The first confirmed case of COVID-19 in Colombia was reported on March 6, 2020. For this reason, on March 25, preventive isolation was declared mandatory. These measures involved the suspension of economic activities and drastically reduced the number of vehicles on the road. The objective of this study is to evaluate the impact of the lockdown due to the COVID-19 pandemic on PM 2.5 concentrations at 5 monitoring stations and aerosol optical depth values of the Terra/MODIS satellite. We analyzed and compared the weekly and monthly concentrations of PM 2.5 before and during the lockdown between the week of January 6 to June 22, 2020, and compared the daily values obtained from the Terra/MODIS satellite for the months of January–June during the years 2018–2020 to elucidate the effects of the lockdown. Similar to other monitored sites in the world, we observed substantial reductions in weekly PM 2.5 concentrations, from 41 to 84% (Bogotá), from 13 to 66% (Funza), from 17 to 57% (Boyacá), from 35 to 86% (Valledupar) and 31 at 60% (Risaralda). Unlike other studies, the aerosol optical depth values increased up to 59% during the months of lockdown compared to previous years and up to 70% of the weekly mean when compared to before the lockdown. These spatiotemporal behaviors of PM 2.5 and the aerosol optical depth in Colombia are influenced by reductions in vehicular flow during quarantine, regional rainfall, and height of the planetary boundary layer. Emissions from economic activities affect pollutant levels in the area. The analysis of the levels of pollutants during the lockdown provides a baseline for regulatory agencies to establish mitigation plans.

Intake fraction was determined in this study to provide insight into population exposures to PM10 that is effectively inhaled due to emissions of an opencast coal mine. We applied the CALPUFF model to a coal mine in Northern Colombia, which has 6 active pits with an annual production of 33.7 million tons. We estimated the intake fractions for 7 towns through the integration of dispersion model results over the population data. The resulting average intake fractions were between 6.13 × 10−9 and 3.66 × 10−8 for PM10. 62.4% of the intake fractions in the domain were calculated within a 23 km radius from the coal mine and coved 44.3% of the total population in this area. We calculated an estimate point for morbidity impacts using standard epidemiological assumptions. It is estimated that there were annually 105835 restricted activity days and 336832 respiratory symptom cases due to the direct impact of the opencast coal mining. These data also provide a framework for improved understanding of the effect of coal mining in Colombia.

ResumenEn esta investigación se evaluó la concentración, composición elemental y fuentes de origen de partículas PM10 y PST. Quince elementos químicos (As, Cd, Ca, Zn, Cu, Cr, Co, Fe, Mg, Mn, Ni, Pb, K, Na y V) se determinaron utilizando espectrometría de absorción atómica. Los niveles de PM10 (19.4 y 51 µg/m 3 ) y PST (27.6 y 53.7 µg/m 3 ) no excedieron estándares internacionales. El Factor de Enriquecimiento (FE) mostró que los elementos de trazadores de suelo están asociados con las partículas PST, mientras que los elementos de origen antropogénicos están asociados con las partículas PM10. El Zn, Cu y Co, mostraron fuerte enriquecimiento en PM10 y PST en las dos estaciones, concluyéndose que son elementos de origen antropogénicos. Para el grupo de trazadores de suelo: Na, As, Pb y Ni, presentaron enriquecimiento moderado. Los resultados mostraron que el Mg, Mn, V y K se originan en el proceso natural del suelo. Palabras clave: PM10, PST, fuentes de contaminacion, traza de elemento, factor de enriquecimiento Elemental Composition and Sources of Inhalable Particles (PM10) and Suspended Total Particles (TSP) in the Urban Area of the City of Riohacha, Colombia AbstractThis research evaluated the concentration, elemental composition and sources of origin of particle PM10 and TSP. Fifteen chemical elements (As, Cd, Ca, Zn, Cu, Cr, Co, Fe, Mg, Mn, Ni, Pb, K, Na and V) were determined using atomic absorption spectrometry. Levels of PM10 (19.4 and 51 µg/m3) and TSP (27.6 and 53.7 µg/m3) did not exceed international standards. The enrichment factor (EF) showed that the soil tracer elements are associated with TSP particles while elements of anthropogenic origin are associated with PM10 particles. Zn, Cu and Co, showed strong enrichment in PM10 and TSP in the two stations, concluding that are elements of anthropogenic origin. For the group of soil trace elements: Na, As, Pb and Ni, showed a moderate enrichment. The results showed that elements such as Mg, Mn, V and K originated from the natural process of soil.