Allergic to modern living, they live off organic foods and shun shopping centres and traffic junctions through fear of becomingly seriously ill.
Take Gillian McCarthy. She has been reduced to living in a tent, 300 yards from the sea, off the coast of Dorset.
A former biochemist, she lives in fear of reactions to perfumes, petrol fumes and even tap water.
Ms McCarthy is a victim of multiple chemical sensitivity (MCS). Until now, she and fellow sufferers have struggled to persuade the authorities that their condition exists other than in their imagination.
But now, in a major breakthrough, the Department of Health and the Health and Safety Executive have ordered a major inquiry into the causes of the syndrome.
The Independent has learned that health officials are increasingly worried about the number of people who attribute their psychological and physical symptoms to exposure to everyday chemicals.
The decision is also a breakthrough for sick Gulf veterans with symptoms similar to MCS, but whose condition the Ministry of Defence does not recognise.
The inquiry, which will be conducted by scientists at the independent Institute of Occupational Medicine in Edinburgh, will take at least six months.
Their first task will be to establish what MCS is. The condition, also known as Chronic Fatigue Syndrome and Total Allergy Syndrome, is characterised by memory loss, fatigue, depression, nausea and breathing difficulties.
Victims usually report that they were exposed to one chemical and then reacted to contact with even the smallest amounts of other chemicals, often found in everyday products. The HSE has meetings with anti-pesticide campaigners, many of whom suffer from MCS.
Emfys Chapman set up the Pesticide Exposure Group of Sufferers (PEGS) in 1988. It now has 8,000 members. She said MCS sufferers were forced to avoid trains because of diesel fumes, roads because of exhaust fumes and even gas appliances.
"A lot of people give up a real life because it becomes too difficult to walk a tightrope all the time."
Mrs Chapman set up PEGS after she suffered a serious allergic reaction to pesticides which were inadvertently sprayed on her farm from the air. She now has extreme reactions to other chemicals and has only 5 per cent muscle power in her left side.
Mrs Chapman, 68, also has defective liver, heart and lungs and has been hospitalised 12 times after accidental exposure to other chemicals: "I have to live a very careful lifestyle."
She cannot eat carrots or lettuce for fear they have been sprayed with organophosphate pesticides and she tries to live off organic vegetables.
Margaret Reichlin, a former head of art at Burlington Danes school, in London, was reduced to living in a shed following an extreme allergic reaction to chemicals used to treat woodworm in her Hampshire cottage.
The exposure left her with a lasting reaction to even small amounts of phenols and chlorines, both of which are extremely common.
She is afraid even to drink tea, because it contains a natural phenol. She has moved back into her home after spending pounds 26,000 to remove all trace of the chemicals.
"It changes your life," she said. "All the things that other people take for granted, you cannot use: household cleaners, make-ups, paints."
Trying to win compensation for the victims has been difficult. Alan Care, a lawyer with the London law firm Leigh, Day & Co, said a claim could only be successful if the victim could identify the initial chemical exposure and prove negligence.
"You cannot sue the whole world's industries," he said. "This is a genuine problem that clients have, but they have got to be able to identify the initiating event."
MCS victims have been compared to canaries sent down mineshafts to test for poison gases, he said: "These people are like the canaries testing the pollutants in the atmosphere for the rest of us."
Treatment of MCS also presents problems, though several people claim to have held their condition in check by using complementary medicine.
Dr Julian Jessel-Kenyon, of the Centre for the Study of Complementary Medicine, in Southampton, said he gave them intravenous minerals and vitamins and asked them to fast, or follow an organic diet, in order to rid the body of toxins.Reuse content