# Radio Frequency Electromagnetic Fields Exposure Assessment in Indoor Environments: A Review
## 3 Results
### RF-EMF Exposure Levels
#### 3.4.1 Exposure in Public Places  
Working Places  
As people spend a large amount of their time in the office during working hours, many previous studies focused on the assessment of the exposure in office buildings, with particular attention paid to the presence of wireless local area networks (WLANs) [17]. As an example, [PERSON] et al. [44] used personal exposure measurements for assessing the exposure of people working in the offices of some companies which are characterized by extensive use of wireless technologies. The measurements were recorded during working hours, after working hours and during the weekends using personal exposimeter that measured the total level of exposure between 88 and 5850 MHz, and the relative contribution of 14 frequency bands used for wireless communications. The results showed that the total mean power density value of the working day was 0.524 mW/m\({}^{2}\) (0.4 V/m in terms of electric field, corresponding to 1.5% of lowest ICNIRP reference level for the 88-5850 MHz frequency band). During the weekend, for the same exposure hours as for the working day, the mean power density value was 0.828 mW/m\({}^{2}\) (0.56 V/m, 2% of lowest ICNIRP reference level for the 88-5850 MHz frequency band, mainly due to the exposure to the GSM (DL) system (0.500 mW/m\({}^{2}\), 0.43 V/m in terms of electric field, 0.7% of the ICNIRP reference level). The study included the exposure due to Wi-Fi in the frequency band between 5.1 and 5.8 GHz, finding that its contribution was relatively small (0.046 mW/m\({}^{2}\), 0.13 V/m in terms of electric field, 0.22% of the ICNIRP reference level), and confirming that the main contributors to RF-EMF exposure are mobile phone systems (0.255 mW/m\({}^{2}\), 0.31 V/m in terms of electric field, 0.53% of the ICNIRP reference level) and DECT systems (0.178 mW/m\({}^{2}\), 0.26 V/m in terms of electric field, 0.45% of the ICNIRP reference level). The authors concluded that the total amount of personal exposure, surprisingly higher during the weekend that during the working days was mainly dependent on the personal habits of the use of such systems, rather than indoor workplace specifics. [PERSON] et al. [45] investigated RF-EMF exposure in offices due to indoor used wireless communication technologies such as WLAN (2400-2483 MHz), Bluetooth (2400-2483 MHz) and Digital Enhanced Cordless Telecommunications (DECT) systems (1880-1900 MHz). Results showed that under usual conditions, the resulting spatially (over body dimensions) averaged and 6-min time-averaged exposure was below 0.1% of the reference level for power density according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines [43], and that none of the devices considered in this study exceeded the limits according to the ICNIRP guidelines. [PERSON] et al. [34] investigated RF-EMF exposure in offices (where exposure can be caused by various transmitters of local fixed indoor and outdoor wireless communication systems), and in buildings (in urban and rural areas in various regions of Poland), using personal exposure assessment. The main sources of exposure were found to be mobile phone base stations (BTS) and radio-television transmitters (RTV). The frequency composition in a particular office depends on the building's location. The E-field recorded during 24 h in buildings from the outdoor BTS had median and 75 th percentile values lower than 0.19 and 0.25 V/m (0.5% and 0.6% of the corresponding ICNIRP reference level), in urban areas and lower that 0.05 and 0.09 V/m (0.1% and 0.2% of the corresponding ICNIRP reference level) in rural areas. In buildings equipped with indoor BTS antennas the E-field median and 75 thpercentile values were lower than 1 V/m, and 1.8 V/m (2.6% and 4.6% of the corresponding ICNIRP reference level), respectively.