Urban heatwaves and mortality: A socioeconomic and environmental study using a novel building heat vulnerability index

Climate change has significantly increased the frequency, intensity, and magnitude of heatwaves, leading to numerous deaths in recent decades. While environmental parameters are known contributors to heat-related mortality, the specific impacts of socioeconomic factors remain less clear. This study introduces a new Building Heat Vulnerable Index (BHVI) to assess and map urban overheating mortality risk during heatwaves at the building level. Using data from the 2018 Montreal heatwave, we employed penalized logistic regression (PLR) to analyze the correlation between heat-related mortality and both environmental and socioeconomic parameters across Montreal. The City Building Energy Model (CityBEM) was used to simulate indoor overheating conditions, providing detailed exposure data. Socioeconomic variables were collected from Censusmapper and Geoportail Quebec. Our analysis revealed that “dwelling density” and “average income” are the most significant factors affecting heat-related mortality. Utilizing the BHVI, we generated a detailed heat vulnerability map identifying risk regions across Montreal, highlighting vulnerable areas with high dwelling density and low average income. Additionally, we thoroughly evaluated the impacts of increasing air conditioning (AC) capacity on mitigating heat vulnerability through bootstrap simulations. The results demonstrated that enhancing AC capacity significantly reduces heat-related mortality risk, particularly in high and critical risk areas. The findings underscore the importance of integrating socioeconomic factors and building-level data into heatwave mortality risk assessments. They suggest that targeted interventions, such as improving AC accessibility in vulnerable neighborhoods, can effectively mitigate heat-related health risks. This study provides valuable insights for policymakers to implement effective heat mitigation strategies in urban environments facing escalating climate challenges.