Dose rates of environmental radiation were determined with NaI (Tl) cristal scintillation survey meter at Misasa, Sekigane and Ikeda spa areas which were known as radioactive spring in the Sanin districts. The results were as follows ; (1) Dose rates of radiation in the air of outdoor at spa areas of Misasa, Sekigane and Ikeda were
11.8±2.3μR/h, 11.3±2.1μR/h and 18.4±5.8μR/h, respectively. Dose rates of radiation in the air of these spa areas were significantly higher (P<0.01) than at none spa area of Kurayoshi city (8.6±1.2μR/h). Dose rates of radiation in the outdoor air at Misasa and Sekigane tends to increase near the spring sources. (2) In the room where spring water is not used, dose rates of radiation in the air were 9.5～10.5μR/h. Dose rates of radiation in the air of the room with facilities using spring water were determined; peloid therapy room: 13.3±0.5μR/h, Hubbard
bath room : 12.5±0.4μR/h, drinking hall : 11.8±0.7μR/h, hot air bathing room : 18.2±1.7μR/h, usual bath room (Onkensen) : 13.0±1.0μR/h and bath room for patients : 17.9±1.2μR/h (males), 17.0±1.2μR/h (females), respectively. Dose rates of radiation in the air of the bath room of Gunze-hotel and Ohashi-hotel-Gankutsunoyu
were 30.1±9.0μR/h and22.3±3.0μR/h, respectively. At Ikeda spa, dose rates of radiation in the air of the guest room and the bath room were range of 13.0～19.0μR/h and 14.0～23.0μR/h.