[en] The measurements of ²²⁰Rn and its progeny concentrations are affected always by ²²²Rn and its progeny. Various types of measurement techniques of ²²⁰Rn and its progeny concentrations had been developed by using the differences between half lives of ²²²Rn and ²²⁰Rn and energies of α- and γ-radiations emitted from ²²²Rn and ²²⁰Rn progeny. Active ²²⁰Rn measurement techniques include the methods of ionization chamber, scintillation cell, two filter, liquid scintillation and activated charcoal. Decay, α-spectroscopy and integrating methods have used to measure ²²⁰Rn progeny concentrations collected on a filter. Passive monitors are suitable to survey mean ²²⁰Rn concentration in the living environment. Cup and activated charcoal monitors have been reported for the passive ²²⁰Rn methods. Calibrations of active and passive ²²⁰Rn monitors should be carried out in the calibration chambers with ²²⁰Rn source outside and inside, respectively. (author)