Log-normality of indoor radon data in the Walloon region of Belgium.
The deviations of the distribution of Belgian indoor radon data from the log-normal trend are examined. Simulated data are generated to provide a theoretical frame for understanding these deviations. It is shown that the 3-component structure of indoor radon (radon from subsoil, outdoor air and building materials) generates deviations in the low- and high-concentration tails, but this low-C trend can be almost completely compensated by the effect of measurement uncertainties and by possible small errors in background subtraction. The predicted low-C and high-C deviations are well observed in the Belgian data, when considering the global distribution of all data. The agreement with the log-normal model is improved when considering data organised in homogeneous geological groups. As the deviation from log-normality is often due to the low-C tail for which there is no interest, it is proposed to use the log-normal fit limited to the high-C half of the distribution. With this prescription, the vast majority of the geological groups of data are compatible with the log-normal model, the remaining deviations being mostly due to a few outliers, and rarely to a "fat tail". With very few exceptions, the log-normal modelling of the high-concentration part of indoor radon data is expected to give reasonable results, provided that the data are organised in homogeneous geological groups.
European Commission, Joint Research Centre (JRC), Institute for Transuranium Elements (ITU), Nuclear Security Unit, Via Enrico Fermi 2749, 21027 Ispra, VA, Italy. Electronic address: giorgia.cinelli@jrc.ec.europa.eu.
Giorgia
G
Cinelli
ISIB, Haute Ecole P.-H. Spaak, Rue Royale 150, 1000 Brussels, Belgium.
François
F
Tondeur
D000396:Air Pollutants, Radioactive / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D000398:Air Pollution, Radioactive / Q000032:analysis*; D001530:Belgium; D006798:Housing; D008962:Models, Theoretical; D011834:Radiation Monitoring / Q000379:methods*; D011886:Radon / Q000032:analysis*
D000396:Air Pollutants, Radioactive; D011886:Radon
Geology; Indoor radon; Log-normal distribution; Walloon region of Belgium