The distribution and drivers of PM in a rapidly urbanizing region: The Belt and Road Initiative in focus.

The accelerating urbanization has led to serious air pollution dominated by PM, posing a critical challenge for the environmental sustainability of the Belt and Road Initiative (BRI). However, a focus on the distribution and drivers of PM concentrations in BRI is lacking. To fill in the gap, this study explores the spatio-temporal distribution of PM concentrations in 74 nations partnering the BRI and identifies the socioeconomic and natural drivers behind the variation through the joint use of spatial autocorrelation and regression analyses. We find that the PM concentrations of BRI show significant spatial autocorrelation and spatial heterogeneity on the national scale. The most heavily polluted regions are observed mainly in China, Southeast Asia, South Asia, West Asia and North Africa, particularly in the Arabian Gulf region. Energy intensity and per capita electricity consumption act as the major drivers of the PM concentrations, whereas the expanding forest area contributes to the decrease in PM concentrations notably. Our findings highlight the need for speeding up new-type urbanization as part of the green BRI practice, calling for international cooperation and coordinated action aimed at enhancing synergies of air-quality and climate policies that at present are mostly launched and implemented in isolation. From a broader point of view, in struggling towards BRI's cleaner air, more attention should be paid to creating policy synergies between the green BRI, the Paris Agreement, and the United Nations 2030 Agenda for Sustainable Development.