In Bangladesh, a nationwide lockdown was imposed on 26 March 2020, due to the COVID-19 pandemic. Due to restricted emissions, it was hypothesized that the air quality has been improved during lockdown throughout the country. The study is intended to assess the impact of nationwide lockdown measures on air quality in Bangladesh. We analyzed satellite data for four different air pollutants (NO2, SO2, CO, and O3) to assess the changes in the atmospheric concentrations of pollutants in major cities as well as across the country. In this study, the concentrations of NO2, SO2, CO, and O3 from 1 February to 30 May of the year 2019 and 2020 were analyzed. The average SO2 and NO2 concentrations were decreased by 43 and 40%, respectively, while tropospheric O3 were found to be increased with a maximum of > 7%. Among the major cities, Dhaka, Gazipur, Chattogram, and Narayanganj were found to be more influenced by the restricted emissions. In Dhaka, NO2 and SO2 concentrations were decreased approximately by 69 and 67%, respectively. Our analysis reveals that NO2 concentrations are highly correlated with the regional COVID-19 cases (r = 0.74). The study concludes that the lockdown measures significantly reduced air pollution because of reduced vehicular and industrial emissions in Bangladesh.

中文翻译：

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由于 COVID-19 爆发而导致的全国封锁对孟加拉国空气质量的影响：时空分析

在孟加拉国，由于 COVID-19 大流行，于 2020 年 3 月 26 日实施了全国封锁。由于排放受限，据推测，在全国范围内的封锁期间，空气质量有所改善。该研究旨在评估全国封锁措施对孟加拉国空气质量的影响。我们分析了四种不同空气污染物（NO2、SO2、CO 和 O3）的卫星数据，以评估主要城市和全国大气污染物浓度的变化。本研究分析了 2019 年和 2020 年 2 月 1 日至 5 月 30 日期间 NO2、SO2、CO 和 O3 的浓度。SO2 和 NO2 的平均浓度分别降低了 43% 和 40%，而对流层 O3 的浓度最高增加了 > 7%。在主要城市中，达卡、加济布尔、Chattogram 和 Narayanganj 受限制排放的影响更大。在达卡，NO2 和 SO2 浓度分别下降了大约 69% 和 67%。我们的分析表明，NO2 浓度与区域 COVID-19 病例高度相关（r = 0.74）。该研究得出的结论是，由于孟加拉国的车辆​​和工业排放减少，封锁措施显着减少了空气污染。