Respiratory infection risk-based ventilation design method

Abstract

A new design method is proposed to calculate outdoor air ventilation rates to control respiratory infection risk in indoor spaces. We propose to use this method in future ventilation standards to complement existing ventilation criteria based on the perceived air quality and pollutant removal. The proposed method makes it possible to calculate the required ventilation rate at a given probability of infection and quanta emission rate. Present work used quanta emission rates for SARS-CoV-2 and consequently the method can be applied for other respiratory viruses with available quanta data. The method was applied to case studies representing typical rooms in public buildings. To reduce the probability of infection, the total airflow rate per infectious person revealed to be the most important parameter to reduce the infection risk. Category I ventilation rate prescribed in the EN 16798-1 standard satisfied many but not all type of spaces examined. The required ventilation rates started from about 80 L/s per room. Large variations between the results for the selected case studies made it impossible to provide a simple rule for estimating the required ventilation rates. Consequently, we conclude that to design rooms with a low infection risk the newly developed ventilation design method must be used.

A novel CO2-based demand-controlled ventilation strategy to limit the spread of COVID-19 in the indoor environment

“…This can be overcome by keeping sufficient physical distance. At 1.5 m distance from the infector, the virus concentration will decrease to a constant level depending on emission and removal mechanism [ 20 ]. Since this study does not consider short-range droplet transmission, in practice, the proposed ventilation strategy hereinafter should be applied together with physical distancing measures.…”

“…In previous works, most assumed that there is only one infector in each building zone [ 20 , 21 ]. However, this is not always the case in real-world scenarios.…”

“…In the existing literatures, several ventilation strategies have been developed to control the COVID-19 infection risk based on the viral emission load. Kurnitski et al [ 20 ] proposed a ventilation design method based on the Wells-Riley model to calculate the required outdoor air ventilation rate to control the COVID-19 infection risk in indoor spaces. The outdoor air ventilation rate can be determined with the quanta emission rate and the given probability of infection.…”

“…Methods proposed in Refs. [ 20 , 21 ] can efficiently determine the proper ventilation rate to control the COVID-19 infection risk. The above methods are designed with the assumption that there is one infectious person in the building zone.…”

Ventilation strategies and design impacts on indoor airborne transmission: A review

“…The results showed infection control strategies, such as wearing masks, physical distancing, and providing more clean air by ventilation systems as approved solutions for opening up businesses. These strategies can be beneficial since it would not be easy to offer simple rules for predicting the necessary ventilation rates to control indoor infections [ 232 ]. Dai and Zhao [ 233 ] empirically examined the relation between ventilation rates and COVID-19 infection risks inside confined areas (i.e., buses and aircraft).…”