18/05/2007 - Panorama on WiFi
Panorama have produced a cutting-edge documentary about electrosensitivity to modern microwave communication systems (e.g. mobile and cordless phones) and especially about WiFi being rolled out in UK schools.
This, or related information, will be aired at the following times:
|BBC News 24
|BBC News 24
WiFi and health risks
To date, as far as we can find out, there has been no proper research done on whether people, especially children, regularly subjected to WiFi signals suffer from any unwanted health effects. WiFi is very similar in most ways to Mobile Phone Masts. They have very similar carrier frequencies and pulsed digital amplitude modulation. The signal strength in a classroom with 15 WiFi enabled laptops will be very similar to the signal strength you would receive from a mobile phone mast 80 to 150 metres away.
There is now considerable research associating serious health effects with living near a phone mast. If living near to mobile phone masts poses a possible health risk, then why are we actively putting wireless devices in schools that fill the classrooms with similar levels of pulsing microwave radiation? Especially as the effects being reported are excatly those we do not want to occur in our children and young people. Many of these effects are increasingly being reported in our children, by parents, teachers and now the UK National Institute for Health and Clinical Excellence (NICE) who are reporting a 4-fold increase over the last ten years in the incidence of ADHD and behavioural problems in our schools. There are likely to be a number of factors involved, but increasing microwave exosure at home and in school is likely to be an important one. Not just WiFi, but most school pupils now have their own mobile phones.
Powerwatch believes that the comments by HPA spokesman, Dr Mike Clark, that a 20 minute mobile phone call gave as much exposure as a year in a wLAN classroom is complete rubbish. Powerwatch's measurements and calculations suggest that a typical 20 minute mobile phone call would cause a similar exposure from a few hours up to one day in the classroom. The current Department of Health Chief Medical Officers' advice is that children and young people should only use a mobile phone for really important calls, and yet here we are forcing our youngsters into almost full-time exposure at school to such pulsing microwave radiation. This is irresponsible and could even be seen as possible child abuse.
We believe that many people are reacting badly to much lower levels (e.g. 0.1 volts per metre (V/m)) than found in a classroom of wireless connected computers (typically several V/m). The symptoms they report are headaches, concentration, learning and behavioural problems, all of which have been rising at our schools in recent years. NICE reports a 4-fold increase in ADHD in young people over the last ten years. The minimum we should be doing is a formal investigation into such problems in schools with and without wireless systems, and monitoring any changes following the introduction of such systems.
We recommend wired ethernet networking as it provides a reliable and established system for networking and data transfer. Pupils' personal laptops, which usually have to be plugged into a mains charger unit, can also easily be plugged into this when they need network access.
NO-ONE is suggesting that the ES / neurovegetative symptoms found near to masts, etc, are due to thermal (heating) issues. So that the way it is measured and the effect calculated is often just not appropriate for these low-level non-thermal signals. It should be dismissed out of hand as 19th century out-of-date old-paradigm scientific thinking. The oft-repeated John Stather (HPA-RPD) quote: "If it doesn't heat you, then it won't harm you" is just complete rubbish. You could say that "If it heats you then it may well harm you". That would, at least, be correct, but it would omit the fact that we are NOT talking about heating effects, but about subtle communication / informational effects.
Technical section about signal levels
Coming back to heating effects (i.e. SAR), Mike Clark is right that a mobile phone, working on full power and with you talking continuously (not listening) can, at a maximum, probably exposue you to about 50% of the SAR limits. However, In normal use, with a good number of signal strength bars showing on the display, the phone will be working at somewhere between one-thousandth and one-twentieth of this level, Let's say 1/50th. 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 typical 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.
Let's relax this to 1/200th c.f. 1/1000th. So there is about a 5-fold difference, in my opinion, between a TYPICAL phone call and being in a classroom with 20 wLAN PCs. So, 20 mins on the phone (typical) would be equivalent to about 2 hours in the classroom, in Powerwatch's opinion. IF (very very very unlikely) the phone was working at full power all of the 20 minutes, then 20 mins == two weeks of daytimes.
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.
Mike Clarke should give a technical explanation of how he came to 20 mins vs one year he quotes. Actually that works out at 1/26300th, anyway, not 1/20,000,000th. So the whole quote seems to be a crap soundbite. A pity that it is being quoted so frequently.
Further details of our measurements will be posted to this website shortly.
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