Changes in Ambient Air Particulate Matter During the COVID-19 Lockdown in an Industrial and Urban Zone in Northern Colombia

The restriction of mobility due to preventive social isolation has improved air quality in many regions of the world. At the same time, global and regional atmospheric phenomena such as dust or biomass burning transport from Sahara can exacerbate particulate matter (PM) mass. In this study, PM10 and PM2.5 concentrations were evaluated in an industrial and urban area during the lockdown period due to COVID-19 in northern Colombia. Aerosol Optical Depth (AOD) observations obtained from the spaceborne MODIS (MOD04-3k) and the active fire data was obtained from VIIRS Active Fire. We measured surface contamination at several stations to quantify the PM10 and PM2.5 changes associated with the general closure of anthropogenic and industrial activities driven by COVID-19 and by the macroscale and/or mesoscale contributions. In the industrial zone, a slight decrease in daily concentrations was detected at the stations located near the mining operations. In the urban area, the decrease is more salient in COVID-19 lockdown. No visible impact on the daily levels of PM10 and PM2.5 was observed. The biomass burning episode has contributed 52% to the daily average of PM10 and 45% to the daily average of PM2.5. The episode due to the passage of Saharan dust through the Caribbean Sea has contributed 79% to the daily average of PM10 (150.75 μg/m3) and on 57% to the daily average of PM2.5.