## 3 Results and Discussion
### DRH and CRH  
The chemical composition of ESDD showed an ion content that can strongly affect the deposit's affinity for water, thus enabling it to promote the formation of an electrolytic solution on the insulators' surface, increasing the hazard related to a decrease in the resistance (or increase in conductance). Thus, the chemical composition of ESDD was replicated and generated in the laboratory as described in Section 2.5 in order to investigate the phase transition of the aerosol accumulated on insulators and its related electrical effect. DRH and CRH curves, averaged for the three temperatures (10\({}^{\circ}\), 22\({}^{\circ}\), and 30 \({}^{\circ}\)C), determined for macroregions 1, 2, and 3, are shown in Figure 9 (the humidograms at the three temperatures are shown in the Supplementary Material, Figure S6). The width of the hysteresis cycle changes depending on the chemical composition of the macroregion and in all cases, the maximum absorption of water vapor is at 90% of relative humidity (2.01 \(\pm\) 0.26 mg H\({}_{2}\)O/mg of deposit). Figure 8: Percentage contribution of each inorganic ion categorized based on sources: ss (patterned) and nss (solid color) for MR1, MR2, and MR3, averaged over the 6 th, 7 th, and 8 th sampling campaigns. \begin{table}
\begin{tabular}{l c c c c c c} \hline  & \multicolumn{2}{c}{**MR1**} & \multicolumn{2}{c}{**MR2**} & \multicolumn{2}{c}{**MR3**} \\  & **ss** & **nss** & **ss** & **nss** & **ss** & **nss** \\ \hline Na\({}^{*}\) & 5.64 \(\pm\) 2.57 & 6.87 \(\pm\) 1.96 & 2.98 \(\pm\) 0.86 & 1.84 \(\pm\) 0.28 & 0.80 \(\pm\) 0.28 & 0.91 \(\pm\) 0.10 \\ K\({}^{*}\) & 0.21 \(\pm\) 0.09 & 1.67 \(\pm\) 0.84 & 0.11 \(\pm\) 0.03 & 0.62 \(\pm\) 0.15 & 0.03 \(\pm\) 0.01 & 0.30 \(\pm\) 0.05 \\ Mg\({}^{2+}\) & 0.66 \(\pm\) 0.29 & 1.06 \(\pm\) 0.32 & 0.35 \(\pm\) 0.10 & 0.37 \(\pm\) 0.07 & 0.10 \(\pm\) 0.03 & 0.27 \(\pm\) 0.07 \\ Ca\({}^{2+}\) & 0.22 \(\pm\) 0.10 & 13.25 \(\pm\) 3.65 & 0.11 \(\pm\) 0.03 & 3.47 \(\pm\) 0.55 & 0.03 \(\pm\) 0.01 & 1.86 \(\pm\) 0.36 \\ Cl\({}^{-}\) & 10.06 \(\pm\) 4.60 & 10.76 \(\pm\) 3.22 & 5.29 \(\pm\) 1.55 & 2.71 \(\pm\) 0.56 & 1.38 \(\pm\) 0.51 & 0.97 \(\pm\) 0.28 \\ SO\({}_{4}\)\({}^{2-}\) & 1.42 \(\pm\) 0.65 & 23.85 \(\pm\) 11.37 & 0.75 \(\pm\) 0.22 & 2.93 \(\pm\) 0.57 & 0.20 \(\pm\) 0.07 & 1.01 \(\pm\) 0.17 \\ \hline \end{tabular}
\end{table} 
Table 3: Contribution of ss and nss sources for Na\({}^{+}\), K\({}^{+}\), Mg\({}^{2+}\), Ca\({}^{2+}\), SO\({}_{4}\)\({}^{2-}\), expressed in \(\mu\)g cm\({}^{-2}\), for MR1, MR2, and MR3 averaged for 6 th, 7 th, and 8 th sampling campaigns. Figure 9: Humidification and dehumidification phases of MR1, MR2, and MR3 averaged for 10, 22, and 30 \({}^{\circ}\)C (the error bars represent the 95% confidence interval). The deliquescence and crystallization regions were identified according to the method described in Section 2.5 (DRH and CRH values at the temperature of 10, 22, and 30 \({}^{\circ}\)C are shown in the Supplementary Material, Table S7). MR1 showed the highest values of DRH (DRH range: 64.7 \(\pm\) 2.9%-73.3 \(\pm\) 2.9 RH) while MR3 the lowest (DRH range: 55.3 \(\pm\) 2.9%-64.7 \(\pm\) 2.9% RH), relating to their chemical composition: the DRH of MR1 is controlled by the great amount of sulfates and vice versa, but the DRH of MR3 is affected by the nitrates. MR2 showed DRH values between MR1 and MR3 (DRH \(\pm\) RH). In fact, as [PERSON] and [PERSON] [37] have pointed out, the sulfate fraction of the whole sulfate plus nitrate [SO4\({}^{2-}\)/(SO4\({}^{2-}\) + NO3\({}^{-}\))] enables us to understand the behavior of DRH; particularly, an increase in the sulfate fraction leads to higher DRHs and vice versa. Also, the CRH depends on chemical composition: MR1 had the highest values of CRH (CRH range: 44.7 \(\pm\) 2.9%-387 \(\pm\) 2.9% RH), MR3 the lowest (CRH range: 30.7 \(\pm\) 2.9%-26.0 \(\pm\) 0.1% RH), and MR2 showed CRH values between MR1 and MR3 (CRH range: 32.7 \(\pm\) 2.9%-38.0 \(\pm\) 0.1% RH). In this respect, [PERSON] et al.