On the two-way interactions of urban thermal environment and air pollution: A review of synergies for identifying climate-resilient mitigation strategies

Abstract

The urban environment is threatened by urban heat island (UHI) effect and air pollution events which have been worsened by population increase, heat waves, and wildfire smoke. It is important to understand that urban air quality and thermal environment are mutually dependent, meaning that the alteration in one can affect the other. This two-way interaction is described in our review through a detailed analysis of physics-based models and their synergistic processes. Then, drawing on the literature, we categorized mitigation plans into four major strategies: modification of urban morphology, integration of urban greenery, incorporation of water bodies, and utilization of cooling materials. The identified mitigation strategies were evaluated for their effectiveness in achieving various reduction targets, such as overheating, strong wind events, and gaseous and aerosol pollutants. These assessment results can be helpful in developing a practical guide for establishing climate-resilient buildings and cities. This study also conducts a co-benefits and conflicts analysis associated with these mitigation strategies, discussing their application potentials for designers, planners, and policymakers in preparing cities to become thermally resilient and healthy. The review emphasizes the need for the formulation of numerical coupling models that will address the “thermo–pollutant” coupling to better comprehend the magnitude of synergies.