Non-ionising radiation is electromagnetic radiation that lacks the energy entirely to remove electrons from an atom or molecule.  It covers a range of wavelengths, from a narrow section of the ultraviolet (UV) and visible spectrum through infrared, microwave and radio frequencies (RF), into extremely low frequency (ELF) bands.  Exposure sources also vary across this spectrum.  While the majority of UV and visible radiation comes from natural sunlight, the lower frequency bands derive mainly from artificial sources, including electrical equipment, telecommunications infrastructure/appliances and powerlines. 

Ultraviolet radiation

In the case of ultra-violet radiation from the sun, known health effects from exposures to UV radiation include skin cancers and corneal damage (burns and cataracts).  Over recent decades, the incidence of these effects appears to be growing, due in part to changes in behaviour (and perhaps climate change) which have increased exposures. 

Exposures to UV radiation are generally modelled using radiative transfer models (or simplifications of them), that attempt to simulate the processes involved in transmission and scattering of solar radiation as it passes through the atmosphere and interacts with the ground surface.

Links to models and to an example of how they can be applied to estimate exposures to UVR are provided under See also, below.

Electromagnetic radiation from telecommunications systems

Definitive evidence for health effects of ectro-magnetic radiation from artificial sources, at levels commonly encountered in the open environment, is lacking, and plausible mechanisms have not been firmly identified.  Nevertheless, public concern remains high, not least about possible risks (e.g. brain cancer) from powerlines, mobile phones and associated base stations.  Precautionary measures to limit public and occupational exposures from these sources have therefore been introduced. 

Exposures to non-ionising radiation from artificial sources are modelled using a range of approaches, including empirically-calibrated path loss models, ray-tracing models, and statistical models.  Many of these have been developed and tested only for specific wavelengths and in a limited range of circumstances, so their extrapolation to other contexts needs to be done with care.

Further information on modelling electromagnetic fields (EMF) associated with telecommunications systems is provided via the link in the panel to the left.