Executive Summary : | The study aims to understand, characterize, and model the mechanism of passive fungal spore release from fungal surfaces. Spore release can occur through an active mechanism or a passive mechanism, such as wind, which is crucial for mathematical models used to predict health and climate risks. Preliminary studies show that passive fungal spore release is influenced by air velocity, surface spore density, and relative humidity. A mathematical model was proposed to predict spore flux, which is estimated as the ratio of energy transferred from the air to the fungal surface divided by the energy needed to 'aerosolise' one spore from a cluster. The energy parameter, E, required to aerosolise a spore is likely a combination of adhesive, gravitational, and breakage energies. Most fungi spores are clustered at the end of a stalk called conidia that bends in the presence of air flow. The bending of the conidia results in lower velocity incident on the spores and consequently lower drag and spore flux. However, the estimation of the flux using the model is limited by assumptions such as the drag force being estimated for upright conidia, the velocity gradient being assumed as a flat surface, the bending of the conidia being affected by the density of the conidia and interconnected structures, and the energy parameter being based on a model fit. The objectives of the study include experimental measurement of the drag force during the bending of the conidia, estimation of the velocity gradient within the microstructure of the conidia, experimental estimation of the energy parameter, refinement of the mathematical model based on experimental observations, and application to the prediction of spore release from test surfaces. |