Assessment of Urban Heat and Pollution Island Impact on Indoor Air Quality and Thermal Conditions in Vulnerable Residential Areas

Cities modify the local climate through profound changes to the natural landscape and emissions of waste heat and materials. Two of the outcomes from these changes are the Urban Heat Island (UHI) and Urban Pollution Island (UPI) phenomena, which together can impact public health and well-being, especially during hot weather. Although these are outdoor urban effects they also affect the indoor environment, particular for poorly insulated building that rely on natural ventilation to manage thermal discomfort. The associated risk is greatest for those living in poor quality housing in city centres. 

The objective of this research is to assess the linkage between outdoor UHI and UPI intensity and indoor thermal and air quality conditions in residential buildings located in a socially vulnerable area. The data collection has been carried out by repeating a mobile transect based on social vulnerability indicators to analyse outdoor conditions, and fixed stations inside dwellings to measure indoor environments, including PM10, PM2.5 and temperature data. This study is being conducted in La Rondilla neighbourhood, Valladolid (Spain), during the late evening hours when the city remains warm and residents are at home, a relevant period for exposure. Preliminary results indicate significant spatial variations in the intensity of heat and air quality, and highlight the influence of outdoor conditions on indoor environments, emphasizing how building characteristics and performance could mitigate their impact. This study has relevance for urban decision-making, on public health, environmental justice and urban planning.