Using radon measurements results at two small depths in local radon risk assessments

An important condition for protecting public health is radiation safety associated with natural sources of radiation. These sources primarily include the radioactive gas radon. Radon is emitted from soils lying in the building base and therefore poses a serious threat to the health of the population living on the lower floors. In this regard, in the design and construction of buildings, radon risks are assessed at building sites. In Europe the volumetric activity of radon (VA) in soil air is measured at depths of 0.8-1 m. The measurement results at such depths are considered constant, depth-independent VA-{\infty} values established as a result of equilibrium between the processes of radon formation (radium decay) and its decrease (diffusion). However, the thickness of the loose soil layer, in which radon flows emerging to the surface are formed, reaches 2-3 m. In addition, measurements are carried out at points located at distances of several meters from each other. For relatively large areas of development, carrying out such measurements is time-consuming, and for loose soils, measurements give an underestimated result. The research demonstrates the measurement results of VA-{1} (0.4 m) and VA-{2} (0.8 m), carried out by means of RRA-03 measuring complex, in dense loams at a depth of 1.5 m at the building base. The obtained VA results were used to calculate the VA-{\infty} values. The research shows that the VA-{\infty} values of homogeneous soils are described by the normal distribution and are agreement with the results of measuring VA in loams at depths of 8 m and 12 m.