Spatial–temporal effects of industrial pollutants and economic development on depopulation in the mega urban agglomeration

The negative effects of industrial pollutants on the whole environment have long been a contentious issue in urbanization. While studies have analyzed the impacts of the economy and industry on depopulation separately, few focus on their combined and interactive effects at the grid level. This study investigates the complex impacts of depopulation from 2010 to 2020 in China's Beijing-Tianjin-Hebei agglomeration. Using remote-sensing and geoinformatics data, we calculated the composite economic index and the composite pollution index to observe the spatial–temporal effects on depopulation. Subsequently, the study employs the interpretable ensemble model to establish the relations between industrial pollutants, economic variables, and population density and obtained nine distinct change types. Findings reveal that many areas still confront population decline due to industrial pollution despite GDP remaining an attraction to the population. The proportion of this type of area in the nine types of changes over 10 years has ranked second steady, reaching 27.175%, 26.964%, and 29.569% in 2015–2010, 2010–2015, and 2010–2020, respectively. In addition, combined with the visualization map of spatial distribution, it is observed that the problem of population loss is particularly serious in lagging cities. Furthermore, the top three pollutants with the most prominent adverse effects are O₃, PM_2.5, and PM₁₀. This study offers important insights into sustainable urban development.