Behavior of cough droplets emitted from Covid-19 patient in hospital isolation room with different ventilation configurations

Abstract

The world is now facing the Covid-19 pandemic and the control of Covid-19 spread in health care facilities is a serious concern. The ventilation system in hospital isolation rooms with infectious patients plays a significant role in minimizing the spread of viruses and the risk of infection in hospital. In this study, computational fluid dynamics (CFD) simulation is applied to investigate the important factors on transport and evaporation of multi-component cough droplets in the isolation room with different ventilation configurations. We analyzed the effects of various air outlet positions on the removal efficiency of infectious droplets in isolation room and proposed the optimum location of exhaust vent in hospital isolation room to maximize the droplet removal efficiencies. We found that the evaporation rate of droplets is strongly dependent on the relative humidity (RH) and, at low RH, the large-sized droplets with Covid-19 virus can evaporate quickly and become small-sized aerosols to stay in air for a long time and the Covid-19 can propagate more easily through the respiratory organs during breathing. It also explains why the Covid-19 can propagate faster in winter with low humidity than in summer with high humidity.

A review on indoor airborne transmission of COVID-19– modelling and mitigation approaches

“…General assumptions for the discrete phase modeling (trajectory of particles in the Lagrangian framework) in the scope of COVID-19 airborne propagation are [ 101 , 116 , 117 ]: Particles are spherical in shape, and their density is equal to that of water [ 118 , 119 ]. Resuspending of particles from surfaces or their coagulation is ignorable.…”

Using CONTAM to design ventilation strategy of negative pressure isolation ward considering different height of door gaps

“…This condition may not be a problem in the design of a single room but can lead to chaotic pressure gradients in a complex building where pressure gradients and airflow directions are tightly controlled. Previous research has studied the behavior of patients in isolation rooms to emit virus-containing droplets, analyzed the impact of air supply and exhaust on virus transmission and suggested methods to minimize virus transmission [ 19 , 20 ]. REN et al [21] compared the efficiency of three ventilation strategies to remove particulate matter in an inpatient unit.…”

Numerical Modeling of Droplet Aerosol Coagulation, Condensation/Evaporation and Deposition Processes

“…Droplet aerosol is one of the crucial ways for most microorganisms (including viruses, bacteria and fungi) to spread in the air [1][2][3][4]. People usually release droplet aerosols by coughing or breathing, and then the droplet aerosols spread through the air until they are inhaled into the body or deposited on surfaces [5,6]. In the transmission process, droplet aerosols will experience a series of dynamical behaviors, such as coagulation, deposition, condensation, and evaporation processes, which significantly affect the particle size distributions and the transportation mechanism of aerosols [7][8][9][10].…”