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The fraction of unattached (fun) nanosized 222Rn short-lived decay products in indoor air has been measured in different environments and the following ranges obtained: 0.03-0.25 in kindergartens, 0.03-0.18 in schools, 0.08-0.20 in wineries, and 0.12-0.68 in a karst cave. The dependence of fun on the environmental conditions (air temperature, relative humidity and pressure), as well as on the working regime has been studied and will be discussed. Applying the dosimetric approach, dose conversion factors were calculated, based on the measured fun values, and compared to the values, obtained from epidemiological studies and currently recommended to be used in radon dosimetry.

Indoor air radon ((222)Rn) concentrations were measured in spring and winter in 30 rooms of 9 elementary schools and 19 rooms of 6 high schools in Prizren, Kosovo, using alpha scintillation cells. Only in three rooms of elementary schools and four rooms of high schools did winter concentrations exceed 400 Bq m(-3).

The sources of radon were investigated in twenty selected schools with high room levels of radiation. A combination of radon measuring techniques was applied: etched track and electret detectors to obtain average indoor air radon concentration. devices to record radon concentration continuously and thus characterise its diurnal variation, and alpha scintillation cells to analyse air from potential sources of radon entry. In some cases, a single strong source was identified (e.g. sinks, sub-floor channels), while in others the poor quality of the basic concrete slab was responsible for high indoor radon concentrations. The combination of etched track and electret detectors and alpha scintillation cells was essential for locating these sources.

In ten high radon level kindergartens, radon sources were sought by applying a combination of several radon measuring techniques: etched track detectors to obtain average indoor air radon concentration, continuous devices to record radon concentration and see its diurnal variation, and alpha scintillation cells to determine radon concentration in the air entering a room from cracks, holes and sinks in the floor and from under-floor channels. In three cases, a strong local radon source was identified while, in the others, the bad quality of the basic concrete slab was responsible for the high indoor radon concentration.

In selected kindergartens and schools, long-term average indoor air radon concentrations were measured by two-month exposure of etched track detectors. Short-term average concentrations were obtained from 7-10 day continuous radon recordings during the exposure of etched track detectors. Only in about 1/3 of cases both averages did agree within ±20%; otherwise they differ considerably. The assumption that short-term results can substitute for long-term data, which is sometimes made to correct radon exposure estimated on the basis of concentrations obtained by etched track detectors, should therefore be treated with caution. [ABSTRACT FROM AUTHOR]