Special Issue on Air Quality in a Changed World: Regional, Ambient, and Indoor Air Concentrations from the COVID to Post-COVID Era (I)

Weiqi Chen, Dong-Bin Kwak, Jonathon Anderson, Kaushik Kanna, Chenxing Pei, Qingfeng Cao, Qisheng Ou This email address is being protected from spambots. You need JavaScript enabled to view it., Seong Chan Kim, Thomas H. Kuehn, David Y.H. Pui

Particle Technology Laboratory, Mechanical Engineering, University of Minnesota, Minneapolis 55455, USA

Received: September 3, 2021
Revised: October 25, 2021
Accepted: October 25, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.210232  

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Cite this article:

Chen, W., Kwak, D.B., Anderson, J., Kanna, K., Pei, C., Cao, Q., Ou, Q., Kim, S.C., Kuehn, T.H., Pui, D.Y.H. (2021). Study on Droplet Dispersion Influenced by Ventilation and Source Configuration in Classroom Settings Using Low-cost Sensor Network. Aerosol Air Qual. Res. 21, 210232. https://doi.org/10.4209/aaqr.210232


  • A particle concentration monitoring network was developed using low-cost sensors.
  • The importance of spatial monitoring and the advance of low-cost sensors were shown.
  • Ventilation and source configuration strongly impact particle spatial distribution.
  • Two recommendations are given to reduce viral transmission in classroom settings.


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.

Keywords: COVID-19, Classroom ventilation, Low-cost sensor, PM2.5, Indoor air monitoring

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