Effect of air cleaner on reducing concentration of indoor-generated viruses with or without natural ventilation

Lee, J.; Park, S. H.; Sung, G. B.; An, I. H.; Lee, K. R.; Hong, S. P.; Yook, S. J.; Koo, H. B.

Coronavirus disease (COVID-19) has infected many people worldwide. As the probability of being infected by the virus increases with an increase in the number of people gathered in an indoor space, methods for reducing its spread indoors are urgently required. In this study, a classroom with 25 students was considered as an indoor space, and an attempt was made to devise a method to reduce the concentration of the viruses generated indoors more effectively. Through numerical analysis, the age of air inside the classroom was compared and analyzed when both the air cleaner and natural ventilation were used. The age of air varied locally in the classroom depending on the position of the air cleaner, confirming its importance in effectively removing particles possibly containing viruses generated indoors. When the air cleaner flow rate was doubled, the age of air was almost halved, implying that the concentration of the particles including viruses generated indoors can be reduced efficiently by increasing the air cleaner flow rate. Natural ventilation performed by completely opening the windows and doors of the classroom reduced the age of air. It was observed that the operation of the air cleaner along with open windows and doors of the classroom reduced the concentration of the particles including viruses generated indoors more effectively. More specifically, when both natural ventilation and air cleaner were applied, the age of air decreased by almost 50% compared with the only air cleaner case and by about 22% compared with the only natural ventilation case. Copyright (c) 2021 American Association for Aerosol Research