title: Influence of avenue-trees on air quality at the urban neighborhood scale. Part II: traffic pollutant concentrations at pedestrian level.
abstract: Flow and dispersion of traffic-emitted pollutants were studied in a generic urban neighborhood for various avenue-tree layouts by employing 3D steady RANS simulations with the realizable k-ε turbulence model. In comparison to the tree-free situation quantitative and qualitative changes with flow reversal in the wind field were observed. Low to moderate increases (<13.2%) in the neighborhood-averaged pollutant concentration were found at pedestrian level. An approximately 1% increase in the neighborhood-averaged concentration was obtained with each percent of the street canyon volumes being occupied by vegetation for occupation fractions between 4 and 14%. The overall pattern of concentration changes relative to the tree-free situation was similar for all avenue-tree layouts. However, pronounced locally restricted decreases or increases in concentration (-87 to +1378%) occurred. The results indicate the necessity to account for existing or planned avenue-trees in neighborhood scaled is dispersion studies. Their consideration is prerequisite for reliable urban air quality assessment.
authors.affiliation: Building Physics and Services, Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. gromke@kit.edu
authors.forename: Christof
authors.initials: C
authors.lastname: Gromke
authors.forename: Bert
authors.initials: B
authors.lastname: Blocken
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004781:Environmental Exposure / Q000032:analysis* / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D015386:Hazardous Substances; D006801:Humans; D008962:Models, Theoretical; D014197:Trees; D001335:Vehicle Emissions / Q000032:analysis*; D016138:Walking; D014919:Wind
chemical_list: D000393:Air Pollutants; D015386:Hazardous Substances; D001335:Vehicle Emissions