  We combine experiments and numerical computations to examine underlying fluid
mechanical processes associated with bioaerosol generation during violent
respiratory manoeuvres, such as coughing or sneezing. Analogous experiments
performed in a cough machine -- consisting of a strong shearing airflow over a
thin liquid film, allow us to illustrate the changes in film topology as it
disintegrates into small droplets. We identify that aerosol generation during
the shearing of the liquid film is mediated by the formation of inflated
bag-like structures. The breakup of these bags is triggered by the appearance
of retracting holes that puncture the bag surface. Consequently, the cascade
from inflated bags to droplets is primarily controlled by the dynamics and
stability of liquid rims bounding these retracting holes. We also reveal the
stabilizing role of fluid viscosity that eventually leads to the generation of
smaller droplets.
