For droplets in the initial diameter range <100 m generated by a cough at 293 K and at 50% RH, the maximum initial droplet sizes that pass through the windows at 1, 1.5 and 2 m are 100, 80 and 65 m, respectively. This corresponds to volume fractions remaining elevated transiting through the window at 1, 1.5 and 2 m of 1, 0.350 and 0.125. As the RH increases, the fractional exposure decreases due to the slower evaporative flux and loss of mass, ensuring the droplets sediment more rapidly. The fractional exposure increases with increasing temperature, due to the enhanced evaporative flux and reduced jet buoyancy. At 2 m separation, the corresponding fraction in number concentration remaining elevated is 0.834 (Fig S6b). This demonstrates the dominant contribution to the volume distribution of the relatively small number of larger droplets compared to more numerous smaller droplets. Indeed, these fractions are qualitatively consistent with the recent computational fluid dynamics models reported by Chen et al. Although Chen et al. considered the fluid dynamics more accurately, our focus is to study the more accurate representation of the microphysical properties of the evolving aerosols.