Measurement of 220Rn/222Rn progeny deposition velocities on surfaces and their comparison with theoretical models

Mishra, Rosaline; Mayya, Y. S.; Kushwaha, H.S.

doi:10.1016/j.jaerosci.2008.08.001

Cited by 110 publications

(41 citation statements)

References 20 publications

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“…(16) have been measured the activity size distribution of the attached radon progeny by a Micro Orifice Uniform Deposit impactor (Model 110 MOUDITM, USA) in Okinawa. The AMAD was observed 267 nm with a range from 234 to 308 and a GSD of 1.7 (range 1.6 and 1.9) which is smaller than our present value Mishra et al (17) have been measured the activity size distribution of the attached aerosols by a developed low pressure cascade impactor. The AMAD was obtained to be 150 nm with GSD of 2.7, which is a factor of two smaller than the present value.…”

Section: Indoor Activity Size Distribution Ofcontrasting

confidence: 84%

“…This distribution has been determined by tagging natural aerosol particles with radon progeny. However, some measurements for attached and unattached activity size distributions of 222 Rn progeny have been performed in the indoor air under realistic natural conditions (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) . Most of the observed data have shown that the size distribution of radon progeny consists of ultrafine clusters with median diameters below 4 nm (unattached activity) and progenies associated with ambient aerosol particles in sizes ranging between 100 and 1000 nm (attached activity).…”

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confidence: 99%

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Lung Depth Dose from Inhalation of 222Rn Progeny

2012

Egypt. J. Biophys. Biomed. Engng.

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N THE CASE of internally deposited radionuclides, direct ……measurement of the energy absorbed from ionizing radiation emitted by the decaying of these radionuclides is rarely, if ever, possible. Therefore, one must rely on dosimetric models to obtain estimates of the spatial and temporal patterns of energy deposition in human lung. These models always require information about the parameters of activity size distributions of radon progeny. In the present work, the attached and unattached activity size distribution of 222 Rn progeny ( 214 Bi and 214 Po) were measured in indoor air of Minia University, Minia, Egypt. The attached fraction was collected using a low-pressure Berner cascade-impactor technique. A constructed wire screen diffusion battery was used for collecting the unattached fraction. Most of the attached activities for 214 Bi progeny were associated with the aerosol particles of the accumulation mode. The AMAD of this mode for 214 Bi was determined to be 350 nm with GSD of 3. The GSD of unattached size distributions for 214 Po is 1.29 with AMTD of 1.25 nm. An analytical method has been developed to compute the local energy deposition of 214 Po alpha particles in a target volume of 1 m spheres located at different depths in bronchial epithelium. In order to reach the target, alpha particles travel either through tissue alone or through air and tissue. While the depth-dose distributions in the case of nuclides uniformly distributed within the epithelium were practically constant with depth, they decreased in an almost linear fashion with increasing depth in the case of nuclides on the airway surface.

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Section: Indoor Activity Size Distribution Ofcontrasting

confidence: 84%

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confidence: 99%

Lung Depth Dose from Inhalation of 222Rn Progeny

2012

Egypt. J. Biophys. Biomed. Engng.

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“…The track registration efficiency was found to be 8.3 % for 212 Po and less than 0.02 % for all other alpha emitters including 222 Rn progeny. The geometric mean of the deposition velocity (V eff ) was found to be 0.077 mh -1 for 220 Rn progeny and 0.132 mh -1 for 222 Rn progeny, for indoor conditions (Mishra et al 2009a). Combining these parameters, the overall sensitivity factor (S) is estimated by Eq.…”

Section: Measurement Of Equilibrium Equivalent Radon/thoron Concentramentioning

confidence: 97%

“…Hence, for calculation of EERC, the tracks obtained from DTPS were eliminated from DRPS, to obtain the exact track density from radon progeny in DRPS (Eq. 4) (Mishra et al 2009a):…”

Section: Measurement Of Equilibrium Equivalent Radon/thoron Concentramentioning

confidence: 99%

Attached, unattached fraction of progeny concentrations and equilibrium factor for dose assessments from 222Rn and 220Rn

Singh

Saini

Mishra

et al. 2016

Radiat Environ Biophys

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In this study, measurements of indoor radon ((222)Rn), thoron ((220)Rn) and their equilibrium equivalent concentration (EEC) were carried out in 96 dwellings from 22 different villages situated in Hamirpur district, Himachal Pradesh, India, by using LR-115 type II-based pinhole twin cup dosimeters and deposition-based progeny sensors (DRPS/DTPS). The annual average indoor (222)Rn and (220)Rn concentrations observed in these dwellings were 63.82 and 89.59 Bq/m(3), respectively, while the average EEC (attached + unattached) for (222)Rn and (220)Rn was 29.28 and 2.74 Bq/m(3). For (222)Rn (f Rn) and (220)Rn (f Tn), the average values of unattached fraction were 0.11 and 0.09, respectively. The equilibrium factors for radon (F Rn) and thoron (F Tn) varied from 0.12 to 0.77 with an average of 0.50, and from 0.01 to 0.34 with an average of 0.05, respectively. The annual inhalation dose due to mouth and nasal breathing was calculated using dose conversion factors and unattached fractions. The indoor annual effective doses for (222)Rn (AEDR) and (220)Rn (AEDT) were found to be 1.92 and 0.83 mSv a(-1), respectively. The values of (222)Rn/(220)Rn concentrations and annual effective doses obtained in the present study are within the safe limits as recommended by the International Commission on Radiological Protection for indoor dwelling exposure conditions.

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“…In many calculations, these parameters were treated as independent and their best estimations were used; and in some works these parameters were chosen uniformly and randomly in some range given in Table 1. Mishra et al (2009) have measured the deposition velocities of 222 Rn (radon) and 220 Rn (thoron) progeny in a chamber and in a test house using passive track detectors.…”

Section: Introductionmentioning

confidence: 99%