A centuries-old salt mine in Pakistan is offering experimental asthma therapy, attracting patients from all over the world.
Khewra, billed as the world's second largest salt mine, has for centuries extracted the crucial mineral for export and has become a tourist attraction complete with a salt mosque and an electric train.
Now, the mine is cashing in on salt therapy, already a draw in the salt mines of eastern Europe and a synthetic clinic in Britain.
Clinics claim that asthma patients and sufferers of other respiratory illnesses benefit from inhaling antibacterial salt particles in a sterile environment, helping loosen mucus and clear the lung passages.
"We don't use any medicine, because the asthmatic allergy patients recover through the air, so we provide them an environment in which their breathing can improve," said Akhlaq Bukhari, head doctor at the Khewra clinic.
Although there have been few clinical studies, salt caves are seen by some as a therapeutic alternative to drugs and there are natural and synthetic salt caves springing up all over the world.
While other clinics offer treatment for bronchitis, cystic fibrosis, and even ear infections, Shah says the Khewra clinic only treats patients whose asthma is triggered by allergies.
"I have come here all the way from Canada. I could not recover there through medicine, but I am feeling better since my arrival here," said Naeem Shamsher, a civil engineer from Canada.
Shamsher had tried medicine doled out by doctors back home but felt little relief and struggled to walk far without becoming breathless, so relatives in Pakistan suggested he visit the Khewra Mines.
"Now I can run and even play soccer just after spending three days in the mine," said Shamsher, who says he feels 60 percent better after the treatment.
The mine, located 160 kilometres (100 miles) south of Pakistan's capital Islamabad, was discovered in 320 BC by Alexander's troops and first developed by British colonial rulers in 1872, mine officials say.
Located deep underground in the mine, the asthma clinic resembles an upmarket guesthouse, with 12 beds covered in white sheets and red blankets in six independent cabins separated with salt bricks and softly lit by lamps.
There is a reception area decorated with salt lamps and a lounge complete with a fountain, sofas and a television set.
The walls and roof of the clinic are made from pure salt and a fan helps maintain the temperature and humidity, creating the so-called "micro-climate" that offers patients relief, Shah says.
A 10-day course at the Khewra Mines salt therapy centre costs 5,300 rupees (62 dollars), with 11 hours a day spent in the caves while nights are spent in a nearby hospital.
Since opening in 2007, the clinic has treated about 500 patients. Shah claims that 60 percent of patients experience some relief from their symptoms and says patients have come from as far as Britain and Saudi Arabia.
But Shahid Abbas, a doctor who runs the private Allergy and Asthma Centre in Islamabad, told AFP that although an asthma or allergy sufferer may get temporary relief, there is no quick-fix cure.
"There is no scientific proof that a person can permanently get rid of asthma by breathing in a salt mine or in a particular environment," he said.
Khaled Sajjad Khokhar, managing director of the Pakistan Mineral Development Corporation, a government body which owns the mine, says they will assess the success of the Khewra clinic before approving its expansion to 100 beds.
But some patients are returning, happy to get even temporary relief.
"This hospital is a blessing, it gave me a second life. I never had problems breathing after spending 10 days over there in 2007," said Pakistani patient Adnan Khan, on his second visit to the clinic.