Chapter 22
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Free Fractions, Attachment Rates, and Plate-Out Rates of Radon Daughters in Houses J. Porstendörfer, A. Reineking, and Κ. H. Becker Isotopenlaboratorium für Biologische und Medizinische, Forschung der Georg-August-Universität, Burckhardtweg 2, D-3400 Göttingen, Federal Republic of Germany The paper summerizes the experimental data on the equilibrium factor, F, the free fraction, f , the attachment rate to the room air aerosol, X, the recoil factor, r , and the plateout rates of the free, q , and the attached, q , radon daughters, determined in eight rooms of different houses. In each room several measurementswerecarried out at different times, with different aerosol sources (cigarette smoke, stove heating etc.) and under low (vοο
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Hopke; Radon and Its Decay Products ACS Symposium Series; American Chemical Society: Washington, DC, 1987.
22. PORSTENDÔRFER ET AL.
Attachment Rates and Plate-Out 299 Rates
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The mean value of the equilibrium factor F in houses was 0.3 - 0.1 without aerosol sources and can increase up to 0.5 with cigarette smoke in the room air. The plateout rates of the free radon decay products on room surfaces are about 200 times higher than the values of the aerosol radon daughters and have a great influence on the radon daughter activity concentrations indoors. In addition this investigation showed that the desorption probability by recoiling of Pb-214 atoms from particle surfaces of atmospheric aerosol is 0.50 - 0.15. Acknowledgments This work is supported by the Commission of the European Communities, contract no. BI-6-0130-D(B) References Brunner, H., W. Burkart, E. Nagel and C. Wernli, Radon in Wohnräumen in der Schweiz - Ergebnisse der Vorstudie 1981/1982, Eidg. Institut für Reaktorforschung, Würenlingen, Report RM-81-82-11. Bundesminister des Innern, Radon in Wohnungen und im Freien, Erhebungsmessungen in der Bundesrepublik Deutschland, BMI-Report (1985). Frey, G., P.K. Hopke and J. Stukel, Effects of Trace Gases and Water Vapor on the Diffusion Coefficient of Polonium-218, Science 211:480-481 (1981). Hogeweg, B., B.F. Bosnjakovic and W.M. Willart, Radiation Aspects of Indoor Environments and Related Radioecological Problems: a Study of the Situation in the Netherlands, Rad. Prot. Dos. 7:327-331 (1984). Israeli, Μ., Deposition Rates of Rn Progeny in Houses, Health Physics 49:1069-1083 (1985). Keller, G. and K.H. Folkerts, Ra-222 Concentrations and Decay Products Equilibrium in Dwellings and in the Open Air, Health Physics 47:385-398 (1984). Knutson, E.O., A.C. George, J.J. Frey and E. Koh, Radon Daughter Plateout, Part II. Prediction Model, Health Physics 45:445-452 (1983). Kolerskii, S.V., Yu.V. Kusnetsov, N.M. Polev and L.S. Ruzer, Effect of Recoil Nuclei being Knocked of Aerosol Particles onto Free-Atom Concentrations of Daughter Emanation Products, Izmeyitel naya Tekhnika 10:57-58 (1973). Mc Gregor, R.G., P. Vasudev, E.G. Letourneau, R.S. Me Cullough, F.A. Prantl and H. Taniguchi, Background concentrations of radon and radon daughters in Canadian homes, Health Physics 39:285-289 (1980). Hopke; Radon and Its Decay Products ACS Symposium Series; American Chemical Society: Washington, DC, 1987.
RADON AND ITS DECAY PRODUCTS
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Mercer, T.T., The Effects of Particle Size on the Escape of Recoiling the RaB Atoms from Particulate Surfaces, Health Physics 31:173-175 (1976). Mercer, T.T. and W.A. Stowe, Radioactive Aerosols Produced by Radon in Room Air: Inhaled Particles III (Edited by Walton, W.H.) pp. 839-850, Old Waking: Unwin Bros. Ltd., (1971). Mohnen, V.A., Die radioaktive Markierung von Aerosolen, Physik 229:109-122 (1969). O'Riordon, A.C. James, G. Rae and A.D. Wrixon, Human Exposure to Radon Decay Products Inside Dwellings in the United Kingdom, National Radiological Protection Board, Chilton, Report NRPB-R152 (1983). Porstendörfer, J., A. Wicke, A. Schraub, The Influence of Exhalation, Ventilation and Deposition Processes upon the Concentration of Radon (Rn-222), Thoron (Rn-220) and their Decay Products in Room Air, Health Physics 34:465-473 (1978). Porstendörfer, J. and T.T. Mercer, Influence of Nuclei Concentration and Humidity upon the Attachment Rate of Atoms in the Atmosphere, Atmospheric Environment 12:2223-2228 (1978). Porstendörfer, J., G. Röhrig and A. Ahmed, Experimental Determination of the Attachment Coefficients of Atoms and Ions on Monodisperse Aerosols, J. of Aerosol Science 10:21-28 (1979). Porstendörfer, J., A. Wicke ad A. Schraub, Methods for a Continuous Registration of Radon, Thoron, and their Decay Products Indoors and Outdoors, in: Natural Radiation Environment III, (Eds.: T.F. Gesell and W.M. Lowder) published by Technical Information Center/US Department of Energy, CONF-780422 (Vol. 2) pp. 1293-1307 (1980). Porstendörfer, J., Behaviour of Radon Daughter Products in Indoor Air, Rad. Prot. Dos. 7:107-113 (1984). Reineking, A. and J. Porstendörfer, High-volume Screen Diffusion Batteries and the Alpha Spectroscopy for Measurements of the Radon Daughter Activity Size Distributions in the Environment, J. of Aerosol Science 17 (1986) (accepted for publication). Swedjemark, G.A. and L. Mjönes, Radon and Radon Daughter Concentrations in Swedish Homes, Rad. Prot. Dos. 7:341-345 (1984). Wicke, A. and J. Porstendörfer, Radon Daughter Euqilibrium in Dwellings, in: Radiation Environment (K.G. Vohra et al., ed.) pp. 481-488, Wiley Eastern Limited, New Delhi (1982). Wicke, A. and J. Porstendörfer, Application of Surface Barrier Detectors for the Measurement of Environmental Radon and Thoron Daughters in Air, in: Proceedings of the International Meeting on Radon-Radon Progeny Measurements, EPA 520/5-83/021 (1983). RECEIVED August 4,1986 Hopke; Radon and Its Decay Products ACS Symposium Series; American Chemical Society: Washington, DC, 1987.
