Investigating the formation of microplastic aerosols and their dispersion in urban environments: A comparative physical modelling study of aerosol and gas dispersion

Aerosols are present in almost all aspects of everyday life. Aerosols affect climate and health and arise in hazardous situations such as industrial accidents. In this study, we examined the generation of microplastic aerosols from polypropylene pipes used in drinking water systems and their dispersion in a simulated accident scenario using wind tunnel modelling. We compared aerosol and gas dispersion from a ground-level point source in a street canyon in a central European town. The results show that 185-nm UVC light generated stable microplastic aerosols (predominantly <1 μm) from the polypropylene. Although both the aerosol and gas dispersions exhibited recirculation and ventilation regions characteristic of an isolated roughness flow regime, their dispersion patterns differed. Vertically, the main gas dispersion field resembled an ellipse, whereas the main aerosol particles dispersion field resembled an anvil. Horizontally, gas was dispersed primarily perpendicular to the buildings, whereas aerosol particles were dispersed both perpendicular and parallel to the buildings.