Quantifying urban heat island and pollutant nexus: A novel geospatial approach

Abstract

The interaction between Urban Heat Island (UHI) effects and air pollution in urban areas significantly impacts both the well-being of inhabitants and the delicate balance of urban ecology and climate. This study investigates the interactions between UHI effects and pollutants (CO, HCHO, aerosols, NO2, O3, and SO2) distribution in Hyderabad over four years (2019–2022) within spatial and thermal interfaces. The study identified that there is a significantly higher concentration of pollutants in the urban areas compared to the rural areas. In urban areas, the UHI indicator shows a strong positive correlation with pollutants like CO, NO2, and O3, a weaker positive correlation with HCHO, and aerosols, and a weak negative correlation with SO2. A comprehensive framework to analyse the combined impact of pollutants, yielding insights into cumulative atmospheric pollution levels - UPI indicator is proposed in this study. The subsequent generation of pollution risk map identified that around 80 % of the urban expanse is highly contaminated zones. The conjunction of thermal hotspots and high contamination zones highlights nuanced UHI-pollution associations, unveiling high-risk zones with elevated temperatures and pollutants. The high-risk zones exhibit elevated annual average concentrations of NO2, aerosols, HCHO, and CO, surpassing the non-high-risk zone by 53.535 %, 21.707 %, 7.561 %, and 1.194 %, respectively. Additionally, the high-risk zones experience a temperature higher than the non-high-risk zone by 2.601 °C. This research informs urban planning and policies, contributing to a holistic understanding of UHI-pollution dynamics and their implications.