Up to the waist in gases
A long time ago, after dangling their legs off the edge of a cavity, someone noticed that the injuries on their feet were beginning to heal. The answer lies in carbon dioxide. As a post-volcanic feature, gases are found flowing from certain spots in the world, which have a therapeutic effect in the bloodstream when inhaled or absorbed through the skin. Naturally, there’s no need to dangle your legs over a cliff, but rather the gas is administered as a treatment in a controlled environment.
In the Northern Hungarian village of Mátraderecske, medicinal gases with a high carbon dioxide content erupt from a depth of approximately 1,000 metres, recommended for heart and circulatory rehabilitation and also recommended due to its high concentration of radon for arterial diseases and peripheral artery disease tied to diabetes.