Spatial and Temporal Characterization of PM2.5 and Meteorological Factors in China During the COVID-19 Period

Abstract Purpose To explore the impact of anthropogenic emissions reductions on air quality in China during the COVID-19 pandemic. The COVID-19 outbreak was accompanied by various global lockdown measures. These measures led to a long - term decline in industrial activities and air pollution emissions, offering a valuable chance to study the influence of anthropogenic emissions cuts on air quality. Methods Based on the anomaly percentage model, we analyzed the time-varying trends of fine particulate matter (PM 2.5 ), precipitable water vapor (PWV), and temperature (T) in 33 provincial-level administrative regions in China from 2010–2020, explored the spatial distribution of their anomalies from 2019–2020, and selected 170 cities with different population density classes to analyze the changes of related indicators during the epidemic. Results During the COVID-19 period, the anomaly values of PM 2.5 fluctuated negatively in all provinces, and 69.7% and 78.8% of the anomaly values of PWV and T fluctuated positively; during the non-COVID-19 period, the anomaly values of PM 2.5 fluctuated positively, and the fluctuations of PWV and T were not obvious; PM 2.5 decreased significantly in southeastern China, and PWV and T increased significantly. As the urban population density increases, the average anomaly percentages and rates of change of PM 2.5 , precipitable water vapor (PWV), and T increase. Conclusion The human activity restrictions implemented during the COVID-19 period greatly changed the pollutant emission situation, resulting in an overall decrease in PM 2.5 and an overall increase in PWV and T. This fully confirms that there is a strong correlation between the intensity of human activities and the atmospheric air quality, and that the reduction of the intensity of human activities has a positive effect on the improvement of air quality. Graphical abstract