||The deployment of fifth generation (5G) will see the evolution and expansion of existing fourth generation (4G) networks and the introduction of new radio access networks in millimetre wavebands. As a result of the use of much higher frequency ranges, the number of base stations will substantially increase. These networks will include a range of installations including smaller cell deployments and advanced antenna technologies. Massive multiple input multiple output (MIMO) antennas will allow the use of very narrow beams that will follow the user with an impact on the surrounding exposure level different from that of current systems. The number of wireless devices will dramatically increase. New technology allows for the use of more efficient systems that require lower communication signal levels. Supplement 9 to ITU-T K-series Recommendations contains an analysis of the impact of the implementation of 5G mobile systems with respect to the exposure level of electromagnetic fields (EMFs) around radiocommunication infrastructure.