Dominik Grządziel

Mean annual 222Rn concentration in homes located in different geological regions of Poland – first approach to whole country area

The paper presents the results of year-long measurements of radon ((222)Rn) concentration inside 129 buildings in Poland in relation to the geological conditions of their foundation. The authors took into account the division of the country into tectonic units, as well as the lithology of the rocks forming the bedrock of these buildings. As expected, the highest value of mean annual (222)Rn concentration (845 Bq/m(3)) was recorded in a building situated in the area of the Sudetes, while the highest geometric mean (characteristic of the expected log-normal data distribution) was calculated based on measurements from buildings located within the East-European craton, in the area of Mazury-Podlasie monocline, where it reached 231 Bq/m(3). Such results reflect geological conditions - the occurrence of crystalline rocks (especially U- and Ra-enriched granites and orthogneisses) on the surface in the Sudetes, and of young post-glacial sediments containing fragments of Scandinavian crystalline rocks, also enriched with U and Ra, in the area of Mazury-Podlasie monocline. However, the least expected result of the investigations was finding out that, contrary to the hitherto widespread belief, none of the major tectonic units of Poland can be excluded from the list of those containing buildings with mean annual (222)Rn concentration exceeding 200 Bq/m(3). The mean annual concentration of radon for all the buildings were much higher than the mean concentration value (49.1 Bq/m(3)) of indoor radon in Poland quoted so far. These results cast a completely new light on the necessity to perform measurements of radon concentration in residential buildings in Poland, no more with reference to small areas with outcrops of crystalline rocks (especially the Sudetes, being the Polish fragment of the European Variscan belt), but for all the major tectonic units within Poland.

The potential health hazard due to elevated radioactivity in old uranium mines in Dolina Białego, Tatra Mountains, Poland

Natural radioactivity is one of the essential components of the environment. Unlike the Sudety mountains area in Poland, the Tatra Mountains were not the subject of wide survey as regards the levels of natural radioactivity. Especially, the concentrations of radon (natural radioactive gas) have not been investigated there in terms of their possible negative health impact. Within the frame of bilateral cooperation between the Institute of Nuclear Physics in Kraków, Poland, and the Jožef Stefan Institute in Ljubljana, Slovenia, the measurements of natural radioactive elements in old uranium mines in the Tatra National Park were performed in June 2010. The investigated sites were located in Dolina Białego (The Valley of the White). One of the mines is situated near the tourist path. The paper presents the results of complex measurements of natural radioactivity in both uranium drifts. The concentration of radon gas inside the mining drifts exceeded 28,000 Bq m−3. Also, very high gamma dose rates were observed (up to 5600 nSv h−1). The maximum concentrations of natural radioactive elements (potassium 40K, radium 226Ra, thorium 232Th) in rock samples amounted to 535, 2137, and 18 Bq kg−1, respectively. The effective dose rates due to radon and thoron inhalation have been assessed as 0.013 mSv h−1 (for the lowest concentration) and 0.121 mSv h−1 (for the highest concentration).

Radon and its decay products in an air-conditioned auditorium in correlation with indoor air parameters

The measurements of radon and its attached decay product activity concentrations were carried out in an occupied and unoccupied auditorium during three air-conditioning modes i.e. air-conditioning system switched off (air-conditioning off), air-conditioning system switched off during the night and switched on during the day (air-conditioning on/off) and air-conditioning system switched on (air-conditioning on). Higher average concentrations of radon and its decay products were recorded in the auditorium when the air-conditioning system was switched off. The average particle mass and CO2 concentrations and indoor air thermal parameters were elevated during the air-conditioning on/off mode. A statistically significant (p < 0.001) positive correlation between the decay product concentrations and the particle number and average particle mass concentrations has been observed in the air-conditioning off mode (r = 0.55 and r = 0.68) and in the air-conditioning on/off mode (r = 0.54 and r = 0.62, respectively). A significant negative correlation has been observed between the decay product concentrations and the indoor air temperature and CO2 concentrations in the air-conditioning off mode (r = −0.86 and r = −0.47, respectively). The obtained results confirmed the impact of the air-conditioning system operation on the decrease of health risks related to the presence of radon and its decay products in air conditioned premises.

Determination of the thoron emanation coefficient using a powder sandwich technique

Thoron (220 Rn) is a natural radioactive gas, tasteless, odourless, colourless, undetectable without proper equipment. This gas is carcinogenic, just like radon (222 Rn) but due to the short half-life (55.6s) and a small amount in the environment, its share in the absorbed radiation dose is often neglected. However, in areas rich in thorium (232Th), the radiation dose from the thoron can be much larger and quite significant. The problem is to measure the concentration of the thoron due to its short decay time as well as the fact that it is alpha-emitting as radon. An even greater challenge is to determine the emanation coefficient for the thoron. The method used in this experiment was developed by S.D. Kanse based on the work of D.J Greeman and adapted to the equipment used in Laboratory of Radiometric Expertise IFJ PAN. In the technique used to determine the thoron emanation coefficient, a closed loop system is used in which thoron is pushed out by means of a flow system from the sample and measured by a AlphaGuad DF2000 detector that is adapted to determine concentration of this gas. A sample of the material is placed between 2 filters in the geometry of the sandwich. This arrangement ensures that the thickness of the powder sample is significantly less than the length of the thoron diffusion, thus avoiding significant loss of the thoron due to intergranular absorption and facilitates the complete removal of this gas escaping from the powder. Using this technique, it is important to determine the concentration of 226Ra and the 232Th, since for the AlphaGuard detector, the ratio between thoron and radon should not exceed 5:1 for proper determination of the thoron concentration. Measurements of 226Ra and 232Th activity were carried out using gamma spectroscopy (HPGe detector). It was examined how the type of filter and grain size of sample affects the obtained results.

Radon Hazards in Relation to Elemental and Isotope Composition of the Geological Structures in the Lubelskie Voivodeship

The study involved investigation of the relationship between the radon concentrations in the ground air – and thus in the indoor air – and the geological structure of the Lubelskie Voivodeship (eastern Poland). Both passive and active methods were used for measuring the radon concentrations in coal, phosphate and chalk mines, caves, wells as well as indoor environments. The study also included elemental, uranium and lead isotope analyses of rocks. The performed research showed that Paleogene and Mesozoic sedimentary rocks rich in radionuclides are the sources of radon in the Lubelskie Voivodeship. In the case of the buildings located in proximity to such rocks, characterized by relatively high radon exhalations, radon remediation methods are recommended. Already at the designing stage of buildings, the measures which protect against the hazardous radon gas should be applied.

Preliminary results of radon survey in thermal spas in V4 countries

Abstract Radon concentration was measured in 11 thermal spas in Visegrad countries (Czech Republic, Hungary, Poland, and Slovakia). The results showed that in 84% of spas radon activity concentration is less than 400 Bq·m−3. However, areas with radon activity concentration exceeding 1000 Bq·m−3 were found in the Czech Republic and Slovakia as well. Preliminary analyses indicated that the highest radon activities in spas were found in places with thermal pools. Radon concentration in waters used in spas ranged from 0.5 Bq/l to 384 Bq/l. The influence of radon activity concentration in water on radon activity in the air inside the spa was observed. It was found to increase indoor radon with increasing radon in the waters. Correlation with indoor radon and radon in water was more significant for baths and less significant for pool waters. In the cases filling of the bath from water taps, significantly contribute to the increased radon was observed in the pool and bath areas of the spa.

Radon equilibrium factor and perceived air quality in an air-conditioned auditorium in Lublin, Poland

The study reports measurements of radon and its decay products and of perceived air quality carried out in an occupied and unoccupied auditorium at the Lublin University of Technology in Lublin, Poland during three air conditioning system operation modes – air conditioning off, air conditioning on and air conditioning on/off. In the air conditioning on/off mode radon and its decay product concentrations and values of perceived air quality were inversely related. During that air conditioning operation mode, the value of the mean equilibrium factor F for the unattached fraction (0.31 ± 0.19) was somewhat higher than for the attached fraction (0.24 ± 0.19) and significant negative correlations were found between F values for attached, unattached and for the sum of both progeny fractions and perceived air quality values. These findings may be of importance as they indicate that in certain air conditioning operation modes indoor air quality deteriorates along with a reduction in the radon health hazard. This, in turn may adversely affect the comfort and productivity of the room users.