Measurements of dose rate and radon gas concentration in schools and kindergartens constructed with using coal-slag as building material

Coals mined in some regions of the Transdanubian Middle Mountains in Hungary have elevatedconcentrations of 226Ra. The slags and ashes derived from these coals have been used as buildingmaterial for schools and kindergartens. As the 226Ra reached up in these waste products of coal-firingsystems, the gamma dose contribution in the buildings, which contained them, was calculated. In theseplaces the absorbed gamma dose rate could be reach the sevenfold of the global average values 80nGy h-1- but the annual effective doses are lower than 1 mSv due to the relatively short time ofoccupancy even in the cases of highest level. The radon levels do not exceed the 102 Bq m-3 during theperiod when the people are in the rooms because of the frequent airing therefore, the assumed annualeffective dose derived from radon not exceed 0.4 mSv.