Every time a call is made or received on a mobile phone, the phone is connected to the aerial for the local cell. The aerial then connects to other aerials until eventually contact is made with the phone at the other end of the call. Aerials radiate energy in the form of electromagnetic waves which induce alternating currents in other aerials with the same frequency.
There are more than 40,000 mobile phone masts in the UK. All of them are sources of radio waves, and the concentration is greatest in the biggest cities, where the population and mobile phone density is biggest. The following table shows typical levels of the radiation from mobile phone masts in the UK, along with some reference levels.
|
Typical Intensity mW/m 2 |
|
|
Typical Level in UK |
0.1 – 1.0 |
|
Maximum Level Measured in School Playground |
8.3 |
|
Reference |
|
|
Pre 2000 Limit in UK |
35,000 |
|
Current UK and EU Level |
4,500 |
|
Current USA Limit |
5,700 |
|
Current Swiss Limit |
450 |
The intensity of radiation obeys the inverse square law for electromagnetic waves, so the further away from a source you go, the lower the intensity of radiation. If you double the distance from a source, the intensity of radiation falls by a factor
If the distance from the source increases by a factor of 10, the intensity of radiation falls by a factor
This means of course that the danger is closest closest to the mast. Many local campaigns are mounted against mobile phone masts being built nearby, even though people are dependent on the presence of those masts to be able to receive mobile phone calls.