By Esther Addley in London

Perhaps it's the impossibly long legs, the waspish waists, the perfect skin or just the fact that they dress so much better than everyone else, but supermodels seem like a different species from the rest of us. Even if they display their fallibility from time to time and are forced to chuck a sickie from the catwalk, their sniffles, we may assume, will be the ailments of the beautiful - anorexia, perhaps, or a spot of depression; a drug addiction at the very worst.

So when the Calvin Klein model Christy Turlington announced last week that she was suffering from emphysema, it was a shock akin to suggesting that pop singer Britney Spears had Alzheimer's or Prince William had developed gout. Because emphysema is emphatically not a disease of the beautiful. Miners get emphysema, or yellow-stained, elderly, too-old-to-stop-now smokers. Not exquisitely lovely 31-year- old women.

Turlington doesn't even smoke, having given up a 20-a-day habit five years ago. The bitterest irony is that she only discovered that she had the illness, albeit at an early stage, after signing up for an anti-smoking campaign which will see her appear in adverts for Britain's National Health Service this winter. The model has been an outspoken voice against cigarettes since her father died of lung cancer three years ago.

Certainly emphysema has precious little glamour about it. The disease is a chronic lung condition in which the millions of bubble- shaped alveoli that make up the spongy surface of the lungs become damaged, causing them to become floppy and less elastic. It becomes increasingly difficult to breathe. In severe cases, the alveoli trap air and are unable to expel it, meaning that the entire chest can become distended into a barrel shape.

"In essence the lungs get blown up like balloons," says Dr Mark Britton, chairman of the British Lung Foundation. "If you take a deep breath and hold it, and then imagine that you have to then breathe in and out up there, you can't actually breathe in very much. So to breathe is like running the 100 yards all the time."

Similarly, because the healthy surface area of the lung is reduced, oxygen exchange becomes less efficient, putting greater strain on the heart. People with emphysema are also more prone to bronchitis and chest infections. And while doctors can treat the symptoms and slow the progression of the disease, there is no cure. Cases of chronic obstructive pulmonary disease (COPD) - the umbrella term for emphysema and chronic bronchitis - slowly worsen over time, and frequently cause early death.

The open secret about emphysema is that it is almost entirely preventable. While a very small number of sufferers have an genetic deficiency which makes them particularly susceptible, almost everyone who has emphysema has acquired it through breathing harmful chemicals - which normally means smoking.

What is less well known, and more worrying, is that emphysema appears to be increasing, particularly among young women. Between 1990 and 1997, according to a study published earlier this year, cases of COPD shot up by a quarter among men and by a terrifying 69 per cent among women. "Women are smoking much younger, so we're probably going to see more young girls having emphysema," says Britton.

In a cruel twist, this makes Turlington a particularly apposite spokesperson for the disease. "When I started modelling I wanted to appear more grown up, and smoking easily did that for me," the model said last week. "By 16 I was on a pack a day. The frightening thing is, my smoking caused permanent damage. It seems so ironic - breathing is part of the process that sustains life; you breathe in cigarettes and they take your breath away."

Happily there is an easy way to slow the progress of the disease, and it is the boring one you expect: stop smoking. This is particularly important, stresses Britton, if anyone in your family has had lung disease.

"Lung disease is the Cinderella of health care," he says. "Everyone knows about cancer and heart disease, but we don't do terribly well talking about lung disease. But I am sure there are quite a few people out there with emphysema who don't know it. There is little doubt that there is more emphysema in younger people than we appreciate."

(From Guardian News)