Living animal species on earth have been exposed to environmental radon from the very beginning of time. The effects of radiation, combined with other natural parameters such as temperature, humidity, salt contents, etc., have most likely influenced the evaluation of different species. Thus, it is important to know and to evaluate the radon levels, among other radioactive elements present in enclosed environments such as caves (Gammage, 1990
Hunyadi et al, 1991), especially since those caves were also the dwellings and refuge of the predecessor of man. In this work we present radon level measurements inside some caves with vestiges of ancient inhabitats and some recently discovered natural caves, using Nuclear Track Detectors.