ScienceDaily: A new study published in the International Journal of Environment and Waste Management suggests that we can improve city environments by planting trees down the middle of streets provided they are not too close together. Christof Gromke now of the WSL Institute for Snow and Avalanche Research SLF in Davos, Switzerland, and Bodo Ruck of the Institute for Hydromechanics at the University of Karlsruhe, Germany, have investigated the effects of trees on ventilation and pollution levels …