## 4 Results and Discussion
### Concentrations of PM\({}_{2.5}\) and Its Related Main Chemical Compounds
Thus, concentrations of carbonaceous aerosol in Trzebinnia (TC = 10.81 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ep_), 19.36 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Hp_) and 5.63 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_NHp_)) were significantly higher compared to the values obtained at majority of stations presented in Table 2, for example, Birmingham (UK) (TC = 3.30 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Marseille (France) (TC = 8.00 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)) and Barcelona (Spain) (TC = 4.20 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)). Slightly similar values of TC concentrations were noted only in Prague (the Czech republic) (TC = 13.11 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)) and Istanbul (Turkey) (TC = 12.66 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)). The TC concentrations in Szczecin (TC = 7.01 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ep_), 10.15 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Hp_) and 3.34 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_NHp_)) was lower than the TC concentrations from Trzebinnia and other stations located in southern Poland. They were also comparable or slightly lower in respect to the values registered in Athens (Greece) (TC = 6.90 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Marseille (France) (TC = 8.00 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Bologna (Italy) (TC = 6.70 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)) as well as in Budapest (Hungary) (TC = 7.44 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ep_)) and Thessaloniki (Greece) (TC = 7.91 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ep_)), where in addition a similar seasonal variation of TC concentrations was observed (Table 2). On the other hand, they were relatively higher compared to the data from many urban stations presented in Table 2, for example, Gdansk (Poland) (TC = 8.65 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Hp_) and 2.20 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_NHp_)), Birmingham (UK) (TC = 3.30 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Duisburg (Germany) (TC = 4.58 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Saint-Omer (France) (TC = 5.21 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Limassol (Cyprus) (TC = 6.90 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)) and majority of stations located in Italy (e.g., Genoa, TC = 4.10 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)) and Spain (e.g., Pamplona, TC = 6.90 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)). Considering the total concentration of secondary inorganic ions, the values recorded in Trzebinnia (SIA = 7.35 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ep_), 10.83 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Hp_) and 5.23 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_NHp_)) were similar or lower than the concentrations of SIA in Zabrze (Poland) (SIA = 10.64 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Hp_) and 4.27 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_NHp_)), Menen (Belgium) (SIA = 12.15 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ws_) and 9.32 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ss_)), Prague (Czech Republic) (SIA = 10.24 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\)), Dunkerque (France) (SIA = 10.14 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ws_) and 16.32 \(\mathrm{\SIUnitSymbolMicro m^{-3}}\) (_Ss_)) as well as Zurich (SIA = 9.10 \(\upmu\)g\(\cdot\)m\({}^{-3}\)) and other stations located in Switzerland. However, they were higher than the values recorded in Paris (France) (SIA = 6.30 \(\upmu\)g\(\cdot\)m\({}^{-3}\)), Madrid (Spain) (SIA = 2.25 \(\upmu\)g\(\cdot\)m\({}^{-3}\) (_Ws_) and 1.98 \(\upmu\)g\(\cdot\)m\({}^{-3}\), (_Ss_)) or Duisburg (Germany) (SIA = 5.80 \(\upmu\)g\(\cdot\)m\({}^{-3}\)).