Theory and practice of radon monitoring with charcoal adsorption.

Because of interest in charcoal adsorption as an inexpensive radon monitoring technique that may be suitable for mass data collection, the theory of radon adsorption from air by a charcoal bed is developed, giving numerical estimates at all stages. The method is practical down to air concentrations of about 0.1 pCi/l. A simple charcoal bed is limited by the fact that its response is highly sensitive to the time interval before termination of the exposure, but two simple methods of avoiding this problem are developed. Simple methods for determining the diffusion constant for the charcoal being used, and for optimizing the depth of the charcoal bed, are presented.