Potential airborne transmission between two isolation cubicles through a shared anteroom

Abstract

a b s t r a c tFull-scale experiments and CFD simulations were performed to study potential inter-cubicle airborne transmissions through a shared anteroom due to the hinged door opening. When doors are closed, current negative pressure designs are effective for the containment of airborne pathogens in the 'dirty' cubicle with an index patient. When the 'dirty' cubicle door is open, airborne agents can move into the other 'clean' cubicle via the shared anteroom. As the door being opened or closed, the door sweeping effect is the main source of the two-way airflow and contaminant exchange through the doorway. When the dirty cubicle door remains fully open, temperature difference and concentration gradient across the doorway induce the two-way buoyancy-driven flow and transport of airborne agents across the doorway. The longer the dirty cubicle door remains fully open (10 s, 30 s or 60 s) or the smaller the air change rate (34e8.5 ACH for each cubicle), the more airborne pathogens are being transported into the 'clean' cubicle and the longer time it takes to remove them after the door is closed. Keeping the door completely open is potentially responsible for the majority of inter-cubicle transmissions if its duration is much longer than the duration of door motion (only 3 s). Our analyses suggest a potential inter-cubicle infection risk if the shared anteroom is used for multiple isolation cubicles. Decreasing the duration of door opening, raising air change rate or using a curtain at the doorway are recommended to reduce inter-cubicle exposure hazards.

Airborne spread of infectious agents in the indoor environment

“…significant downwash that occurs behind the body has the effect of laterally spreading the lower portions of the wake. 59,60 Using large eddy simulation, Choi and Edwards 55,61 found that backward transport (opposite to the direction of walking) can also occur because of downwash effects and tip vortex formation. Wakeinduced transport of material in the direction of the walking motion continues because of inertial effects, even after the person stops.…”

Airflow patterns through single hinged and sliding doors in hospital isolation rooms – Effect of ventilation, flow differential and passage

“…In principle, increasing ventilation rates can generate more turbulence which in turn can enhance the mixing across the open doorway [41]. However, it should be noted that in general, increased ventilation rates improve the containment as the concentration of particles and gaseous agents are more quickly diluted already in an isolation room [21,38]. Hence, less agents are dispersed from an isolation room into an anteroom and subsequently less of a fraction can enter other neighboring spaces [21].…”

“…These heat loads can heat up the rooms and generate temperature difference between an isolation room and an anteroom or a corridor. Already a small temperature difference induces continuous two-way air exchange across open doorway substantially increasing the total air volume migration during door operation [21,53]. This effect becomes increasingly important when door is kept open long periods [20e22].…”

“…Enhanced usage has led to increased interest in containment testing and to door operation induced air and contaminant transport [19e34]. A wide variety of different methods have been used to study the issue, including: computational fluid dynamics (CFD) [23,26,30e32,34], small-scale models [19,22,24,29], full-scale models [20] and field studies [21,25,27,28,32,33].…”

Numerical simulation of the effect of visitor's movement on bacteria-carrying particles distribution in hospital isolation room

“…Some of the human health concerns necessitate strict observation and control over infection transmission within hospitals for infectious diseases, such as measles, chickenpox, Severe Acute Respiratory Syndrome (SARS), tuberculosis (TB), and in uenza [1]. To implement appropriate infection control measures and prevent the transmission of contagious diseases from a patient to other people or from outsiders, such as health care personnel and visitors, to the susceptible patient, hospitals must have Airborne Infection Isolation Room (AIIR) which is a safe and healthy environment for patients with infectious diseases [2].…”