Background: To study,estimate and discuss the variations of the aerosol optical depth (AOD),black carbon,sulfate and organic matter,in the atmosphere in Blida City of Algeria,which was greatly affected by COVID-19 pandemic.Methods: We analyzed the effects of changes in the total AOD,black carbon,sulfate,and organic matter in the atmosphere (λ =550 nm) in the same period of 2019 and 2020,following the COVID-19 epidemic in Blida City,which was the most-affected city in Algeria.Results: The quarantine that was enacted to limit the spread of COVID-19 resulted in side effects that were identifiable in the total AOD and in some of its atmospheric components.Comparing these variables in 2019 and 2020 (in the months during the quarantine) revealed that in April,the BCAOD values were much lower in 2020than in 2019.Conclusion: Based on the effects of the emerging COVID-19,the research listed the changes received from the AOD,and is considered as a comparative study and represents a significant side effect of the quarantine that was mainly designed to limit COVID-19.