Radon concentration in soil gas: a comparison of methods

Various methods to determine 222Rn concentration in soil gas were tested at two sites with different soil types in a depth of about 1 m. They included instantaneous (spot), continuous (real-time) and time-averaging procedures. The first test site had a porous soil with high gravel content. At this site, radon concentrations obtained with the different methods agreed within the error limits of the procedures. The other site exhibited a largely impermeable clay soil and at this site, the measured radon concentrations differed up to a factor of two depending on the method. The applicability of the various procedures in the field is discussed.