Brain EM Exposure for Voice Calls of Mobile Phones in Wireless Communication Environment of Seoul, Korea

The aim of this paper is to present the measurement results of the transmitted (Tx) power levels of mobile phones in currently operating wireless communication networks in Seoul in 2015 and 2017 and the calculation results of the specific absorption rate (SAR) in the brain for voice calls while holding a mobile phone against the user's ear when operating at the measured mean power level. The Tx power levels of mobile phones using Code Division Multiple Access (CDMA) 2000, Wide CDMA (WCDMA), and Long-Term Evolution (LTE) networks were compared for the three main mobile network operators in South Korea. The actual mean Tx power level was less than 0.5% of the maximum power for the CDMA2000 and WCDMA networks. In the LTE networks, however, an extremely wide gap in Tx power was observed between the operators; two of the operators showed a mean power of less than 0.1% of the maximum, whereas the other showed mean powers of the three bands within the range of 0.8%-20% of the maximum power. The measurement results suggest that the SAR in the user's brain is strongly dependent on the year the phone was used, the user-subscribed mobile operator, and the proportion of time connected to the network/technology. The maximum 1-g peak spatial-average SAR (psSAR) level at the mean Tx power in an LTE network was 4.8 mW/kg (for a child head model). A maximum gap of 25 dB in the psSAR was observed between all networks considered.