Protestors clueless on wireless health risks
Scare stories about mobile phones cooking our brains come and go as regularly as the seasons. Irrational and unexplained results are periodically hailed by the media as the death knell for the mobile industry.
Schools, colleges and universities advise against - or even ban - the use of wi-fi, and services are closed down as a potential health risk.
There are many protest groups actively campaigning against wireless in any form because of some unknown and unquantified potential risk to health. These groups include those preventing base station towers being erected close to their schools or in the middle of their communities.
Unfortunately their lack of understanding actually has an inverse reality impact. If they understood the basic physics involved they would be asking for more towers and not fewer. Living really close to a mobile phone base station tower is the safest place to be.
Here is what is happening. The mobile phone pressed close to your ear adjusts its transmit power according to the distance from the base station.
That means the further from the tower the lower the power received by a mobile and the higher the power transmitted back as a result.
So if you get really close to a base station your mobile sees lots of signal and therefore transmits back a minimal amount in turn. Interesting, isn’t it? That is the inverse perception of the protestors.
The detailed physics is also interesting. Near-field emissions - those that are mainly magnetic field coupling - fall away at a rate of 1/d^6 while the far-field radiation - that is, electro-magnetic waves - die at the slower rate of 1/d^2 where d is the distance from a transmitter.
These inverse distance laws lead to the situation whereby the power entering the human head from a tower is generally less than 1,000 times smaller than that produced by a mobile.
Hence, to reduce the exposure to radiation to a minimum it is always better to be really close to the base station to ensure the mobile is emitting a minimum energy.
And what of wi-fi and WiMax? Various emission limits and active control systems, plus deployment methods generally render these systems less power aggressive than mobile networks. And of course the same inverse distance/power laws apply.
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Read more : silicon.com