# Radio Frequency Electromagnetic Fields Exposure Assessment in Indoor Environments: A Review
## 3 Results
### Educational Buildings
#### 3.4.4 Comparison between Different Types of Indoor Environments
The overall results for all the environments showed median time-averaged levels of exposure in the 70-3000 MHz band equal to 0.4 mV/m and median time-averaged RF power densities in the range of 1-10 \(\mu\)W/m\({}^{2}\) at distances of about 1 m from a laptop when its Wi-Fi client was communicating with the network. A study by [PERSON] et al. [5] was focused on the characterization RF-EMF exposure levels and their temporal trends in typical everyday environments, including public transports, and indoor settings, by using micro-environmental measurements in Basel (Switzerland), Ghent and Brussels (Belgium). Measurements were collected every 4 s during 10-50 min per environment and measurement day. Linear temporal trends were analyzed by mixed linear regression models. The highest total RF-EMF exposure levels were found in public transports. In trains the exposure levels ranged between 0.83 V/m in Ghent (2.96% of the ICNIRP reference level) and 1.06 V/m in Brussels (3.79% of the ICNIRP reference level) and were higher compared to those of other environments, such as airports (maximum mean level equal to 0.54 V/m in Basel, 1.53% of the ICNIRP reference level), train station (maximum mean level equal to 0.57 V/m in Brussels, 2.03% of the ICNIRP reference level) and shopping centers (maximum mean level equal to 0.37 V/m in Bruxelles, 1.32% of the ICNIRP reference level). Mobile phones were the main exposure source in trains, whereas in other public transports and indoor environments mobile phone base stations (downlink exposure) had also a considerable impact on the exposure level. In a study by [PERSON] et al. [30] exposure to RF base stations for wireless technologies was assessed at 68 indoor locations, in Belgium, the Netherlands, and Sweden. The authors did not reported the levels of exposure observed in the different environment, but just the median and 95 th percentiles considering the measures in all the considered locations. A total electric field with median value and 95 th percentile equal to 0.28 V/m and 2.18 V/m, respectively, was found in indoor environments (equal to 1% and 7.8% of the ICNIRP reference level). The most influencing contribute was the exposure due to DECT, with exposure levels described by median value and 95 th percentile equal to 0.12 V/m and 1.50 V/m (0.21% and 2.6% of the ICNIRP reference level), while contributions of LTE and WiMAX are on average 1%. Comparing the indoor exposure to the levels measured in the same areas, but outside buildings, thus in outdoor conditions, the authors found that 95 th percentiles for total indoor and outdoor exposures did not differ much and were about 2.2 V/m. Higher total outdoor values of mobile telecommunication signals were obtained than at indoor locations, because only downlink exposure due to base stations was considered (discarding the contribution of uplink exposure due to mobile phones), which are outdoor sources and are dominant outdoor. Moreover, the propagation of base station signals into houses and buildings is subject to penetration losses. Also in [79] the authors compared personal exposure obtained in different countries, i.e., Belgium and Australia, considering different microenvironments, included indoor places such as apartments, libraries, shopping centers and different types of transportation. Results showed that levels of exposure across the indoor environments were much lower than those outdoor, with the highest values in the library in Belgium (equal to 0.99 V/m) and the airport in Australia (equal to 0.27 V/m). In a study by [PERSON] et al. [21] the authors investigated the RF-EMF exposure level by using personal exposure measurements during daily activities of 98 volunteers living in The Netherlands. The mean exposure over 24 h, excluding own mobile phone use, was 0.180 mW/m\({}^{2}\) (0.26 V/m, equal to 0.93% of the ICNIRP reference level). During daytime exposure was about the same, but during night it was about half, and in the evening it was about twice as high.