THE worries of some parents in Stronsay, Orkney over the 5G mast at their children’s school are understandable, but misguided ("Pupils are kept home from school amid 5G health fears", The Herald, August 21). Health warnings relating to mobile phone use by children relate entirely to the mobile phone as a source of radio frequency radiation in very close proximity to the head — probably harmless, but discouraged on the precautionary principle. The radiation in question is quite different from damaging x-rays or gamma rays and does not cause DNA damage that can lead to cancer. Its only effect is to very slightly heat tissue in close proximity to the source.

Proximity is the key issue, because the intensity of radiation declines according to the Inverse-square Law. Put simply, beginning with a phone one inch away from the ear, the radiation two inches from the phone will be one divided by two squared or one quarter of that at one inch. Three inches away a ninth, four inches away a 16th, five inches away a 25th, and so on. The same applies to radiation from mobile phone masts which, in any case, have a very low power output (around 50 watts compared with around 800 watts from a domestic microwave oven).

So, if parents are concerned about the effects of mobile phone radiation on their children, they should discourage them from holding their phones close to their ears. A mast, because of its height and distance away, should be much less worrying.

Rev David A Collins, Dundee DD5.