## 3 Materials and Methods
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Location**} & \multirow{2}{*}{**Period**} & \multicolumn{10}{c}{**Concentation [log=m\({}^{-3}\)]**} \\ \cline{2-13}  & & **PM\({}_{\rm{ES}}\)** & **SO\({}_{\rm{A}}\)\({}^{-2}\)** & **NO\({}_{\rm{D}}\)\({}^{-2}\)** & **NH\({}_{\rm{A}}\)\({}^{+}\)** & **Cl\({}^{-}\)** & **K\({}^{+}\)** & **Na\({}^{+}\)** & **Mg\({}^{\rm{B}}\)** & **Ca\({}^{\rm{B}}\)** & **EC** & **OC** \\ \hline \multirow{3}{*}{[PERSON] (GR), C [99]} & App 2011–May 2012 & 37.7 & 3.96 & 2.4 & 3.8 & 0.99 & 0.14 & 0.29 & 0.07 & 1.43 & 1.29 & 6.62 \\  & H: Arp 2011–May 2012 & 41.9 & 3.96 & 3.07 & 4.85 & 0.37 & 0.12 & 0.14 & 0.05 & 1.6 & 1.5 & 8.84 \\  & NH Apr 2011–May 2012 & 32.9 & 3.96 & 1.61 & 2.86 & 0.4 & 0.16 & 0.47 & 0.09 & 1.25 & 1.05 & 4.06 \\ \hline [PERSON] (CC), C [10] & Jan 2012–Jan 2013 [38] & 13.1 & 4.5 & 1.1 & - & - & - & - & - & - & 0.7 & 1.8 \\ \hline [PERSON] (HT), A [101] & Mar 2013–Jan 2013 & 14.4 & 2.76 & 0.34 & 0.71 & 0.17 & 0.18 & 0.34 & 0.03 & 0.2 & 0.52 & 2.97 \\ \hline [PERSON] (HT), A [7] & 2011-Jan 2013 & 27.6 & 2.4 & 5.1 & - & - & - & - & - & - & 1.6 & 5.1 \\ \hline [PERSON] (HT), D [101] & App 2002–Mar 2013 & 20 & 1.7 & 2.4 & 1.1 & 0.12 & 0.29 & 0.31 & - & 0.15 & - & - \\ \hline [PERSON] (HT), D [102] & App 2002–Mar 2013 & 28 & 2.4 & 5 & 2.3 & 0.19 & 0.31 & 0.15 & - & 0.15 & - & - \\ \hline [PERSON] (HT), D [102] & App 2002–Mar 2013 & 29 & 2.4 & 4.6 & 2 & 0.19 & 0.39 & 0.47 & - & 0.16 & - & - \\ \hline Roying (HT), D [102] & App 2012–Mar 2013 & 27 & 2.6 & 5.2 & 2.3 & 0.24 & 0.3 & 0.23 & - & 0.15 & - & - \\ \hline Genon (HT), A [56] & Mar–Sep 2011 & 14 & 3.6\({}^{(4)}\) & 0.5 & 1.4 & - & 0.06 & 0.1 & - & - & 1.4 & 2.7 \\ \hline Venice (HT), A [56] & Jan–Dec 2011 & 30 & 3.4\({}^{(4)}\) & 5.4 & 2.3 & - & 0.4 & 0.2 & - & - & 5.8 \\ \hline Barcelona (IS), A [56] & Feb-Dec 2011 & 18.6 & 2.8\({}^{(4)}\) & 1 & 1 & - & - & 0.3 & - & - & 1.2 & 3 \\ \hline Madrid (IS), A [56] & Jan–Feb 2011 & 13.8 & 0.61 & 1.16 & 0.48 & 0.15 & 0.05 & 0.17 & 0.01 & 0.1 & 1.53 & 1.2 \\  & Jun 2009 & 16.8 & 1.02 & 0.69 & 0.27 & 0.16 & 0.05 & 0.2 & 0.03 & 0.21 & 0.94 & 2.71 \\ \hline Huoxis (ES), A [104] & Apr 2008–Dec 2009 & 19.3 & 2.8 & 1 & 0.8 & 0.2 & - & 0.5 & - & - & 0.6\({}^{(4)}\) & 3.22 \\ \hline Pant Pantova (BS), C [105] & 2009 & 15 & 2.07 & 1.63 & 1.24 & 0.08 & - & - & - & - & 4.04 \\ \hline Eibe (IS), A [44] & Oct 2008–Oct 2009 & 15 & 2.76 & 1.22 & 0.85 & 0.19 & 0.24 & 0.43 & 0.04 & 0.42 & - & - \\ \hline Vilencios (IS), C [59] & 2004, 2005 & 24 & 3.8 & 2.7 & 1.8 & 0.8 & - & - & - & - & 7.2 \\ \hline L'Eliana (IS), B [50] & 2004, 2005 & 22 & 2.6 & 1.6 & 1.2 & 0.4 & - & - & - & - & 5 \\ \hline launched (IR), C [106] & Jan 2010–May 2011 & 40 & 427 & 1.22 & 1.24 & 0.34 & - & - & - & 12.66 \\ \hline Country abbreviations (code ISO 3166), PT–Pollard, CZ–Cereb Republic, FL–Finalary, UK–United Kingdom; DE–Germany; BE–Belgium; NL–Netherlands; FR–France; CH–Switzerland; HU–Hungary; GR––Gewee; CN–Cyprus; IT–Italy; PS–Spain; TR––Turkey. Designations of stations: A–urban background station; B––suburban background station; C––mixed urban stations (with influences from different emission sources). D–urban station located within residential zone; E–urban station with influences from industrial sources. H–heating season (months: Jan–Mar and Oct-Dec); NH––non-heating season (months: Apr-Sep). [10] expressed as concentration of non-sex salt sulphates, nss-SO\({}_{2}\)\({}^{-2}\); [10] non-dust days. [6]) EC as BC. The values emitted based on the percentage contribution of particular compound in the PM\({}_{5,2}\) mass were written in italics. [ENDFOOTNOTE]  
\end{table} 
Table 2: _Cont._Figure 2: Contributions of secondary inorganic ions and total carbon in PM\({}_{2.5}\) [%] from selected rural background stations in Europe. (the results obtained within the project no. 2011/03/N/ST10/05542 were marked by red dotted line). Figure 3: Contributions of secondary inorganic ions and total carbon in PM\({}_{2.5}\) [%] from selected urban and urban background stations in Europe.