Disparities in the impact of urban heat island effect on particulate pollutants at different pollution stages - A case study of the “2 + 36” cities

Urban heat island (UHI) and atmospheric pollution are critical ecological challenges in urban areas. China's air quality presents a stage-specific “polluting first and cleaning up later” model. However, the differential impact of UHI on particulate matter (PM) pollution across various stages remains unclear. This study utilizes land surface temperature (LST) data between 2000 and 2021 to calculate the surface urban heat island intensity (SUHII) across the “2 + 36” cities, a key pollution prevention and control area. The inflection points of PM pollution in each city were identified through piecewise linear regression, dividing the study period into distinct pollution stage. The geographical and temporal weighted regression (GTWR) model was employed to analyze the varying impacts of SUHII on PM pollution across different stages. The result indicate that UHI persisted significantly during the study period. The impact of SUHII on PM pollution exhibits pronounced temporal and regional characteristics, with an increasing influence of Nighttine SUHII (N_SUHII) on pollution. This finding highlights a crucial entry point for future pollution control measures. Moreover, under the influence of SUHII, ecological factors such as enhanced vegetation index and precipitation may paradoxically exacerbate PM pollution at certain times. These findings reveal the multifaceted causes and dynamics of urban PM pollution in developing countries, validate the necessity of implementing targeted management measures in the context of future climate change, and are important for the formulation of strategies to promote sustainable urban development.