Accurate measurement of unattached radon progeny is important for dose evaluation of radon exposure. For quality control of field surveys, a series of comparison measurements were carried out using three commercial unattached radon progeny monitors in real environments as well as in a radon chamber. The results show that the radon equilibrium equivalent concentrations (EECs) of different monitors agree very well, mostly within +/- 3.0% where there is no thoron progeny interference in the radon chamber. However, the unattached fraction of radon progeny is not so consistent, and the relative dif...
