Impacts of COVID‐19 Restrictions on Regional and Local Air Quality Across Selected West African Cities

Abstract

The emergence of COVID‐19 brought with it panic and a sense of urgency causing governments to impose strict restrictions on human activities and vehicular movements. With anthropogenic emissions, especially waste management (domestic and municipal), traffic and industrial activities, said to be a significant contributor to ambient air pollution, this study assessed the impacts of the imposed restrictions on the concentrations and size distribution of atmospheric aerosols and concentration of gaseous pollutants over West African sub‐region and seven major COVID‐19 epicenters in the sub‐region. Satellite retrievals and reanalysis datasets were used to study the impact of the restrictions on Aerosol Optical Depth (AOD) and atmospheric concentrations NO 2 , SO 2 , CO and O 3 . The anomalies were computed for 2020 relative to 2017‐2019 (the reference years). In 2020 relative to the reference years, for area‐averaged AOD levels, there was a consequential mean percentage change of between ‐6.7 ± 21.0 % and 19.2 ± 27.9 % in the epicenters and ‐10.1 ± 15.4 % over the sub‐region. The levels of NO 2 and SO 2 also reduced substantially at the epicenters, especially during the periods when the restrictions were highly enforced. However, the atmospheric levels of CO and ozone increased slightly in 2020 compared to the reference years. This study shows that “a one cap fits all” policy cannot reduced the level of air pollutants and that traffic and industrial processes are not the predominant sources of CO in major cities in the sub‐region.