Identifying critical building morphological design factors of street-level air pollution dispersion in high-density built environment using mobile monitoring

In high-density cities, optimization of their compact urban forms is important for the enhancement of pollution dispersion, improvement of the air quality, and healthy urban living. This study aims to identify critical building morphological design factors and provide a scientific basis for urban planning optimization. Through a long-term mobile monitoring campaign, a four-month (spanning across summer and winter seasons) spatiotemporal street-level PM2.5 dataset was acquired. On top of that, the small-scale spatial variability of PM2.5 in the high-density downtown area of Hong Kong was mapped. Seventeen building morphological factors were also calculated for the monitoring area using geographical information system (GIS). Multivariate statistical analysis was then conducted to correlate the PM2.5 data and morphological data. The results indicate that the building morphology of the high-density environment of Hong Kong explains up to 37% of the spatial variability in the mobile monitored PM2.5. The building morphological factors with the highest correlation to PM2.5 concentration are building volume density, building coverage ratio, podium layer frontal area index and building height variability. The quantitative correlation between PM2.5 and morphological factors can be adopted to develop scientifically robust and straightforward optimization strategies for planners. This will allow considerations of pollution dispersion to be incorporated in planning practices at an early stage.