Risk assessment model of SAS-CoV-2 infection through ventilation systems

 In order to assess the impact of the possible dangerous events in ventilation systems on the indoor virus concentration or the probability of virus infection of indoor population, according to the transmission mechanism of the SAS-CoV-2, based on the air infectious disease probability model and the risk matrix method, a risk assessment model of SAS-CoV-2 infection through ventilation systems is proposed. The model includes the main parameters such as the probability of occurrence of dangerous events, the outdoor air rate, the respiratory ventilation rate and the exposure time, which have an important influence on virus transmission. Taking the virus infection probability of indoor population as a quantitative indicator of the consequences, the results show that the virus infection probability of indoor population is affected by the probability of dangerous events and the severity of their consequences. The greater the possibility of dangerous events and the impact on the key parameters of ventilation systems such as outdoor air rate and sterilization efficiency, the greater the average infection probability of the susceptible population.