FIG. 4.
(a) Probability Density Function (PDF) f of droplet diameter for cough55 and the number of virions N as a function of the initial droplet size Ds,0 at t = 0. Average and maximum viral load ρv = 7 × 106 copies/ml and ρv = 2.35 × 109 copies/ml of SARS-CoV-2, respectively, are assumed from Ref. 25. (b) Droplet and/or dried droplet nuclei size distributions at different time t and distance XD from the origin of the respiratory jet for T∞ = 21.44 °C and RH∞ = 50%. The curves at the last three time instants end abruptly due to the loss of droplets due to settling beyond that particular diameter. For t > τd = 22.87 s or XD > 3.52 m, all airborne droplets have been desiccated to the corresponding droplet nuclei. The size distribution remains invariant for t > τd.