The key factor in shaping the historical and future PM2.5 urban-rural pattern in China

Since 2000, rapid urbanization and emissions reduction efforts in China have significantly reshaped emissions, underlying surfaces, and meteorological conditions, altering the PM_2.5 urban-rural distribution. However, the relative contributions of various factors to historical PM_2.5 urban-rural patterns and the sensitive factor shaping future patterns remain unclear. This study quantified the relative contributions of emissions, urban landscape patterns (ULP), and meteorology to PM_2.5 urban-rural differences (URD-PM_2.5) across 299 Chinese cities from 2000 to 2020, and further identified the dominant drivers changing historical URD-PM_2.5 and the sensitive factor reshaping future URD-PM_2.5. The results show that URD-PM_2.5 evolution from 2000 to 2020 can be divided into two typical periods: the Stable High-level Period (SHP, 2000–2013), and the Rapid Decline Period (RDP, 2013–2020). During these periods, the relative contribution of emissions to URD-PM_2.5 consistently increased (nationally from 29 % to 45 %), while that of meteorology decrease continuously (nationally from 49 % to 34 %). And emissions gradually replaced meteorology as the dominant driver during RDP. The relative contribution of ULP remained stable. Furthermore, URD-PM_2.5 in 173 cities was observed to become increasingly sensitive to emissions, 110 cities in southern and southwestern China are increasingly sensitive to ULP, while 16 cities in northeastern China are increasingly sensitive to meteorology. These findings highlight the different contributions of emissions and meteorology to PM_2.5 urban-rural patterns at different periods, and suggest more scientifically targeted policies tailored to specific cities' conditions are needed according to their sensitive factors in future to collaboratively‌ improve urban-rural air quality.