Fitting normal distributions of the observed thorium, radium, emanating radium, potassium and emanating power data for concrete and brick in Hungary

One half of the samples received at different times from all of the building material factories under investigation show normal, the other half show lognormal distribution (mixed distribution) of parameters at a confidence level of 0.05. By substituting the arithmetical means of each of the natural activities into formulae for simple models it was found that the radon and thoron activity is expected to increase by about 25% while the burden from external radiation to decrease by a factor of 2.3 in the new prefabricated concrete apartments as compared with the traditional apartments with brick walls and concrete ceiling. Reference level for the radiological grading of concrete and brick produced in Hungary is presented. (author)