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A comparative analysis of the radon concentrations in modern multi-storey residential buildings of high energy efficiency class and buildings typical for urban areas of the twentieth century was carried out. The study was conducted in Russian cities located in various climatic zones – Ekaterinburg, Krasnodar, St. Petersburg, Salekhard, Chelyabinsk. The radon concentration in samples of buildings was measured using integrated radon radiometers based on nuclear track detectors according to a single method. The surveyed sample included 498 apartments in multi-apartment buildings. Among all the examined building types, the highest average radon concentration is observed in modern energy-efficient houses – 43 Bq/m3. In other types of buildings, the following average radon concentrations were obtained: brick 2–5 floors – 35 Bq/m3; panel 5 floors – 32 Bq/m3; panel 7–12 floors 1970-1990 years of construction – 22 Bq/m3; brick> 5 floors 1970–1980 years of construction – 20 Bq m3; panel, built since 1990 – 24 Bq/m3. The results of the study confirm the assumption that radon concentration in modern multi-storey energy-efficient houses is on average higher than in typical residential buildings of the Soviet period. The increased accumulation of radon in energy-efficient buildings is associated with a decrease in the building envelope permeability and the contribution of fresh air to the general air exchange. Despite the fact that there were no cases of exceeding hygienic standards for the indoor radon concentration in the framework of this study, the higher radon concentration in buildings of increased energy efficiency requires attention from the point of view of implementing the principle of optimization of radiation protection. In the future, extensive construction of energy-efficient buildings may increase the average and collective doses to the urban population in the Russian Federation.

During past decades, specialists perform an epidemiological observation of the population exposed to the impact of radioactive discharges into the Techa River. The Techa River cohort studies have identified excess cases of leukemia and solid cancers associated with radiation exposure. At the same time natural sources of radiation, such as radon and its decay products, known to be significant human radiation exposure factor, are not sufficiently studied on this territory. The purpose of the study is to assess the mean value and the distribution indices of radon concentration in 14 settlements affected by radioactive contamination. Radon inspection in settlements located on the Techa River (Chelyabinsk and Kurgan regions) was executed. The measurements were performed in 511 dwellings. For radon inspection there were applied detectors based on LR-115 Kodak Track. The analysis shows the sample both to be representative and allow to estimate radon exposure for inhabitants. The average radon concentration in dwellings is 150 Bq/m3, which results in an annual effective dose of 11 mSv. The estimated number of dwellings with radon concentrations above ECC radon action level 200 Bq/m3 is 19. The factors affecting indoor radon accumulation were established. The radiation dose due to the inhalation of radon, accumulated over a long period of time, seems to be generally comparable to doses associated with the radioactive discharges into the Techa River during the 1949-1956.

According to results of the survey in Ekaterinburg, Russia, indoor radon concentrations above the city average level have been found in each of the studied buildings with high energy efficiency class. Measures to increase energy efficiency were confirmed to decrease the air exchange rate and accumulation of high radon concentrations indoors. Despite of recommendations to use mechanical ventilation with heat recovery as the main scenario for reducing elevated radon concentrations in energy-efficient buildings, the use of such systems did not show an obvious advantage. In real situation, mechanical ventilation system is not used properly both in the automatic and manual mode, which does not give an obvious advantage over the natural ventilation in the climate of the Middle Urals in Ekaterinburg.

An automated system has been developed for measuring advective radon flux density with the function of creating a pressure gradient between the soil and the accumulation chamber. The technical characteristics of the developed system are also presented.

A radon survey has been carried out around the town of Niska Banja (Serbia) in a region partly located over travertine formations, showing an enhanced level of natural radioactivity. Outdoor and indoor radon concentrations were measured seasonally over the whole year, using CR-39 diffusion type radon detectors. Outdoor measurements were performed at 56 points distributed over both travertine and alluvium sediment formations. Indoor radon concentrations were measured in 102 living rooms and bedrooms of 65 family houses. In about 50% of all measurement sites, radon concentration was measured over each season separately, making it possible to estimate seasonal variations, which were then used to correct values measured over different periods, and to estimate annual values. The average annual indoor radon concentration was estimated at over 1500 Bq/m(3) and at about 650 Bq/m(3) in parts of Niska Banja located over travertine and alluvium sediment formations, respectively, with maximum values exceeding 6000 Bq/m(3). The aver age value of outdoor annual radon concentration was 57 Bq/m(3), with a maximum value of 168 Bq/m(3). The high values of indoor and outdoor radon concentrations found at Niska Banja make this region a high natural background radiation area. Statistical analysis of our data confirms that the level of indoor radon concentration depends primarily on the underlying soil and building characteristics. (c) 2006 Elsevier Ltd. All rights reserved.