The existing radon and radon progeny measurement instruments are described in this article. The various methods and instruments used depend on whether radon or radon/thoron progeny or daughter products are being measured, the duration of the measurement, whether short‐term or long‐term and the type of radiation being detected (alpha, beta, or gamma). The modes of detection used include the following: activated charcoal radon monitors, electret ion chamber, registration of nuclear tracks in solid‐state materials, liquid scintillation, ionization chambers, scintillation detectors with zinc sulfide, ZnS(Ag), alpha particle spectrometers with silicon diodes, surface barrier or diffused junction detectors, and gamma‐ray spectrometry with NaI(Tl) scintillation crystals or germanium lithium (GeLi) semiconductor detectors, fiber optics sensors and glass. The advantages and disadvantages will be described for various portable instruments used for measuring radon, thoron, and their daughter products. Comparison studies among the radon monitors will be included.
The reader is referred in particular to George
1
and National Council on Radiation Protection (NCRP) Report 97
2
for additional information.