Strategizing the relation between urbanization and air pollution: Empirical evidence from global countries

While urbanization has boosted the global economy, it is putting increasing pressure on air quality. Previous studies on the link between urbanization and air pollution have tended to focus on individual aspects of urbanization. In addition, research into the global scale has been scarce. This study constructed an urbanization index system integrating demographic, spatial, economic, and social components and divided 190 countries into 4 subpanels according to the national income levels, in order to identify the heterogeneity effects of urbanization on PM2.5 pollutants for the period 1998–2014 from a global perspective. The results of the panel regression models prove that the effect of urbanization on atmospheric contamination varied significantly across the income-based subpanels. The model analysis shows that demographic urbanization has a significant positive effect on PM2.5 concentrations in all subpanels. Spatial urbanization had exerted a negative effect on air pollution in high-income countries and a positive influence on air pollution in other countries. Social urbanization, in contrast, presented the opposite trend. Additionally, the model analysis shows that the economic urbanization in upper-middle-income and high-income groups can effectively alleviate PM2.5 pollutants. This study indicated that the level of development needs to be taken into account when government policy makers formulate targeted measures to control haze and improve air quality.