Changes in Air Quality from the COVID to the Post-COVID Era in the Beijing-Tianjin-Tangshan Region in China

This article discussed air quality changes in the Beijing-Tianjin-Tangshan (BTT) region. The index (AQI) values, and concentrations of PM2.5, PM10, SO2, CO, NO2, O3 BTT region during COVID-19 outbreak 2020 were, respectively, 79.4, 47.2 ?g m-3, 73.4 10.3 0.87 mg 33.6 90.7 m-3. However, they 102.7, 61.4 121.0 9.0 0.88 40.1 84.0 m-3 same period 2021, which is an increase 29.2%, 30.1%, 64.8%, -12.9%, 1.94 %, 19.5%, -7.4% compared with values 2020. combined proportions grade I II were 16.7% higher than those so has deteriorated rapidly from to post-COVID era 2021. possible reasons for poorer are that frequency dusty weather pollutant discharge increased, meteorological conditions have been relatively unfavorable. average AQI 2021 respectively decreased by 14.8%, 29.0%, 14.6%, 22.5%, 37.4%, 8.7%, It also worth noting all pollution consistent. 18.4% 2020, indicates obviously improved a series clean policies actions, as well favorable atmospheric diffusion conditions. These results indicate play very important role improving quality.