Radon concentrations in housing, 1930-2000

Radon levels in housing

The radon levels in housing built after 1980 are on average 50% higher than in housing built before 1970. The increase in radon levels indoors is caused by the fact that more radon is released by the building materials now used and by the fact that newly built homes are better insulated than they used to be. As a result, ventilation in homes has worsened.
Thirty per cent of the average total radiation dose consists of the inert gases radon (222Rn) and thoron (220Rn). Thoron, another isotope of radon, contributes approximately one tenth of this dose. Radon, a radioactive inert gas, arises from radium and is emitted naturally from soil and building materials. It can exhale from the soil and building material and accumulate indoors to a greater or lesser degree depending on the ventilation. The building materials themselves also produce radiation because of their natural radioactive content.

Policy

In the past, central government has declared its intention to maintain the average radon levels indoors at the 1994 level. The concrete result of this policy has been the development of the Radiation Performance Standard (SPN). In the case of new buildings, this includes a maximum for the exposure of the inhabitants to radiation generated by the building materials used and to radon levels. This means that the doses generated by the inhalation of radon decay products and external exposure to radioactivity in building materials are combined. The intention is to include the standard in the Building Decree.

Relevance

Inhabitants may receive a radiation dose as a result of the inhalation of radon and, in particular, the equally radioactive decay products. The main consequence of exposure to radon is the development of lung cancer. The average individual dose resulting from the inhalation of radon decay products was approximately 700 µSv in 2000. This dose corresponds to approximately 800 deaths annually in the Netherlands. The average individual dose resulting from external radiation from building materials was approximately 280 µSv in 2000. This dose corresponds to approximately 220 deaths annually in the Netherlands.

Technical note

The figures shows the average radon levels for all housing and the radon levels in new housing in periods of ten years. The national average prior to 1994 is based on measurements. Figures for the subsequent years are based on estimates which assume that the same average level is found new housing as in housing built in the last years in which measurements were taken. Since the percentage of new housing is increasing, and because mainly older housing is being demolished, there has been a slight increase in the average radiation level for housing as a whole.

References

Blaauboer, R. (2001). Blootstelling van de Nederlandse bevolking aan externe straling vanuit de omgeving. NVS Nieuws 26(3): 29-33.
Janssen, M.P.M., L. de Vries, J.C. Phaff, E.R. van der Graaf, R.O. Blaauboer, P. Stoop and J. Lembrechts (1998). Modeling radon transport in Dutch dwellings. RIVM (report no. 610 050 005), Bilthoven.
Lembrechts J., (2001). Blootstelling van de Nederlandse bevolking aan radon. NVS Nieuws 26(3): 23-26
Stoop, P., P. Glastra, Y. Hiemstra, L. de Vries, J. Lembrechts (1998). Results of the second Dutch national survey on radon in dwellings. RIVM (report no. 610 058 006), Bilthoven.

Relevant sections and indicators in the Environmental Data Compendium

Relevant information outside of the Environmental Data Compendium

More information can be found about the application of the Radiation Performance Standard (SPN) on the website of the Ministry of Housing, Spatial Planning and the Environment.
Blaauboer, R.O. en M.J.M. Pruppers (2000). Externe straling van bouwmaterialen: Resultaten van MARMER-berekeningen aan een referentiewoning. RIVM (report no. 610 050 006), Bilthoven.