Global distribution and evolvement of urbanization and PM_2.5 (1998–2015)

PM_2.5 concentrations increased and have been one of the major social issues along with rapid urbanization in many regions of the world in recent decades. The development of urbanization differed among regions, PM_2.5 pollution also presented discrepant distribution across the world. Thus, this paper aimed to grasp the profile of global distribution of urbanization and PM_2.5 and their evolutionary relationships. Based on global data for the proportion of the urban population and PM_2.5 concentrations in 1998–2015, this paper investigated the spatial distribution, temporal variation, and evolutionary relationships of global urbanization and PM_2.5. The results showed PM_2.5 presented an increasing trend along with urbanization during the study period, but there was a variety of evolutionary relationships in different countries and regions. Most countries in East Asia, Southeast Asia, South Asia, and some African countries developed with the rapid increase in both urbanization and PM_2.5. Under the impact of other socioeconomic factors, such as industry and economic growth, the development of urbanization increased PM_2.5 concentrations in most Asian countries and some African countries, but decreased PM_2.5 concentrations in most European and American countries. The findings of this study revealed the spatial distributions of global urbanization and PM_2.5 pollution and provided an interpretation on the evolution of urbanization-PM_2.5 relationships, which can contribute to urbanization policies making aimed at successful PM_2.5 pollution control and abatement.