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How Bad Can Wi-fi Be?
An anonymous reader writes "Sunday night in the UK, the BBC broadcast an alarmist Panorama news programme that suggested wireless networking might be damaging our health. Their evidence? Well, they admitted there wasn't any, but they made liberal use of the word 'radiation', along with scary graphics of pulsating wifi base stations. They rounded-up a handful of worried scientists, but ignored the majority of those who believe wifi is perfectly harmless. Some quotes from the BBC News website companion piece: 'The radiation Wi-Fi emits is similar to that from mobile phone masts ... children's skulls are thinner and still forming and tests have shown they absorb more radiation than adults'. What's the science here? Can skulls really 'absorb' EM radiation? The wifi signal is in the same part of the EM spectrum as cellphones but it's not 'similar' to mobile phone masts, is it? Isn't a phone mast several hundred/thousand times stronger? Wasn't safety considered when they drew up the 802.11 specs?"
802.11b/g uses 2.4GHz radio waves. That's the same frequency range as microwave ovens. Microwave ovens work because the microwaves are absorbed by the bonds in the water molecules of food (which is why dry food does not cook in microwave ovens).
So yes, human tissue that contains water can absorb WiFi radiation. That is a fact.
What is not known is: how much absorption of that radiation is bad for the kids?
And in other news from the BBC http://news.bbc.co.uk/2/hi/technology/6676129.stm
not a pretty sight, is it?
the FCC has specifications of radiation density versus frequency that are limits in their rulebooks, limits used to isolate access to radio facilities from microwaves to commercial broadcasters... to ham radio operators burning electrons in the basement. these have been codified by medical research. if you're going for an advanced ham license, you have to study the milliwatts per meter limits, the question occasionally comes up on the test.
so there are 3/4 million americans who know this, not just ten academics in the tower.
where the hell did this whining of Luddites come from, and why wasn't it left there?
if this is supposed to be a new economy, how come they still want my old fashioned money?
Here
Basicaly in the old country they have a government official who is unprepared to admit radio waves, mobile phones etc, are safe; no matter what the evidence.
Old COBOL programmers never die. They just code in C.
You obviously didn't see the program, one person in it complaining wifi gives her headaches had covered her entire room in tin foil to protect her from it all :p
So, your WIFI is 1 meter away and the cell tower is 1 kilometer away, which delivers more power where you are at. Take the cell tower number and divide by a million (1000^2) and you'll see that WIFI yields greater exposure. Doesn't mean there is a problem, but it is not just power level at the antenna that is important.s -selling-solar.html
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Fusion power from your roof: http://mdsolar.blogspot.com/2007/01/slashdot-user
The operating frequency of microwave ovens was chosen to be in an unlicensed (ISM) frequency band, that would provide good penetration into foods, and lent itself to the mass production of inexpensive magnetron tubes.
The lowest resonant frequency for a water molecule is 22.235 GHz, or nearly 10X the operating frequency of a microwave oven.
Remember "News for Nerds, Stuff that Matters"? Help make it a reality again! http://soylentnews.org
Unfortunately, in the UK at least, the number of scientifically trained journalists can probably be counted on one of Ben Goldacre's fingers.
Interesting that none of the phone mast posts seem to have remembered the inverse square law - sorry if you did and I missed you - which mean that radiation levels at the ground are a tiny fraction of what you get from the phone. And that nobody has mentioned all the radiation we used to get from TV and radio sets. As I recall, the radiation you get from an old tube superhet set (from the IF) is much more intense than the radiation from WiFi. It is lower frequency, but then the skin effect is less, and as anybody who ever played about with NMR will recall, VHF does things to organic molecules.
We'd better take action now. Let's get rid of all that nasty radioactivity - oops, Madam, there goes your granite kitchen work surfaces and your low-sodium salt. And all the radiation sources beginning with the most intense. So we've now turned off the Sun, mobile phones, radio, TV, electrical generating. We can't use coal (have you looked at what you get in the ash). So we can just sit in the dark and freeze.
As for the leukaemia cases - I have long believed that a far more convincing explanation is exposure to farm chemicals, pesticides, and the new virus and bacterial strains resulting from population movement. It is possible that farming overspray with chemicals which have been subsequently banned is a more probable cause of leukaemia clusters than, say, living near a rural electrical supply line. In the UK, and probably in the US too, the parts of Government which deal with farming tend to be extremely secretive and their decisions are often hard to understand. To my mind, they are far more likely to suppress information about such things than the relatively open parts of Government which deal with non-farming health and safety.
Pining for the fjords
Actually, 2.45 GHz isn't the maximum of the absorbance for microwaves. If it was, all the energy would be dumped at the surface of food, and there would be virtually no penetration. Water absorbs over a broad spectral range, at least in the liquid phase, where quantised rotational bands can be ignored.
And what you say about the different energies of radiation is mostly true, although EM radiation covers a range that includes UV, x-rays and gamma radiation, which are not very good for you.
The frequency of wireless networks is well below that of light which is not dangerous. It only begins to become dangerous at around the frequency of UV radiation.
The only possibly danger (as with microwave ovens) is a heating effect, but the transmittors are far to weak and it would be relatively easy to prove if they were powerful enough.
Different parts of the EM-spectrum probe different aspects of molecules. (Visible light probes electronic structure, infrared light interacts with molecular vibrations, etc.) Even the radiofrequency range of the spectrum interacts with molecules in a chemically-specific way: microwave-region EM-radiation probes the rotational modes of molecules, and radiofrequency spectroscopy can also probe nuclear states (see NMR).
If I've misunderstood what you meant, please set me straight.
(By the way, I do agree that the energy from a WiFi signal will be absorbed by most common materials and lead to a barely noticeable increase in temperature. But that doesn't mean that the process is not chemical-specific. For instance, some materials will absorb more of the WiFi signal than others.)
Panorama isn't a "news" program, it's an investigative reporting program, which is quite different.
Towards the end of the program in question, they did start to admit more and more that there is absolutely no evidence or even much likelihood of harm from Wi-Fi, which was good although it was maybe too little, too late. My (and I think many others') main issue with the program was their over-use of the scare word "radiation" in a way that implied every Wi-Fi router is a mini unshielded nuclear reactor.
But, I've seen many far worse "this common piece of technology is going to kill us all" programs on TV and was really expecting it to be far more "scare story" like than it actually was.
7 real studies have been done.
5 5v1
The "electrosensitive" crackpots couldn't detect a mobile phone signal even after 50 minutes of continuous exposure.
http://www.bmj.com/cgi/eletters/bmj.38765.519850.
It could be psychosomatic, it could be some other mental or physical illness, but it isn't EM radiation that's making them ill.
GCHQ Quantum Insert installed. If only our tongues were made of glass, how much more careful we would be when we speak
This has been the way of the BBC for as long as anyone can remember.
There are two sides to every story. Exactly TWO. Two diametrically opposed sides. Never a third. Never just one. Always TWO. No shades of grey permitted. No announcing a discovery without finding a skeptic to denounce it.
If 99 scientists were to state that the sky is blue, the BBC would go out of their way to find some crackpot to claim the sky is actually red. And then give the two sides equal standing.
Worse, Panorama has never been held up even to the standards of the BBC, as they go after the tabloid illiterate crowd.
the AC
Hemos is like...sci-fi fans;he thinks technology is cool, but he hasn't bothered to understand the science it's based on
Oblig. citation...
/ Documents/bulletins/oet56/oet56e4.pdf
http://www.fcc.gov/Bureaus/Engineering_Technology
see page 15 for limits on acceptable uncontrolled exposure in the relevant frequency range (1 mW/ cm^2).
They did however mention that Sweden recognises electro-sensitivity as an official disability
The show's out of date then. There was a WSJ article last week or the week before that specifically discussed Sweden kicking so-called electro-sensitive people off disability.
Brain cells respond to EM in ways inherent in biological design. EM has been demonstrated to have all manner of effects upon the human body and nervous system. Acupuncture is one of the more obvious ones; (metal needle inserted and set to rotating cuts through the Earth's magnetic field and 'injects' a current into the patient. This affects how cells function. Pain responses can be turned off.)
Basically EM in a random noise makes the brain fuzz out and it makes people easier to manipulate. It makes them dozey and dumb.
-FL