Background: Human exposure to Radon-222 gas is one of the most important natural radiation sources of radioactive gases, and inhalation of this gas and its decay products can cause lung cancer. Therefore, this study was conducted to measure Rn-222 concentration and determine annual effective dose of radon inhalation in the vicinity of hot springs in Kerman province, southeastern Iran. Materials and Methods: This study was carried out on 16 hot springs of Kerman province. Concentration of Rn-222 was measured using RAD-7 electronic system. Also, annual effective dose amounts of inhalation were estimated according to the formula provided by UNSCEAR (2000). Results: Minimum and maximum amounts of Rn-222 concentration in the samples were equal to 0.158±0.129 and 56.100±5.680 Bql-1, respectively. Annual effective dose amounts of inhalation were determined between 0.000±0.000 to 0.177±0.017 mSvy-1. Concentration of radon was more than 11 Bql-1 (the safe limit set by the EPA) in 5 samples collected from hot springs. Annual effective dose of inhalation of radon was more than 0.1 mSvy-1 (the safe limit set by the WHO) in Jooshan hot spring. Conclusion: By comparing concentration amounts of the samples with the EPA safe limit, it was concluded that, 11 hot springs were safe. Also, annual effective dose amounts of inhalation of all hot springs, except one of them were lower than the safe limit set by WHO.

Background: Natural and artificial radioactive materials are the most important sources of radiation for human existing in all over the world, thus investigating their radioactivity is of great importance because of their ionizing properties and harmful effects on human health. Therefore, this study was conducted to measure radionuclides concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in sediment samples collected from various hot springs in Kerman province and also determining received annual effective dose. Materials and Methods: Thirteen sediment samples were collected from different hot springs and concentrations of radionuclides in sediment samples were measured via spectrometry method and using HPGe detector. To evaluate radiation hazards caused by these radionuclides, radium equivalent activity, absorbed dose rate in air, and annual effective dose of samples were calculated. Results: Concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in sediment samples varied from 21.01±0.71 to 193.16±1.72, 16.84±1.21 to 245.92±2.69, 90.13±3.37 to 667.81±14.59 and <MDA to 5.81±0.66 Bqkg^-1, respectively. Also, minimum and maximum values of annual effective dose were determined as 0.17±0.00 and 1.48±0.01 in mSvy^-1, respectively. Conclusion: Comparison of radionuclides concentrations and annual effective dose obtained in this study with the worlds̓ average values determined by UNSCEAR (2000) reports showed that concentrations of ²²⁶Ra and ²³²Th in 69% and concentration of ⁴⁰K in 46% of measured samples were higher than the worlds̓ average values. Also, annual effective dose of 30% of samples was found to be higher than the worlds̓ average value.