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To investigate the behaviours and influence factors of radon progeny in rural dwellings in China, site measurements of radon equilibrium factor, unattached fraction and some important indoor environmental factors, such as aerosol concentration, aerosol size distribution and ventilation rate, were carried out in three typical types of dwellings, and...
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Inhalation of radon and its progeny are the most important component of public exposure to natural radiations. Many epidemiological studies have established the fact that radon and radon progeny are associated with increased incidence of lung cancer. Beside health concerns, radon is an important consideration in other fields, e.g. hydrological rese...
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... According to the ICRP recommendations, the indoor equilibrium factor was estimated a value 0.4. However, previous experimental studies have shown that the meteorological factors such as the ventilation rate, temperature and moisture have impacts on indoor equilibrium factor (Rozas et al., 2016;Chen et al., 1998;Li et al., 2011;Ramola et al., 2003;Chu and Liu, 1996). ...
The equilibrium factor is an important parameter for reasonably estimating the population dose from radon. However, the equilibrium factor value depended mainly on the ventilation rate and the meteorological factors. Therefore, this study focuses on investigating numerically the influence of the ventilation rate, temperature and humidity on equilibrium factor between radon and its progeny. The numerical results showed that ventilation rate, temperature and humidity have significant impacts on indoor equilibrium factor. The variations of equilibrium factor with the ventilation, temperature and relative humidity are discussed. Moreover, the committed equivalent doses due to ²¹⁸Po and ²¹⁴Po radon short-lived progeny were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of indoor air. The annual effective dose due to radon short lived progeny from the inhalation of indoor air by the members of the public was investigated.
... Different from EEC, the unattached fraction varies from 3.86% to 14.03% within 24 h, and has no obvious diurnal variation. This can be explained by the fact that the unattached fraction of radon progeny is influenced by more environmental factors, such as aerosol concentration and size distribution as well as ventilation [18], and the level of f p is a comprehensive result. ...
The unattached fraction of radon progeny is one of the most important factors for radon exposure evaluation through the dosimetric approach. To better understand its level and variation in the real environment, a series of field measurements were carried out indoors and outdoors, and radon equilibrium equivalent concentration was also measured. The dose contribution of unattached radon progeny was evaluated in addition.
The results show that no clear variation trend of the unattached fraction of radon progeny is observed in an indoor or outdoor environment. The average unattached fraction of radon progeny for the indoors and outdoors are (8.7 ± 1.6)% and (9.7 ± 2.1)%, respectively. The dose contribution of unattached radon progeny to total radon exposure is some 38.8% in an indoor environment, suggesting the importance of the evaluation on unattached radon progeny.
After decades of development, the indoor environment in China has changed. A systematic review was conducted from peer-reviewed scientific papers with field test data of indoor radon in China from 2000 to 2020 for three types of buildings. The mean concentrations of indoor radon for dwellings, school buildings, and office buildings are 54.6, 56.1, and 54.9 Bq/m³. The indoor radon concentration was related to seasons, climate regions, ventilation, decoration, and other factors such as soil and outdoor air. Colder seasons, especially in severe colder areas of China, newer decorated buildings, closed windows, and doors were all associated with higher indoor radon concentrations. Variables like climate region and ventilation showed statistical significance in the correlation analysis. Regarding the increasing trend of indoor radon concentration in China during the last two decades, further study of indoor radon is necessary especially for school buildings and office buildings, and will help access its environmental burden of disease in China more accurately.
Radon exposure limits are given in terms of radon gas concentration in the air. However, in the calculation of radon dose to the lung, the radon equilibrium equivalent concentration is used. The measured equilibrium factor times the measured radon gas concentration estimates the equilibrium equivalent concentration. Therefore, the equilibrium factor is an important factor in radon dose calculations. A review of published measurements of equilibrium factors shows a range of values reported in studies from more than 20 countries, measured in indoor residential, indoor public, and outdoor environments. Values for ²²²Rn are reported and discussed here, with special attention paid to results from India and China, where measured equilibrium factors are reported for hundreds and thousands of households, respectively. The wide range of equilibrium factors suggests that location-specific values are more appropriate than a worldwide average value in the calculation of lung bronchial dose.
The activity concentrations of ²¹⁸Po, ²¹⁴Pb and ²¹⁴Bi [i.e. C(²¹⁸Po), C(²¹⁴Pb), and C(²¹⁴Bi)] and the calculated concentration ratios [i.e. 1:C(²¹⁴Pb)/C(²¹⁸Po):C(²¹⁴Bi)/C(²¹⁸Po)] are necessary for assessing radon and its progenies exposure. In this study, a measurement method of radon progenies concentrations with both high sensitivity and low uncertainty, was developed based on the Kerr method. The field measurement results of radon progeny concentrations and calculated concentration ratios in both typical indoor and outdoor environments in Beijing, China, were reported. The effects of air exchange rate on concentration ratios of radon progenies in indoor environments were discussed.
Some low-income people of Pakistan live in traditional windowless one- to two-room houses made of mud. The data on radon concentration in such houses of Pakistan was scarce in the literature. Therefore, 60 mud houses in the vicinity of the city of Lahore (the capital of the Punjab province of Pakistan) were selected for survey of radon in these houses. The passive integrating technique with CN-85 track detectors was employed for the measurement of radon. Indoor and outdoor radon concentrations were determined to be 114.88 +/- 66.79 (18.37 - 269.58) and 10.78 +/- 2.70 (8.08 - 13.57) Bq m(-3), respectively. Radon concentration was higher in the mud-made houses than that in the dwellings constructed of bricks and Portland cement. Radon exhalation rate from the walls and floors of the mud houses was measured to find the correlation with indoor radon concentration. A weak positive correlation was observed between these two quantities. From the measured concentration of radon, annual effective dose and excess lifetime cancer risk were derived to be 2.54 +/- 1.47 (0.41-5.95) mSv and (15.34 +/- 8.92)x10(-3) (1.53 +/- 0.89 %), respectively. Relatively higher radon concentration in the mud houses was due to the little exchange of air in these houses. Ventilation is recommended for the mitigation of radon from these houses.
The unattached fraction of radon progeny (fp) is one of the most important factors for accurate evaluation of the effective dose from a unit of radon exposure, and it may vary greatly in different environments. For precise evaluation of the indoor radon exposure dose and the influence of unattached radon progeny, a pilot survey of fp in different environments was carried out in China with a portable and integrating monitor. The dose conversion factors for radon progeny are calculated with LUDEP® code, and the dose contributions from the unattached and the attached radon progenies were simultaneously evaluated based on the results of field measurements.
The results show that even though the concentrations of radon progeny vary significantly among different indoor environments, the variations of fp seem relatively small (9.3–16.9%). The dose contribution from unattached radon progeny is generally larger (30.2–46.2%) in an indoor environment.
