Analysis on the risk of respiratory virus transmission by air conditioning system operation based on experimental evidence.

Yonghong Jia,Lei Guo,Yin Zhang,Yue Xiang,Li Zhang,Luyao Guo,Shurui Guo,Enshen Long,Zhu Cheng

doi:10.1007/s11356-021-14495-0

Yonghong Jia, Lei Guo + Show 7 more

Open Access

https://doi.org/10.1007/s11356-021-14495-0

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Abstract

It is important to know whether SARS-CoV-2 is spread through the air conditioning systems. Taking the central air conditioning system as an example, we analyze the mechanism and potential health risk of respiratory virus transmission in air-conditioned rooms and propose a method to study the risk of virus transmission in central air conditioning systems by investigating the data from medical experiments. The virus carrying capacity and the decay characteristics of indoor pathogen droplets are studied in this research. Additionally, the effects of air temperature and relative humidity on the virus survival in the air or on surfaces are investigated. The removal efficiency of infectious droplet nuclei by using an air conditioning filter was then determined. Thus, the transmission risk during the operation of the centralized air conditioning system is evaluated. The results show that the indoor temperature and humidity are controlled in the range of 20–25 °C and 40–70% by central air conditioning during the epidemic period, which not only benefits the health and comfort of residents, but also weakens the vitality of the virus. The larger the droplet size, the longer the viruses survive. Since the filter efficiency of the air conditioning filter increases with the increase in particle size, increasing the number of air changes of the circulating air volume can accelerate the removal of potential pathogen particles. Therefore, scientific operation of centralized air conditioning systems during the epidemic period has more advantages than disadvantages.Graphical abstract

Highlights

Since the end of 2019, the COVID-19 epidemic caused by SARS-COV-2 coronavirus has spread rapidly around the world, reaching more than 200 countries and regions with global implication
Regarding the risk of indoor virus transmission, in 2010, Chen and Liao (Chen and Liao 2010) studied the transmission risk of different influenza viruses in an indoor environment based on the Wells–Riley mathematical model, and the results showed that the risk of indoor virus infection was negatively correlated with the air changes per hour (ACH) rate, where ACH is the ratio of the amount of clean air entering a room (m3/h) to the room (m3) per hour
It reminds us that the number of small droplets floating with the air in the air conditioning system may be much larger than that of larger droplets, but the total volume of the small droplets is much smaller than the total volume of the large droplets, so the small droplets are not the main contradiction of propagation

Summary

Introduction

Since the end of 2019, the COVID-19 epidemic caused by SARS-COV-2 coronavirus has spread rapidly around the world, reaching more than 200 countries and regions with global implication ("WHO announces COVID-19 outbreak a pandemic (http://www.euro.who.int/en/health-topics/healthemergencies/coronavirus-covid-19/news/news/2020/3/whoannounces-covid-19-outbreak-a-pandemic). The above medical experiments of the indoor temperature and humidity environment on virus survival and animal infection transmission suggest that during the outbreak of respiratory viruses, especially in the winter, raising the indoor air temperature through the air conditioning or heating systems can achieve thermal comfort for the human body, which is more conducive to inhibit virus activity and reduce the risk of infection between people.

Results

Conclusion