Experts including Asthma UK are backing the treatment, called Halotherapy.
Salt therapy claims to work by clearing the airways of mucus and reducing inflammation triggered by allergies to dust, pollen or pollution.
These particles, invisible to the naked eye, penetrate deep into the respiratory system. Minerals including potassium and magnesium are said to help reduce inflammation and clean out mucus blocking the airways.
Experts have already found that asthmatics can breathe easier if they are sent down salt mines.
A Finnish study found that sufferers' lungs were less likely to show allergic "hyper-responsiveness" to their environment