# Radio Frequency Electromagnetic Fields Exposure Assessment in Indoor Environments: A Review
## 4 Discussion  
The review of the research efforts towards assessing RF-EMF exposure in indoor environments in the last ten years reveals that comparing the results of exposure assessment in different studies is challenging and includes a lot of uncertainty. The various results show a limited representativeness, both because of the peculiarity of the experimental protocol used in each case and because often not all the context information is reported. Spot and long-term RF measurement campaigns described in different studies presented differences about the choice of the measurement sites in indoor environments. As defining a procedure that could be truly representative for population exposure is challenging and no standard procedure has been established so far, it was not possible to exclude that some of the studies reporting the highest or the lowest levels of exposure could have focused a priori on areas with enhanced exposure levels or with reduced exposure levels, respectively. Another important challenge for comparing the typical RF-EMF exposure values was the different kinds of devices used for exposure measurement, as different measurement settings may be chosen, with respect to frequency bands considered and to the sampling rate of the instrument. As to studies based on personal measurements, the use of different recruitment strategies, or the limited numbers of participants or microenvironments could make a direct comparison difficult. The results obtained in these studies could arise from few measurements in a high number of very different indoor environments, and could have been presented using different analysis methods, thus making very difficult to summarize general information about the levels of exposure. For both spot and long term measurements and personal measurements studies, the exposure levels reported in different publications where based on different averaging times (minutes, hours days). Moreover, different studies used different approaches for the handling of those values found to be below the detection limit of the measurement device. All these aspects could make results obtained in different studies difficult to compare. Finally, results obtained by computational methods could be difficult to be summarized in order be representative for population exposure, as they are strongly depending on the exposure scenarios simulated in each specific study. Nevertheless, some overall exposure patterns can be derived to characterize the typical levels and contribution of different sources to the total RF-EMF exposure in various microenvironments. Table 3 shows, a summary of the RF EMF exposure levels measured in different indoor locations obtained by spot and personal measurement and reported in literature. More specifically, the minimum and the maximum values among the mean and median values reported by the examined paper were reported in Table 3. No further arithmetic mean was applied, and all the studies for which the authors did not report median or mean values of thee exposure or did not detail the specific environment in which the value was observed were discarded. It should be notice that no normalization of averaging times was applied. As a first common point among all the considered studies, all the results showed that in all considered environments the levels of exposure were well below the ICNIRP guidelines for general public exposure [43]. The highest maximum mean level of total exposure (i.e., the exposure due to the whole RF-EMF frequency band) was found in offices and was equal to 1.14 V/m. This value, reported by [70] as the total level recorded in offices in Belgium, was higher than all the mean/median values reported by all the other considered studies. Discarding this value, the maximum mean value for the total exposure in offices was found to be equal to 0.72 V/m.