Computational fluid-dynamics (CFD) simulations are used to profile air-pollutant concentrations. CFD is used to model the effectiveness of trees at dispersing road traffic emissions. The methodology used in this study uses real buildings and trees data from LIDAR to reconstruct a 3D representation of Leicester City Centre. It focuses on a 2 × 2 km area which is on a scale larger than those usually used in other CFD studies. Furthermore, the primary focus of this study is on the interaction of trees with wind flow dynamics.