Salt therapy: Where's the evidence?

Today there was a Groupon offer for salt therapy from the "Salt Chalet Arizona."  Sufferers of respiratory illnesses are offered the chance to sit in a room containing salt for claimed relief of symptoms.  I posted the following at the Salt Chalet Arizona's blog, which is awaiting moderation:

“Although there have been few clinical studies” — are there any that provide any empirical support for the claims made on this site? It seems to me that solid empirical support for safety and efficacy are absolutely essential requirements for any medical claim. What is the mechanism of relief, is that relief more than would be expected from a placebo effect, does it last, and are there any harmful short or long term consequences?

To its credit, the blog's repost of a newspaper article about a similar service offered via a Pakistani salt mine includes the following skeptical passage:

But Shahid Abbas, a doctor who runs the private Allergy and Asthma Centre in Islamabad, said 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.