*Article* **Radon Activity Concentrations in Natural Hot Spring Water: Dose Assessment and Health Perspective**

**Eka Djatnika Nugraha 1,2, Masahiro Hosoda 2,3, June Mellawati 1, Untara Untara 1, Ilsa Rosianna 4, Yuki Tamakuma 2,3, Oumar Bobbo Modibo 2, Chutima Kranrod 3, Kusdiana Kusdiana <sup>1</sup> and Shinji Tokonami 3,\***


**Abstract:** The world community has long used natural hot springs for tourist and medicinal purposes. In Indonesia, the province of West Java, which is naturally surrounded by volcanoes, is the main destination for hot spring tourism. This paper is the first report on radon measurements in tourism natural hot spring water in Indonesia as part of radiation protection for public health. The purpose of this paper is to study the contribution of radon doses from natural hot spring water and thereby facilitate radiation protection for public health. A total of 18 water samples were measured with an electrostatic collection type radon monitor (RAD7, Durridge Co., USA). The concentration of radon in natural hot spring water samples in the West Java region, Indonesia ranges from 0.26 to 31 Bq L<sup>−</sup>1. An estimate of the annual effective dose in the natural hot spring water area ranges from 0.51 to 0.71 mSv with a mean of 0.60 mSv for workers. Meanwhile, the annual effective dose for the public ranges from 0.10 to 0.14 mSv with an average of 0.12 mSv. This value is within the range of the average committed effective dose from inhalation and terrestrial radiation for the general public, 1.7 mSv annually.

**Keywords:** radon; hot spring; dose assessment; public health
