Analysing urban inequalities in environment and health at the neighbourhood scale in Dublin through a new open-access ‘Health Rating Index’

• A composite ‘Health Rating Index’ (HRI) can be used to assess environmental health at the small area level • Built environment, transport, and socioeconomic features are the most important predictors of HRI • HRI is spatially-clustered • ‘Healthier’ small areas have more non-auto commuting, higher population density, longer distances to the nearest road, and higher socioeconomic status • Nonlinear relationships are modelled using novel spatial random forest approach This paper examines the spatial distribution of accessibility to health benefits and exposure to health risks at the small area level in Dublin, Ireland for six key factors: primary healthcare, green space, blue space, air pollution, road noise, and housing quality. The primary goal is to combine granular spatial data on these features into a composite open-source 'Health Rating Index' (HRI) and analyse its relationship to characteristics of the built, social, and transportation environment. To create the HRI, we calculated spatial accessibility to health 'benefits' using Enhanced Two-Step Floating Catchment Area (E2SFCA) methods with multiple distance decay functions, and estimated Years of Life Lost (YLL) per capita from health 'risks' (air pollution and road noise) using age-sex stratified mortality rates. We standardized and combined these six factors (testing three weighting approaches), and then used spatial cross-validation random forest with bootstrap confidence intervals to assess the relationship between HRI and sociodemographic and built environment features. Importantly, the paper’s spatial modelling approach, implemented through a new R package ‘SArf’, explicitly addresses spatial autocorrelation through within-fold spatial lag computation to prevent data leakage. Results show the HRI pattern is highly spatially-clustered, and that small areas with worse environmental health conditions tend to be more disadvantaged, older, less dense, and closer to major roads. This research provides useful insights on the ways in which transport investments, social disadvantage, environmental conditions, and health outcomes are critically linked in urban areas.