Radon in the dry carbon dioxide spa of Mátraderecske, Hungary

The fi nal product of a post-volcanic activity is the exhalation of a low-temperature (<100°C) deep origin mofette gas, which contains mostly carbon dioxide. Examples of mofettes are the Torjai-Büdös cave in Transylvania, Romania [1] or the CO2 seepage in Mátraderecske, Hungary [2]. The term ‘mofette’ derives from the Latin word ‘mephitis,’ which means smelly exhalation [3]. Along its path to the surface, the deep origin gas also intakes different radon isotopes from the rocks and soils. Therefore, the variation of surface radon exhalation can be a tracer of spots of CO2 outgassing. Mofettes are often used for therapeutic treatments in the form of dry CO2 spas, where the risks associated with radon exposures should also be a concern. Carbon dioxide bath has a several-century tradition in countries where gas discharges were found, even the ancient Romans knew this treatment. The curative gas is applicable for treating cardiac and peripheral artery diseases (arteriosclerosis in the lower limbs, coronary diseases), high blood pressure, arterial complications in diabetics, postoperative treatment following arterial surgeries. The human body reacts to the absorbed gas in a way that the blood vessels in the skin become dilated, the capillary circulation is intensifi ed, the speed of blood fl ow is increased (e.g. the circulatory performance is increased) and the oxygen supply provided to the Radon in the dry carbon dioxide spa of Mátraderecske, Hungary Erzsébet Sóki, István Csige