In atmospheric dispersion problems, mapping pollutant concentrations within the first tens or hundreds of meters from the emission point source still remains a modelling challenge. Computational fluid dynamics (CFD) approaches provide relevant insights into turbulent flow and pollutant concentration patterns in complex terrain such as urban and mountainous areas. At the forefront of CFD approaches, large-eddy simulations (LES) are a promising way to represent time and space variability of turbulent atmospheric flows and to assess public short-term exposures. LES are subject to uncertainties due to the intrinsic variability of environmental factors, among whom the large-scale meteorological forcing and the emission source characteristics.