Promoting Urban Sustainable Development: Underground Wastewater Treatment Plant Alleviates Urban Air Pollution

As a new type of urban infrastructure, the underground wastewater treatment plant (UWTP) is originally constructed to better meet the needs of urban sustainable development and to further improve land use efficiency. In addressing urbanization challenges, UWTPs not only improve water quality but also hold the potential to mitigate air pollution through their enclosed treatment processes. This paper uses data from Chinese cities to analyze the effect of UWTP on PM2.5 concentration. The results reveal that UWTP significantly reduces PM2.5 concentrations, where an increase in wastewater treatment capability corresponds to a larger decline in PM2.5. In particular, the effect of reducing PM2.5 is pronounced in full‐UWTP, those using anaerobic–anoxic–oxic processes and membrane bioreactor processes, and UWTP implementing higher emission standards. Regional heterogeneity analysis shows that there are differences in the effectiveness of UWTP in reducing PM2.5 concentration under different urban characteristics. In addition, the reduction in PM2.5 brought about by UWTP has produced significant health benefits, including approximately a 0.158% decrease in all‐cause mortality and savings of around $1.3377 billion in healthcare costs.