No abstract available

[en] Anhydrous calcium sulfate has been identified for use as a desiccant in radon monitoring. However, the influence of a desiccant on radon measurements has not been investigated. Therefore, AlphaGUARD monitors working in flow and mode with and without a desiccant, and in diffusion mode as reference were used for radon measurements in the radon chamber at the National Institute of Radiological Sciences, Japan. The radon concentration in the air in the radon chamber was maintained at a constant level and measured at three levels of relative humidity: low, normal and high. Comparison of the results with the reference value showed that the differences were below 4%, which is within the acceptable range (below 10%). Consequently, when radon concentration was measured with the desiccant, we considered that the influence of the desiccant can be ignored. (author)