the average frequency of medical cessation was considerably lowered following the intervention [ 104 ].…”

Design and in-vitro testing of a portable patient isolation chamber for bedside aerosol containment and filtration

“…Room pressurization has also been extensively used, and recommended by standards as another engineering technique to limit the spread of pathogens within the hospital. However, pressurization alone does not provide a safer environment for those inside a negative room and cannot always be achieved for rooms that are initially designed with positive pressure (e.g., operating rooms) [ 19 , 20 ]. Several researchers studied air purifiers as another viable option to remove pathogenic agents from the space [ 21 , 22 ].…”