They r usually part of healing centers. Typically u spend around 1 hour in there. Room full of salt and in addition they pump salt dust through vents during the time.
Also sometimes you will have guided meditations or just regular meditations in the room during the time. For instance we had someone with singing bowls and tuning forks for a session.
From their website:
Halotherapy is a non-invasive treatment that allows the body to utilize aerosolized salt as a method of natural healing. At ..., you are surrounded by thousands of pounds of pink Himalayan salt on the walls and floor, in an environment that recreates the microclimate of naturally occurring subterranean salt caves (speleotherapy). Our generator crushes additional salt into micron sized particles and disperses it throughout the salt cave air. As clients relax during their 45-minute session, the air in the cave is closely monitored to maintain a precise concentration of aerosolized salt, keeping it in a therapeutic range. Breathing in the micron-sized salt particles stimulates an anti-inflammatory response, reducing irritated airways and thinning mucus in the bronchial tubes and lungs. As such, salt cave therapy is beneficial for those suffering with asthma, allergy-related symptoms, bronchitis, COPD and the common cold.
The dry salt aerosol environment in the cave is also beneficial for your skin. The anti-inflammatory properties of the salt can reduce the redness, swelling and irritation, often associated with eczema, psoriasis and acne.
In addition to being antibacterial, antiviral and antifungal, halotherapy also provides one other key benefit – stress reduction. As you relax in the unique and peaceful environment of our salt cave, you will likely experience a sense of calm and well-being.