Mobile devices and base stations use radiofrequency (RF) fields to send and receive calls and data. RF fields are a form of low-energy electromagnetic field (EMF) – energy transmitted as waves through space. EMFs surround us all the time. They occur naturally as well as from artificial sources.
EMFs are created whenever an electric current flows. In nature, they are created by lightning and also occur in the human nervous system. Light from the sun is a form of EMF. They are also created whenever an electrical appliance is connected to the mains supply, including many in daily use such as refrigerators, hairdryers and computers.
Many electrical appliances don’t just create EMF – they rely on it to work. Television, radio, cordless devices, remote control handsets, baby monitors and the communication systems used by emergency services all communicate using EMF. So do wireless technologies such as WiFi, which is increasingly used by computer networks, to connect to the internet and to connect different electronic items.
There are many forms of EMF operating at different frequencies. Frequency is related to wavelength – the distance between one wave and the next. The closer together the waves are, the higher the frequency will be.
Some very short electromagnetic wavelengths carry so much energy they can cause molecules to change. Examples include the x-rays used for medical diagnosis and radiotherapy treatment. These are known as ionising fields. Other wavelengths, such as those used by mobile devices and base stations, do not have enough energy to cause molecules to change. These are non-ionising fields. All types of EMF fall into these two categories.