Radon and thoron levels, their spatial and seasonal variations in adobe dwellings – a case study at the great Hungarian plain

Abstract

Radon and thoron isotopes are responsible for approximately half of the average annual effective dose to humans. Although the half-life of thoron is short, it can potentially enter indoor air from adobe walls. Adobe was a traditional construction material in the Great Hungarian Plain. Its major raw materials are the alluvial sediments of the area. Here, seasonal radon and thoron activity concentrations were measured in 53 adobe dwellings in 7 settlements by pairs of etched track detectors. The results show that the annual average radon and thoron activity concentrations are elevated in these dwellings and that the proportions with values higher than 300 Bq m(-3) are 14-17 and 29-32% for radon and thoron, respectively. The calculated radon inhalation dose is significantly higher than the world average value, exceeding 10 mSv y(-1) in 7% of the dwellings of this study. Thoron also can be a significant contributor to the inhalation dose with about 30% in the total inhalation dose. The changes of weather conditions seem to be more relevant in the variation of measurement results than the differences in the local sedimentary geology. Still, the highest values were detected on clay. Through the year, radon follows the average temperature changes and is affected by the ventilation, whereas thoron rather seems to follow the amount of precipitation.

Thoron emanation and exhalation of Slovenian soils determined by a PIC detector-equipped radon monitor

“…This is why exposure to thoron and its progenies can be comparable to or even higher than to radon and its progenies. According to some recent surveys, it has been found that elevated thoron concentrations can be observed in some regions of elevated radiological risk [2,[14][15][16][17][18][19][20]. In order to measure radon/thoron exhalation, the accumulation chamber technique can be used.…”

Indoor radon levels in Hungarian kindergartens

“…It has an expected pattern, lowest in summer and highest in autumn, winter and spring. Seasonal variation of radon in kindergartens is less than in residential homes [18,22,23]. In Hungary the mechanical ventilation is not typical, such as e.g.…”

220Rn (Thoron) Geohazard in Room Air of Earthen Dwellings in Vietnam

“…Only in recent years has indoor thoron exposure gained attention as a public health concern when increased concentrations were found in dwellings dug into clay-rich soil and in certain types of traditional houses with unfired earthen architecture in China [17][18][19], India [20], Germany [21], Hungary [22], and Japan [23]. These studies demonstrated that in nearly all the housing types examined, thoron concentrations exceeded those of radon, especially in locations proximal to interior walls.…”