25_Mar_2021_Short_Paper_Ventilation_Occupancy_Parameters - 2021.04.21.21255898v1.full.pdf
Abstract.Some infectious diseases, including COVID-19,can be transmitted via aerosols thatare emitted by an infectious person and inhaled bysusceptible individuals. Although physicaldistancing effectively reduces short-range airbornetransmission, many infections have occurredwhen sharing room air despite maintaining distancing.We propose two simple parameters asindicators of infection risk for this situation. Theycombine the key factors that control airbornedisease transmission indoors: virus-containing aerosolgeneration rate, breathing flow rate,masking and its quality, ventilation and air cleaningrates, number of occupants, and duration ofexposure. COVID-19 outbreaks show a clear trend inrelation to these parameters that isconsistent with an airborne infection model, supportingthe importance of airborne transmissionfor these outbreaks. The observed trends of outbreaksize vs. risk parameters allow us torecommend values of the parameters to minimize COVID-19indoor infection risk. All of thepre-pandemic spaces are in a regime where they arehighly sensitive to mitigation efforts.Measles outbreaks occur at much lower risk parametervalues than COVID-19, whiletuberculosis outbreaks are observed at much higherrisk parameter values. Since both diseasesare accepted as airborne, the fact that COVID-19 isless contagious than measles does not ruleout airborne transmission. It is important that futureoutbreak reports include ventilationinformation, to allow expanding our knowledge of thecircumstances conducive to airbornetransmission of different diseases