The air quality changes and air pollution characteristics in Guilin during the COVID-19 prevention and control period were analyzed by the paired t-test, Wilcoxon signed rank-sum test, chi-square test and pollutant characteristic radar chart using the mean daily AQI and the concentration of 6 air pollutants (PM2.5, PM10, SO2, NO2, CO, O3) from January to March of 2017–2021. The results showed that the air quality in Guilin was generally good. Compared with 2017–2019, the mean daily AQI in 2020 decreased by 29.59%, and the coal burning, dust and motor vehicle pollution reduced, indicating that the air quality was improved significantly. In the strict pandemic prevention and control period, the AQI and the days with PM2.5 pollution decreased by 52.14% and 70.59% respectively, and the days with PM10, PM2.5, SO2, NO2 all decreased by more than 50%. Later, the coal and motor vehicle pollution showed signs of increase, suggesting that the type of air pollution changed from combined pollution to coal burning pollution. Compared with 2020, the coal burning, dust and motor vehicle pollution in 2021 experienced a retaliatory rebound, and the air quality basically recovered to the pre-pandemic level, suggesting that the type of air pollution changed from coal burning and motor vehicle pollution to coal burning and dust pollution.
