Nonetheless, salt therapy, also known as halotherapy, a venerable treatment in Central Europe and Asia, is now being offered at spas, resorts and stand-alone facilities in the United States in the form of salt beds, salt rooms and salt booths. Floors and walls that are lined with salt blocks and salt crystals, and zero-gravity chairs (recliners designed to relax the back), are the norm. A device known as a halogenerator grinds sodium chloride into a dry aerosol, then disperses it to mimic the microclimate of a salt cave.
Perhaps unsurprisingly, salt spas seem to be sprouting in pockets of the United States that attract the rich. For example, at the Montauk Salt Cave, which opened two years ago in the Hamptons, a session costs $40 for adults. There’s a children’s hour ($40 per child, but adult guardians may enter free) as well as yoga classes and reiki healing amid the Himalayan salt. At the Wellery, a pop-up “wellness center” at Saks Fifth Avenue in Manhattan, weary shoppers can refresh themselves in one of several salt booths (10 minutes for $25) until the end of October.
“The ability to look at salt and see its helpful properties has become a significant part of our business,” said Allan Share, the president of the Spa Industry Association.
In 2012, there were a dozen halotherapy facilities — places with halogenerators — in North America, according to Leo M. Tonkin, the founder and chief executive of Salt Chamber, a supplier of dry salt therapy equipment, based in Boca Raton, Fla.
“In the last four years, the number has grown to 300 salt chambers,” said Mr. Tonkin, who is also the founder of the Salt Therapy Association, a trade group. “There’s been a rapid growth in stand-alone salt facilities and…