Effective Indoor Dose of Gamma Radiation from Building Materials: Comparison of Several Methods for Estimation and Possible Underestimate.

This paper compares several methods for estimation of the effective indoor dose of gamma radiation from building materials. It was found that specific dose ratios proposed for 3 cm thick layers in one recommendation gives 2.8 times lower value of gamma dose than other methods. The most common case is that granite has an elevated content of natural radionuclides and it is usually used in the form of decorative layers. If the decision about restricted or non-restricted use of granite as a building material is based on method which underestimate gamma dose, there is reasonable concern that materials having elevated concentrations of natural radionuclides than allowed will be used in dwellings. In addition, it is pointed out that existing regulations allow in some cases non-restricted use of building materials even in the case when their activity concentrations exceed exception limits.