This is what Artificial Intelligence on my Edge Browser had to say about it, which gives a little more info worth considering.

Halotherapy, also known as salt therapy, involves breathing in air with tiny salt particles to improve breathing. It is considered an alternative treatment for lung problems such as asthma, bronchitis, and cough 1. The salt used in halotherapy is pure grade sodium chloride, also known as medical-grade or pharmaceutical-grade salt, which is the highest purity salt, often used in medical applications. It is 99.99% NaCl and contains no insoluble ingredients and is free from all other contaminants 2.

Table salt, on the other hand, is a mixture of sodium and chloride ions, often with added iodine and anti-caking agents 3. The purity of table salt is lower than that of medical-grade salt, and it may contain other additives that are not present in medical-grade salt 3.

In summary, the salts used in halotherapy are different from table salt in terms of purity and composition 2.

I think that it is probably best to do a lot of research, as I am doing, and to talk to one's doctor before deciding to try it. I do have high blood pressure also, so I can understand the concern that some people have! At the same time, it does seem to offer hope for improvement, and it has an interesting history as to how it came about and how it became a treatment for different ailments, including COPD.