Spatial Assessment of Heat Health Risk in Brussels Through GIS and Local Climate Zone Analysis

Climate change and rapid urbanization are increasing the frequency and intensity of extreme heat events, posing significant risks to public health in cities. Although numerous studies have investigated urban heat islands and heat vulnerability, spatially explicit assessments integrating environmental, demographic, and urban morphological characteristics remain limited, particularly in European cities. This study presents the first Heat–Health Risk Index (HHRI) assessment for the Brussels Capital Region, combining remote sensing, demographic information, and Local Climate Zone (LCZ) classification within a Geographic Information System (GIS) framework to evaluate the spatial distribution of heat health risk. The HHRI was developed by integrating three components (hazard, exposure, and vulnerability) derived from Landsat 8/9 imagery, WorldPop population data, and LCZ classification generated following the WUDAPT methodology. Hazard was represented by Land Surface Temperature (LST), exposure combined population density and built-up intensity (NDBI), while vulnerability incorporated vegetation (NDVI), surface water (MNDWI), and age-sensitive population groups. Principal Component Analysis (PCA) was applied to determine indicator weights, and the resulting HHRI was analyzed across different LCZs using zonal statistics. The results revealed pronounced spatial variability in heat health risk across Brussels, with the highest HHRI values concentrated within the densely urbanized central municipalities and the lowest values occurring in the vegetated southern and southeastern areas. LCZ analysis showed that Compact Low-Rise (LCZ 3) and Compact Mid-Rise (LCZ 2) exhibited the highest proportions of high and very high risk, whereas natural LCZs, particularly Dense Trees (LCZ A) and Low Plants (LCZ D), consistently functioned as urban cooling environments associated with low heat health risk. This study addresses an important research gap by providing the first LCZ-based HHRI assessment for Brussels and Belgium. The proposed open-data and reproducible methodology offer a transferable framework for identifying priority intervention areas and supporting evidence-based climate adaptation and urban planning in European cities.