The variation of the adsorbed radon rate during the exposure time using charcoal canister was studied applying moving air environment inside the radon chamber and compared to the static air measurements. The air movement increases the accumulation time leading to more accurate results. Different types of membrane have been tested as diffusion barrier for activated charcoal canisters. The Makrofol and aluminized polycar bonate improve the adsorption/desorption rate more than the polyethylene

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... rane. The measured effec tive half-life time showed a remarkable correlation with the previously measured permeability constant for corresponding membranes. Different types of commercially available charcoal were investigated to develop a local version of charcoal canister for radon measurements. Applying static and moving air environments, the break point and radon collection efficiency were determined at different temperatures. Both of the tempera ture and air movement accelerate the appearance of the break point. The efficiency of the locally developed charcoal is 87% and 84.5% of that Calgon PCB charcoal used by EPA.