Here we present a new, empirically derived treatment for the evaporation of respiratory fluid droplets and apply to a simple 2-dimensional respiratory droplet evaporation/sedimentation/momentum model to assess the impact on sedimentation outcomes. We show that for initial droplet diameters above 100 µm, the ambient conditions (RH and temperature) and representation of the composition/hygroscopic response has little impact on the sedimentation distance and previous models assuming aqueous sodium chloride will provide a fair representation. Below 100 µm, and particularly below 80 µm, the increased settling time means evaporation plays a significant role in influencing the size and compositional changes that occur during the sedimentation process. Under these circumstances the application of an appropriate microphysical treatment and correct specification of the ambient conditions are crucial to accurately assess sedimentation distance and time. Failure to account for the composition can lead to sedimentation distance differences > 1 m, and beyond, under dryer conditions. Likewise, increasing the ambient temperature from 283 to 303 K can increase the sedimentation distance by well above 2 m.