Title: Effects of trees on the dilution of vehicle exhaust emissions in urban street canyons
Author: Christof Gromke, Bodo Ruck
WSL Institute for Snow and Avalanche Research SLF, Research Unit Snow and Permafrost, Team Snow Cover and Micrometeorology, Flueelastrasse 11, CH-7260 Davos Dorf, Switzerland.
Laboratory of Building- and Environmental Aerodynamics, Institute for Hydromechanics, University of Karlsruhe, Kaiserstr. 12, 76128 Karlsruhe, Germany
Journal: Int. J. of Environment and Waste Management, 2009 Vol.4, No.1/2, pp.225 - 242
Abstract: In order to investigate the natural ventilation and air quality of urban street canyons with trees, boundary layer wind tunnel studies at a small-scale model have been performed. Concentrations in street canyons with a tracer gas emitting line source at the ground level and one row of trees arranged along the canyon centre have been measured for several equidistant tree spacings. In the case of flow approaching perpendicular to the street axis, increases in pollutant concentration at the leeward canyon wall and decreases at the windward canyon wall were found when compared with the tree-free canyon.
Keywords: street canyons; traffic-induced turbulence; boundary layer wind tunnels; concentration measurements; pollutant dispersion; air exchange; traffic emissions; city planning; trees; air quality; vehicle emissions; exhaust emissions; air pollution; tree spacings; urban streets.