Accessibility versus air pollution: A geography of externalities in the Brussels agglomeration

This paper proposes a novel approach to investigate the geography of accessibility and air pollution and tests it on the case of the Brussels Capital Region. First, we find a strong positive correlation between accessibility and air pollution, highlighting a trade-off that exists between two emblematic but antithetical externalities of agglomerations. Next, we focus on the outliers that escape this trade-off and we develop a methodology to combine their respective levels of accessibility and air pollution into a ‘desirability’ indicator. Finally, we analyse the distribution of the most and the least desirable neighbourhoods across the city: while we observe flagrant patterns of inequality, these do not reflect the socio-economic structure of the region, in apparent contrast with the literature on transport justice and environmental justice. The results show how positive and negative socio-ecological externalities can be two sides of the same agglomeration coin. The methodology proves to be relevant to further comparative research and policy making concerned with promoting a balanced progress of social, economic and environmental priorities.