Spatiotemporal Investigations of Multi-Sensor Air Pollution Data over Bangladesh during COVID-19 Lockdown

Zhongfeng Qiu,Janet E Nichol,Pravash Tiwari,Farhan Mustafa,Sajib Sarker,Birhanu Asmerom Habtemicheal,Muhammad Bilal,Muhammad Ashfaqur Rahman,Yu Wang,Sanjit Kumar Mondal,Mansour Almazroui,Md Arfan Ali,Usman Mazhar

doi:10.3390/rs13050877

Abstract

This study investigates spatiotemporal changes in air pollution (particulate as well as gases) during the COVID-19 lockdown period over major cities of Bangladesh. The study investigated the aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua satellites, PM2.5 and PM10 from Copernicus Atmosphere Monitoring Service (CAMS), and NO2 and O3 from TROPOMI-5P, from March to June 2019–2020. Additionally, aerosol subtypes from the Cloud-Aerosol Lidar and Infrared Pathfinder (CALIPSO) were used to explore the aerosol types. The strict lockdown (26 March–30 May 2020) led to a significant reduction in AOD (up to 47%) in all major cities, while the partial lockdown (June 2020) led to increased and decreased AOD over the study area. Significant reductions in PM2.5 (37–77%) and PM10 (33–70%) were also observed throughout the country during the strict lockdown and partial lockdown. The NO2 levels decreased by 3–25% in March 2020 in the cities of Rajshahi, Chattogram, Sylhet, Khulna, Barisal, and Mymensingh, in April by 3–43% in Dhaka, Chattogram, Khulna, Barisal, Bhola, and Mymensingh, and May by 12–42% in Rajshahi, Sylhet, Mymensingh, and Rangpur. During the partial lockdown in June, NO2 decreased (9–35%) in Dhaka, Chattogram, Sylhet, Khulna, Barisal, and Rangpur compared to 2019. On the other hand, increases were observed in ozone (O3) levels, with an average increase of 3–12% throughout the country during the strict lockdown and only a slight reduction of 1–3% in O3 during the partial lockdown. In terms of aerosol types, CALIPSO observed high levels of polluted dust followed by dust, smoke, polluted continental, and clean marine-type aerosols over the country in 2019, but all types were decreased during the lockdown. The study concludes that the strict lockdown measures were able to significantly improve air quality conditions over Bangladesh due to the shutdown of industries, vehicles, and movement of people.

Highlights

The novel infectious disease Coronavirus, known as COVID-19, is caused by the SARS-CoV-2
Reduction in particulate matter pollution is reported in another study over Dhaka city; the results indicate that the mean PM2.5 concentration decreased by around 23% in 2020 compared to the mean concentration in
Smoketype aerosols decreased between 17% and 73% over most parts of the country during the 2020 strict lockdown month of April when compared to 2019, but showed surprisingly large increases of 40% and 600% during the 2020 lockdown months of March and May, respectively (Figures 14 and 15)

Summary

Introduction

The novel infectious disease Coronavirus, known as COVID-19, is caused by the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). It was first identified in December 2019 in Wuhan province, China [1]. The COVID-19 outbreak was declared a pandemic by the World Health Organization [2] on 12 March 2020. The global death toll was 2,116,714 and active corona cases were 25,683,638 (dated: 23 January 2021) [3]. South Asia, with almost a quarter of the world’s population, has been severely affected by the pandemic. The eight South Asian countries had 285,979 active cases and 177,276 deaths linked to COVID19 up to 23 January 2021. Uncertainty about the course of the pandemic is bound to hamper health as well as the economy

Objectives

Methods

Discussion

Conclusion