Estimation of airborne viral emission: quanta emission rate of SARS-CoV-2 for infection risk assessment

Giorgio Buonanno; Luca Stabile; Lidia Morawska

As discussed in the Materials and methods section, the quanta emission rate, ERq, depends on 225 several parameters. In Figure 1 the ERq (quanta h -1 ) trends are reported as a function of the viral 226 load in the sputum (cv, RNA copies mL -1 ) for different expiratory activities (whispered counting, 227 voiced counting, speaking, breathing) and different activity levels (resting, standing, light exercise). 228 To represent the large variabilities (over several orders of magnitude) of ERq as a function of cv, the 229 graph is reported on a bi-logarithmic scale. 230 To benchmark the proposed approach for the estimation of the quanta emission rate, we 231 considered the case of seasonal influenza for which more data are available in terms of both viral 232 load in sputum and quanta emission rate. As an example, (Hirose et al., 2016) found an average 233 value of RNA concentration in sputum for influenza equal to 2.38×10 7 copies mL -1 . Thus, applying 234 the findings of the proposed approach in the case of a standing subject, a corresponding ERq varying 235 between 3.7 (breathing) and 114 quanta h -1 (speaking) is estimated: this value is in good agreement 236