Evaluating the effects of COVID-19 lockdowns on air quality across some African countries

Abstract

The COVID-19 lockdown served as a pivotal moment to analyze significant changes in air quality due to unprecedented reductions in emissions across major African countries. This study assesses the alterations in air quality, focusing on key pollutants such as CO, NO₂, O₃, SO₂ and aerosol particles during the lockdown period in 2020. Utilizing chemical reanalysis data from the state-of-the-art multi-component satellite data assimilation system at the Jet Propulsion Laboratory, quarterly anomalies were calculated for March to May (MAM) and June to August (JJA). The analysis reveals a significant decline in CO, NO₂, O₃ and nitrate aerosols across most African nations, with more pronounced decreases observed during the JJA period. However, notable discrepancies emerged: quarterly dual anomalies indicated a reduction in NO₂ and SO₂ levels in Northern Africa, while quarterly anomalies suggested an increase, indicating that containment policies affected these trends. In Southern Africa (SA), both quarters witnessed increases in SO₂ levels, likely due to relaxed restrictions and heightened energy demands. Additionally, the rise in O₃ levels in SA may be associated with the decrease in NO₂. The increase in sulfate and ammonium aerosols in Northern and Southern Africa is likely attributed to dust events and elevated residential emissions, respectively. The findings from this study highlight that air quality changes are influenced by a combination of natural and anthropogenic factors, stressing the urgent need for stricter emission standards for coal-fired plants and the promotion of clean energy initiatives throughout African countries.