Determination of radon prone areas by probabilistic analysis of indoor survey results and geological prognostic maps in the Czech Republic

Probability mapping of indoor radon-prone areas using disjunctive kriging

After a reference to the use of maps of radon-prone areas for indoor radon risk management, and to the methods used to produce them, there is a brief illustration of the geostatistical method of disjunctive kriging (DK) introduced by G. Matheron as a substitute for conditional expectation. There are some good reasons of using this method for the mapping of radon-prone areas as follows: (1) spatial correlation is exploited; (2) unbiasedness is conserved even in the conditions of quasi-stationarity; (3) lognormality of the data is not required; (4) choosing the point estimation allows drawing up smooth probability maps. An application of DK is also presented for the production of probability maps in a campaign of indoor radon measurements conducted by Institute for Environmental Protection and Research, in the provinces of Rome and Viterbo (Central Italy). In the application, it is assessed in particular how much the spatial correlation, even though low, influences the results.

Indoor radon concentrations in Adana, Turkey

The indoor radon concentration in Adana, Turkey was measured in living rooms of 52 houses during winter 2005 and 57 houses during summer 2005. Forty-four houses were selected for both winter and summer researches for estimating seasonal variations. Indoor radon concentrations were measured seasonally over hotter and colder 2 months over the whole year, using CR-39 passive nuclear track radon detectors. The radon concentrations were ranged from 15 to 97 Bq m(-3) on January-February 2005 for 60 d and from 5 to 70 Bq m(-3) on June-July 2005 for 60 d. The average summer concentration measured was 25.8 Bq m(-3) and the average winter concentration was 48.9 Bq m(-3) in 44 houses that observed seasonal variations. The differences between winter and summer periods were ranged from 1 to 77 Bq m(-3). The average value in both winter and summer periods is 37 Bq m(-3) in 44 houses that observed seasonal variations. This value is below the worldwide indoor radon concentration distribution of 46 Bq m(-3). The annual effective dose equivalent from (222)Rn was 0.9 mSv y(-1).

Radon programme: presence and future

An overview of radon programme experience is presented. The paper summarises broad topics concerning radon issue: philosophy of radon policy, radon measurements strategies with respect to indoor radon variation, progress in radon measurement of an individual house (radon diagnosis), national programmes, the role of preventive measures and interventions with respect to existing and future exposure and knowledge of radon risk, problems of remediation strategies, radon mapping process and sense of delineation of radon prone areas, public awareness on radon issue and publicity campaign. Some research activities are proposed aiming at effective solutions for radon issues in the future.

Radon concentration in houses over a closed Hungarian uranium mine

High radon concentration (average 410 kBq m-3) has been measured in a tunnel of a uranium mine, located 15-55 m below the village of Kovágószolos, Hungary. The mine was closed in 1997; the artificial ventilation of the tunnel was then terminated and recultivation works begun. In this paper, a study has been made as to whether the tunnel has an influence on the radon concentration of surface dwellings over the mining tunnel. At different distances from the surface projection of the mining tunnel, radon concentration, the gamma dose, radon exhalation and radon concentration of soil gas were measured. The average radon concentration in the dwellings was 483 Bq m-3. Significantly higher radon concentrations (average 667 Bq m-3) were measured in houses within +/-150 m from the surface projection of the mining tunnel +50 m, compared with the houses further than the 300-m belt (average 291 Bq m-3). The average radon concentration of the soil gas was 88.8 kBq m-3, the average radon exhalation was 71.4 Bq m-2 s-1 and higher values were measured over the passage as well. Frequent fissures crossing the passage and running up to the surface and the high radon concentration generated in the passage (average 410 kBq m-3) may influence the radon concentration of the houses over the mining tunnel.

Final results of the Austrian Radon Project

The Austrian Radon Project started in 1992 and ended in 2001. The Austrian Radon Project had two aims: firstly, finding areas of enhanced indoor radon concentration for future radon mitigations, and, secondly, defining areas with elevated radon risk where radon safe construction is necessary for new houses. The project was based on systematic indoor measurements in randomly selected houses using different types of detectors. Successful intercomparison tests were made in a radon chamber, but simultaneous measurements by different detectors normally used in homes deviated sometimes up to a factor of two. We have to assume that this results from manipulations of the detectors by the inhabitants. The mean radon concentration in Austrian homes was found to be 99 Bq m(-3). A radon potential was derived from the results of the measurements and the information received from questionnaires. This radon potential was defined as an expected radon concentration in a standard situation and characterizes the radon risk from ground sources with all the influences of different living situations eliminated. A mean radon potential was computed for every municipality and the information is displayed as a map. The uncertainty and the reliability of the classification of municipalities according to the radon potential are discussed in more detail and compared with results from Switzerland.