## 4 Conclusions  
This research paper provides a comprehensive investigation into the characteristics of micro- and nano-pollutants, focusing on those originating from the degradation of tires and roads in winter season. The study was conducted in Poznan, Poland, characterized by transitional and temperate climatic conditions. During this period, the streets are typically treated with salt to mitigate ice formation, and the majority of private vehicle users transition to softer tires. These factors contribute to an accelerated rate of tire degradation, leading to an increased generation of the pollutants under investigation. The initial phase of the study involved the extraction of micro- and nano-pollutants from collected sediments, including snow, sand, and standing water, using organic solvents. The resulting solutions were then analyzed to determine their concentration, particle size, and qualitative composition, utilizing spectroscopic techniques for a comprehensive characterization. The residue, primarily composed of sand and residual organic matter, was left after the extraction process. This residue underwent extensive analysis to identify its composition. The pollutants characterized in this study exhibited a diverse chemical composition and a broad size range, spanning from 1 mm to as small as 1 nm. EDS mapping revealed that the primary fraction consisted of sand and organic compounds. Traces of iron were also detected, likely originating from the wear of brake pads and discs. Spectroscopic studies of the extracted particles confirmed the presence of tire rubber residues. DLS studies showed that a smaller particle size characterizes the extracts obtained during DCM washing. The EDS identified only carbon in these samples. Thermogravimetric analysis of the extracts allowed for the determination that the DCM fraction contains a high concentration of carbon black, while lighter particles such as oils and plasticizers transition to the iPr-OH fraction. An intriguing observation made during the study was the role of snow in the collection of these pollutants. It was noted that the presence of snow near roads appeared to inhibit  
Figure 13: X-ray diffraction of the analyzed samples. the migration of pollutants, thereby acting as a filter and capturing/agglomerating a larger quantity of particles. A particularly surprising finding of the study was the primary source of the pollutants found in the accumulated snow sediment, as depicted in Figure 14. Contrary to initial expectations, the majority of these pollutants were traced back to worn tires and asphalt, rather than from exhaust gases and oils produced during driving. This finding underscores the significant environmental impact of tire and road wear, highlighting an area that warrants further investigation and action. In conclusion, this study provides valuable insights into the nature and sources of micro- and nano-pollutants and underscores the need for more sustainable practices in road maintenance and vehicle usage. It is anticipated that these findings will stimulate further research in this field and inform decisions aimed at mitigating environmental pollution. Conceptualization, R.E.P. ; methodology, R.E.P. and M.F. ; validation, R.E.P., M.F. and B.S. ; formal analysis, M.F, D.P., B.S., E.R.-R. and R.E.P. ; investigation, M.F., D.P. and E.R.-R.; resources, R.E.P. ; data curation, R.E.P. and M.F. ; writing--original draft preparation, M.F., D.P., B.S. and E.R.-R.; writing--review and editing, R.E.P. ; visualization, M.F. and R.K.; supervision, R.E.P. ; funding acquisition, R.E.P. All authors have read and agreed to the published version of the manuscript. This work was funded by the Smart Growth Operational Programme, project no. POIR.04.02. 00-00-D003/20-00; European Funds, project no. RPWP.01.01.00-30-0004/18; and Ministry of Science and Higher Education, project no. 21/529535/SPUB/SP/2022. Not applicable. The data are contained within the article. The authors declare no conflicts of interest.