BASIC THEORY FOR THE DIFFUSIVE SAMPLING OF RADON

From the closed-form solution of the Fickian equation describing the u ptake of radon by a diffusive sampler, the following are calculated: 1 ) the optimal estimate of the time-weighted average radon concentratio n; 2) the effect of the geometry of the diffusive sampler on performan ce; 3) the maximum sampling time consistent with a predetermined maxim um error in the estimated time-weighted average concentration of radon ; and 4) the effects of temperature and pressure on the performance of the sampler. It is shown that the maximum sampling error can be great ly reduced by dividing the adsorbent bed into two layers placed in ser ies and by using a weighted average of the uptakes on the two layers.