[en] After a short description of the history of radon measurements in mines, the results of bare track detector application in dwellings are commented on. Many related methods and problems are discussed. Most experiences are similar to the published ones, but details are specific for Central Europe (absence of air-conditioning, etc.). (author)

No abstract available

[en] The results of a large-scale survey of radon concentrations in Norwegian dwellings are reported. Measurements of radon have been made in a total of 7500 dwellings. The dwellings were randomly selected and the number in each municipality is proportional to its population. The measurements were performed using etched track detectors from the National Radiological Protection Board in the UK. One detector was placed in the main bedroom in each dwelling for 6 months. The annual average of radon concentration in Norwegian bedrooms is calculated to be 51 Bq.m^-3. The frequency distribution is approximately log-normal with a geometric mean of 26 Bq.m^-3 and about 4% of the bedrooms have concentrations above 200 Bq.m^-3. The radon concentrations are found to be about 40% higher for bedrooms in single-family houses than in blocks of flats and other multifamily houses. In a large proportion of single-family houses the living room and the kitchen are located on the ground floor and the bedrooms on the first floor. An additional factor is that the winters of 1987-1988 and 1988-1989 were much warmer than normal. Taking these factors into account, the average radon concentration in Norwegian dwellings is estimated to be between 55 and 65 Bq.m^-3. (author)

[en] Information is given about the radon programme in Czechoslovakia after the democratic revolution in 1989, i.e. organisation, implementation steps, limits. Results for radon exposure and radon evaluation for Jachymov, a special situation, and for Petrovice, as an example of a high radon risk area, are given. (author)

[en] A short study was carried out investigating a reported problem of shadow flicker and flashing from the blades of a turbine. The incidence of this phenomenon was confirmed and the duration and frequency of occurrence assessed. The shadow flicker period would be short and only occur at certain times, but could cause irritation. A device to stop the turbine when shadow flicker occurred was recommended and is described. A recommendation was made that turbines should be sited at least ten diameters distance from habitations, and more if sited to the East/Southwest, and the shadow path identified. (author)

[en] Short communication

[en] This paper reviews existing models of radon entry into houses. The primary mechanism of radon entry in houses with high indoor concentrations is, in most cases, convective entry of radon-bearing soil gas from the surrounding soil. Models using analytical solutions to idealised geometrical configurations with simplified boundary conditions obtain analytical tractability of equations to be solved at the cost of severe approximations; their strength is in the insights they offer with their solutions. Models based on lumped parameters attempt to characterise the significant physical behavioural characteristics of the soil gas and radon flow. When realistic approximations are desired for the boundary conditions and terms in the governing equations, numerical models must be used; these are usually based on finite difference or finite element solutions to the governing equations. The models are briefly reviewed and their strengths and limitations are discussed. (author)

[en] By solving the diffusion equation for the axial-symmetric geometry of in situ radon exhalation measurements, the effect of the presence of the measuring device on the exhalation rate was determined. From analyses of the calculated growth of the radon concentration in the device, it turned out that exhalation rates deduced from measurements underestimate the 'free' exhalation rate by at most a factor of 2. Analyses of a few measurements showed that erroneous results can be avoided by analysing the full growth curves. (author)

[en] In this paper a model is presented for analysis of the radon concentrations in a compartment in terms of contributions from transport by flows of air between compartments and from radon sources in the compartment. Measurements were made to study the effect of increased natural ventilation of the crawl space. Comparison with previous results reveals that this simple countermeasure does not reduce the radon concentration in this particular dwelling. Contrary to earlier conclusions based on qualitative arguments, the radon concentration in the dwelling is not predominantly determined by flow from crawl space. (author)

No abstract available