Variation characteristics and coordinated emission reduction of air pollutants in megacity of Chengdu-Chongqing economic circle under dual carbon goal

Abstract

The air pollution process and impact mechanism of megacities located in complex terrain are particularly complex. As a typical megacity in China, Chengdu has unique topographical and meteorological conditions, and its pollution control is difficult. This study systematically elucidated the variation characteristics of six criteria air pollutants in Chengdu between 2014 and 2020. Besides, the PM<sub>2.5</sub>/PM<sub>10</sub> and NO<sub>2</sub>/SO<sub>2</sub> ratios were discussed. Furthermore, a detailed analysis of the correlation between air pollutants was carried out. Finally, the collaborative path of carbon reduction and air pollution control is discussed. The results indicated that SO<sub>2</sub>, PM<sub>2.5</sub>, PM<sub>10</sub> and CO were significantly decreased by 62.9%, 50.8%, 45.5%, and 36.7%, respectively. PM<sub>2.5</sub> and O<sub>3</sub> compliance rates are very low, and O<sub>3</sub> increases with fluctuations. SO<sub>2</sub>, NO<sub>2</sub>, CO, PM showed a “U-shaped” seasonal variation, and there was a “seesaw” phenomenon between O<sub>3</sub> and PM<sub>2.5</sub>. The continuous changing trends also found in the ratios of PM<sub>2.5</sub>/PM<sub>10</sub> and NO<sub>2</sub>/SO<sub>2</sub>. The results highlight the importance of coordinated reduction of carbon emissions and pollutants in Chengdu. This research can improve the prediction accuracy of air pollution in complex terrain areas under global warming, and improve the understanding of the formation mechanism of air pollution in special terrains around the world.