Regional differences of air pollution in China: comparison of clustering analysis and systematic clustering methods of panel data based on gray relational analysis

Ecological environment deterioration caused by air pollution (AP) seriously threatens human life and health, with academic circles focusing on how to improve AP control efficiency, promote regional collaborative regulatory control of AP, and ensure the safety of human life. This research thus uses time-based systematic clustering of cross-sectional data and gray correlation clustering of panel data to analyze AP situations and regional differences (RD) via AP index data of 31 provinces and cities in China from 2014 to 2018. The results show that the air quality of these provinces and cities has improved and that the concentration of pollutants has declined to varying degrees, but AP in Beijing, Tianjin, and other places is still more serious. While the effect of AP improvement in some areas is not distinct, the trend of regional AP continues to be quite serious. This paper reveals current RD of AP in China and offers some suggestions and recommendations on pollution control, such as further optimizing the industrial structure and energy consumption structure and improving people's concept of ecological civilization.