Epidemic thunderstorm asthma (ETSA) outbreaks are triggered by airborne pollen allergens combined with thunderstorm activity. ETSA can affect anyone, as observed in the world’s largest ETSA event in Australia. Allergens from rye grass pollen affect the respiratory airways and the fundamental physicochemical causes, biochemical interactions, and the role of the thunderstorm in ETSA have been the source of much speculation. In this thesis, the physicochemical interactions of thunderstorm-derived reactive oxygen nitrogen species (RONS) and pollen-derived molecules are examined. It is hypothesised that RONS from the plasma-activated water (PAW) react with the airborne pollen allergens, exerting physicochemical changes to enhance allergenicity and subsequently causing ETSA. Simple biomimetic models are demonstrated, examining the key biointerfacial interactions and the influences of the conditions of plasma formation, pH, and temperature, employing advanced interface-sensitive techniques including QCM-D and neutron reflectometry. Firstly, cellulose-mucin interactions were analysed, mimicking the interactions between the walls of inhaled pollen (intine) and mucosa of the respiratory tract (mucin). Interaction with plasma-treated cellulose surfaces led to adsorption and conformational alterations to mucin, potentially indicating changes to the permeability of the mucosa. Secondly, the effect of PAW on the interactions between a model-allergen plant protein and lipid monolayers mimicking alveolar surfactant was studied. The protein took up RONS and PAW-treated protein showed stronger adsorption to the lipid monolayers, implying PAW-treatment enhances transport of the protein into lung tissue. Lastly, the effect of PAW on allergen penetration into epithelial bilayers was elucidated. Solid-supported model lipid bilayers were allowed to interact with model allergen and rye grass derived proteins to deduce the structural integrity of the membrane. PAW-treatment increased adsorption of the proteins to the lipid bilayers, and enabled the penetration into the membrane, corroborating the enhanced allergenicity of PAW-treated allergens. Overall, PAW was seen to enhance three relevant nonspecific biointerfacial interactions; these physicochemical studies complement extant in vitro cell studies in an effort to enable the development of effective monitoring platforms, diagnostics, and therapeutic interventions for the prevention and treatment of ETSA.