Characterization of non-conventional pollutants (BTEX) in air by means of chemometrics techniques

Abstract

In this work, chemometric and spatial interpolation methods were used to characterize non-conventional pollutants in the atmosphere of the city of Santiago de Cali (Colombia), The contaminants were monitored using passive diffusion samplers during two (2) periods (January to February and March to April) in two consecutive years before the pandemic (2020). None of the cases exceeded the concentration limits established by the National Air Quality Standard. The Cluster analysis allowed evidencing the existence of groups, which correspond to low, medium and high influence sites of the pollutants. The Principal Components Analysis (PCA) led to gathered all the variables in two constituents: the first one (PC1) could be related as an indicator of pollutant mobile sources due to the similar contribution of pollutants, while the second one (PC2) as an indicator for punctual emissions of toluene, as it was the one that contributed the most. The performance of the spatial analysis drove to identify the downtown and north of the city as areas of high-influence of PC1, at the same time, a substantial decrease in its effects to the periphery, particularly towards the south. On the other hand, with the Inverse Distance Weighting (IDW) it was possible to observe the hot-spots of both PCs, particularly real estate construction areas and the downtown industrial sector of the city. Finally, it was found a cancer risk in downtown and north-eastern areas of the city, related to the exposure to benzene and ethylbenzene; observation that coincide in the area of incidence of PC1.