From mining to fire outbreaks: The relative impact of pollutants sources on air quality in the metropolitan area of Belo Horizonte

Approximately 9 million deaths occur annually due to chronic and acute exposure to air pollutants. Road transportation, industries, and power plants contribute to decreasing air quality, especially in underdeveloped high-density urban areas. In Brazil, the Metropolitan Area of Belo Horizonte (MABH), in Minas Gerais state, has miscellaneous pollutant sources, experiencing periods with poor air quality. In this sense, the available emissions inventories were analyzed considering the air quality data from 2021, annulus and bivariate polar plots, and Conditional Bivariate Probability Function (CPF) analysis was used to identify the pollutant sources during two distinct periods in 2021. Additionally, this study presents an overview of pollutant concentrations in the MABH air quality six-year monitoring networking statistical analysis to identify tendency patterns in fire outbreaks and pollutants records between 2016 and 2021 by Mann-Kendall's test. In the MABH urban areas, through the emissions inventory, annulus and bivariate polar plots identified the influences on the air quality by the local high-pollutant emitters, indicating a high mixing emissions sources that result in the elevated nitrogen dioxide (NO2) concentrations during the morning and late afternoon due to vehicular emissions, particle matter less than 10 and 2.5 mu m in diameter (PM10 and PM2.5) concentrations related due to mining activities plus industrial activities highly affected the air quality mainly in the areas near to these emissions sources. The ozone (O3) concentrations were attributed to high nitrogen oxides (NOx) and volatile organic compounds (VOC) emissions in the industrial and urban areas. The highest Spearman correlations between fire outbreaks and pollutants in 2021 were observed in September and the lowest in November. During 2021, the analysis revealed many air pollutant sources, including vehicular, industrial, and mining. There was also a significant contribution from pollutants advected from the areas with a high density of fire outbreaks. In the mining station, the PM2.5/PM10 ratios were lower in November, probably because of the hygroscopic growth of particulate matter in PM10 size. From 2016 to 2021, the Ce<acute accent>lvia station had the highest daily mean concentration of PM2.5 (160.29 mu g m-3), and the Filhinha Gama station had the highest daily mean concentration of PM10 (221.21 mu g m-3). The stations in an industrial area recorded the higher sulfur dioxide (SO2, 98.47 mu g m-3) and NO2 (168.03 mu g m-3) concentrations in Petrovale and Piratininga stations. The lowest PM10 and PM2.5 concentration levels were recorded at the E. M. Pe. Vicente Assun & ccedil;ao station (1.89 mu g m- 3 and 2.75 mu g m-3) and the Comunidade do Feijao station (2.07 mu g m- 3 and 1.30 mu g m- 3), both in Brumadinho city. Sao Jose<acute accent> da Lapa had the highest average concentration of PM10 (60 and 70 g m- 3, Delegacia Civil - Centro station), and Contagem City had the highest average concentration of PM2.5 (20-25 mu g m- 3, Cidade Industrial station). The fire outbreak data corroborates with the Mann-Kendall Seasonal results as a raising in fire outbreak records. Our findings highlight the necessity of further study by atmospheric and air quality models and relevant methods to identify and quantify the contribution of each air pollution source in the worst air quality days in the MABH.