Distribution of microbial pathogens into aerosol and the implications for airborne infection transmission

​​Airborne transmission of infection relies on microorganisms within the human respiratory system to be released in aerosols that are small enough to remain airborne and to be inhaled by a susceptible person. Current transmission models use a microbial source which includes a size distribution of particles but assumes distribution of microorganisms is uniform by volume. However experimental data measuring viral emissions suggests that there may be proportionally more pathogens in the smaller aerosols; this may be due to measurement methods, the properties of the fluid, the properties of the microorganism or mechanisms for aerosol generation. This project aims to explore this phenomena and to evaluate the implications for modelling transmission risks. The project will involve systematic review of published literature to understand the current evidence for partitioning of microorganisms into different aerosol sizes, experimental studies using controlled generation of microbial aerosols in a specialist test chamber facility and potentially studies of aerosol emissions from human sources, and applying different assumptions around microbial partitioning into CFD or risk models to explore how this would influence the predicted risk of infection.​