Estimated mean radon levels in dwellings

Data source
The information comes from the JRC campaign to collect nationally available information for radon mapping in 34 European countries. The focal points in the country institutions in the relevant radon areas answered a questionnaire produced by the JRC. More information about the database used for each country is available on the European Forum on Radon Mapping web site (14).

Description of data
The indicator consists of a presentation per country of three important key values of the distribution of annual radon level in dwellings:

estimated arithmetic mean of radon concentration
estimated percentage of dwellings with annual mean levels of radon above 200 Bq/m3
estimated percentage of dwellings with annual mean levels of radon above 400 Bq/m3.
Method of calculating the indicator
The estimated values are given by institutions which deal with indoor radon and maintain information about radon distribution over the country. The survey reference has been quoted as well as its period, the number of dwellings concerned and the method of sampling (Table 1).

Geographical coverage
Austria, Belgium, the Czech Republic, Finland, France, Germany, Hungary, the Netherlands, Poland, Romania, Spain and the United Kingdom.

Period of coverage
The data were collected in 2005 with an addendum in 2008 for Belgium. But the results concern widely differing periods between countries.

Frequency of update
Not specified yet.

Data quality
It is important to stress that the radon measurements were not made with a standardized protocol in all countries. In some countries the sample was selected randomly on a national basis, so that the results can be directly extrapolated in order to generate estimates. In others, the samples were not randomly selected and corrections were needed to estimate the radon distribution. Some countries relied on information from regional campaigns and did not give precise descriptions of the methodology used to assess the estimated distribution. Direct comparisons between results are, therefore, to be viewed with great caution.

Radon levels are susceptible to change with modifications to buildings or the renewal of the building stock, or the efficiency of regional or national action programmes. Regular national surveys or targeted surveys of new buildings or buildings of concern are, therefore, necessary to assess the evolution or efficiency of a policy. Coordination between countries is necessary to promote the use of national (and/or regional) survey protocols with a minimum set of standard criteria allowing for direct comparisons. Furthermore, as radon levels are strongly linked to local geological characteristics, the ideal scale to assess and compare radon distribution would be the regional one. Regional mapping based on a standardized assessment protocol could be an excellent tool for making comparisons.