Single- and multi-elemental pollution indices as a useful tool for the evaluation of road dust contaminated by trace elements in Wrocław, Poland

The challenge still is to quantify the impact of traffic volume, road type, age of the road, and the presence of road infrastructure on the content of trace elements in road dust. Samples of road dust were collected at the intersections and roundabouts of the main roads of Wrocław and the county, where traffic was accelerated. This research aimed to identify the level of Cu, Zn, Pb, Cr, Ni, and Cd in road dust, and determine the quality of road dust using individual and integrated pollution indices. A strong anthropogenic influence was noted, which causes a heterogeneous distribution of metal concentrations in the tested road dust. The principal component analysis (PCA) analysis showed that traffic intensity affects mainly the metal content in road dust. The strong Spearman’s correlations indicate the connection of trace elements to road traffic. Individual and integrated pollution indices confirm the enrichment of road dust with tested elements, although the permissible metal concentrations according to the Polish standard were not exceeded. A medium or high probability of road dust toxicity was recorded.