Avaliação de material particulado em suspensão em ambientes escolares usando a técnica de fluorescência de raios X

Abstract

The present study addresses the characterization of atmospheric suspended particulate matter in eight primary and secondary schools located in the metropolitan region of Rio de Janeiro. Sampling was conducted during the winter and summer seasons using a 9-stage cascade impactor (PIXE International Corporation), allowing for the simultaneous collection of particulate matter in the fine fraction, up to 2.5 µm (PM2.5), and coarse fraction, from 2.5 µm to 10 µm (PM10). An aluminum cyclone (SKC) was also used to collect respirable particulate matter (PM4.0). Experimental X-ray fluorescence measurements for the samples obtained with the impactor were performed using a commercial ARTAX 200 system (Bruker). For the cyclone samples, measurements were taken using the EPSILON 1 system. It was possible to detect the presence of the following elements in the impactor samples: Si, S, Cl, K, Ca, Ti, Mn, Fe, Cu, and Zn. Hierarchical cluster classification analysis based on dendrogram analysis was conducted. It was possible to evaluate the similarity of the detected chemical elements and identify possible sources of particulate matter: marine aerosol, soil resuspension, construction activities, fossil fuel and biomass burning, vehicular traffic, and industrial activities. In the quantitative analysis using EPSILON 1 for the cyclone sampling, it was possible to quantify the concentrations of the elements: Si, S, Cl, K, Ca, Fe, Cu, and Zn. No significant differences were observed among the detected elements due to seasonality. The obtained results were compared with other research studies on particulate matter and showed no discrepancies. All concentration values were within the range of values presented in the literature. The present study on air quality in school environments indicates that the levels of particulate matter found in these educational facilities often mirror those observed in large urban centers with high pollution rates. Therefore, the results suggest the need for public policies that consider strategies to reduce particulate matter concentrations in school environments that may be harmful to health and, consequently, to learning.