Authors:E. Tóth, F. Deák, Cs. Gyurkócza, Zs. Kasztovszky, R. Kuczi, G. Marx, B. Nagy, S. Oberstedt, L. Sajó-Bohus, Cs. Sükösd, G. Tóth, and N. Vajda
For the public, indoor radon is the main source of exposure from ionizing radiation. Radon gas originates from the radioactive decay chain of uranium deposited in rocks or in building materials. In the reviews mostly a rather steady radon exhalation has been assumed. In a village of North-East Hungary, however, high radon concentrations have been measured, differing strongly in neighbouring houses and varying in time, due to the interplay of several geochemical phenomena.