As a professional scientist and engineer, I have been extensively involved with radio and microwave signals and the study of brain signals.
Radio masts are again an issue (March 5) but it seems some people still do not recognise that there is no risk to health from mast signals. Their signal strengths are too low to cause damage by heating, just as broadcast radio and TV signals are too low to be a health risk. They are low at the mast and decrease rapidly with distance. Hence scares about possible harm to children in nearby schools are unfounded.
However, a possible danger can be said to be associated with mobile handsets. It is possible, but not definitely proven, that lengthy use of a handset placed against the ear may cause heating of brain tissue or that the high frequency signals might affect brain cells. One outcome could be brain tumours. It seems, though, that very few seem to be concerned about this more real possibility.
BW Jervis, Button Hill, S11