Using urban form to increase the capacity of cities to manage noise and air quality

The top two environmental factors adversely affecting human health in Europe are air and noise pollution, with road traffic being the largest source. Urban density plays an important role in reducing car traffic. However, the benefits of reduced emissions per capita can still mean higher emissions locally, because of the number of people in the area. Therefore, this paper investigates how morphological parameters influence the local distribution of noise and air pollution. A parametric approach, based on the Spacematrix method, is used to study the impact of morphological parameters on the distribution of air and noise pollution, controlling for traffic mode, flows and speed. To compare the impact of exposure to noise and air pollution, their respective health burden is calculated using disability- adjusted life years (DALYs). The results, based on 31 models of different forms, show that the degree of openness greatly affects performance with opposite effects for noise and air pollution. Building types with slightly open yards, like open corner blocks, may provide an attractive compromise solution due to their relatively good noise exposure situation at the same time as the dispersion of air pollutants improves. Adding sound absorbing vegetation is an effective measure to mitigate noise, especially for blocks with openings, limiting the propagation of sound into the yard. Further, densification is beneficial for health if the increase in density does not increase traffic volume in the same proportion. Densification by adding towers on a perimeter building block gives the best results for health as it combines a less noisy yard, thanks to the enclosure of the yard with towers, which enhances turbulent mixing of air within the street canyon.