Sedimentation distance is also strongly dependent on RH (see Fig ). At lower RH values, the droplet loses a larger fraction of moisture content and mass over a shorter time frame, and therefore travels longer distances from source. comparison of sedimentation distance is possible. Hygroscopic response has the greatest impact on sedimentation distance at low RH (when the evaporation rate is highest) and at intermediate droplet size (<80 µm). However, for larger droplet sizes and at most environmental RHs, the exact choice for the representation of aerosol hygroscopic response has little impact on the sedimentation distance and previous models assuming aqueous sodium chloride will provide a fair approximation. Indeed, when comparing predictions assuming a droplet composed of aqueous sodium chloride to saliva, the change in sedimentation distance for most large initial droplet sizes and RHs is <0.1 m. However, it is important to note that an accurate understanding of the time-dependent moisture content may play an important role in understanding the survival of viruses and bacteria in evaporating droplets. Timescales for sedimentation can be estimated in quiescent air and scale with the square of the radius for particles larger than 1 m diameter, i.e. in the continuum limit in the absence of a slip correction factor. At terminal settling velocity, water droplets of 1 mm, 100 m, 10 m and 1 m diameter sediment 1 m in ~30 ms, 3 s, 300 s and 8 h, respectively. Of course, these sedimentation time scales are so long for small droplets that they are largely dispersed and carried by convective air currents. We report the calculated sedimentation times and the dependence on droplet diameter and RH in Fig assuming the hygroscopic growth is consistent with the saliva formulation. As an example, a 100 m initial diameter droplet takes between 6.3 s and 21.9 s to sediment depending on the ambient RH. During the transport time to deposition, any pathogen in the aerosols or droplets will be exposed to UV light and the "open air" factor, potentially degrading the viability of the pathogen through the action of atmospheric oxidants or UV light. For example, timescales for degradation of SARS-CoV-2 in aerosol by UV light (the timescale for a reduction of viral load of 1 order of magnitude) have been measured to be <10 minutes in regions of mid-intensity UV, and <5 minutes in areas of high irradiance.