Short-term human intervention did not significantly improve urban air quality

Short-term interventions may create a false sense of progress in addressing air quality issues. We find that despite the implementation of several short-term strategies during the coronavirus disease 2019 (COVID-19) pandemic, such as traffic restrictions, the anticipated improvements in air quality were not realized. On the contrary, the regional transportation of pollutants and the formation of secondary aerosols may still influence the air quality. Through a comprehensive analysis of air quality data collected before, during, and after the interventions in COVID-19, employing nonlinear statistical methods to assess changes in key pollutants, it can be inferred that the long-term memory mechanisms, nonlinear dynamic mechanisms of the atmospheric system play a crucial role in the evolution of air pollutants. Thus, the short-term human intervention did not significantly improve urban air quality. Besides, when pollution processes occur, the reason may not be unique, we must comprehensively interpret it. Policymakers are encouraged to consider more comprehensive and long-term strategies that integrate continuous monitoring and evaluation of air quality interventions.