Measurements of indoor radon (222Rn) concentrations were carried out by using LR-115 II solid statenuclear track detectors (SSNTD). One hundred forty detectors were placed randomly in Patras housesfor two periods of three months exposure, from December 1996 to November 1997. The observedmean radon values compared with the standard recommended values are low, while the maximumrecorded value is found to be within the limits. The influence of seasonal variation as well thedistance from the ground on radon level were also investigated.

The use of two mapping methods, kriging and moving average, in mapping the indoor radon risk, isinvestigated. Both methods are applied to three databases: simulated radon data, data collected inSouthern Belgium with low sampling density, and data collected in Luxembourg. We use commercialsoftware (SURFERR 6) for kriging, as well as softwares developed by the authors, especially for the radoncase, for kriging and for moving average. Simulated data prove to be very useful in this context. Weconclude that kriging as implemented in SURFERR 6 may not be well adapted to radon mapping.

Sub-slab depressurization (SSD) systems in the form of radon sumps are being considered as themost effective and the cheapest radon remedial measures for existing buildings. Detailedmeasurements were made in 17 family houses that had been remediated using this system.Measurements results indicate that the performance of SSD systems depends substantially on thesoil permeability and on the presence or absence of a drainage layer beneath the floors.

Two methods for determining the 222Rn diffusion coefficient in building materials are presented.Experimentally, the measurement of radon release rates under well-controlled conditions, using aflush and adsorption technique, underlies both methods. However, the theoretical principle of thetwo methods differs. The first method uses samples with a cubical or rectangular geometry andhas, as a prerequisite that a 100% radon tight surface covering method is available.

The International Commission on Radiological Protection (ICRP) recommends the use of a singleconversion factor, derived from epidemiological studies of exposure to uranium miners, for thedetermination of the effective dose from inhalation of radon progeny. Dosimetric models of radonprogeny inhalation predict that the dose conversion factors (DCF) are dependent upon the form ofthe radon progeny activity size distribution. The measurement of these activity size distributions isdifficult and an alternative approach has been proposed.

Legal regulations on the utilization of raws and materials assigned for construction are applied inPoland taking into account radiation protection. A qualification coefficient f2 = SRa, where SRa is the 226Ra concentration in the material expressed in Bq/kg, connected with the limitation of radium concentration in the product due to the emanation of 222Rn (in parallel with qualification coefficient f1 limiting whole-body exposure for gamma radiation) is used for the purpose of limitation of the 222Rn concentration in buildings assigned for permanent residence of people.

The wind speed and wind direction affected concentration of indoor radon in seven houses, which arelocated in three region of southern Finland. In the case of houses (B - F) which are built on upperslope of a permeable esker, according to the analysis of covariance the highest concentration of indoorradon, 20 - 33% over grand mean, was observed when wind (v?0.4 m.s-1) direction was perpendicularthe esker, leading to increasing pressure of soil gas and consequently to increased radon entry andconcentration.

Historic low-level radioactive wastes are located in Port Hope, Ontario, Canada. The radioactivecontaminants, mainly radium-226 and natural uranium, were deposited by a radium refining industrythat operated within the town from the 1930s to the 1950s.A national program for the assessment and remediation of communities affected by radioactivecontamination was initiated in 1975 by a Federal-Provincial Task Force on Radioactivity andterminated in 1982.

Three different methods were used to measure radon concentration in groundwater near Baia Mare andin other places of touristic interest from Maramures, the northest district of Romania. The majority ofthe samples have been measured using two methods of alpha detection. The Radon Emanometermethod has a sensibility ofl 0.074 Bq/l (2 pCi/l) and it uses a device of Russian provenience. We madeseventy (70) different measurements with this device.

There is a currently growing interest in the effect of exposure to 222Rn, because it became recognised as an important “pollutant” factor of the environment. Possible lung cancer incidence due to exposure to environmental radon levels may thus account for