The Impact of Urban Form on Particle Dispersion in a Residential Neighborhood

Airborne particulate matter poses a significant risk to human health and well being. This risk is especially acute in urban suburbs where a majority of the population lives and where a significant amount of localized pollution sources from automobiles are present. Although the various impacts on urban inhabitants have been documented, the role of urban form on exposure levels in the near source region is not well understood. Here, the impact of source location, street layout, and tree density on local pollution concentrations at pedestrian levels is explored using the QUIC (Quick Urban Industrial Complex) dispersion modeling system. The QUIC system uses a diagnostic, mass consistent wind field solver QUIC-URB to efficiently solve for three-dimensional winds around resolved buildings and trees and a Lagrangian dispersion model QUIC-PLUME for pollutant transport modeling. Before examining the impact of urban form, the ability of QUIC-URB and QUIC-PLUME to represent winds and dispersion in suburban neighborhoods with significant tree cover is evaluated through comparisons with field data collected during a July 2017 near source particle release experiment performed in the Sunset neighborhood of Vancouver, Canada. Plume shape parameter comparisons with the data indicate QUIC captures the primary signature of the urban environment on plume dispersion. The model is then used to evaluate how different urban building layout features (streets, intersections, alleys), tree distributions (leaf area index and height), and source locations impact pedestrian level pollution concentrations.