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The Western Mail recently reported in slightly hysterical tone that wireless computer networks should be banned from the nation’s classrooms because of fears about their effects on health.

MP Urges Ban in WiFi Technology in Schools

Why should we ban WiFi in schools? The reasons we are being given are that parents are concerned; that we don’t know the effects of WiFi microwave radiation yet; that one teacher claimed to be getting ill whenever teaching in front of a transmitter; and that we should apply the precautionary principle.

The result? Ysgol Pantycelyn in Carmarthern switched off its WiFi network (despite the benefits these networks bring to teaching). A few other schools in England have similarly shut down their wireless networks.

Now all of the reasons above suffer from a failure to consider the scientific basis for the claims being made. They show our penchant for listening to anecdotal evidence and rating it much more highly than scientific evidence. This is a dangerous error in our thinking. We are geared up to accept personal testimony, even though such testimony is necessarily limited and often flawed.

Who can argue that there is a problem if a teacher is feeling ill when teaching in front of WiFi equipment?

Except it turns out that in a controlled experiment when the access point was sometimes off and sometimes on, but the teacher in question did not know when it was off, he continued to claim to be feeling ill when he believed (wrongly) that the access point was on.

But that spoiler won’t be widely reported. No studies have indicated that people can detect WiFi radiation.

Someone will reply that the wavelength of WiFi radiation is in the microwave band is it not? So much so that microwave ovens are one of the largest sources of interference to WiFi equipment. So aren’t we cooking people by emitting this radiation?

Look - there is a clue here in the word “interference” above. If Microwave ovens are causing interference then they have been emitting some microwave radiation (more than from access points) for many years. Have we banned microwave ovens yet?

No, because the levels of emissions are essentially harmless.

How do we know?

Because we are surrounded by microwave radiation wherever we go. I suppose we could go and live at the bottom of a deep shaft mine to avoid it. But then we would probably die of vitamin D deficiency instead.

For people living on the surface of the Earth, we are constantly bombarded by radiation at every wavelength (including plenty of microwave background radiation).

And here is the important point. In the UK at least, WiFi radiation is strictly limited to 100mw (the limit is higher in the US). That limit has a very specific purpose. It means that unless you pretty much swallow the WiFi antenna, you are not going to absorb any more radiation from the WiFi network than from the background radiation.

What is more, the signal itself is deliberately encoded to look just like background radiation. The signal is spread over several wavebands to keep the power down, and “chipped” so that it looks just like microwave “static” unless you know what to look for and how to decode it.

And the power is kept so low so that multiple users of the same wave bands can coexist. Unlike mobile phones, for instance, which use much higher powers because the cell network has exclusive use of the waveband, and does not want to put base stations every 100 metres!

So there is no scientific reason at all to suspect WiFi networks. This is the advice given by government agencies and many local authorities (although some wash their hands of the affair with useless “advice” that it is “up to the individual schools”). We don’t need to worry about the safety of WiFi networks.

But all people hear is the anecdotal story (without refutation), and the words “radiation” and “developing children”, and it won’t be long before we see a wrong headed national campaign by some newspaper to ban this dangerous hazard in our schools.