Thoron in indoor air: modeling for a better exposure estimate

Abstract

The radioactive noble gas radon with its decay products is well known as a health risk. After increased concentrations of the isotope (220)Rn (thoron) have been found in traditional Chinese mud-walled cave dwellings, the need for a model that describes the occurrence of thoron and its decay products indoors has arisen. This work presents such a model from the emergence of thoron in the building material until the decay to the stable (208)Pb and discusses the various influences on the occurrence of these nuclides. The model makes possible to predict the exposure of people staying in a room to thoron and its decay products and--combined with a dose model--to calculate their inhalation doses from easily measurable data.

Outdoor thoron and progeny in a thorium rich area with old decommissioned mines and waste rock

“…However, non-negligible activity concentrations and doses of thoron and TnP have been reported (Mayya et al, 2012;Schery, 1990;Steinh€ ausler, 1996) and recent research verifies that TnP deposited in the respiratory tract contribute significantly to dose (Ishikawa et al, 2007;Kranrod et al, 2010;Nikezic et al, 2010). Furthermore, due to its short half-life, the concentration of thoron is highly dependent on the distance from the source, and concentrations of the gas and its decay products at any particular location, indoor or outdoor, may not be closely related (Meisenberg and Tschiersch, 2011;UNSCEAR, 2000UNSCEAR, , 2006. Thoron equilibrium factors (F) therefore involve large uncertainties and measurements of thoron gas concentration are not suitable for dose assessment purposes (UNSCEAR, 2000(UNSCEAR, , 2006.…”

External radiation exposure of the Angolan population living in adobe houses

“…Average values of 226 Ra in Cabinda and Menongue are the same within standard deviation as Hungarian adobe [36], Australian mud-bricks [38], Bangladesh and Egyptian red clay bricks [39,40], as well as Cameroonian and Spain soils [26,41], whereas in Huambo they are higher. If the average is considered for all samples together (47 ± 30 Bq kg −1 ), the value is higher than the world reference value (Table 3) raising the attention to a potential radiation risk if pore structure is advantageous for radon and thoron exhalation [42,43]. This is the topic of another paper in preparation of the authors.…”

Affected Model of Indoor Radon Concentrations Based on Lifestyle, Greenery Ratio, and Radon Levels in Groundwater

“…In addition, building structure, cracks in the building, and long-term heating can indirectly influence indoor radon concentrations via greenery ratio. As part of efforts to reduce indoor radon concentrations, several prediction model using indoor ventilation and outdoor radon concentration were conducted for predicting the indoor radon concentration [17][18][19]. However, there was no approach to identify the multiplex variables that affect indoor radon concentrations and to identify the relationships between them.…”