Outdoor measurements of thoron progeny in a 232Th-rich area with deposition-based alpha track detectors and corrections for wind bias

  • Hallvard Haanes Norwegian Radiation and Nuclear Safety Authority, Østerås; and Centre for Environmental Radioactivity (CERAD CoE), Norwegian University of Life Sciences (NMBU), Norway https://orcid.org/0000-0001-8820-7839
  • Hilde Kristin Skjerdal Norwegian Radiation and Nuclear Safety Authority, Østerås, Norway
  • Rosaline Mishra Bhabha Atomic Research Centre, Trombay, Mumbai, India
  • Anne Liv Rudjord Norwegian Radiation and Nuclear Safety Authority, Østerås; and Centre for Environmental Radioactivity (CERAD CoE), Norwegian University of Life Sciences (NMBU), Norway
Keywords: radon, thoron, thoron progeny, radon progeny, deposition alpha track detector, wind bias


Radon and thoron progeny are important contributors to dose from naturally occurring radionuclides, especially in high background areas and with naturally occurring radioactive material (NORM) legacy sites. Due to the short half-life of thoron, measurements of thoron progeny with a longer half-life should be used for risk and dose assessment. Deposition-based alpha track detectors for such progeny are, however, biased by air movement, especially outdoors where winds may be strong but variable. We used deposition detectors for thoron progeny and radon progeny, as well as alpha track gas detectors for 220Rn and 222Rn, outdoors within the Fen complex in Norway, an area with both elevated levels of naturally occurring radionuclides and NORM legacy sites. Different detector types were used and showed different results. We measured airflow along deposition detectors during deployment to assess wind bias and used statistical models to attain location-specific sheltering factors. These models assess how explanatory terms like point measurements with anemometer, predicted airflow along detectors, and levels of 220Rn and 222Rn explained variation in deposition detector measurements of TnP and RnP. For all the detector types, unrealistically, high equilibrium values (F) were found between progenitor noble gas and progeny before correcting for wind bias. Results suggest a magnitude of wind bias on TnP deposition detectors being a fraction of 0.74–0.96 (mean: 0.87) of the total measurement.


Download data is not yet available.


  1. UNSCEAR. Sources and effects of ionizing radiation. Volume I: sources. Annex B: Exposures from natural radiation sources. UNSCEAR report to the General Assembly, with annexes. New York, NY: United Nations Scientific Committee on the Effect of Atomic Radiation; 2000.

  2. UNSCEAR. Effects of ionizing radiation. Volume II, Annex E: Sources-to-effects assessment for radon in homes and workplaces. UNSCEAR report to the General Assembly, with annexes. New York, NY: United Nations Scientific Committee on the Effect of Atomic Radiation; 2006.

  3. Ramola RC, Gusain GS, Rautela BS, Sagar DV, Prasad G, Shahoo SK, et al. Levels of thoron and progeny in high background radiation area of southeastern coast of Odisha, India. Radiat Protect Dosim 2012; 152(1–3): 62–5. doi: 10.1093/rpd/ncs188

  4. Ishimori Y, Lange K, Martin P, Mayya YS, Phaneuf M. Measurement and calculation of radon releases from NORM residues. 2013. Technical reports series no. 474, ISSN 0074–1914, Vienna: International Atomic Energy Agency, 2013.

  5. Haanes H, Finne IE, Kolstad T, Mauring A, Dahlgren S, Rudjord AL. Outdoor thoron and progeny in a thorium rich area with old decommissioned mines and waste rock. J Environ Radioact 2016; 10(162–163): 23–32. doi: 10.1016/j.jenvrad.2016.05.005

  6. Popic JM, Bhatt CR, Salbu B, Skipperud L. Outdoor 220Rn, 222Rn and terrestrial gamma radiation levels: investigation study in the thorium rich Fen Complex, Norway. J Environ Monit 2012; 14(1): 193–201. doi: 10.1039/C1EM10726G

  7. Stranden E. Thoron (220Rn) daughter to radon (222Rn) daughter ratios in thorium-rich areas. Health Physics 1984; 47(5): 784–5.

  8. Stranden E. The radiological impact of mining in a Th-rich Norwegian area. Health Physics 1985; 48(4): 415–20. doi: 10.1097/00004032-198504000-00003

  9. Meisenberg O, Tschiersch J. Thoron in indoor air: modeling for a better exposure estimate. Indoor Air 2011; 21(3): 240–52. doi: 10.1111/j.1600-0668.2010.00697.x

  10. Bangotra P, Mehra R, Kaur K, Kanse S, Mishra R, Sahoo BK. Estimation of EEC, unattached fraction and equilibrium factor for the assessment of radiological dose using pin-hole cup dosimeters and deposition based progeny sensors. J Environ Radioactiv 2015; 148(0): 67–73. doi: 10.1016/j.jenvrad.2015.06.010

  11. Janik M, Tokonami S, Kranrod C, Sorimachi A, Ishikawa T, Hosoda M, et al. Comparative analysis of radon, thoron and thoron progeny concentration measurements. J Radiat Res Appl Sci 2013; 54(4): 597–610. doi: 10.1093/jrr/rrs129

  12. Mayya YS, Mishra R, Prajith R, Gole AC, Sapra BK, Chougaonkar MP, et al. Deposition-based passive monitors for assigning radon, thoron inhalation doses for epidemiological studies. Radiat Protect Dosim 2012; 152(1–3): 18–24. doi: 10.1093/rpd/ncs196

  13. Mishra R, Mayya YS. Study of a deposition-based direct thoron progeny sensor (DTPS) technique for estimating equilibrium equivalent thoron concentration (EETC) in indoor environment. Radiat Meas 2008; 43(8): 1408–16. doi: 10.1016/j.radmeas.2008.03.002

  14. Porstendörfer J. Properties and behaviour of radon and thoron and their decay products in the air. J Aerosol Sci 1994; 25(2): 219–63. doi: 10.1016/0021-8502(94)90077-9

  15. Zhuo W, Iida T. Estimation of thoron progeny concentrations in dwellings with their deposition rate measurements. Japanese J Health Phys 2000; 35(3): 365–70. doi: 10.5453/jhps.35.365

  16. Mishra R, Prajith R, Sapra BK, Mayya YS. Response of direct thoron progeny sensors (DTPS) to various aerosol concentrations and ventilation rates. Nuclear instruments and methods in physics research section B: beam interactions with materials and atoms. Sci Direct 2010; 268(6): 671–5. doi: 10.1016/j.nimb.2009.12.012

  17. Lai ACK, Nazaroff WW. Modelling indoor particle deposition from turbulent flow into smooth surfaces. J Aerosol Sci 2000; 31(4): 463–76. doi: 10.1016/S0021-8502(99)00536-4

  18. Mishra R, Prajith R, Rout RP, Sriamirullah J, Sapra BK. Effect of air velocity on inhalation doses due to radon and thoron progeny in a test chamber. Radiat Protect Dosim 2020; 189(3): 401–5. doi: 10.1093/rpd/ncaa054

  19. Andersen T. Secondary processes in carbonatites: petrology of “rødberg” (hematite-calcite-dolomite carbonatite) in the Fen central complex, Telemark (South Norway). Lithos 1984; 17(0): 227–45. doi: 10.1016/0024-4937(84)90022-7

  20. Brøgger WC. Die eruptivgesteine des Kristianiagebietes. IV. Fangebiet in Telemark, Norwegen. 1921. Norske skrifter udgit av (published by) Videnskapsselskabet i (in) Kristiania 1921; I. Math. Nat. Klasse. No. 9:1–408.

  21. Dahlgren S. Fenfeltet – et stykke eksplosiv geologi. (in Norwegian). Stein, magasin for populærgeologi 1993; 144–5.

  22. Haanes H, Rudjord AL. Significance of seasonal outdoor releases of thoron from airflow through a point source during natural ventilation of a mine-complex in thorium-rich bedrock. Atmos Pollut Res 2018; 9(6): 1000–8. doi: 10.1016/j.apr.2018.03.007

  23. Mishra R, Prajith R, Sapra BK, Mayya YS. An integrated approach for the assessment of the thoron progeny exposures using direct thoron progeny sensors. Radiat Prot Dosim 2010; 141(4): 363–6. doi: 10.1093/rpd/ncq236

  24. Mayya YS, Mishra R, Prajith R, Sapra BK, Kushwaha HS. Wire-mesh capped deposition sensors: novel passive tool for coarse fraction flux estimation of radon thoron progeny in indoor environments. Sci Total Environ 2010; 409(2): 378–83. doi: 10.1016/j.scitotenv.2010.10.007

  25. Mishra R, Rout R, Prajith R, Jalalluddin S, Sapra BK, Mayya YS. Innovative easy-to-use passive technique for 222RN and 220RN decay product detection. Radiat Protect Dosim 2016; 171(2): 181–186. doi: 10.1093/rpd/ncw053

  26. Roupsard P, Amielh M, Maro D, Coppalle A, Branger H, Connan O, et al. Measurement in a wind tunnel of dry deposition velocities of submicron aerosol with associated turbulence onto rough and smooth urban surfaces. J Aerosol Sci 2013; 55: 12–24. doi: 10.1016/j.jaerosci.2012.07.006

  27. Aalto P, Hameri K, Paatero P, Kulmala M, Bellander T, Berglind N, et al. Aerosol particle number concentration measurements in five European cities using TSI-3022 condensation particle counter over a three-year period during health effects of air pollution on susceptible subpopulations. J Air Waste Manag Assoc 2005; 55(8): 1064–76. doi: 10.1080/10473289.2005.10464702

  28. R Core Team. R: a language and environment for statistical computing. 2020 (version 4.0.2, June 2020), In: Computing RFfS, editor. Vienna, Austria. Available from: https://www.R-project.org/.

  29. Pebesma EJ, Bivand RS. Classes and methods for spatial data in R. R News 2005; 5(2): 9–13.

  30. Bivand R, Keitt T, Rowlingson B. Rgdal: Bindings for the ‘Geospatial’ data abstractation library. R package version 1.4–4. 2019 (cited and used June 2020). Available from: https://CRAN.R-project.org/package=rgdal

  31. Carslaw DC, Ropkins K. Openair – an R package for air quality data analysis. Environ Model Software 2012; 27–28: 52–61. doi: 10.1016/j.envsoft.2011.09.008

  32. Chen J, Harley NH. A review of indoor and outdoor radon equilibrium factors-part I: 222Rn. Health Phys 2018; 115(4): 490–9. doi: 10.1097/HP.0000000000000909

  33. Nikolaev VA, Ilić R. Etched track radiometers in radon measurements: a review. Radiat Meas 1999; 30(1): 1–13. doi: 10.1016/S1350-4487(98)00086-9

  34. O’Sullivan D, Thompson A, Adams JA, Beahm LP. New results on the investigation of the variation of nuclear track detector response with temperature. Nucl Tracks Radiat Meas 1984; 8(1): 143–6. doi: 10.1016/0735-245X(84)90074-7

  35. Kodaira S, Yasuda N, Tawara H, Ogura K, Doke T, Hasebe N, et al. Temperature and pressure conditions for the appropriate performance of charge and mass resolutions in balloon-borne CR–39 track detector for the heavy cosmic rays. Nuclear instruments and methods in physics research section B: beam interactions with materials and atoms. Sci Direct 2009; 267(10): 1817–22. doi: 10.1016/j.nimb.2009.03.001

  36. Kleinschmidt R, Watson D, Janik M, Gillmore G. The presence and dosimetry of radon and thoron in a historical, underground metalliferous mine. J Sustain Min 2018; 17(3): 120–30. doi: 10.1016/j.jsm.2018.06.003

How to Cite
Haanes, H., Skjerdal, H. K., Mishra, R., & Rudjord, A. L. (2021). Outdoor measurements of thoron progeny in a <sup>232</sup&gt;Th-rich area with deposition-based alpha track detectors and corrections for wind bias. Journal of the European Radon Association, 2. https://doi.org/10.35815/radon.v2.6130
Original Research Articles