How much urban air quality is affected by local emissions: A unique case study from a megacity in the Pearl River Delta, China - Tang, M. X.; Huang, X. F.; Yao, P. T.; Wang, R. H.; Li, Z. J.; Liang, C. X.; Peng, X.; Cao, L. M.; Du, K.; Yu, K.; Guo, S. (Atmospheric EnvironmentAtmospheric Environment, 2023)