UK schools are rushing to bring “the magic of Wi-Fi”, as one naïve UK Department of Education and Skills spokesperson put it, to their children. Already 70% of secondary schools and 50% of primary schools have classrooms where whole lessons and study times using Wi-Fi computers take place, and no-one knows what the health implications may be because, just as for mobile phones, microwave ovens, irradiated food - the list is endless - no-one has done any more than the most cursory research, and no Government cares enough about its citizens or children to insist that high quality long term safety research is carried out before yet another highly profitable piece of quick buck hi-tech is wheeled out.

We should all be very worried:

• In the Panorama report on Wi-Fi in the classroom and the health risks of mobile phones (BBC1 21/5/07) Powerwatch UK director Alasdair Philips showed that the head of a child using a Wi-Fi lap top computer on its desk was exposed to levels of microwave radiation three times stronger than that experienced where the main beam of radiation intensity from a mobile phone mast hits the ground nearby
• Schoolchildren often work with the laptops on their laps, radiating their reproductive organs with the same strong fields. Professor Lawrie Challis, who heads the UK Government’s Mobile Telecommunications and Health Research Committee, tells us that the radiation is the same as that put out by a mobile phone during a call, making an average lesson the equivalent of a 40 minute call
• Several European provincial Governments have already taken action to ban or limit, the use of Wi-Fi in the classroom. Dr Gerd Oberfeld, head of Salzburg’s Public Department of Environmental Health considers Wi-Fi dangerous, especially for children, and has called for their removal

Ed.- Health Protection Agency spokesperson Mike Clark recently stated that, in radiation terms, a year’s worth of Wi-Fi based lessons were the equivalent of just one 20-minute mobile phone call. Alasdair took serious issue with this astonishing statement. He calculated that, on the contrary, it took just one one hour lesson using 20 wi-fi lap tops to expose children’s heads to the equivalent of a 20-minute mobile phone call, while the whole body of anyone in the room absorbed the same amount of radiation as that put out during a one hour call.

(13089) Nick Anderson. Green Health Watch 22.5.07

Alasdair of Powerwatch UK, an acknowledged authority on microwave radiation, disagreed profoundly with this statement ...

“This statement, very unhelpfully publicised by Mike Clark, senior spokesperson for the Health Protection Agency, is both factually incorrect and highly misleading. Whilst he is right to say that a mobile phone, working on full power and with you talking continuously (not listening) can technically expose you up to about 50% of the SAR limits. In normal use, with a good number of signal strength bars showing on the display (say 75% signal level), the phone will be working at somewhere between one-thousandth and one-twentieth of this level. Let’s average this at about one fiftieth as a reasonable level for the phone to be operating at most of the time. Then, if you are talking 50% of the time, this would reduce the transmitted pulses (using DTX) by another factor of 2. So, a typical exposure would not be 50% of the SAR limit but more like 0.5% of the SAR limit which we should assume to be 0.5% of the the ICNIRP limit (for a typical call).

Now we come to a slightly different exposure regime in the classroom in that you are not holding the wLAN card to your head. 2.4 GHz wLANs (most common in the UK) operate at 0.1 watts output power (5-6 GHz ones can use up to 20 times this). So we have one wLAN node in the classroom (0.1 W) and, say, 20 laptops all at 0.1 W. However, they are only transmitting much power when actually transferring files. So, let’s say that we have the equivalent of one laptop operating absolutely continuously (actually the combined output of 20 may well be more that this). So we have 0.2 W. Let’s say that we are on average 1 metre from the antennas. This seems reasonable based on the fact that there are 20 in the room. So E = sq.root (30*0.2)/1 = 2.5 V/m equivalent continuous. Now the ICNIRP guidance at 2.4 GHz is 61.5 V/m. So the signal strength is 1/25th of what is allowed. Power is proportional to signal strength squared so that would be 1/625th of the ICNIRP power level.

So, we have a mobile phone call next to head typically 0.5% (1/200th) of the ICNIRP guidance. We also have being in a 20 PC wLAN classroom being something in the order of 0.2% (or 1/625th) of ICNIRP guidance, about a 3-fold difference. Therefore 20 minutes on a mobile phone running at typical power levels would be equivalent to about 1 hour in a classroom with 20 wLAN PCs, appoximately two standard lessons.

There are other differences. In the phone call situation, almost all the energy goes into the user’s head and hand. In a classroom situation the whole body aborbs this lower level of power, so the “total body burden” if we were to compare it with ionising radiation (for example), would actually be very similar.

Addendum:
The above calculations are based on absorbed power levels, which is based on the idea that the only thing that microwaves do is heat you. As we are looking at non-thermal effects we believe that signal strength is likely to be a more appropriate metric (measured in volts per metre). This has the advantage of not being averaged over time, and we can therefore tell the difference between exposure from a continuous wave signal and one where the signal consists of a number of short pulses with gaps”.