Structural equation modeling of the combined effect of urban population, gross regional product and area on air pollution in selected Chinese cities

Abstract

Expansion of urban scale, including the growth of population, gross regional product and city area, have led to an increase in the city's air pollution. Previous research has often emphasized the adverse effect of urban scale on air pollution levels through the expansion of residents' activities. However, the expansion of urban scale can also induce the green technological innovation and change in the industry structure via the effect of agglomeration, thus leading to reduction of air pollution to some extent. Association mechanisms between urban scale and air pollution are complex and poorly understood. In this context, this study aims to identify the combined effects of urban scale on air pollution through residents' activities, industry structure and technique impact in 292 selected Chinese cities from 2015 to 2020, using the structural equation modeling. Results suggested that the expansion of urban scale had a positive impact on air pollution levels through residents' activities (average impact coefficient: 0.509). But urban scale promoted the impact of green technological innovation and optimization in the industry structure, causing a decrease in air pollution levels. The average impact coefficients of urban scale on air pollution levels through technique impact and industry structure were −0.202 and −0.018, respectively. Furthermore, the multiple-group analysis found that with the growth of urban population, there was an increase in the association strength of urban scale on air pollution via technique impact, while there was a great deal of difference for the industry structure. Findings from this study can contribute to a more comprehensive understanding of the impact of urban scale on air pollution, which will provide a theoretical basis for air pollution prevention and control policies.