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Objective To primarily investigate the indoor radon concentrations in the urban and rural dwellings in Yinchuan, China, and to estimate the effective dose. Methods A total of 67 dwellings, which included 49 urban households and 18 rural households in Yinchuan, were selected to cumulatively measure the indoor radon concentrations for more than 3 months using solid state nuclear track detection. Results The arithmetic mean, geometric mean, median, and range of indoor radon concentrations in urban and rural areas in Yinchuan were 64 Bq/m3, 59 Bq/m3, 57 Bq/m3, and 25-172 Bq/m3, respectively. Surveillance sites with an indoor radon concentration higher than 100 Bq/m3 accounted for 7.5%. Indoor radon concentrations in rural areas were higher than those in urban areas. Indoor radon concentrations were highest in winter and lowest in summer. The effective dose of indoor radon exposure among residents in Yinchuan was 1.86 mSv/a. Conclusion The results of indoor radon concentrations measured in this investigation in Yinchuan are significantly higher than those measured in the 1990s. The annual effective dose is higher than the mean levels in the world and China.
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@#<b>Objective</b> To monitor the indoor radon concentration of urban residents in Shiyan, China, and to analyze the related influencing factors. <b>Methods</b> From April to July, 2019, RSKS standard detectors were used to measure the indoor radon concentration of 125 households in Shiyan, and the results were analyzed. <b>Results</b> The indoor radon concentration of residents in Shiyan showed a skewed distribution, ranging from 13.8 to 145 Bq/m<sup>3</sup>, and <i>M</i> (<i>P</i><sub>25</sub>,<i>P</i><sub>75</sub>) was 38.3 (29.0,62.0) Bq/m<sup>3</sup>. The estimated annual effective dose of radon and radon daughters from inhalation was 0.52-5.50 mSv, and <i>M</i> (<i>P</i><sub>25</sub>,<i>P</i><sub>75</sub>) was 1.45 (1.10, 2.36) mSv, which was consistent with literature. Building structure (<i>H</i> = 14.10, <i>P</i> < 0.001), floor (<i>H</i> = 24.41, <i>P</i> < 0.001), and geographical region (<i>H</i> = 8.963, <i>P</i> < 0.05) were influencing factors of indoor radon concentration, and the differences were significant. <b>Conclusion</b> The indoor radon concentration of urban residents in Shiyan is lower than the national standard limit. However, in daily life, it is still necessary to take appropriate measures to reduce the concentration of indoor radon as much as possible.
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@#<b>Objective</b> To investigate and analyze the levels of γ dose rate and radon concentration at all sites in a large open-pit coal mine with radioactivity that had been mined for many years in Xinjiang, China, and to estimate the effective dose exposed to the personnel. <b>Methods</b> A portable γ dose-rate instrument FH40G was used for fixed-point monitoring of the mining area, and a continuous radon detector was used for 24 h continuous monitoring of radon concentration level in the site. The personnel exposure dose was estimated according to the measured γ dose rate and radon concentration. <b>Results</b> In this open-pit coal mine, the range of γ dose rate was 51.4-435.8 nGy/h; the mean 24 h radon concentration was 15-25 Bq/m<sup>3</sup>; the range of annual effective dose to the personnel was 0.29-1.29 mSv/a. <b>Conclusion</b> According to the results of the survey, radon concentration levels at all sites are low, and no remedial action is required. The personnel exposure dose at most of the sites is far below the standard requirements, and some protective measures need to be taken in some areas of the dump.
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@#<b>Objective</b> To investigate the indoor radon concentration and its changing trend in northeastern China. <b>Methods</b> We measured indoor radon levels cumulatively for over three months by solid state nuclear track detection in a total of 261 houses in multi-story or high-rise buildings in Shenyang, Changchun, Harbin, Heihe, and Yichun in northeastern China. The measurement lasted one year in Changchun for seasonal changes. <b>Results</b> The average indoor radon concentration in the five cities was 88 Bq/m<sup>3</sup>, ranging from 12 to 558 Bq/m<sup>3</sup>. The indoor radon concentrations were ≤ 100 Bq/m<sup>3</sup> in 75.1% of the houses, and ≤ 300 Bq/m<sup>3</sup> in 97.7% of the houses. The indoor radon concentration increased with the age of buildings. The indoor radon concentration was highest in winter, and it was higher in summer than in autumn and spring. <b>Conclusion</b> The indoor radon concentration in northeastern China increased compared with the data of 1980s and 1990s. It is highest in the winter heating season, and higher in summer than in spring and autumn. Indoor radon exposure deserves attention.
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Objective:To study the levels and variation of equilibrium factor in indoor environment.Methods:A one-year continuous measurement of radon concentration and equilibrium equivalent radon concentration was carried out in an indoor office building of Nanning city. The effective data acquisition rates of radon gas and radon progeny were 99.9% and 86.7%, respectively.Results:The annual average activity concentration and equilibrium equivalent radon concentration in indoor environment were (50.9±20.7)and (15.5±10.1)Bq/m 3, both of which had the same diurnal and seasonal variation. The average annual value of equilibrium factor was 0.30±0.12, showing no obvious diurnal variation. The distribution of monthly mean value of equilibrium factor showed a similar trend to that of radon and radon progeny. The highest and the lowest value appeared in November and June, respectively, with 0.47±0.24 and 0.19±0.06. Conclusions:Due to the large variation range of monthly mean value of equilibrium factor in indoor environment, when annual effective dose of radon exposure was estimated based on radon gas concentration, attention should be paid to choose the quantity value of equilibrium factor and the uncertainty caused by the change of equilibrium factor should be considered.
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@#Abstract: Objective In order to understand the radon exposure level of homes in Chongqing, this survey was carried out on the indoor radon concentration in 38 districts and counties of Chongqing. Methods According to the population ratio of every 100 000 people, one monitoring site was arranged, and the number of parallel samples was 10% of the distribution sites. The monitoring sites covered 38 districts and counties in Chongqing. A total of 1 019 residential monitoring sites in 38 districts and counties in Chongqing were measured with radon accumulation detectors from July 2020 to June 2021. Results The five districts/counties in Chongqing having the highest average concentration of residential radon in the year were Xiushan County 78.8 Bq/m3, Qianjiang District 78.0 Bq/m3, Yubei District 73.9 Bq/m3, Youyang County 71.4 Bq/m3 and Shapingba District 69.8 Bq/m3. The five districts/counties with the lowest mean concentration of indoor radon were 37.6 Bq/m3 in Zhongxian County, 36.4 Bq/m3 in Changshou District, 33.7 Bq/m3 in Kaizhou District, 33.2 Bq/m3 in Liangping District and 27.3 Bq/m3 in Wushan County. The concentration levels of radon in four seasons were 46.0 Bq/m3, 53.4 Bq/m3, 45.1 Bq/m3 and 59.5 Bq/m3, respectively. The concentration of radon was higher in Summer and Winter, and lower in Spring and Autumn, and the difference of concentration among four seasons was statistically significant (P<0.001). The radon concentration of newly built buildings after 2017 was relatively high, up to 61.8 Bq /m3, but there was no statistical significance in radon concentration in different building ages (P>0.05). The concentration of radon in rooms of buildings with less than 10 floors was higher, up to 63.2 Bq /m3, and there were significant differences in radon concentration among rooms of different floors (P<0.05). The average annual radon concentration in houses in Chongqing was about (51.6±19.5) Bq/m3, and the average annual effective dose of inhaling radon and its progeny by house-related people was about (1.38±0.52) mSv. Conclusion The average annual radon concentration level of houses in Chongqing is within the standard limit value recommended by China, but the prevention and control of radon should be strengthened.
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Objective:To obtain the distribution characteristics of radon levels in drinking water in cities of China and analysis their influencing factors.Methods:A total of 31 cities were selected and 406 tap water samples were collected in accordance with the sampling plan based on administrative division. Radon concentrations in the water samples were determined by using RAD7 H 2O measuring devices, and the closed loop liquid-gas balance method and grab method . The radon concentrations in the gas loop were measured by using semiconductor detector. After four measurement periods, radon concentrations in water were calculated. Results:The arithmetic mean of radon concentrations in drinking water from 31 cities was (4.92±9.44) Bq/L and the geometric mean (0.71±7.77) Bq/L, ranging from less than the lower detection limit (LLD) to 43.15 Bq/L. For 84.2% of drinking water samples, radon concentrations were less than US EPA recommended 11.1 Bq/L, all lower than the EU-recommended value of 100 Bq/L.Conclusions:The radon concentrations in drinking water are higher in northeastern, northwestern, southwestern, northern China than those in southern, central China and eastern China. The factors influencing radon concentrations in drinking water are closely related to geological structure and water source type. Compared with the global values, the radon concentrations in drinking water in our cities are low and safe in general in China.
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Objective To explore the source and control of radon in high radon houses in geothermal fields; Methods Radon concentration in indoor and soil was measured by ATD detector in winter and summer; radionuclides in building materials were measured by gamma-ray spectrometry; radionuclides dose rates of building materials were measured by 6150 A D/ 6H X-γ ray detector; and radon reduction technology was applied to one of the houses;Results The average radon concentrations in 32 rooms were （106.4 ± 63.7） Bq/m3 (summer) and （421.3 ± 138.2） Bq/m3 (winter), and the concentrations in 12.5% (summer) and 96.9% (winter) of the rooms exceed 150 Bq/m3. The average radon concentration in soil around buildings was 12890 Bq/m3 (n = 24), which is 1.7 times of the typical soil radon concentration in Beijing (7600 Bq/m3). After soil decompression, the radon concentration in the house could be reduced to less than 100 Bq/m3. The radon reduction rates of active decompression and passive decompression were 94.6% and 71.4%, respectively. Conclusion The effect of soil decompression on reducing radon concentration in the bottom rooms is obvious. Attention should be paid to the radon in residential environment of geothermal field.
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Objective To investigate the residential radon concentration in typical areas of Hubei Province and assess the dose hazards of radon to human body. Methods According to geographical location, five cities including Wuhan, Enshi, Shiyan, Xianning and Daye were selected, and the stratified cluster sampling and monitoring were conducted in accordance with the residential building structure. From April to July, 2019, RSKS standard detectors were placed in the bedroom or living room of the tested families. After continuously sampling for three months, those detectors were returned back to the laboratory for test readings using Radosys system. Results A total of 651 detectors were deployed in 577 households of 70 communities, and 634 detectors were recovered. The recovery rate of detectors was 97.4%. The indoor residential radon concentration in Hubei Province showed a logarithmic normal distribution, with a median (25% quantile and 75% quantile) of 40.52 (29.13,64.74) Bq/m3 and an annual effective dose of 2.02 mSv. The indoor radon concentrations in Wuhan and Enshi were significantly higher than those in Shiyan, Xianning and Daye (P<0.05). The indoor radon concentrations in brick wood or civil structures were significantly higher than those in reinforced concrete structures (P<0.05), and indoor radon concentration in the first floor was significantly higher than those in other floors (P<0.05). The indoor radon concentrations after 2010 were significantly lower than those between 2001 and 2010 (P<0.05). Conclusion The number of households with indoor radon concentrations exceeding the national limit in newly-built buildings accounted for 10.1%; The indoor residential radon concentration levels of in Hubei Province were influenced by building structure, age and floor.
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Objective To investigate the relationship between indoor radon concentration and air exchange rate for new residential building.Methods The indoor radon concentration and air exchange rate were measured in two new roughcast houses in Guangzhou and Hefei,respectively.The radon concentration was measured using radon instrument.The air exchange rate was measured by using tracer gas dilution method.Results The indoor radon concentrations measured in Guanzhou for two bedrooms in a 48-hour closed condition were 106 and 115 Bq/m3,the range of 17-181 and 6-224 Bq/m3.Air exchange rates were 0.16/h and 0.21/h.In Hefei,the twice measured values for one bedroom were 148 and 186 Bq/m3,the range of 8-224 and 14-290 Bq/m3,and air exchange rates were 0.14/h and 0.12/h.The indoor radon concentration exponentially decreased with the increase of air exchange rates.Conclusions Attention should be paid to the indoor radon pollution issue that may arise in new residential buildings of energy-saving design due to low air exchange rate.
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Objective To investigate the levels and distribution of radon in dwellings in Shenzhen cities of China.Methods A total of 108 low-,multi-,middle-and high-rise buildings were selected.Indoor radon concentrations were measured by using solid track detector.Results The arithmetic mean of indoor radon concentrations in Shenzhen was 64 Bq/m3,and geometric mean was 58 Bq/m3,in range of 15 to 155 Bq/m3.The average indoor radon concentration in Bao'an district was 50 Bq/m3 with the lowest value,and that in Pingshan new district was 87 Bq/m3 with the highest value.There were 12 measuring points where indoor radon concentrations were higher than 100 Bq/m3 in Shenzhen,accounting for 11.1％ of the total number.Shapiro-Wilk test showed that the frequency distribution of indoor radon concentration in Shenzhen follows lognormal distribution (P ＞ 0.05).The indoor radon concentrations showed a downward trend from 1990 to 2015.The indoor radon concentration decreases with the elevated floors except 10th and above floors.Conclusions The indoor radon concentrations in Shenzhen increased by 35％,compared to the previous investigations.It is recommended that efforts continue to improve radioactive materials standards about building material and to enhance the natural ventilation in high-rise buildings in order to lower the radiation hazards from radon.
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Objective To analyze the indoor radon level and distribution characteristic in different geological background by studying the indoor radon level in three typical areas in Zhuhai City.Methods The region of investigation includes three districts:granite area in Zhuhai District,granite area in Doumen District and the Quaternary sedimentary area in Doumen District.Activated charcoal adsorption method was used to measure the indoor radon concentrations.In some sampling sites,solid state nuclear track detectors were used at the same time for the indoor radon measurement.Results The average indoor radon level included 80 buildings was (66.0 ± 49.8) Bq/m3 using activated charcoal adsorption method and the maximum value was 1078.5 Bq/m3.The results of 23 sampling sites show that the average indoor radon level using solid state nuclear track detectors was (88.8 ± 49.1) Bq/m3,and (69.5 ± 37.7) Bq/m3 by activated charcoal adsorption method.The indoor radon concentration was (73.6 ± 61.0),(87.5 ± 58.3) and (48.6 ± 22.6) Bq/m3 in granite area in Zhuhai District,granite area in Doumen District and the Quaternary sedimentary area in Doumen District,respectively.Conclusions The surface lithology of an area has a certain impact on the indoor radon level.The indoor radon level in granite area in Zhuhai District and Doumen District is apparently higher than that in the Quaternary sedimentary area in Doumen District.The study of indoor radon level and distribution characteristic should be discussed in combination with geological background of area.
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Objective To investigate the radiation level around Jiangzha hot spring,and to analyze the sources of pollution.Methods The radon and its progeny concentration,γ dose rate in hot spring living district and surrounding area were measured with ATD monitors,radon and WL continuous measurement devices,γ dose rate meter.Results The radon concentration in water was 23 -764 Bq/L.Radon concentration indoors,outdoor and in bathing place were 254 -876 799,688 -709 and 3590-15 299 Bq/m3,respectively.γ dose rate were 205 -28718 nGy/h indoor,4104- 18254 n Gy/h outdoors.Conclusions Jiangzha hot spring is an area with rare high radon and high nature radiation.Its radiation level and health effects are worthy for further attention.