Analysis of NO₂ pollution over Bangladesh between the two covid-19 caused lockdown in 2020 and 2021 using Sentinel 5P products.

Due to the covid-19 pandemic, all countries around the world have imposed nationwide lockdowns to control the spreading of the virus. During the lockdown period, many countries had seen a drastic drop in air pollution. In Bangladesh, two nationwide lockdowns were imposed on 26th March- 30th May in 2020 and on 3rd April till the study period of 31 May in 2021. This study was aimed to analyze the NO₂ pollution over Bangladesh during the two periods of lockdown. Tropospheric NO₂ column spatial configuration was measured over Bangladesh using Sentinel 5P data. Map of monthly average concentration of Tropospheric NO₂ of 2020 and 2021 over Bangladesh had been produced using HARP toolkit and python. Then the map was compared with the same period Sentinel 5P products map of 2019. It had been found that during the first lockdown in Bangladesh between 26th March- 30th May-2020, a drastic decrease of NO₂ concentration had been observed in April month but increased in May. But during the second lockdown from 3rd April in 2021, the NO₂ concentration was found much higher in concentration. Most of the pollution occurred in the Dhaka district. During the second lockdown, the restriction was much easier than the first one that impacted the NO₂ concentration. This kind of study can be the essence for the authority to look closely at air quality and use sentinel data to improve air quality monitoring in the future.