Assessment of the annual radon concentration is often required in indoor radon surveys of territories and individual dwellings for comparison with reference levels, studying factors affecting radon accumulation in dwellings, assessment of exposure in epidemiological studies, etc. The indoor radon surveys were carried out in multistorey buildings in eight Russian cities using solid state nuclear track detectors with an exposure period of three months. For these surveys, the estimation of annual indoor radon concentration was required to compare radon levels in buildings of high- and low-energy-efficiency classes located in different cities. To develop approaches to seasonal normalization in high-rise buildings, long-term one-hour radon concentration series obtained applying radon-monitors in 20 flats were analyzed. The dependency of indoor radon concentration on the indoor–outdoor temperature difference was studied taking into account the known natural, technogenic and anthropogenic factors affecting radon levels. The developed model of seasonal variations in multistorey buildings includes winter, summer, and demi-season periods, which differ both in ventilation intensity and dependency of radon concentration on the temperature difference. The developed model allows to estimate annual radon concentration taking into account the actual distribution of outdoor temperatures during the exposure of the track detectors.

The measurement of radon flux from soil surface is the useful tool for the assessment of radon-prone areas and monitoring of radon releases from uranium mining and milling residues. The accumulation chambers with hollow headspace and chambers with activated charcoal are the most used devices for these purposes. Systematic errors of the measurements strongly depend on the geometry of the chamber and diffusion coefficient of the radon in soil. The calibration system for the attestation of devices for radon flux measurements was constructed. The calibration measurements of accumulation chambers and chambers with activated charcoal were conducted. The good agreement between the results of 2D modelling of radon flux and measurements results was observed. It was demonstrated that reliable measurements of radon flux can be obtained by chambers with activated charcoal (equivalent volume ∼75 l) or by accumulation chambers with hollow headspace of ∼7–10 l and volume/surface ratio (height) of >15 cm.

The radon survey of kindergartens has been conducted in Sverdlovskaya oblast during 2013–16. Indoor radon concentrations have been measured in 180 kindergartens in 21 villages and 10 towns. The LR-115 nuclear track detectors were placed in 560 rooms (three or four rooms per kindergarten) during 2–3 months. To obtain annual values, radon measurements were carried in the cold and warm seasons. The arithmetic and geometric means of annual indoor radon concentrations in rooms are 59 and 42 Bq/m³ respectively, GSD = 2.33. Analysis of the building factors affecting radon entry is presented. The detailed radon survey was performed in one kindergarten where exceeding of national action radon level was observed.

Роль искажающих факторов в радоновом эпидемиологическом исследовании