The aim of this study is to determine harmful radioactive gas(Rn^222)-concentrations in soils and to suggest the anormalous regions of Rn^222 -concentration in Taejeon area. The range of Rn^222 -concentration in the soils (45 samples) of the survey area is 100 to 2,475 (pCi/L) and mean±δ of those values is 489±05 (pCi/L).
The 2% (4 samples) of soil-gas samples (45 ones) collected in the survey area is corresponded to high risk level, 53% (24 samples) to medium one and 43% (19 samples) to low one. Especially, The Rn^222-concentration is relatively higher in schistose granite region than in other rock units (two-mica granite and biotite granite) in the survey area.
The Rn^222-concentration is propotional to the uranium contents in the soils. The soil hardness among the various factors is correlative with Rn^222-concentrations. To prevent the damage from Rn^222 -concentrations, it is necessary to close the cracks of underground structure and to consider methods reducing Rn222-concentration for the anormalous regions.

• 김승오(초당대학교 환경공학과) | Seung-Oh Kim (Dept. of Environmental Engineering, Chodang University)
• 김해경(광주교육대학교 과학교육과) | Hai-Gyoung Kim (Dept. of Science Education, Kwangju National University of Education)