Abstract
The COVID‐19 virus can transmit through airborne expiratory droplets and thus, the viral transmission can take place between the occupants in the isolated room. With the school re-opening under the current COVID‐19 pandemic, it is urgent to improve the classroom ventilation system to mitigate the risk of virus transmission. The present study developed a particle concentration monitoring network (PCMN) using low‐cost sensors and deployed it to explore the dispersion of the droplet particles under different ventilation settings and aerosol configurations. Our experiment shows the advance of using a low‐cost sensor network on spatiotemporal air monitoring and demonstrates indoor particle concentration level and distribution are strongly impacted by the ventilation setting and source location. Two recommendations on reducing the viral risk in the classroom were derived from the study. The first is the respiratory droplet source, e.g., the instructor, should be in the location such that the particle dispersion opposes the ventilation flow. The second is the air handling unit (AHU) and fan coil unit (FCU) should be both turned on during class hours despite whether there is a need for thermal comfort, as it allows higher and more uniform ventilation flow to resolve the issue of the dead air zone. © The Author(s).
Highlights
It is known that the COVID-19 virus can be carried by the airborne expiratory droplets from an infected individual (Asadi et al, 2020; Buonanno et al, 2020; Feng et al, 2020; Leung et al, 2020; Morawska and Cao, 2020) and transmit infection via airflows generated by room ventilation, air conditioners, or wind (Kwon et al, 2020; Moses et al, 2020)
The risk of virus dispersion under different ventilation conditions and source configuration in a typical University classroom was studied by using particle concentration monitoring network (PCMN) to monitor the spatial particle concentration change over time
The results show that the ventilation conditions and source locations have significant impacts on the droplet particle dispersion in the room
Summary
It is known that the COVID-19 virus can be carried by the airborne expiratory droplets from an infected individual (Asadi et al, 2020; Buonanno et al, 2020; Feng et al, 2020; Leung et al, 2020; Morawska and Cao, 2020) and transmit infection via airflows generated by room ventilation, air conditioners, or wind (Kwon et al, 2020; Moses et al, 2020). Only a few experimental studies have been conducted on respiratory droplet dispersion which is critical in validating numerical simulations and designing optimum ventilation systems to mitigate virus transmission between indoor occupants, since current heating, ventilation, and air conditioning (HVAC) settings are designed for thermal comfort, filtration of outdoor contaminant, and energy saving, but not for minimizing the viral dispersion inside the room This type of study requires spatiotemporal air monitoring, which can be the paradigm of the low-cost sensor technology raised in recent years (Jayaratne et al, 2020; Owoade et al, 2021; Rai et al, 2017). Only a few of them emphasized the high-resolution spatial distribution/dispersion of airborne particles
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