The influence of the built environment in the social impact of the low emission zones of Madrid (Spain)

• LEZ social impacts are connected to car dependence and the built environment. • Built-environment dimensions mediate LEZ exposure in Madrid. • Urban centrality dimension is linked to higher car usage in Madrid’ periphery. • Results support spatial assessments and LEZ integration with urban planning. • Social justice reflections should support – not oppose – sustainable urban models. Low Emission Zones (LEZ) are one of the main policies to combat air pollution problems caused by urban traffic. Controversies about the potential social impact of access restrictions offset their benefits to public health and quality of life. At the core of this impact lies car dependency, which is influenced by both socioeconomic and built-environment factors. Despite their implications, built-environment factors are often missing from most recommendations on LEZ spatial design. This research aims to capture the relationships between the built environment, private vehicle use, and the exposure of residents in the 131 neighbourhoods of the municipality of Madrid (Spain) to the deployment of access restrictions. A principal components analysis identified common patterns in urban characteristics related to urban centrality, compact urban morphology, and proximity to suburban-rail environments. These three resulting components were included in a structural equation model, mediating the effect of socioeconomic and mobility factors on private vehicle use, which in turn influenced the probability of residents being affected in each deployment area. The results show how the built environment – particularly, the urban centrality component – influences residents’ exposure to LEZs, playing a key role in reducing car use in the outer rings (the city’s periphery and metropolitan area). Therefore, it is expected that the social impacts of the final phase of Madrid’s LEZ expansion will require greater attention to the socioeconomic and urban characteristics of the periphery.