The materials derived from the earth crust (rock, earth) contain the natural radionuclides uranium (U-238), thorium (Th-232), their daughter radioisotopes, such as radium (Ra-226, daughter of U-238), as well as potassium (K-40). Consequently, the building materials contain natural radionuclides in concentrations that vary.

Depending on their type and their origin the concentrations of radioactivity in the building materials may vary from very low to high levels. International organizations (ICRP, IAEA) and the European Commission have issued recommendations regarding the use of these materials in construction of buildings, in order to ensure the radiation protection of the population. The recommendations are based on dosimetric assessments, taking into account adverse assumptions and scenarios for population exposure to gamma radiation because of these materials. Relevant provisions are included in the European Basic Safety Standards (EC Directive 2013/59/Euratom). 

According to the national Radiation Protection regulations (article 75 of the presidential decree 101/2018), the control of building materials is based on the determination of the activity concentration index I (Annex XIII of the presidential decree 101/2018), which is obtained from the following formula: 

I = C _Ra226 /300 Bq/kg + C _Th232 /200 Bq/kg + C _K40 /3000 Bq/kg

I = C _Ra226 /300 Bq/kg + C _Th232 /200 Bq/kg + C _K40 /3000 Bq/kg, όπου C _Ra226, C _Th232 και C _K40 are the activity concentrations in Bq / kg of the respective radionuclides in the building material.

The activity concentration index can be used as a conservative screening tool for identifying materials that may cause the reference level of 1 mSv per year from external exposure to gamma radiation emitted by building materials to be exceeded (definition and guidance on the use of the index I are given in Annex VIII of the presidential decree 101/2018). 

ΕΕΑΕ has issued a recommendation (relevant Decision was made during the 266th ΕΕΑΕ Board meeting on the 20th of December 2019) about the indoors use of building materials as defined in Annex ΧΙΙΙ of the presidential decree 101/2018 (Indicative list of types of building materials considered with regard to their emitted gamma radiation). The recommendation was based on the guidelines given in the document "Radiological Protection Principles concerning the Natural Radioactivity of Building Materials", RP 112, 1999, published by the European Commission. EEAE informs the Ministry of Environment and Energy about this recommendation, in line with the provisions of par. 3, art. 75 of the presidential decree 101/2018.

Click to see the relevant ΕΕΑΕ recommendation (available only in Greek language).