## 3 Results and Discussion
### Health Risk Assessment
[115] also observed this dependency. According to standard _ILCR_ risk assessment guidelines, values below 1 \(\times\) 10\({}^{-6}\) are considered negligible. Values between 1 \(\times\) 10\({}^{-6}\) (1 in 1,000,000) and 1 \(\times\) 10\({}^{-4}\) (1 in 10,000) indicate a potential cancer risk, whereas values exceeding 1 \(\times\) 10\({}^{-4}\) are associated with a high potential risk and may necessitate corrective action [116]. In Polish agglomerations, based on the methodology applied in our study, no _ILCR_ values below 1 \(\times\) 10\({}^{-6}\) were recorded at any monitoring site. At all locations, _ILCR_ values fell within the 1 \(\times\) 10\({}^{-6}\) to 1 \(\times\) 10\({}^{-4}\) range. For males, the values ranged from 2.69 \(\times\) 10\({}^{-6}\) (Lublin) to 1.11 \(\times\) 10\({}^{-5}\) (Upper Silesia), and for females, from 1.20 \(\times\) 10\({}^{-6}\) (Warsaw, Lublin) to 4.87 \(\times\) 10\({}^{-6}\) (Upper Silesia). Upper Silesia is known as one of the most polluted regions in Poland [85; 117]. In our study, we found that the levels of PAHs have the biggest effect on the _ILCR_ value, followed by As, Cd, Ni, and Pb, making up 43.2%, 36.3%, 14.3%, 5.0%, and 1.2% of the total, respectively (Table S4). Interestingly, arsenic accounts for the largest share of the _ILCR_ value in Wroclaw (60%), corresponding to values of 5.04 \(\times\) 10\({}^{-6}\) and 2.21 \(\times\) 10\({}^{-6}\) for men and women, respectively. A similar pattern was observed for Warsaw and the Tricity area, although in these cases, the impact of As on the _ILCR_ value is only slightly greater than that of PAHs. The _ILCR_ value in Upper Silesia during the studied time period is the highest in Poland for both men and women. Each year, the content of the analysed components exceeds 1200 ppm. The total amount of PAH concentrations is about 18 to 32 times greater than the amounts of As and Cd, but their impact on the _ILCR_ is ranked as follows: PAHs make up 42.3%, As 30.1%, Cd 22.2%, Ni 3.7%, and Pb 1.7%. The inhalation carcinogenic risk reported by other researchers (Table 3) varies significantly depending on location, age group, pollution level, and season. The highest risks were observed in Zabol, Iran, where the _ILCR_ for adults was 4.5 \(\times\) 10\({}^{-4}\), and in Bengbu, China, where the values for adults ranged from 1.51 \(\times\) 10\({}^{-4}\) to 8.11 \(\times\) 10\({}^{-4}\). Seasonal and scenario-based differences, as observed in Poland, Los Angeles, and Milan, demonstrate the significant impact of heating periods, smog episodes, and local air quality on exposure levels. For instance, in Poland's Silesian Voivodeghip, _ILCR_ values ranged from 6.72 \(\times\) 10\({}^{-6}\) to 9.74 \(\times\) 10\({}^{-5}\) during the heating season, dropping to 0.6 \(\times\) 10\({}^{-6}\) to 8.7 \(\times\) 10\({}^{-6}\) outside of it. In Los Angeles, the _ILCR_ varied from 2.07 \(\times\) 10\({}^{-6}\) to 3.36 \(\times\) 10\({}^{-6}\) between the best- and worst-case scenarios. Although the _ILCR_ values in Polish cities in this study are lower than those in the most polluted areas, they are still important for public health, showing that we need to keep managing air quality. Toxicological studies by [PERSON] et al. [122] have demonstrated a higher risk of heavy metal exposure among the Zabrze population compared to the Warsaw population. These findings are consistent with the results of our study. Furthermore, numerous researchers have observed that adults may be slightly more susceptible to developing cancer due to exposure to heavy metals and PAHs than children [114; 122; 123; 124]. However, it should be noted that children are more vulnerable to the adverse effects of environmental pollution and even lower _ILCR_ values in children than in adults may pose a significant risk to their health. The calculated lifetime lung cancer risk values are based solely on exposure via inhalation to the PAHs and four heavy metals contained in PM\({}_{10}\).