Experiences of radiological examinations of buildings in Hungary.

Natural radioisotopes occur everywhere in the environment, being a source of exposure to the general population. Everyone is continuously exposed to terrestrial and cosmic radiations both indoors and outdoors, which are the main contributors to external exposure of individuals. There were made many ambient dose rate and indoor gamma radiation and radon concentration measurements in Hungarian by different laboratories. The main goal of the present work is the summarisation and evaluation of the latest results of the Laboratory of National Public Health Center National Research Directorate for Radiobiology and Radiohygiene. The reviewed examinations were made between 1995 and 2016. The average ambient dose rate was 103 ± 17 nSv/h and the average indoor gamma dose rate was 155 ± 47 nSv/h based on the data of 382 and 581 sampling points, respectively. The average indoor radon concentration was 108 Bq/m(3) with the median value of 75 Bq/m(3) based on the data of 415 sampling points. We performed an additional analysis of the results of 233 personal surveyed buildings where sophisticated gamma radiation and/or indoor radon concentration measurements were made. We were also interested in has got any affect the presence of slag to the radiation levels of the buildings? We found that usually elevated radiation can be detected in houses which contain slag compared to buildings without slag. In addition we conclude that the recommended minimum duration of short-term radon measurement shall be at least three days even if it does by closed conditions.