Atmospheric Black Carbon Evaluation in Two Sites of San Luis Potosí City During the Years 2018–2020

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Nevertheless, there is a lot to know about air pollutants in Mexico’s largest cities, like San Luis Potosi City, which is one of the 12 most crowded cities and is expected to grow in the next years; however, there is little information about air pollutant levels mainly particulate matter in their regulated size fractions (PM10 or PM2.5), and its main component of the Organic fraction: Black Carbon (BC), which is especially important because of its chemical properties and their effects on human health, air pollution, and climate change. This work presents a one-year BC monitoring in the northern part of the city (2018–2019) and another one-year BC monitoring in the southern area (2019–2020) during the health contingency situation due to the SARX-CoV-2 virus to obtain direct equivalent black carbon (eBC) concentrations and their main fractions related to fossil fuel and biomass burning using aethalometer AE-33, as well as other air pollutants concentrations measured at the same periods by the governmental local monitoring network (SEGAM). At the North, BC mass annual average concentration was (1.11 µg m−3), divided into seasonal stations, the cold season was the highest with (1.44 µg m−3), followed by the dry season (1.23 µg m−3), rainy season (0.94 µg m−3) and finally warm dry season (0.83 µg m−3). In the south, BC annual average concentration was (1.96 µg m−3); divided into seasons, the highest was the dry season with (2.73 µg m−3), followed by the cold season (2.37 µg m−3), dry warm season (1.61 µg m−3) and the rainy season (1.28 µg m−3). One of the main findings was the dominance of annual mean concentrations of BC originating from fossil fuels (BCff) on the north site in the city was 0.97 and on the south site (BCff) was 0.91 due to some forest fires during the monitoring period. This study presented information from two zones of a growing city in Mexico to generate new air pollutant indicators to have a better understanding of pollutant interactions in the city, to decrease the emission precursor sources, and reduce the health risks in the population.