- 期刊
- OpenAccess
Assessment of COVID-19 Impacts on Air Quality in Ulaanbaatar, Mongolia, Based on Terrestrial and Sentinel-5P TROPOMI Data
摘要
The study aims to reveal the impact of three sequential strict-lockdowns of COVID-19 measures on the air pollutants including NO_2, SO_2, PM_(10), and PM_(2.5) in Ulaanbaatar, Mongolia during November 2020-February 2021 based on air quality network and satellite data. Based on measurements of automatic air quality sites in Ulaanbaatar, we found a substantial decrease in NO_2 (up to 45%), PM_(10) (72%), and PM_(2.5) (59%) compared to the same periods in the previous five years. On the other hand, up to a threefold increase in SO_2 concentration was seen. Compared to 2015-2020, the number of days exceeding the national air quality standard level of NO_2 decreased by 55% during November 2020-February 2021. A similar trend was observed for PM_(10) and PM_(2.5) (30% and 14%, respectively). Conversely, days exceeding the national air quality standard level of SO_2 increased by 58%. The third strict-lockdown exhibited significant reductions in pollutant concentrations. The percentage exceeding the national standard level for NO_2, PM_(10), and PM_(2.5) constituted 23%, 50%, and 67% during the lockdown periods while it was 89%, 84%, and 91%, respectively, for the same periods in the previous five years. Even though Sentinel 5P-TROPOMI data do not fully reflect the above findings, they add valuable insights into the spatial pollution pattern during strict-lockdown and non-lockdown periods. The study demonstrates that measures taken during the strict-lockdown periods clearly influenced the values of daily patterns of NO_2, PM_(10), and PM_(2.5) concentrations. On the contrary, it is important to note that SO_2 concentration increased during the last two winter months after 2019.
延伸閱讀
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