Modelling the viral load dependence of residence times of virus laden droplets from COVID-19 infected subjects in indoor environments
In the ongoing COVID-19 pandemic situation, exposure assessment and control strategies for aerosol transmission path are feebly understood. A recent study pointed out that Poissonian fluctuations in viral loading of airborne droplets significantly modifies the size spectrum of the virus laden droplets (termed as “virusol”). Herein we develop theory of residence time of the virusols, as contrasted with clean droplets in indoor air using a comprehensive “Falling-to-Mixing-plateout” model that considers all the important processes. This model fills the existing gap between Wells falling drop model and the stirred chamber models. The effect of various parameters on mean residence time are examined in detail. Significantly, the mean residence time of virusols is found to increase nonlinearly with the viral load in the ejecta, ranging from ~125 s at low viral loads (<104/mL) to about 1150 s at high viral loads (>1011/mL). The implications are further discussed.
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Supplementary Information (SI): 1. Derivation of analytical solution for the 1-D and 3-D theoretical models, and comparison of their results. 2. Table S2: Input Parameters & constants
Posted 11 Jan, 2021
Modelling the viral load dependence of residence times of virus laden droplets from COVID-19 infected subjects in indoor environments
Posted 11 Jan, 2021
In the ongoing COVID-19 pandemic situation, exposure assessment and control strategies for aerosol transmission path are feebly understood. A recent study pointed out that Poissonian fluctuations in viral loading of airborne droplets significantly modifies the size spectrum of the virus laden droplets (termed as “virusol”). Herein we develop theory of residence time of the virusols, as contrasted with clean droplets in indoor air using a comprehensive “Falling-to-Mixing-plateout” model that considers all the important processes. This model fills the existing gap between Wells falling drop model and the stirred chamber models. The effect of various parameters on mean residence time are examined in detail. Significantly, the mean residence time of virusols is found to increase nonlinearly with the viral load in the ejecta, ranging from ~125 s at low viral loads (<104/mL) to about 1150 s at high viral loads (>1011/mL). The implications are further discussed.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Due to technical limitations, full-text HTML conversion of this manuscript could not be completed. However, the manuscript can be downloaded and accessed as a PDF.