Long-term Variability in Black Carbon Emissions Constrained by Gap-filled Absorption Aerosol Optical Depth and Associated Premature Mortality in China

Black carbon (BC) plays an important role in air quality, public health, and climate, while its long-term variations in emissions and health effect were insufficiently understood for China. Here, we present the spatiotemporal evolution of BC emissions and the associated premature mortality in China during 2000-2020 based on an integrated framework combining satellite observations, a machine learning technique, a “top-down” inversion approach, and an exposure-response model. We found that the “bottom-up” approach likely underestimated BC emissions, particularly in less developed western and remote areas. Pollution controls were estimated to reduce the annual BC emissions by 26% during 2010-2020, reversing the 8% growth during 2000-2010. BC emissions in the main coal-producing provinces declined by 2010 but rebounded afterwards. By contrast, provinces with higher economic and urbanization levels experienced emission growth (0.05-0.10 Mg/km2/yr) by 2010 and declined greatly (0.07-0.23 Mg/km2/yr) during 2010-2020. The national annual BC-associated premature mortality ranged between 733,910 (95% confidence interval: 676,790-800,250) and 937,980 cases (864,510-1,023,400) for different years. The changing BC emissions contributed 78,590 cases (72,520-85,600) growth within 2000-2005 and 133,360 (123,150-145,180) reduction within 2010-2015. Strategies differentiated by region are needed for further reducing BC emissions and its health and climate impacts.