Some schools are removing wi-fi networks after complaints from parents that their children suffer headaches. In what sounds like a re-run of mobile phone radiation panic, is there evidence for harm?
By Claire Heald
BBC News Magazine
Sitting too close to the TV. Standing in front of the microwave. Spending too long on the mobile. Living under a pylon, or next to a phone mast. We've always worried about what the technology around us might do to our bodies.
Now, wi-fi is rolling out from the humble coffee shop hotspot to create swathes of wireless networks in towns and cities.
But some are concerned that we don't know enough about the health effects of electromagnetic radiation - the radio waves that allow the computer network to transmit (along with longwave, FM and TV and phone frequencies).
For others, headaches and skin rashes - that they feel are due to the radio waves - are prompting a big switch off.
The worry for parents is that children, who have thinner skulls and developing systems, are exposed to more gadgets and gizmos than previous generations. What might these be doing to their bodies?
Health expert advice is to limit mobile phone use among young people as a precaution. The government advises users to keep calls short.
Engineer Anthony Wood, a father with two young children from Bristol, refuses to install a wi-fi network to link his family's three home computers.
"I don't like the idea of transmitting a microwave into your brain. The frequency is important, not just the power. The higher the frequency, the more energy there is in the waves. I think wi-fi waves are close to microwaves, yet they're on all the time.
"I see no evidence to suggest they could be harmful, but it takes an enormous amount of evidence to prove anything. I don't understand the medical side very well but I do understand the technical side - that of frequency and power. That's why I decided against installing a wireless network."
Teachers have also raised concerns. A staff member who develops shocking headaches after a day in the classroom may be a cliche. But this is what happened to Michael Bevington, a classics teacher at top independent school Stowe, in Buckinghamshire, after wi-fi was installed in his classroom.
"I had thought, 'great, we can make use of it'. But then I started getting a series of headaches that got worse over the next few days."
Pains in the joints, heart palpitations and nausea followed, and he could tell if the wi-fi transmitters were on or off.
Like a number of other schools, Stowe has turned off some of its transmitters. But Mr Bevington says he is now sensitive to other sources of electro-magnetic radiation, such as phones, microwaves and fluorescent lights. He also has problems with city centre hotspots and his neighbours' wi-fi networks.
"The amount of microwave radiation in society needs to be completely reviewed. It's making it impossible for a small number of people," he says.
Other than anecdotal, what is the evidence to suggest a risk? There is no scientific proof that wi-fi can cause harm. But there is also a lack of research.
Experimental psychologist Dr Stacy Eltiti, of the University of Essex, researches sensitivity to telephone masts. The 3G signal is transmitted at a frequency not far off that of wi-fi at about 2.4 gigahertz. Hence her results, due in 2007, may hold some clues to wi-fi sensitivity as well.
"Everyone is exposed to mobile phone masts," she says. "You can opt not to own a computer or a mobile phone, but you go into your local town centre and they're everywhere. If there are physical impacts, we can investigate what these are."
The current official advice is that exposure to wi-fi radio waves is comparatively low.
Wi-fi networks are rolling out apace
"In classrooms, a typical exposure is at 20 millionths of the guideline levels, whereas a mobile phone is 50% of guidelines," says Dr Michael Clark, science spokesman for the Health Protection Agency.
"Twenty minutes on a mobile phone call is equivalent to a year in that classroom. It's a completely different level of exposure. These are non-ionising radio waves. They're not X-rays, or gamma rays, or ultra violet. It's completely different in energy terms. I'm looking outside now and that's electromagnetic radiation - visible light. Radio energies are a million times less energetic than ultraviolet light."
But as people claim sensitivity to radio waves, he would welcome more research, given the rapid introduction of the new technology.
But currently, the more common concerns for users lie in wi-fi's cost, patchy coverage and network security.
As Peter Green, a senior lecturer at the University of Manchester says: "You wouldn't put your wi-fi right next to your bed, but I know more people who are turning it off because they are worried about security and other people hacking into their network."
Add your comments on this story, using the form below.
I think it's a load of scaremongering with uncertainties and coincidences. Denmark has completed the largest survey of mobile phones and cancer rates over 20 years with tens of thousands of people. And the findings - no significant measurable difference. Wi-fi uses much less powerful signals than mobile phones. Do the maths people.
Scott Andrews, Colwyn Bay, UK
I used to get intense headaches at work all the time. I attributed it to mobile phones at first, and had I heard of this scare I would have also suggested wi-fi. It turned out it was due to drinking any diet/light drink with sweetener!
Sam Hatoum, London
Whilst working in a school last year, I had similar symptoms to Michael Bevington but on a much larger scale. After months in observation in hospital and numerous tests, my symptoms were explained to be a serious muscular convergence insufficiency of the eyes and a diplopia. Apparently many people who suffer from migraines, or regular and severe headaches, may have these conditions but as opticians and doctors do not normally test for these conditions, most of the public are unaware of them. The pain of such headaches can increase if not dealt with and can be serious to the point that at times the patient nears unconsciousness. These headaches which arise from the conditions named above are often blamed on fluorescent lights and radiation.
David Pattle, London, UK
I'm currently sitting in a university library peppered with wi-fi transmitters. The university has some 17,000 students all of whom use the library at some point or another. I have yet to see or hear of anyone complaining of headaches when using the building.
Charles Levine, Glasgow, Scotland
If this was scaremongering and coincidences then why did all the major mobile phone distributors bring out a radiation protector to slot into the ear piece, obviously there is some sort of danger, put no one can prove just how much.
Damien McCourt, Belfast
Ten or 12 years ago people claimed to be suffering similar symptoms, the culprit then was the ozone emissions from laser printers. Nearly 30 years ago the major Bank I worked for was prepared to provide lead aprons(!) for their male employees concerned at being exposed to these new fangled computers. There appears to be a tipping point and when "new" technology becomes commonplace such health concerns seem to evaporate.
Anne Robins, Guildford, UK
The BBC may edit your comments and not all emails will be published. Your comments may be published on any BBC media worldwide.