# Radio Frequency Electromagnetic Fields Exposure Assessment in Indoor Environments: A Review
## 3 Results
### Educational Buildings
#### Exposure in Private Places  
A high number of studies focused on the assessment of the exposure in residential environments, both using measurements and simulations tools. A residential RF exposure assessment was performed by [PERSON] et al. [28] by measuring the electric field in fixed positions in bedrooms in 1348 households in Germany in 12 frequency bands from 88 MHz to 2.50 GHz, with the aim of investigating the contribution of different RF-EMF sources (FM radio, analogue TV and DVB-T, TETRA, GSM900 downlink, GSM1800 downlink, UMTS downlink, DECT, and wireless LAN and Bluetooth) to the total exposure. Measurements were carried out from 8 a.m. to 9 p.m. in 4 positions in each bedroom, and at each position 75 measurements were taken within 5 min. The first 5 of 75 measures in every position were deleted (resulting in 280 measuring values for every frequency range per household), Results showed that the exposure levels were often below the detection limit (electrical field strength: 0.05 V/m) of the dosimeter, while the total exposure varied, depending on residential characteristics (urban vs. rural areas) and on the floor of the building where measurementstook place. DECT and WiFi accounted for 82% of total exposure level, with mean values of power density equal to 22.45 \(\mu\)W/m\({}^{2}\) and 6.37 \(\mu\)W/m\({}^{2}\) (0.09 and 0.04 V/m, in terms of electric field strength, 0.16% and 0.08% of the respective ICNIRP reference levels). Exposure from mobile phone base stations accounted for only 6.3% to total exposure, while the contribution of the uplink sources, such as mobile phones, was not included in the study. Another cross-sectional study by [PERSON] et al. [55] in houses placed near to base stations in Austria showed that total RF EMF exposure measured in bedrooms of 336 households, including mobile telecommunication signals, was far below recommended levels, with maximum values of power density equal to 4.1 mW/m\({}^{2}\) (1.24 V/m in terms of electric field strength); the greater portion of that exposure was from mobile telecommunications (geometric mean 73%). Overall 5% of the estimated maximum exposure levels were above 1 mW/m\({}^{2}\). Distance of the houses from antennas was 24-600 m in the rural area and 20-250 m in the urban area. The mean value of electric field strength was slightly higher in a rural area (0.13 V/m) than in an urban area (0.08 V/m). This discrepancy was due to the fact that only those households were selected that were close to mobile phone base stations, and base stations in rural areas typically transmit higher power as they are required to transmit over larger distances. A study by [PERSON] et al. [56] proposed a geospatial model to predict the radiofrequency electromagnetic field in indoor environments from fixed site transmitters for use in epidemiological exposure assessment, used in some of the studies described in the followings (see, e.g., [3]). Findings showed that mean value of the RF-EMF exposure in residential buildings was equal to 0.13 V/m. In the study by [PERSON] [57], the exposure due to Wi-Fi networks was analyzed in different locations of a two floor house located in a residential area, by moving the router-terminal devices in different positions, and considering different types of traffic which sent through the network. The results showed maximum background exposure to WLAN equal to 39 mV/m when the Wifi network under exam is turned off, and a maximum exposure equal to 2.6 V/m in the far field region of the transmitters when the WiFi network is turned on. Concerning the type of traffic, oscillations up to 10 dB were detected for exactly the same position, depending on the type of traffic was being sent. Differences around 62 dB in mean values between the different rooms of the house were found. All values were below the threshold of 61 V/m prescribed at 2100 MHz by the ICNIRP guidelines for general public [43].