Droplets expelled during human expiratory activities and their origin

Abstract

This paper presents the findings of the most comprehensive program of study to date aimed at quantifying the number, size distribution and evaporation of droplets produced during virtually any expiratory activity. This international research program included teams of investigators from a number of universities, with each group contributing to essential aspects of the research. This research revealed many previously unknown aspects of expiratory aerosol dynamics and characteristics. This paper will focus on the findings that the time taken for expiratory droplets to achieve short term equilibrium is comparable to that for pure water droplets and that the droplet size distributions have distinct features reflecting specific production mechanisms whose intensity varies with the nature of the activity.