## 4 Conclusions  
Air pollution from PM\({}_{10}\) and other harmful substances, especially polycyclic aromatic hydrocarbons (PAHs) and heavy metals such as lead (Pb), cadmium (Cd), arsenic (As), and nickel (Ni), remains a significant environmental issue in Poland, particularly in densely populated urban areas. Although recent data show a downward trend in emissions and atmospheric concentrations of these pollutants, levels in many Polish agglomerations, such as Upper Silesia, Wroclaw, Cracow, and Lodz, still exceed EU and WHO standards. Of particular concern are the concentrations of benzo[a]pyrene (B[a]P), which exceed permissible levels several times over during winter. In Cracow, the average annual concentration of B[a]P was as high as 4.89 ng\(\cdot\)m\({}^{-3}\), which is well above the EU's recommended value of 1 ng\(\cdot\)m\({}^{-3}\) and the WHO's guideline of 0.12 ng\(\cdot\)m\({}^{-3}\). Cluster analysis revealed three groups of agglomerations that differed in terms of pollutant concentration levels and structure. These groups reflect the influence of regional emission sources, urbanisation, and meteorological conditions. The first group (Upper Silesia and Wroclaw) exhibited the highest concentrations of heavy metals and PAHs, with an average lead level of 14.97 \(\pm\) 7.27 ng\(\cdot\)m\({}^{-3}\) and \(\sum\)PAHs of 15.53 \(\pm\) 6.44 ng\(\cdot\)m\({}^{-3}\). The second group (Cracow, Lodz, Warsaw, and Lublin) showed medium pollution levels dominated by traffic emissions, while the third group (Szczecin and Tricity) had the lowest concentrations and favourable airing conditions. The study also included a cancer risk assessment using the Incremental Lifetime Cancer Risk (_ILCR_) method, with a focus on inhalation as the primary exposure pathway. This procedure enabled the actual impact of the hazardous substances contained in PM\({}_{10}\) (and PM\({}_{10}\) itself) on public health to be estimated. The highest average _ILCR_ values were recorded in Upper Silesia (9.18 \(\times\) 10\({}^{-6}\) for males and 3.96 \(\times\) 10\({}^{-6}\) for females), and the lowest in the Warsaw area (3.16 \(\times\) 10\({}^{-6}\) for males and 1.40 \(\times\) 10\({}^{-6}\) for females). The calculated _ILCR_ values for both sexes ranged from 1.20 \(\times\) 10\({}^{-6}\) to 1.11 \(\times\) 10\({}^{-5}\), indicating a level of health risk that cannot be considered negligible. It is important to emphasise that this study focused on only a few pollutants. However, particulate matter is a chemically complex mixture containing many other toxic components, such as additional organic compounds, elemental carbon, and potentially carcinogenic metals (e.g., Cr(VI)), which were not included in our analysis. Furthermore, the risk assessment is based on several assumptions, including toxic equivalency factors (_TEFs_) for polycyclic aromatic hydrocarbons (PAHs), standardised average body weights, inhalation rates, and other exposure parameters. While inhaling ambient air is the main way in which the general population is exposed to PAHs and heavy metals, other pathways, such as dermal contact, ingestion, and combined exposure, can also contribute to the total absorbed dose. Consequently, the actual health risk associated with PM\({}_{10}\) exposure may be underestimated. Another limitation relates to the frequency and continuity of data collection at certain monitoring stations, particularly in cities such as Szczecin. Insufficient data coverage may have affected the accuracy of the calculated annual average concentrations and, consequently, the _ILCR_ estimates. Although we used all available measurements to provide the most reliable exposure assessment possible, the limited temporal coverage could have resulted in an under- or overestimation of actual exposure levels. To obtain a more comprehensive picture of the health risks associated with air pollution, future studies should consider a broader range of pollutants and their temporal variability.