The Atmospheric Deposition of Polycyclic Aromatic Hydrocarbons in the Metropolitan City of Rome in the Year 2022/2023

The measurement of atmospheric deposition fluxes is an excellent tool for assessing the contamination of territory and the subsequent exposure of the population to major contaminants through the food chain. In this context, the aim of this study was to measure the polycyclic aromatic hydrocarbon (PAH) deposition fluxes in the city of Rome (ISS Station) during the year 2022/2023 at two different heights above the ground (vertical profile), in order to evaluate the influence that the vertical profile has on PAH deposition. Two measuring positions were identified, one at street level and one at a height of 20 m. The collection of bulk atmospheric depositions was carried out approximately every 30 days, and the PAHs were determined according to the indications given in ISTISAN Report 06/38 and Standard UNI EN 15980:2011. The results show that throughout the year, the deposition rates of settleable dust were always higher at the lower (annual average of 48.5 mg m-2 day-1) collection position than at the higher position (annual average of 17.5 mg m-2 day-1). Despite this difference, the concentrations and profiles of the main PAHs analyzed, as indicated in EU Directive 2024/2881, in the dust collected at the two positions were almost similar, showing that the vertical profile did not influence the composition and concentration of PAHs in the collected settleable dust. Furthermore, a comparison of the deposition rates of sedimentable dust and PAHs with the legislative references currently present in Europe was made, highlighting that in the city of Rome during the monitoring period of this study, the values of dust and PAHs were lower than the limit and guide values and were also in line with other Italian urban locations.