Goemans P, de Waard IR, Blaauboer RO, Smetsers RCGM, de Groot GM
RIVM Report 2018-0027
Radon concentrations are low at almost all workplaces and public buildings in the Netherlands. The average radon concentration in workplaces and public buildings within this study is 15,9 Bq/m3 (Becquerel per cubic metre). The average radon concentration in buildings worldwide is around 40 Bq/m3. The radon concentrations exceeded 300 Bq/m3 only in a very few specific cases in this study, such as groundwater treatment stations at water companies, and underground rooms such as caves. As seen in dwellings, the radon concentrations are slightly higher in workplaces and public buildings in the southern part of Limburg and the Meuse-Rhine-Waal river delta. This is due to elevated concentrations of natural radionuclides in the soil.
This was shown by a survey carried out by the RIVM at several hundred workplaces and public buildings in the Netherlands in the period 2016-2017. The reason for this survey was the European obligation to establish national reference levels for both radon in workplaces and radon in public buildings. On 6 February 2018 the Dutch government adopted national radon reference levels of 100 Bq/m3 in the Dutch Decree on Basic Safety Standards Radiation Protection (Bbs). In exceptional cases, the Minister can establish a higher reference level, of up to 300 Bq/m3.
Within this survey, measurements are carried out on radon as well as thoron progeny and gamma radiation. They both contribute, along with radon, to exposure from natural radionuclides in buildings. The results of the current thoron progeny measurements in Dutch workplaces and public buildings are in line with values that, according to international organisations, are to be expected in buildings. The gamma radiation measurements are comparable with those of studies carried out earlier in the Netherlands and are relatively favourable.
Radon and thoron are naturally occurring radioactive noble gasses, which are formed in soil and building materials made from soil. Indoor radon levels in the building arise partly from exhalation of radon from the soil and partly by exhalation of radon from building materials. Thoron in buildings originates from the inner building shell and specifically some applied finishing materials on walls and ceilings. Inhalation of non-gaseous radioactive decay products of radon and thoron contributes to the induction of lung cancer, particularly in smokers.
This study was commissioned by the Ministry of Social Affairs and Employment (SZW) and the Authority for Nuclear Safety and Radiation Protection (ANVS).