I know this thread is a couple years old, but the subject is still relevant. I'm also new to healingwell and just saw this discussion.
The principle underlying halotherapy dates to about 2500BC when records show the ancient Greeks and Chinese in particular recognized people who were exposed to concentrated salt environments had fewer respiratory issues. In the Middle Ages, European monks noticed that people who worked in salt mines not only had fewer respiratory conditions but people who suffered from some of them found relief after working in the mines. A Polish physician in 1843 was one of the first modern writers on the benefits of salt therapy and proposed it as a treatment mode. His colleague opened a sanitarium in a salt mine in Poland, which remains active today. In the middle 20th century, what we now consider modern science began to understand the methodology involved after studying people who took shelter in salt mines during World War II.
Today, people understand the mechanics far better and recognize the benefits of a concentrated salt environment for respiration. Because salt has bacteriocidal, anti-inflammatory and mucus relieving properties, inhaling it while sitting in a location with properly managed concentrations offers relief from a range of respiratory and skin conditions. One of the simplest descriptions is that inhaled salt has a toothbrush-like effect in clearing contaminants along the respiratory tract. As mucus and other substances are collected, they are either expelled by coughing or exhaling or by excretion through natural processes.
If you consider halotherapy, find a location that uses a halogenerator to disperse aerosolized salt. The salt on the walls, ceilings, and/or floors is almost purely decorative. Think of it this way; if it's not in the air, it's not getting in your lungs.
I hope this is helpful for someone.