Summary - K.156 (08/2024) - Time and spatial averaging in RF-EMF exposure assessment

The level of radiofrequency electromagnetic field (RF-EMF) exposure depends on the type of radio communication systems and how they are used by users. This level may change over time and space.
In terms of time variability, some systems such as broadcasting represent a rather constant and stable level of exposure to RF electromagnetic fields and do not depend on the time of day or frequency of use. In other systems such as mobile communications, it depends on traffic volumes. Beamforming antennas, which are being introduced in 5th generation wireless network (5G) mobile systems, provide additional variability in exposure levels over time.
The level of electromagnetic field exposure also varies at different points and varies even within the volume occupied by the human body. Additionally, in the case of a new 5G mobile system, it may change depending on the location of its users.
For this reason, appropriate averaging techniques are used to assess the actual level of exposure that can be expected in areas accessible to people.
Recommendation ITU-T K.156 focuses on several considerations that need to be addressed during RF-EMF level evaluation.
In this Recommendation electromagnetic field (EMF) levels variation in time and space are not considered because of different weather and radiowave propagation conditions.