## 3 Materials and Methods
### Scenario of the Incidence of SAR and Temperature Variation on Human Tissues in Indoor Environments  
The workplace, with its 33%, represents the most frequented habitat during the day by humans. For this reason, the structural and architectural characteristics actively contribute to achieving high standards of well-being and quality of life, which are crucial for the success of any activity. Among the technical aspects, monitoring the values generated by sources of electromagnetic waves plays an important role in health quality. The scenario monitoring was carried out within an indoor environment (Figure 1) with well-defined architectural elements. In order to solve the problem of signal dissipation [50,51], the area of study and monitoring was reduced, leading the study back to the equivalence theorem of the electromagnetic field theory. Figure 1 presents two three-dimensional representations of an indoor environment used to study the interaction between Wi-Fi signals and the human body, with the support of SAR sensors for the electromagnetic absorption assessment. Figure 1 depicts in more detail the multi-room environment with walls, doors, and windows. Cartesian axes (\(x,y,z\)) define the spatial coordinates, with the numbered scale ranging from 0 to about 4 m along each direction. The presence of an open door (brown) provides a signal interaction with adjacent spaces. This study volume was delimited by yellow lines, indicating the perimeter of signal acquisition and modelling. The Wi-Fi source was strategically placed to assess the  
signal distribution in a more realistic environment with obstacles, while SAR sensors were mounted on the walls to detect the electromagnetic field at multiple locations and estimate the specific absorption rate (SAR). Their distribution in multiple lo-cations indicates multi-angle data collection to better understand signal propagation. This study implemented a model divided into two types. The first concerns the measurement of the incidence of SAR and temperature variation on a stationary subject in the room (Figure 2a). The second type involves the study of the incidence of SAR and temperature variation on a moving subject (Figure 2b). Both subjects talked on a 5G technology mobile phone in an enclosed environment where there were sources of low- and high-frequency electromagnetic waves. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) establishes the impact of low- and high-frequency electromagnetic waves on human health, both regarding the electric field and the limits of SAR values created by these electric fields. For frequencies used in mobile telecommunications, the Italian limit is 6 V/m, while the ICNIRP recommends 61 V/m. The SAR limit in Italy, as in many other countries, is 2 W/kg for the head and trunk [52]. Figure 3 shows the variation in the electric field limit values for exposure of the general population established by the ICNIRP and the HHI as a function of frequency. Figure 1: Scenario analysed in indoor environment—(**a**) body area monitored (head); (**b**) Wi-Fi source; (**c**) SAR sensors. Figure 2: Measurement environments: (**a**) stationary subject; (**b**) moving subject. The impact of frequency on SAR and temperature is crucial, as lower frequencies (e.g., 100 MHz) penetrate tissues more deeply, distributing SAR over a larger volume, while higher frequencies (e.g., 27 GHz) cause localized heating. Heat dissipation depends on blood perfusion and tissue thermal conductivity, with higher frequencies surpassing the dissipation capacity more quickly, leading to greater temperature increases. SAR values were computed using permittivity and electrical conductivity (\(\epsilon_{r}\), \(\sigma\)), as shown in Table 1[53]. Lower frequencies result in gradual, diffuse heating, whereas higher frequencies induce rapid, localized temperature rises, affecting tissue response to electromagnetic exposure.