Airborne Radon-222 Measurement by Active Sampling with Charcoal Adsorption and Gamma-Ray Spectrometry.

A simple method for measuring radon concentration in air is presented. Airborne radon is adsorbed in a charcoal bed by an active air sampling. In time, the adsorbed radon comes to attain radioactive equilibrium with its short-lived progeny Pb-214. Utilizing this fact, radon concentration is derived from gamma-ray measurement of Pb-214. This method is estimated to be capable of detecting radon concentration in air down to 0.79 Bq.m(-3). The adsorption coefficient obtained with the method is compared with what is obtainable with passive sampling. Applications of this method to indoor and outdoor radon measurements are described.