Effect of lockdown due to COVID-19 on environmental pollutant: a comparative study between top three countries of the world

Pandemic from Corona Virus Diseases 2019 (SARS-COVID-19) is a serious hazard to human health and life which is responsible for the significant economic losses across the world. Sometime it resulted into death of human being. Since environmental factors have significant effects on COVID-19 transmission, and vice-versa, therefore lockdown condition which is expected to reduce environmental pollution is an important step to affect COVID transmission through the environment. The associated ambient air pollutant: (O₃), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and Carbon mono oxide (CO) are directly linked to enhance risk of stroke, heart disease, asthma, and lung cancer and are also affected by the number of cases of COVID-19. In order to have quantitative estimate and comparative study of these pollutants, aerosol optical depth (AOD), surface temperature, ozone, carbon mono oxide (CO) and nitrogen dioxide (NO₂), aerosol size distribution over India, have been analysed during lock down period 01 March–30 June, 2020. The analysis of pollutants during lockdown period has been compared to 05 year mean value (2015–2019) estimated during the same period. The satellite based measurement of AOD from MODIS show a decrease in AOD during the lockdown period by 40% in Indian region as compared to 5-year mean level (2015–2019) whereas ground based AOD from AERONET reduced to 75% at Kanpur and 74% at Gandhi College in India. The drop in AOD observed during lockdown is a clear cut indication of reduced level of air pollution. Peak of aerosol size distribution over Kanpur and Gandhi College has also been analysed which show a reduction by 33–50% from the 05-year average level. Enhancement in total ozone column ~ 8% from average level is noticed during the lockdown period which is attributed to suppression in NO₂ and CO concentration which is supposed to destroy the formation of ozone through chemical reactions. Influence of lockdown on concentration of environmental pollutants in Indian region has also been compared to top other two countries of the world: USA and Brazil. The pattern of day-to-day variation of COVID cases at India and Brazil is same whereas for USA patterns are significantly different. The comparative analysis of other pollutants between all the three countries has also been discussed and fall in temperature due to lockdown condition over USA is found larger than that over India and Brazil.