• 한국산업보건학회지
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• 제26권2호
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• pp.109-118
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• 2016

Objectives: To review reference levels by the international and domestic management and provide the basis for setting occupational exposure limits(OELs) of radon in Korea Methods: Government's organizations with laws and systems for monitoring radon exposure were investigated and compared. There are five laws governing Indoor Air Quality(IAQ) control such as Occupational Safety and Health Act, Indoor Air Quality Control in Public Use Facilities, Etc. Act, School Health Act, Public Health Control Act and Parking Lot Act in Korea. It was surveyed that a total of 32 countries including 24 countries in the European Union(EU), six countries in Asian and two countries in North America setting the reference levels for radon in the world. Results: In Korea, there are set guidelines for radon in the Ministry of Environment and the Ministry of Education. Reference levels of radon for existing dwellings were $150{\sim}400Bq/m^3$ for Western European countries, and $200{\sim}1,500Bq/m^3$ in Eastern European countries. Approximately 67% of those EU countries were set up $400Bq/m^3$ to the standards for existing dwellings. EU countries such as Luxembourg, Finland, Norway, Sweden and Russia had adopted mandatory level for radon. Radon guidelines for new dwellings were set more strictly reference level($200Bq/m^3$) than existing dwellings. Conclusions: International organizations such as ICRP, UNSCEAR and NCRP, etc. had recommended the guidelines for radon. It was calculated the relation of the dose conversion factors with the annual effective doses. the OELs of radon suggest to need to establish $150Bq/m^3$ for office room and $400{\sim}1,000Bq/m^3$ for the workplace.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4096-4101
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• 2023

Radon is a radioactive gas produced from the uranium-238 series. Radon gas affects public health and is the second cause of lung cancer. The study samples were collected from one area of the city of Jazan, southwest of the Kingdom of Saudi Arabia. The influence of engineering and physical parameters on the emanation coefficient of gas and other gas parameters was studied. Parameters for radon were measured using a CR-39 Solid-State Nuclear Track Detector (SSNTD) through a sealed emission container. The results showed that the emanation coefficient was affected directly by the change in the grain size of the soil. All parameters of measured radon gas have the same behavior as the emanation coefficient. The relationship between particle size and emanation coefficient showed a good correlation. The values of the emanation coefficient were inversely affected by the mass of the sample, and the rest of the parameters showed an inverse behavior. The results showed that increasing the volume of the container increases the accumulation of radon sons on the wall of the container, which increases the emission factor. The rest of the parameters of radon gas showed an inverse behavior with increasing container size. The results concluded that changing the engineering and physical parameters has a significant impact on both the emanation coefficient and all radon parameters. The emanation coefficient affects the values of the radiation dose of an alpha particle.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2370-2378
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• 2020

Building materials contribute significantly to the indoor radon and thoron levels. Therefore, parameters that influence the exhalation rates of radon and thoron from building material need to be analyzed closely. As a preliminary study, the effects of humidity on exhalation rates were measured using a system with an accumulation chamber and RAD7 detector for Korean brick, Korean soil, and Indonesian brick. Resulting doses to a person who resides in a room constructed from the building materials were assessed by UNSCEAR method for different air exchange rates. The measurements have revealed that Korean brick exhaled the highest radon and thoron while Indonesian brick exhaled the lowest thoron. Results showed that for a typical low dense material, radon and thoron exhalation rate will increase until reached its maximum at a certain value of humidity and will remain saturated above it. Analysis on concentration and effective dose showed that radon is strongly affected by air exchange rate (ACH). This is showed by about 66 times decrease of radon dose from 0.00 h^-1 to those of 0.50 h^-1 ACH and decrease by a factor of 2 from 0.50 h^-1 to those of 0.80 h^-1. In case of thoron, the ACH doesn't have significant effects on effective dose.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1289-1296
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• 2020

The estimation of radioactivity level is vital for population health risk assessment and geological point of view and can be evaluated as rate of exhalation and source concentration (²²⁶Ra, ²³²Th and ⁴⁰K). The present study deals with the soil samples for investigation of radionuclides content and exhalation rates of radon -thoron gas from different sites in northern Haryana, India. Absorbed dose and associated index estimated in the present study are the measures of environmental radioactivity to inhalation dose. Effective doses received by different tissues and organs by considering different occupancy and conditions are also measured. Exhalation rates of radon and thoron are measured with active scintillation monitors based on alpha spectroscopy namely scintillation radon (SRM) and thoron (STM) monitors respectively. Sample height was optimized before measurement of thoron exhalation rate using STM. Average values of radon and thoron exhalation are found 16.6 ± 0.7 mBqkg^-1h^-1 and 132.1 ± 2.6 mBqm^-2s^-1 respectively. Also, a simple approach was also adopted, to evaluate the thoron exhalation which accomplished a lot of challenges, the results are compared with the data obtained experimentally. The study is useful in the nationwide mapping of radon and thoron exhalation rates for understanding the environmental radioactivity status.

• 한국환경과학회지
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• 제15권4호
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• pp.311-317
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• 2006

The purpose of this study was to investigate Rn concentration and annual radiation exposure level in the basement and first floor. The Rn Cup monitors were placed in different environments such as shopping stage, office building, Apartment, Hospital, house in Seoul from Match 1996 to April 1997 and CR-39 films were collected every two months. The mean radon concentration in the basement of house($88.6\;Bq/m^3$) showed the highest level among the areas, while radon concentration on the first floor of house($50.5\;Bq/m^3$) showed the higher than other areas. The annual radiation exposure dose that person on the floor / in the basement of differential place in the seoul can be exposed during living was estimated from 24.11 to 87.64 mRem/yr. This radiation dose is significantly lower than 130mRem maximum radiation dosage from the radon nuclide prescribed by the ICRP, with respect to the overall average exposure of the working adult. this study indicated that possible radon sources on the first floor / in the basement areas are radon intrusion from soil gas, construction materials, or ground water leaking. Further study is needed to quantitatively assess major contributions of radon-222 and health effect to radon exposure.

• 한국산업보건학회지
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• 제27권1호
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• pp.38-45
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• 2017

Objectives: Radon may be second only to smoking as a cause of lung cancer. Radon is a colorless, tasteless radioactive gas that is formed via the radioactive decay of radium. Therefore, radon levels can build up based on the amount of radium contained in construction materials such as phospho-gypsum board or when ventilation rates are low. This study provides our findings from evaluation of radon gas at facilities and offices in an industrial complex. Methods: We evaluated the office rooms and processes of 12 manufacturing factories from May 14, 2014 to September 23, 2014. Short-term data were measured by using real-time monitoring detectors(Model 1030, Sun Nuclear Co., USA) indoors in the office buildings. The radon measurements were recorded at 30-minute intervals over approximately 48 hours. The limit of detection of this instrument is $3.7Bq/m^3$. Also, long-term data were measured by using ${\alpha}-track$ radon detectors(${\alpha}-track$, Rn-tech Co., Korea) in the office and factory buildings. Our detectors were exposed for over 90 days, resulting in a minimum detectable concentration of $7.4Bq/m^3$. Detectors were placed 150-220 cm above the floor. Results: Radon concentrations averaged $20.6{\pm}17.0Bq/m^3$($3.7-115.8Bq/m^3$) in the overall area. The monthly mean concentration of radon by building materials were in the order of gypsum>concrete>cement. Radon concentrations were measured using ${\alpha}-track$ in parallel with direct-reading radon detectors and the two metric methods for radon monitoring were compared. A t-test for the two sampling methods showed that there is no difference between the average radon concentrations(p<0.05). Most of the office buildings did not have central air-conditioning, but several rooms had window- or ceiling-mounted units. Employees could also open windows. The first, second and third floors were used mainly for office work. Conclusions: Radon levels measured during this assessment in the office rooms of buildings and processes in factories were well below the ICRP reference level of $1,000Bq/m^3$ for workplaces and also below the lower USEPA residential guideline of $148Bq/m^3$. The range of indoor annual effective dose due to radon exposure for workers working in the office and factory buildings was 0.01 to 1.45 mSv/yr. Construction materials such as phospho-gypsum board, concrete and cement were the main emission sources for workers' exposure.

• Environmental Analysis Health and Toxicology
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• 제24권3호
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• pp.203-211
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• 2009

A lesser degree of research is available with respect to indoor radon characteristics associated with occupants' exposure. The present study evaluated the radon levels in several public-access buildings or underground facilities, and their temporal variation in underground facilities. Radon measurements were conducted in 2005 and 2006, utilizing a continuous radon detector. A solid alpha detector (RAD7) was utilized to measure indoor radon levels. The mean radon concentrations obtained from the building or facilities were in a descending order: platforms of Daegu subway line 2, 2005 (32 $Bq/m^3$), hot-air bathroom (14 $Bq/m^3$), basement of office building (14 $Bq/m^3$), underground parking garage (14 $Bq/m^3$), underground shop (12 $Bq/m^3$), nursery (10 $Bq/m^3$), platforms of Daegu subway line 2, 2006 (9.0 $Bq/m^3$), platforms of Daegu subway line 1, 2006 (8.9 $Bq/m^3$), supermarket (7.9 $Bq/m^3$), hospital (7.3 $Bq/m^3$), and second-floor of office building (5.7 $Bq/m^3$). In general, underground-level facilities exhibited higher radon levels as compared with ground-level facilities. It was suggested that ventilation is an important parameter regarding the indoor levels of a subway. There was a decreasing or increasing trend in hourly-radon levels in a subway, whereas no trend were observed in a basement of office building. In addition, the radon levels in the subway lines 1 and 2 varied according to the platforms. The radon levels in the present study were much lower than those of previous studies. The average annual effective dose (AED) of radiation from indoor radon exposure was estimated to be between 0.043 and 0.242 mSv/yr, depending on facility types. These AEDs were substantially lower than the worldwide average AED (2.4 mSv/yr).

• Journal of Radiation Protection and Research
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• 제32권3호
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• pp.97-104
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• 2007

전주시에 소재한 아파트의 큰 방과 작은 방을 대상으로 실내 체적과 측정되는 라돈 농도와의 상관 관계를 분석하였다. 또한 실내의 라돈 농도를 측정하여 실내의 시간별 라돈 농도의 변화를 파악하고 이를 토대로 실내 라돈의 년간 피폭선량을 계산하였다. 본 연구를 위하여 각각 8개의 아파트 큰 방과 작은 방을 대상으로 라돈 농도를 측정하였으며, 큰 방의 평균 체적은 $31.59\;m^3$ 그리고 작은 방의 평균 체적은 $16.82\;m^3$이었다. 큰 방의 평균 라돈 농도는 $71.73\;Bq/m^3$, 작은 방의 평균 라돈 농도는 $108.51\;Bq/m^3$로 측정되어 실내 체적과 실내 라돈 농도는 반비례 관계로 나타났다. 밀폐된 실내 라돈 농도의 주 발생원이 건축자재임을 감안하여 건물 벽의 표면적을 체적으로 나누어 계측해 본 결과 표면적/체적의 비가 클수록 측정되는 실내 라돈 농도가 크게 나타났다. 실내 라돈 농도의 하루 중 시간에 따른 변화를 조사한 결과 오전 $8{\sim}10$시에 일 최고 농도($114.5\;Bq/m^3$)를 보였고, 오후 $2{\sim}4$시에 일 최저농도($67.7\;Bq/m^3$)를 나타냈으며, 하루 중 라돈 농도의 변화는 약 $46.8\;Bq/m^3$이었다. 8개 지점의 실내 라돈의 연간 피폭선량을 계산해 본 결과 0.3에서 2.16 mSv/yr사이로 나타나, 일부 아파트의 피폭선량이 국제방사선영향과학위원회(UNSCEAR)가 제시한 수치인 1.3 mSv/yr를 초과했다.

• Journal of Radiation Protection and Research
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• 제16권1호
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• pp.1-13
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• 1991

국내 12개 지역의 340여 실내에서 측정한 라돈농도로부터 단순한 수학적 폐선량 평가모형을 이용하여 주민의 실효선량당량을 평가하였다. 수동적 시간적분형 CR-39 라돈컵으로 1990년 4월부터 10월까지 $3{\sim}4$개월 동안 측정 한 실내의 라돈농도는 지역별로 $33.82{\sim}61.42 Bq/m^3$(평균 : $48.90 Bq/m^3$)의 분포를 보였으며, 이로 인한 라돈자핵종의 평형등가라 돈농도$(EEC_{Rn})$는 라돈과 자핵종간의 평형인자의 값 0.4를 적용했을 때 $13.53{\sim}24.57Bq/m^3$(평균 : $19.55 Bq/m^3$)으로 예상되었다. 국제방사선방어위원회의 폐모형에 근거한 본 연구의 폐선량 평가모형에서 유도된 단위 평형등가라돈농도의 피폭당 실효선량당량환산 인자는 $1.07{\times}10^{-5}\;mSv/Bq\;h\;m^{-3}$으로 국제방사선방어위원회나 국제연합 방사선영향평가 과학위원회(UNSCEAR)에서 권고한 값과 잘 일치하였다. 동 선량환산인자와 CR-39 라돈 컵으로 측정 한 실내 의 평균 평형등가라돈농도를 년간 $0.75 m^3/h$의 호흡율로 호흡한 것으로 가정했을 때, 주민이 받는 년평균 폐선량당량 및 실효선량당량은 갹각 20.90 mSv 및 1.25 mSv인 것으로 평가되었다. 동 피폭선량은 국제연합(UNSCEAR)에서 1988년에 발표한 일반인의 년평균 자연방사선피폭 실효선량당량인 2.40mSv의 거의 50%에 상당하였다.

• Journal of Korean Society for Atmospheric Environment
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• 제17권E2호
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• pp.43-51
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• 2001

A report by the national research council in the United States suggested that many lung cancer deaths each year be associated with breathing radon in indoor air. Most of the indoor radon comes directly from soil beneath the basement of foundations. Recently, radon released from groundwater is found to contribute to the total inhalation risk from indoor air. This study presents the quantitative assessment of human exposures to radon released from the groundwater into indoor air. At first, a three-compartment model is developed to describe the transfer and distribution of radon released from groundwater in a house through showering, washing clothes, and flushing toilets. Then, to estimate a daily human exposure through inhalation of such radon for an adult. a physiologically-based pharmacokinetic(PBPK) model is developed. The use of a PBPK model for the inhaled radon could provide useful information regarding the distribution of radon among the organs of the human body. Indoor exposure patterns as input to the PBPK model are a more realistic situation associated with indoor radon pollution generated from a three-compartment model describing volatilization of radon from domestic water into household air. Combining the two models for inhaled radon in indoor air can be used to estimate a quantitative human exposure through the inhalation of indoor radon for adults based on two sets of exposure scenarios. The results obtained from the present study would help increase the quantitative understanding of risk assessment issues associated with the indoor radon released from groundwater.