Impact of Avenue-Trees on Traffic Pollutant Concentrations on the Urban Neighborhood Scale

Traffic pollutant concentrations at the pedestrian level in a generic urban neighborhood were studied. Scenarios without and with avenue-trees were investigated with Computational Fluid Dynamics (CFD) by employing a Reynolds Stress Model (RSM) to which extra terms are added accounting for the effects of vegetation on the wind. The avenue-trees showed a significant impact on the traffic pollutant dispersion and flow fields in the street canyons and intersections. In the presence of trees, a faster build-up of concentrations was found for the wind-parallel streets. In the wind-perpendicular streets, considerably higher pollutant concentrations at the buildings’ leeward walls were found.