Geochemical characterization and health risk assessment of surface and green barrier deposited PM particles in the proximity of a kindergarten

The particulate matter (PM) is a key health risk factor in urban areas. Different approaches have been developed worldwide to deal with PM pollution, includingnature-based solutions (NBSs). This study presents the results of the geochemical characterization of a green barrier established between a kindergarten and a street. In2018 and 2019, PM deposits on green barrier and tree leaves were investigated to reveal particle size distribution and geochemical composition. In addition, the contentsof potentially toxic elements (PTEs) found in kindergarten outdoor and street dust were determined to assess the imposed health risk. The results showed that based on thechemical composition, the studied PM deposits had grouped into two clusters of major elements: carbonates and aluminosilicates clustered with Fe oxides/hydroxides.However, the presence of several PTE, including Mo, Cu, Mn, Cr and Ba was also highlighted. The efficiency of the green barrier in impeding Cu-containing particlesdiffusion was proven, since street dust Cu contents increased during the study period, while the Cu content in kindergarten outdoor dust displayed a decreasing trend. Thenon-carcinogenic risk associated to PTE in the street and outdoor dust suggested that the multi-elemental risk level in the study area was above the allowable limit, with thehighest share in risk level attributed to Cr which had the tendency to decrease due to the presence of the barrier. The results of this study can serve as a basis for greenbarrier PM capturing efficiency monitoring and securing a healthy environment for kindergarten children.