Time series analysis of PM2.5 pollution risk based on the supply and demand of PM2.5 removal service: a case study of the urban areas of Beijing - Song, Zhelu; Wang, Cun; Hou, Ying; Wang, Bo; Chen, Weiping (Environmental Monitoring and Assessment: An International Journal Devoted to Progress in the Use of Monitoring Data in Assessing Environmental Risks to Humans and the Environment, 2024)