Landscape and Health: Effects, Potential and Strategies ... - WSL

Parallelsession: Landscape characteristics/elements and health
76
An invisible component of the landscape: radon exposure
distribution in Switzerland
Hauri Dimitri 1 , Zimmermann Frank 2 , Kuehni Claudia E. 3 & Röösli Martin 1
1
Swiss Tropical and Public Health Institute, Socinstr. 57, 4051 Basel,
Dimitri.hauri@unibas.ch, martin.roosli@unibas.ch
2
Department of Radiation Oncology, University Hospital, Petersgraben 4, 4031 Basel,
FZimmermann@uhbs.ch
3
Institute of Social and Preventive Medicine, Finkenhubelweg 11, 3012 Bern,
kuehni@ispm.unibe.ch
Radon is a nuclide of a long radioactive decay chain, originating from uranium, a
naturally occurring element in granitic and metamorphic rocks. It emanates from soils
and is able to concentrate inside of buildings. The effect of indoor radon exposure on
lung cancer has been proven whereas the WHO indicates between 3 and 14% of all
lung cancer deaths being related to radon. Thus, radon might be a health relevant
factor that has to be considered when investigating the association between
landscape and health. The aim of this analysis is to evaluate the spatial distribution of
indoor radon levels in Switzerland.
The predictions were based on a multivariable log linear regression model. For the
prediction model development, we used 35,700 randomly selected measurements
from the Swiss radon database collected between 1994 and 2004 all over
Switzerland. As predictors we considered geographic/geologic data and building
characteristics. The model was validated with 8,900 additional measurements not
used for model development. Predictions were calculated for the living room of all
households situated on the ground floor using data from the Swiss building registry
(n= 1.2 Mio households).
Mean predicted radon concentration (geometric mean) for living room at ground floor
levels was 80.9 Bq/m³, ranging from 20.3 Bq/m³ to 363.2 Bq/m³ with the 10th, 50th
and 90th percentiles being equal to 44.1, 72.3 and 129.2 Bq/m³ respectively. We
predicted higher radon concentrations for the Alps and the Jurassic regions. The
highest mean predicted radon concentration of all cantons is found in the canton
Glarus in the Alps (184.6 Bq/m³). We predicted lower radon concentrations for the
Central Plateau whereas the lowest mean predicted radon concentration of all
cantons is found in the canton Appenzell Innerrhoden (33.4 Bq/m³). Lower radon
concentrations were also predicted for newer buildings, upper floors, apartments,
cities and agglomerations.
The predictions show that average radon exposure is relatively high in Switzerland
due to the geology. The WHO estimates that the risk for lung cancer increases by
20% per 100 Bq/m³ without a threshold for no effect and recommends constructional
action if 100 Bq/m³ is exceeded.
The prediction model is suitable to identify apartments with high and low radon
concentration and to assess average radon exposure of the Swiss population.