Urban compactness and the trade-off between air pollution emission and exposure: Lessons from a spatially explicit theoretical model

Air pollution is a major concern in urban areas worldwide. The interplay between urban structure and air pollution from an environmental, health and social perspective is the focus of our work: we model how urban structure impacts traffic-induced pollutant emissions and the exposure of residents to those pollutants.
We present a chain of models applied to theoretical monocentric space: a residential choice model with endogenous open-space and road network, a commuting traffic generation and road assignment model and a pollutant emissions, dispersion and exposure model. The theoretical study approach decouples results from location specific characteristics and enables us to analyse how the preference of households for green amenities, a transport tax, the provision of public transport alternatives and local neighbourhood design impact the environment (total emissions) as well as residents’ health (population exposure) and utility.
We emphasise that environmental strategies in the form of urban compaction have a strong impact on the exposure of households to pollutants, especially close to the centre, in addition to their reduction of welfare. Our results suggest that more beneficial policy outcomes can be obtained from strategies which preserve green spaces close to the centre or which intend a greater shift from car to public transport. Further, we find indication that different local designs of neighbourhoods have much stronger impacts on the exposure–emission tension than city-wide land use or transport options.