Atmospheric Pollutants Assessment during the COVID-19 Lockdown Using Remote Sensing and Ground-based Measurements in Buenos Aires, Argentina

The COVID-19 outbreak measures of lockdown have generated exceptional urban behavior conditions allowing the analysis of a unique scenario. We examined the atmospheric emissions in Buenos Aires, Argentina, based on urban and industrial continuous monitoring of NO2, PM10 and PM2.5, and NO2 (TROPOMI/Sentinel-5p) and AOD (MAIAC/MODIS, Aqua) satellite products, in addition with meteorological data. We considered the time intervals before and after the announcement of lockdown, including the same periods for 2019. The results showed that NO2 and PM10 concentrations fell by similar to 30% and 44%, respectively, at urban stations during lockdown compared to 2019. An increase in PM at the industrial station (64% PM2.5 and 8% PM10) could be due to the contribution of industrial sources other than vehicle traffic. Also, we observed a reduction of the tropospheric NO2 column density mean by 54% at urban stations, and AOD values decreased between 38% and 66% during 2020. Concerning the spatial distribution, the tropospheric NO2 column showed a significant reduction of NO2 for the monthly mean in the metropolitan area at lockdown. Similarly, the AOD highest values had a greater extension for 2020 during the pre-lockdown monthly period. After the strict lockdown, concentration values increased steadily, particularly in ground-based measurements. Therefore, we were able to demonstrate the complementarity of ground-based and satellite data measurements of NO2 and aerosol to identify the effects of lockdown measures on the spatial and temporal variability of pollutants.