It takes me seven phone calls and five attempts on Skype before I manage to hold a conversation with Phil Inkley. When I visit him a week later I see that the wire from his laptop dangles precariously through his caravan window and over a few metres of wet woodland to a dongle concealed in a box in the far corner of the land. Sometimes it works.

After our conversations are repeatedly abandoned because of interference and delays, Phil cycles six miles to the nearest phone box. It is out of order. The next box contains no phone. Phil texts from a mobile phone he seldom dares to use to tell me the situation and adds: "You can see I'm not just physically isolated from people, it's very difficult to speak to them remotely too."

For Phil, it is this isolation which is one of the most difficult aspects of suffering from self-diagnosed electromagnetic hypersensitivity (EHS). Daily symptoms include nosebleeds, headaches, heart palpitations, lethargy and tinnitus. Electro-hypersensitive people attribute such symptoms to electromagnetic fields (EMFs) such as those emitted by Wi-Fi, mobile phones, DECT phones and certain light sources, and say symptoms worsen with close proximity.

Phil's illness is totally dominating his life. He now lives in a caravan in the woods in Hampshire in an attempt to distance himself from EMFs. He is constantly worried that he will be asked to move on. When symptoms have been really bad he has retreated further into the forest, at one point living in an abandoned children's den and cooking on an open fire.

"I've been through hellishly desperate times with this," he says. "People don't believe that EMFs are the cause of EHS and it gets you in such a state. You're battling for your existence and people think it's all in your head." He breaks down in tears, not for the last time during our interview. The strain of his situation is taking its toll.

Solitary as Phil's suffering seems, he is not alone. Estimates of the prevalence of EHS in the developed world vary, but most surveys indicate somewhere between 2% and 5%. The best-known sufferer is Dr Gro Harlem Brundtland, the former prime minister of Norway, medical doctor and former director general of the World Health Organisation. She brought EHS into the mainstream when she said she was sensitive to radio waves from mobile phones in 2002. She was accused by some of scaremongering, and there is debate over whether she jumped or was pushed from the WHO. Either way, to the consternation of campaign groups, she has now gone quiet on the subject.

Phil says he first experienced symptoms around the time that Wi-Fi came along. He had been working as a sound technician and, being from a "techy" background, regularly fixed computers for family and friends. After a day working around strong Wi-Fi he would feel pressure at his temples and fluttering pains in his chest.

It was when he encountered the very same symptoms tuning in a hands-free phone kit for his dad that he began searching for an explanation. "I looked online at some reports about EHS from independent scientists. I didn't like what I was reading so tried to leave it [EMFs] alone," he says.

While EHS is not very well understood, the probability of any serious health risks from EMFs have been widely rebutted by the WHO, national radiation authorities, the mobile phone industry and the majority of researchers.

There have been a number of studies testing the role of EMFs in causing EHS. Sufferers were exposed to EMFs similar to those that they attributed to the cause of their symptoms under single- or double-blind conditions. Most of these studies indicated that EHS individuals could not detect EMF exposure any more accurately than non-EHS individuals. A 2005 review of 31 of the experiments stated that EHS is unrelated to the presence of EMFs, but said that more research was required.

Some researchers have postulated that one possibility for the results is that subjects expected a negative effect and so experienced one, and that this can be expanded to explain why EHS sufferers feel symptoms when near to EMFs more generally. Another theory is that there are some other physical causes such as flickering lights or problems with visual display units (VDUs).

However, the methodology and analysis of the studies have been questioned by EHS sufferers, campaigners and some scientists. There have been claims that the studies were influenced by the huge political and financial implications of a link being found, a view backed by Prof Andrew Marino at Louisiana State University, whose own research does suggest links between mobile phone radiation and illness. He criticised the studies, saying they were sponsored by the communications companies Telenor and NetCom. Researchers have denied they were influenced in any way.

Phil is in firm agreement with those who believe that politics are at play. When I express doubt over the conspiracy theories, he reminds me that the tobacco industry managed to cover up the dangers of smoking for 40 years with apparent backing from the establishment.

He also compares current feelings about EHS to those about ME and Gulf war syndrome in the past - illnesses that were said not to really exist or be purely psychological and that, while still not fully understood, are now taken much more seriously.

I ask him if he has considered that his symptoms could have a psychological cause.

"I wanted to believe I was going mad. It would have been easier," he says. "But I knew I wasn't. I hoped for a while that the gas boiler was leaking carbon monoxide and giving me headaches and that I was imagining the rest. But it wasn't."

After Phil's illness started to worsen to include convulsions and blackouts he began to ask for help, but does not feel he has received any.

"I was getting really scared about what was happening to me but I thought, 'This is England. I'll just get in touch with the authorities and explain and they'll sort it out.' That's how naive I was."

Phil's GP simply informed him that there was no convincing evidence that electromagnetic radiation has any detrimental health effects. He then contacted the Health Protection Agency, leaving several messages, but no one ever got back to him - until he received a voicemail telling him not to call again.

In 2005 the HPA reported that considering only whether electromagnetic radiation was a causative factor was not meeting the needs of sufferers, although continued research in this area was essential. Whatever the cause, EHS symptoms are real and they can be severe and extremely disabling. Sufferers are not getting the support they need.

Phil describes his condition as "living in a nuclear war". He asks: "Can you imagine what it's like when your environment becomes so aggressive to your health?" His voice trembles and he looks desperate.

Phil could certainly do with moral support and financial help to stop him slipping further towards the edge of society. But what he really wants is for people to believe he is right about the causes of EHS. He'd like more independent studies to be undertaken and seriously considered.

It is not clear whether more studies will be conducted in the near future. It's even less clear that they will ever yield the results he is looking for.