We were impartial about Tetra masts until the Bognor mast began to affect us in a mild way.

We got to know people living close to the mast site who were quite severely affected, so we did what research we could as a typical older couple.

No research on either side was conclusive but the people we got to know in Bognor were not hypochondriacs or swayed by mass hysteria and/or autosuggestion.

We spent short periods of time in a house near the Bognor mast and left feeling unwell. We also experienced disturbed sleep in our own home that broke life-long patterns. We have occasionally woken up at night before or been awake at night before but we have never been so hyperactively wide awake so instantly.

The impact will be greater if a network of these masts is created. The UK Tetra system is the only one that runs close to the human body's own cycle at 17.6 hertz. This alone is cause for concern, especially as children and the vulnerable seem most affected.

Several informed people have come to the conclusion that Tetra might not be safe, for example, Dr Gerald Hyland of the International Institute of Biophysics said: "These things (Tetra masts) are a potential threat to the health of some people and you cannot say who is vulnerable until it is too late."

Sir David Lane, director of the Cancer Research UK Cell Transformation Group at the University of Dundee said Tetra masts "may constitute a health hazard to people living near installation sites."

The Stewart report on Mobile Phones and Health, published in May 2000, concluded that although the evidence to date did not suggest adverse health effects, a precautionary approach should be adopted. A number of recommendations were made to government and industry.

The issues raised were not restricted to public mobile phones and it was clear that similar considerations would also apply to private mobile radio systems such as the airwave service which is currently being rolled out for police forces in England, Scotland and Wales.

The Home Office said the Stewart report's findings did not apply to Tetra, based on the findings of the Defence Scientific Technology Laboratory.

As part of its charter to protect public health and in response to public concern, the World Health Organisation established the International EMF Project in 1996 to assess the scientific evidence of possible health effects of EMF in the frequency range from 0 to 300 gHz. This assessment is ongoing.

We believe there is reasonable doubt as to whether or not Tetra is safe. Therefore, whether people are ill or not, there is good reason to halt installation of Tetra masts and call for further research, independent of government and 02 Airwaves.

-Mr D and Mrs S L Lawrence, Aldwick