## 3 Results and Discussion
### Concentration of PAHs  
The study of the presence of PAHs at 8 monitoring points revealed the presence of 7 analyzed substances from this group, including benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, dibenzo(a,h)anthracene, and indeno(1,2,3-cd)pyrene. The concentrations of total PAHs in the air varied depending on the location (Figure 3). The highest total PAH concentration was recorded at 34.50 ng/m\({}^{3}\) (station 6), while the lowest concentration reached 0.35 ng/m\({}^{3}\) (station 1). These differences are the result of varying intensities of industrial and transport activities, as well as local emission sources. The highest annual average concentration of PAHs was recorded for BbF at 2.64 ng/m\({}^{3}\) (Figure 4). In contrast, the lowest concentration was for dibenzo(a,h)anthracene, which was 0.05 ng/m\({}^{3}\). The concentration of DBahA was the lowest at all analyzed monitoring points, except for the measurement station 8 in Szczecin, where the value reached 1.80 ng/m\({}^{3}\). The concentration of dibenzo(a,h)anthracene at this point during the year ranged from 0.16 to 4.41 ng/m\({}^{3}\). The higher concentrations of DBahA in Szczecin may result from several factors. The complexity of dibenzo(a,h)anthracene emission sources in Szczecin stems from a combination of industrial and transport activities, as well as local heating methods. DBahA may be emitted from specific sources present in Szczecin, such as local transport, industrial processes, or combustion, which are less intense in other locations. The diagnostic index BbF/BkF allows differentiation between emissions related to industry and those from transport and biomass combustion. A BbF/BkF value \(>\) 0.5 indicates  
Figure 3: The concentration of total PAHs at individual monitoring stations. emissions associated with coal and biomass combustion, while a BBF/BkF value < 0.5 suggests emissions related to road traffic, primarily from internal combustion vehicles, especially diesel. In Szczecin, this value ranged from 1.81 to 2.74, while for the entire country, it oscillated between 1.39 and 2.45. Additionally, the presence of BaP and BjF will indicate emissions from fossil fuel combustion, while the presence of BaA will suggest biomass and wood combustion, and the presence of BaP, IP, and DBahA will be associated with transport emissions. The concentration of benzo(a)pyrene ranged from 0.18 to 2.09 ng/m\({}^{3}\). These values exceed the permissible annual limit set by European Union regulations, which is 1 ng/m\({}^{3}\). According to this regulation, no exceedance of the permissible benzo(a)pyrene concentration in the air should occur. The highest concentration of BaP was observed at station 6, located in Katowice, while the lowest was recorded in Szczecin (station 8). The observed concentrations may induce DNA damage. BaP is recognized as a potential reference mutagen and is frequently used as an indicator for PAHs, with the WHO considering it a reliable measure of PAH toxicity. Similar research was conducted by [PERSON] et al. (2007) [6]. They also showed that the PAH levels in coastal cities were much lower than those in inland cities, primarily due to the significant influence of sea conditions on their weather. In a study by [PERSON] et al. (2024) [23], BaP levels in ambient particulate matter were reported to range between 0.01 and 15.0 ng/m\({}^{3}\). Total PAH concentrations were lowest in rural areas (0.03-0.60 ng/m\({}^{3}\)) and highest in industrial and densely urbanized regions, with values ranging from 1344.4 to 12,300 ng/m\({}^{3}\). [PERSON] et al. (2023) [5] conducted a study in Colombia. The average daily concentrations of BaP ranged from 0.41 to 0.60 ng/m\({}^{3}\), with the maximum recorded concentration reaching 0.92 ng/m\({}^{3}\). The authors indicate a significant variation in PAH levels depending on the location, with the highest concentrations observed in areas directly associated with mining activities.