Likewise with droplets, aerosols are also “globs” of saliva, mucus and water, but are considerably smaller. Because of their size, they evaporate faster and travel farther, and usually remain airborne for a prolonged period of time. Aerosols usually have an aerodynamic diameter smaller than 5um.. They are more susceptible to being inhaled and reaching the alveolar region of the lungs, due to to their small size. There are also cases where droplets evaporate and eventually become aerosol particles, referred to as droplet nuclei.