If the only question in the battle over mobile phone masts was whether they were dangerous, the dispute over the placement of Esat Digifone's antennae on Garda masts would have ended years ago. Something is fuelling the debate, but it has nothing to do with radio waves or science.

People looking for health risks should forget the masts and consider the mobile telephones they happily carry about in their pockets. In normal use, the handset will deliver 10,000 times more radiation than the mast overhead. The current scientific focus is not on the radio wave energy coming from the mast, it is on the handsets and whether these might cause health effects after long-term use.

Antennae which broadcast radio waves are nothing new. We have had broadcast television since 1961, longer for those on the Border who picked up the early days of BBC and ITN. Wireless radio and its attendant technology has been with us much longer.

Both television and radio broadcast antennae emit much more power than that put out by a typical mobile phone mast antenna. The big RTE masts shove out 800,000 watts of power compared with the focused beam from a mobile antenna, which has an apparent strength of about 300 watts.

Yet we did not see protests as RTE developed its systems and improved its coverage over the years. Nor was there much noise when TV3 was introduced, increasing the broadcast signals that are daily pumped out over our heads.

There were vigorous protests and claims about health risks when Radio Tara, subsequently Atlantic 252, put up its enormous long-wave antenna in Co Meath and began broadcasting. There were fewer people then to push the issue of safety, however, and claims that the unsightly structure contravened the county development plan fell on deaf ears.

If any of these antennae were emitting something that was dangerous or harmful to health, then we would have very clear data by now showing that this was so. Television and radio broadcast systems are everywhere. There is a halo of similar radiation blanketing all of our airports as radar picks out approaching aircraft.

Mobile phone systems are in widespread use across the world, with market penetration of one in three for some Scandinavian countries. In the US mobile phones are sold for a single cent to encourage consumer purchases.

Estimates vary but there could be as many as 100 million mobile users in the world today, and a predicted 350 million by 2000. They use their mobiles an average of an hour per day.

Esat says it has 200,000 of the estimated 500,000 mobile phone subscribers in Ireland. The users here and abroad represent a massive sample available for epidemiological studies which could show whether mobile-related illnesses were occurring at a detectable level.

All these mobiles need masts to carry the antennae. Esat already has 500 in place, Eircell has even more. These and the hundreds of thousands in other countries again provide those looking at disease incidence with plenty of people living close to masts.

Intensive work in this area has failed to produce anything that strongly suggests that life near these masts is dangerous. Independent scientists involved in this work would be more than happy to let us know if health effects did emerge.

All of these scientists could not be pawns in some powerful game being played out by the telecommunications companies. Not all of the research is paid for by these companies and therefore not all of it is tainted by claims of factual misrepresentation.

The most interesting data which suggest that there might be health effects do not relate to phone masts at all but to the levels of radiation coming from the mobile handset.

Dr Mike Repacholi of the World Health Organisation in Geneva is the author of an Australian study which found an increased incidence of lymphoma cancers in mice exposed to mobile phone handset radiation. He said, however, that the work could not be applied to humans.

There is another study by Washington State University which indicated increased DNA damage to rats exposed to radio waves in the frequencies emitted by mobile handsets. The dose received by the rats was higher than that received by a human user, however, and again the work was not readily applicable to humans.

The handset radiation is on average 10,000 times stronger than the mast radiation reaching the ground, because of well understood and straightforward physics. The radio waves are strongest as they leave the antenna but, just like the ripples on a pond caused when you throw a stone, they begin to lose energy immediately. The further you are from the source, the weaker the wave.

If the signal strength is 100 per cent right at the antenna, 10 metres away it is only one per cent or one hundredth the strength. By 20 metres away it is just 0.0025 per cent. If you take measurements around a mast the signal on the ground will be tiny compared with its original strength.

By the same token, some users have the bad habit of placing their mobile handset antennae right against their heads as they chat on the phone. Even though the original signal strength is lower on the handset, there is no distance between your head and the antenna to allow the signal to weaken.

Protesters in Kerrykeel last week would have been more at risk of being hurt when scuffling with the gardai than from living right under the mast.

If some of them were using mobiles to rally support, they would have received much more radiation from their handsets than they would after years of having the mast in their town. And if any of them are smokers, then they are daily shortening their lives and their mobile radiation exposure is of no account by comparison.

Research continues in an effort to find evidence that either the masts or the handsets represent a health risk. Nothing conclusive has yet been found but this will not deter scientists from continuing the search.

It may be that there are hidden effects which will emerge only over time, although they have yet to emerge for those living near television or radio masts. If such effects are detected, those using the phones should be more worried than those living near the masts.