Radon-222 concentrations and the environmental radiation dose rates at Misasa spa districts, Japan

We have been carrying out continuously the measurements of Rn-222 concentrations in air with a set of indoors and outdoors using the convenient and highly sensitive Pico-rad detectors with active carbon adsorber for several years at Misasa spa districts. Rn-222 concentrations in air on geologically formed granite layers were higher than those basaltic layers. And the mean γ radiation dose rates at Misasa spa districts measured by means of optically stimulated luminescence (OSL) dosemeters for 3 months, they showed the similar tendency to those of Rn-222 on geological map.