RESUMEN
Human beings are constantly exposed to different radiations that have always been recognized as a health hazard. Radon-222 and its daughter products are major sources of natural radiations and a significant total inhalation dose is related to them. Hence, the measurement of radon activity in the environment has gained an increasing importance. In this study, with the measurement of radon concentration, the indoor radon activity level and radon effective dose rate in Jooshan hot spring were determined. Concentration of radon gas inside the pool of Jooshan hot spring was measured using the active detector Rad7 type and the annual effective dose was estimated for individuals inhaling the indoor air of this pool for a specified period of time. Concentration of indoor air radon gas was 98.3 +/- 4.9 Bq/m3 and for a person staying in the pool twice a week and each time for two hours, the annual effective dose rate, due to the inhalation of radon, equals to 0.06 +/- 0.003 mSv/y. Comparison of the obtained effective dose with the standards of Environmental protection Agency and Health physics Society, it can be concluded that for individuals that normally use Jooshan hot spring pool, the resulted dose is in the recommended range