The COVID-19 pandemic has significantly affected economic activities all around the world. Though it took a huge amount of human breathes as well as increases unemployment, it puts a positive impression on the environment. To stop the speedy extend of this disease, the maximum Government has imposed a strict lockdown on their citizens which creates a constructive impact on the atmosphere. Air pollutant concentration has been investigated in this study to analyze the impact of lockdown on the environment. Based on the air pollutant concentration, Air Quality Index (AQI) is deliberated. The Air Quality Index indicates the most and least polluted cities in the world. A higher value of AQI represents the higher polluted city and a lesser value of Air Quality Index represents a less polluted city. The impact of lockdown on air quality has been studied in this work and it is observed that the air pollutant concentration has reduced in every city of the world during the lockdown period. It has been also detected that the PM 2.5 and PM 10 are the most affecting air concentrator which controls the air quality of all the selected places during and after lockdown.Keywords Air Quality Index (AQI) . Particle pollution . Ground-level ozone (O 3 ) . Carbon monoxide (CO) . Nitrogen dioxide (NO 2 ) . Sulphur dioxide (SO 2 ) Highlights • COVID-19 is a pandemic declared by WHO.• The effect of human happenings due to COVID-19 in 10 most polluted cities in the world was estimated after lockdown.• Based on the air pollutant concentration, Air Quality Index (AQI) is calculated.• PM 2.5 is mostly responsible for major air pollution.• PM 10 , CO, SO 2 , O 3 , and NO 2 are other major air pollutants.
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