## 4 Discussion  
Although our analysis was based on spot measurements, which have inherent limitations in capturing temporal variations, they still provide practical and informative records of EMF levels across different environments. Such measurements are particularly valuable for assessing conformity with national exposure limits, identifying spatial exposure patterns, and determining the dominant contributing technologies across varying urban densities. While this study focused on idle traffic conditions, it is important to note that 5G systems employ advanced technologies such as beamforming and massive MIMO, which introduce directional and time-varying exposure characteristics. These effects become more pronounced during periods of active user transmission. As highlighted by [PERSON] et al. [23],  
Figure 5: Logarithm (log10) of the recorded electric field values versus the logarithm (log10) of the average distance to the five closest 5G BS operating at 3.5 GHz, with a linear regression line included. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Number of Closest BS** & \multicolumn{3}{c}{**3.5 GHz Band**} \\ \hline
**n** & **Attica (Urban)** & **C. Macedonia (Urban)** & **Attica (Suburban)** \\ \hline
1 & \(-\)0.28 & \(-\)0.53 & \(-\)0.32 \\ \hline
2 & \(-\)0.28 & \(-\)0.59 & \(-\)0.29 \\ \hline
3 & \(-\)0.22 & \(-\)0.58 & \(-\)0.31 \\ \hline
4 & \(-\)0.23 & \(-\)0.55 & \(-\)0.34 \\ \hline
5 & \(-\)0.20 & \(-\)0.55 & \(-\)0.32 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: [PERSON]’s correlation coefficients between the E-field and the average distance to the nth closest BS. real-world 5G NR exposure levels can vary significantly depending on factors such as beam direction, user location, and network traffic load. In the first part of our study, we demonstrated that EMF measurements were higher in the urban areas than in the suburban areas, consistent with findings from previous research in Greece [3, 13]. This difference likely arose from the lower population density and reduced number of BS in the suburban areas. Consequently, EMF contributions in the suburban areas were less dominated by cellular networks. In contrast, in the two urban areas, the contribution from cellular frequencies was clearly higher than that from other wireless applications. The largest contribution to cellular frequency exposure originated from 4G networks across all the areas, indicating that these networks were predominantly utilized compared to other cellular technologies at the time the measurements were conducted. The low 5G EMF levels measured in Greece without generating user traffic are consistent with recent European studies that have evaluated baseline exposure under similar non-traffic conditions in the same frequency bands. The French spectrum regulator ANFR conducted extensive measurements across 1062 operational 5G sites in the 3.5 GHz band and reported that, under idle conditions, the mean electric field strength was only 0.11 V/m [24]. Prior to 5G activation, this band exhibited only residual background levels averaging 0.02 V/m, highlighting the negligible contribution of 5G to ambient exposure in the absence of user activity. Likewise, [PERSON] et al. found that the 3.5 GHz 5G NR band contributed negligibly to the overall exposure in the non-user scenario, becoming a dominant source only during active downlink transmission [25]. Exploring how the recorded electric field around the 3.5 GHz band changes with distance from BS, we generally observed that greater distance was associated with a decrease in electric field levels, though this trend was not uniformly consistent. Variability in the results can be attributed to additional influential factors such as LOS or NLOS conditions, variations in antenna power and gain, and surrounding built environments. Each of these factors significantly impacts the electric field at any given location. In AI models designed to predict EMF levels, the distance to the BS is treated as a standalone feature.