Measurements of radon and radon daughters in 11 buildings in five states, using active or passive solar heating showed no significant increase in concentration over the levels measured in buildings with conventional heating systems. Radon levels in two buildings using rock storage in their active solar systems exceeded the U.S. Nuclear Regulatory Commission's 10 CFR 20 limit of 3 pCi/l for continuous exposure. In the remainder of the buildings, radon concentrations were found to be at levels considered to be normal.
Radon concentrations were measured in about 1000 Dutch dwellings and at 200 outside locations using passive monitors. A median concentration of 24 Bq/m3 was found for the dwellings with a highest value of 190 Bq/m3. Seasonal effects were found to be small. Correlations were observed between median radon concentrations and construction parameters including ventilation rate. The concentrations outside show an unexpected dependence on the location. Comparison with previous grab-sampling data on radon-daughter concentrations reveals an average equilibrium factor of 0.3.
Three different investigations of radon in Swedish dwellings are presented - a nationwide study conducted primarily to determine the collective dose to the Swedish population from exposure to radon and radon daughter, a supplementary study of newly built detached houses in order to find out whether theregulations in the Building Code prescribes acceptable radon levels in new houses built on normal ground, and measurements made by the local authorities in order to find houses with levels of radon daughters above the norm.
To develop effective monitoring and control programs for indoor radon it is important to understand the causes of the broad range of concentrations that have been observed. Measurements of indoor radon concentration and air-exchange rate in dwellings in several countries indicate that this variability arises largely from differences among structures in the rate of radon entry.
The results of our investigations in the Federal Republic of Germany on the Rn-222 and Rn-220 daughter product concentration in dwellings and in the open air are presented. The median Rn-222 concentration indoors was approximately 4 times hig
In Sweden there are two major sources to indoor radon, the building material and radon from uranium rich soils. It is now widely accepted that indoor radon daughter concentration in Sweden, higher than 1000 Bq/m3 is most frequently caused by
In large areas of the Swiss Alps, the high radium content of rocks and soil, which results in high source terms for radon from the ground, may produce considerable indoor levels of radon in dwellings with low air infiltration. During the winter
Describes use of a radioactive tracer for measuring ventilation rates. Finds krypton 85 is the most suitable gas although xenon 133 and argon 41 have been used. Mentions various studies using radioactive tracers made in both France and England. Suggests commercial sources for krypton 85.
Describes a method for the investigation of ventilation rate in mechanically ventilated closed rooms. The room air is labelled with a radioactive isotope and the ventilation rate inferred from the reduction in radioactivity found by repeated sampling at different locations . Notes the results apply only when the room air is well mixed. Defines a parameter, the "ventilation factor" which describes the variation in ventilation rate. Gives examples of the use of this method.
Discusses the principles involved in measuring air change rates using tracers and gives the theory. Outlines the preparation of the tracer and the test procedure in stables. Finds that satisfactory results can be obtained when the concentration of krypton-85 is only one tenth of the maximum allowable. Lists the advantages of the method.
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