Source terms for benchmarking models of SARS-CoV-2 transmission via aerosols and droplets

Abstract

There is ongoing and rapid advancement in approaches to modelling the fate of exhaled particles in different environments relevant to disease transmission. It is important that models are verified by comparison with each other using a common set of input parameters to ensure that model differences can be interpreted in terms of model physics rather than unspecified differences in model input parameters. In this paper, we define parameters necessary for such benchmarking of models of airborne particles exhaled by humans and transported in the environment during breathing and speaking.

Keywords: SARS-CoV-2; disease transmission; exhaled aerosols; model benchmarking; source terms.

Figure 1.

Graphical representation of the breathing flow rate.

Figure 2.

Graphical representation of jet projection (θ) and spreading (ϕ) angles.

Figure 3.

Exhaled particle size distributions resulting from (a) breathing and (b) speaking from (i) Johnson et al. [27] corrected for particle shrinkage and representing the PSD at the mouth (BLO model), (ii) Johnson et al. [27] not corrected for particle shrinkage, (iii) Gregson et al. [32] (70–80 dBA in (b)), (iv) Gregson et al. [32] (90–100 dBA in (b)), (v) Asadi et al. [31] (electronic supplementary material, figure S10), (vi) Chao et al. [29], (vii) Xie et al. [28] and (viii) Duguid [26]. Parameters of lognormal distributions and further information on the sources of data are included in electronic supplementary material, S2.

Figure 4.

(a) Number and (b) volume weighted particle size distributions, and cumulative fractions of (c) particle number and (d) volume as a function of particle diameter for breathing and speaking.