Impacts of coal use phase-out in China on the atmospheric environment: (1) emissions, surface concentrations and exceedance of air quality standards

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Coal combustion is one of the main sources of greenhouse gases and various air pollutants. Gradually reducing the use of coal is an important strategy for controlling air pollution and achieving the goal of “carbon neutrality” in China. This study originally extracts the proportion of coal sources from emission inventories of key pollutants from different sectors and quantifies the emissions from coal sources in China during 2015. Additionally, it evaluates the peak potential impacts on the concentrations of key pollutants and overall air quality in China resulting from ceasing coal usage with the Community Earth System Model version 2 (CESM2). The results show that the emissions of sulfur dioxide (SO2), nitric oxide (NO) and black carbon (BC) from coal sources account for more than half of the total anthropogenic emissions in China. After the phase-out of coal use, the concentrations of SO2, nitrogen oxides (NOx), carbon monoxide (CO) and 2.5-μm Particulate Matter (PM2.5) could markedly decrease by approximately 30∼50%, accounting for 50–80% of anthropogenic sources and even more than 80% in individual provinces. The exceedance of SO2, nitrogen dioxide (NO2), CO and PM2.5 under the air quality standard of China is also greatly reduced. Only the concentration and exceedance of ozone (O3) increase significantly in certain parts of China and in some seasons. Sensitivity analysis also shows that most air pollutants decrease linearly or nearly linearly with the increase of coal-ban proportion. Therefore, this study suggests that the strength of coal removal needs to be gradually enhanced. And the emissions from other kinds of fossil fuels should also be controlled during the process of ending coal use to reduce the pollution levels of CO, Volatile Organic Compounds (VOCs), O3 and organic aerosols. This research thoroughly assesses the ultimate limit of contributions of coal usage to the air pollution of China, which could serve as a valuable reference for future policy formulation.