Spatial and Temporal Analysis of Aerosol Levels in Colombia Using Aerosol Optical Depth (AOD)

Air pollution is one of the primary environmental concerns in public health, resulting in millions of premature deaths annually. Particulate matter (PM) is an important indicator of atmospheric pollution due to its ability to penetrate the lungs and cardiovascular system. However, the spatial and temporal coverage of air quality measurements remains a considerable challenge. In Colombia, there are 23 Air Quality Monitoring Systems, of which only 48% have adequate temporal representativeness. Currently, 209 monitoring sites have been installed, distributed in 63% of the departments and covering only 8% of the municipalities. However, only 39% of these sites are in operation, covering 43% of the departments and 4% of the municipalities. This limitation highlights the need to explore alternative and complementary estimates to obtain a more comprehensive understanding of air quality in the country. In this context, analyzing satellite-derived Aerosol Optical Depth (AOD)  is essential to understanding the dynamics of atmospheric pollution and assessing its impact on climate and public health. This study analyzes changes in aerosol levels in Colombia using AOD, with the aim of identifying spatial and temporal patterns in the Caribbean, Andean, Pacific, Orinoquía, and Amazon subregions. The MAIAC collection 6.1 algorithm in Google Earth Engine (GEE) was used to analyze annual AOD data over a 20-year period, from 2005 to 2024. The results indicate that the Orinoquía and Amazon regions showed the greatest increases in aerosol levels, possibly associated with activities such as deforestation and biomass burning. A notable finding was the link between the highest aerosol levels and dry periods associated with the El Niño phenomenon, which promotes forest fires and the resuspension of soil particles. In contrast, the lowest aerosol levels were recorded during La Niña periods, characterized by wetter and cooler conditions. In 2020, despite the reduction in anthropogenic activity due to the COVID-19 pandemic lockdown, high aerosol levels were observed in the coastal and continental areas of Colombia. These elevated levels can be attributed to a high incidence of forest fires and the entry of intercontinental air masses loaded with Saharan dust. The study highlights the complexity of pollution sources and the need to consider both anthropogenic and natural factors. The approach used allowed for a detailed analysis of the distribution and changes in aerosol levels across different subregions of the country.