This study was designed to verify what effect the use of a natural ventilation system can have on improving indoor air quality with regard to radon in various concentration ranges in an apartment house. The results show that both high (2~3 times higher than 148 m3) and low (similar to 148 Bq/m3) levels of indoor radon concentrations can be reduced close to and/or below the Korean IAQ guideline within 6 hours when the natural ventilation system is operated at approximately an air change rate of 0.5. In the case of an air change rate of 0.3, however, the indoor radon levels cannot meet the national guidelines and the reduction effect was insufficient with regard to various radon concentrations. Typically, the air change rate of a natural ventilation system is affected by meteorological factors such as temperature, relative humidity, wind speed, pressure. Its effectiveness varies according to such factors, for that reason, the reduction effects on radon did not increase proportionally with the ventilation time in this study.

We investigated the distributions of airborne radon concentration on the platforms of the stations of Seoul Metro by the underground depth of each subway line, and explored the correlation between the radon concentration and the depth and geological conditions around each underground station. The measurements of radon levels were performed in 254 subway stations within Seoul Metro Lines 1 to 8 using the passive sampler (RADUET). Radon concentration data from 2007 to 2017, as well as the depth of each subway station were obtained from the Seoul Metro corporation. The geological information of each subway station were purchased from the Korea Institute of Geoscience and Mineral Resources. Student t-test and correlation analyses were performed to compare the levels of radon by the depth of subway stations, and to investigate the association of radon levels based on geological information. The geometric mean concentration of the all subway stations was 27.9 Bq/m3 ( range, 3 . 7Bq/ m3~124.0 Bq/m3). The depth of Lines 5-8 (geometric mean, –20.3 m) was significantly deeper by about 50% or more than that of Lines 1-4 (–13.1 m) (P<0.01). The radon levels increased significantly in deeper depths and as the number of Lines increased (P<0.05). A significant higher mean concentration of radon above the igneous rock (33.0 Bq/m3) was observed, comparing to that of non-igneous rock (27.5 Bq/m3) (P<0.00001). Our findings indicate that the deeper the subway is built or the more it is constructed on the granite area, the more careful management, including frequent ventilation and measurement monitoring, is necessary.

Radon is a radioactive gas material, which is not detectable by humans because of the absence of color and odor. Radon gas can exist indoors through a number of pathways and long-term exposure to such material can affect the human body, which may result in serious health issues such as lung-cancer. It is thus essential to reduce and maintain indoor radon concentration in order that potential health risks from radon can be diminished. In order to achieve the aforementioned goals, it is requisite to utilize a practical detector which is capable of continuous radon monitoring. In relation to this, a recently developed prototype radon detector, i.e., RS9A, provides highperformance comparable to existing research-grade radon detectors for the purpose of continuous radon monitoring in the air. Furthermore, RS9A is a convenient piece of equipment for use by the public as it is compact in size and affordable. In this paper, we conducted continuous measurements of indoor radon concentrations by using sets of RS9A and evaluated the equivalence of RS9A in terms of quality assurance.

Radon is known to be one of the representative carcinogen materials, and may cause severe health damage to the human body with long-term exposure. Without proper treatment such as natural and mechanical ventilation, indoor radon concentration tends to increase as time passes. In this aspect, it is necessary to maintain indoor radon concentration below the domestic indoor air quality (IAQ) management standard by continuous monitoring. However, the number of practical devices which can detect radon concentration is scarce and most of the existing devices are very costly. Among such devices, the RS9A, a prototype of a radon detector, detects indoor radon concentration and is priced significantly lower compared to other existing radon detectors. In this paper, we investigated the RS9A for the continuous detection of indoor radon gas and compared its performance to a commercially available radon detector (RadonEye). We measured indoor radon concentrations at two separate sites by using both detectors simultaneously. The indoor radon concentrations measured by the aforementioned detectors revealed a high correlation. Therefore, the RS9A can be considered as an appropriate candidate for use as a continuous indoor radon monitoring system.

In this study, indoor radon concentrations were measured in 56 multiple-use facilities located in Gwangju area from December 2017 to December 2018. The average indoor radon concentration in underground space was 51.70 Bq/m3, and that of the 1st floor was 38.73 Bq/m3, indicating that the indoor radon concentration of underground space was higher than that of the 1st floor. The indoor radon concentration was investigated according to the presence or absence of underground space. The concentration of radon on the 1st floor with underground space was 37.25 Bq/m3, and the concentration of radon on the ground floor without underground space was 47.94 Bq/m3. In the absence of underground space, indoor radon concentration was high. The indoor radon concentration of buildings over 30 years old was 87.26 Bq/m3, indicating a significantly higher indoor radon concentration compared to those of buildings less than 30 years old. The indoor radon concentration was investigated according to the operation of a ventilator. The indoor radon concentration of space without an operating ventilator was 52.17 Bq/m3, and that of space with a ventilator in operation for more than 8 hours per day was 36.31 Bq/m3. This result shows that the indoor radon concentration in the space with an operating ventilator is lower than the space where the ventilator is not in operation. The indoor radon concentration in the space with an operating ventilation system was lower than that on the same floor of the same building, and the indoor radon concentration of enclosed space was about 4.4 times higher than that of open space in the same building. In addition, the indoor radon concentration was measured according to the spatial features. The concentration of indoor radon of enclosed space was 64.76 Bq/m3, which is higher than those of an open space and an active space.

Radon (222Rn) gas is a main source of ionizing radiation of natural origin. It typically moves up through the ground to the air above and into building or home through cracks and other holes in the foundation. Significantly, the Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today. This survey covers the determination of indoor radon concentrations at home from 2013 to 2014 in some areas of Gangwondo, every three months (seasonal) during one year using an alpha-track detector. The results showed that the annual average concentration of indoor radon was 84.5 Bq/m3 (GM: 64.5 Bq/m3) at homes. Indoor radon level was the highest in winter and the lowest in summer. Geometric mean radon concentration in winter was 1.03~2.58 times higher than other seasons. The data obtained from this study provide a basis for the preparation of legal regulation and public health protection manuals in this area.

The objective of this study is to investigate indoor radon concentrations and identify influencing factors for one of the representative house type in South Korea. We surveyed 3,000 detached houses using alpha track (raduet) between November 2013 and March 2014. The Arithmetic mean radon concentration of the houses studied was 147.9 Bq/m3 (GM=106.4 Bq/m3), and the range was 11.8 to 1,936.6 Bq/m3. The Arithmetic mean radon concentration in living rooms was 134.2 Bq/m3 (GM=98.8 Bq/m3), much higher value compar with the Arithmetic mean radon concentration in bedrooms (153.0 Bq/m3). The year of constructon, basement status, ventilation frequency and heating period in a house were identified as major factors influencing indoor radon concentrations. The indoor radon concentrations in houses that were constructed prior to 1990 and that had basements were higher than those in the comparison groups. On the other hand, houses that were frequently ventilated and had a short heating period showed a tendency toward lower indoor radon concentration.

This study was performed as the preliminary research to calculate the concentration of radon exposure and the annual effective dose in public hot spring bath-house. The research found that public bathhouses are the primary cause of the indoor air radon concentration inside a hot spring bathhouse. The indoor radon concentration inside a bathhouse differs significantly by region and among bathhouses in the same region, indicating that the indoor air radon concentration is affected by many factors. The annual effective indoor radon dose by exposure is estimated to range from 1.2×10−2mSv/y to 2.5×10−2mSv/y. Since this research is considered as preliminary research, further and additional relevant research to more reliably calculate the result are necessary, including accumulative research for indoor radon concentrations, and research for exposure coefficients such as the behavior patterns of public bathhouse users, etc.

In this study, this researcher measured the indoor concentration of radon in elementary schools located in Chungcheongnamdo, and conducted a questionnaire survey from June 2008 to June 2011. Indoor radon densities of elementary schools by season were 86.4 Bq/m3 in winter, 71.2 Bq/m3 in fall, 61.1 Bq/m3 in spring, and 40.5 Bq/ m3 in summer in order. Among flooring materials by construction material, the radon level of concrete was 57.8 Bq/ m3, and cement was 71.5 Bq/m3. For exterior wall materials, it was established that the density of cement, concrete, wood, and soil was 102.9 Bq/m3, 64.4 Bq/m3, 51.0 Bq/m3, and 48.7 Bq/m3, respectively. In addition, for radon densities according to distances between a detector and floors, 150 cm and under was recorded at 99.3 Bq/m3, 151 to 200 cm was recorded at 62.6 Bq/m3, and 201 cm and more was recorded at 59.2 Bq/m3 sequentially. From the results of analyzing correlations between radon concentrations and factors affecting the indoor radon concentrations in elementary schools, it was discovered that the nearer the distances to floors were and the older the construction was(r = 0.300), the higher were indoor radon concentrations. With regard to factors influencing the indoor radon concentrations in elementary schools, derived from multiple regression analysis, it was revealed that distances from floors has the greatest influence(β = 0.354, p < 0.05). And it was determined that the construction year was also a factor contributing to indoor radon levels. This had an explanation power of 27.9%.

In this study, the concentration distribution of radon, we analyzed from 55 house, 37 government office, 54 schoolfrom June 2008-June 2011 in Chungnam area. From the result of surveying indoor radon degree of 146 facilities,the annual average geometric concentration of indoor radon was 69.4Bq/m³, 40.5Bq/m³, 51.4Bq/m³ in house,government office, school respectively. As for distribution of concentration based on seasons, the radonconcentration showed the highest concentration in winter in all facilities. According to the result of the analysisby dividing the construction year, into before 60s, 60-70s, 80-90s and 2000s, the radon concentration was lowerin all the newly constructed facilities. As for difference in radon concentration due to the presence or absence ofbasement, concentration of house, government office and schools having basement was 52.2Bq/m³, 44.5Bq/m³,36.4Bq/m³ that of having no basement was 75.2Bq/m³, 53.6Bq/m³, 67.4Bq/m³ respectively. Place having nobasement tend to show higher concentration.

Developing proper reduction strategies of indoor radon which have been an important issue in Korea requires proper information on source characteristics a phosphate gypsum board which is a common building material used for inter-wall thermal protection in Korea could be a major source of indoor radon level. This study evaluated the correlation between indoor radon concentration and the attribution of gypsum board content in building materials. In this study we valuated indoor/outdoor radon from 58 facilities selected based on the information availability of gypsum content in the building material across 8 different cities in Korea. Our results showed that indoor radon concentrations were 2 to 3 times higher than outdoor but those results were not significantly attributed from gypsum contents in the building material. Indeed, phosphate content in gypsum board did not significantly play a role in indoor radon level variations. It is concluded that physical environmental condition such as temperature, relative humidity, radon exhalation rate out of each building materials, as well as pathway from external sources (e.g., soil) needs to be identified to develop indoor radon reduction strategies.

This study investigated the indoor radon concentration of 44 elementary schools in Gyeongsang-do from June 2008 to May 2009. The results obtained from this investigation are as follows. As for distribution of concentration based on seasons, the radon concentration was 77.4Bq/m³ in winter, 71.8Bq/m³ in autumn, 47.8Bq/m³ in spring and 40.4Bq/m³ in summer of Gyeongsangnam-do. And Gyeongsangbuk-do was 155.4Bq/m³ in winter, 124.3Bq/m³ in autumn, 82.7Bq/m³ in spring and 58.0Bq/m³ in summer, showing the highest concentration in winter. As for difference in radon concentration according to whether there is basement, concentration of schools having basement was 37.2Bq/m³, that of schools having no basement was 62.1Bq/m³ in Gyeongsangnam-do. In Gyeongsangbuk-do, schools having basement showed 53.9Bq/m³ of concentration and schools having no basement 124.7Bq/m³. Schools having no basement tend to show higher concentration. Indoor radon concentration according to the constructing year was 64.5Bq/m³ in schools built before 1990, 34.9Bq/m³ during 1990s and 32.8Bq/m³ during 2000s in Gyeongsangnam-do, and 110.5Bq/m³, 83.5Bq/m³ and 48.3Bq/m³ in Gyeongsangbuk-do respectively.

The objective of this study was to identify the primary source of radon in Seoul subway stations, and to investigate a relationship between geology and radon. Especially, we expected that the granite areas would have substantially high levels of radon in subway stations. The indoor radon concentrations in subway stations were lognormally distributed. The geometric mean and geometric standard deviation of indoor radon concentration were 48.11 Bq/㎥ and 2.15, respectively. Indoor radon concentrations of eight measuring sites exceeded U.S. EPA criteria (148 Bq/㎥). The geological structure of the subway station regions under this study is characterized by biotite granite, alluvium, banded biotite gneiss and diluvium. Results indicate that bedrock geology can account for a significant portion of the indoor radon in subway stations. Indoor radon concentrations of one subway station were higher than those of other stations. The bed rock in this particular subway station was that of alluvium. We assumed that the unusual increase in measured radon concentration should be related mainly to the existence of the near inferred fault zone (p<0.0001). We selected ten subway stations with homogeneous bedrock type in order to compare radon concentrations of each basement level. There was a significant difference in radon concentration, depending on the basement levels in subway stations (p<0.05).

라돈은 자연방사성원소로 호흡을 통해 인체에 피폭된다. 본 연구에서는 2017년 6월 1일부터 2017년 8월 28일까지 3개월 동안 A대학의 8개 건축물에 대해 실내 라돈농도를 측정하여 비교하였고, 연간 유효선량을 도출하였다. 본 연구에서 A대학의 건축물 Hall G 와 Hall F의 라돈농도는 각각 81 Bq/㎥, 14 Bq/㎥ 로 나타났으며, 전체 조사 건축물의 평균 실내 라돈농도는 41.63 Bq/㎥로 나타났다. 대학 내 학습공간과 생활공간에 대한 연간 유효선량 환산치의 평균은 0.40 mSv/y이며 최대 연간 유효선량은 0.78 mSv/y, 최소 연간 유효선량은 0.13 mSv/y로 나타났다. 학교는 학생들이 오랜 시간 머무르는 공간이므로 건축물에 대한 적절한 환기와 관리를 통해 실내라돈 농도를 낮추는 것이 라돈에 대한 자연방사선 피폭을 낮추는 방법이다.

This research, sponsored by the Korean Ministry of Environment in 2014, was the first epidemiological study in Korea that investigated the health impact assessment of radon exposure. Its purpose was to construct a model that calculated the annual mean cumulative radon exposure concentrations, so that reliable conclusions could be drawn from environment-control group research. Radon causes chronic lung cancer. Therefore, the long-term measurement of radon exposure concentration, over one year, is needed in order to develop a health impact assessment for radon. Hence, based on the seasonal correction model suggested by Pinel et al.(1995), a predictive model of annual mean radon concentration was developed using the year-long seasonal measurement data from the National Institute of Environmental Research, the Korea Institute of Nuclear Safety, the Hanyang University Outdoor Radon Concentration Observatory, and the results from a 3-month (one season) survey, which is the official test method for radon measurement designated by the Korean Ministry of Environment. In addition, a model for evaluating the effective annual dose for radon was developed, using dosimetric methods. The model took into account the predictive model for annual mean radon concentrations and the activity characteristics of the residents

본 연구는 G광역시 N유치원을 대상으로 창문을 닫고 열은 상태에서 라돈 가스를 측정하였다. 측정 결과 라돈가스를 측정한 N유치원의 실내 평균 라돈농도는 창문을 닫았을 때 2.9pCi, 창문을 열었을 때 0.8pCi로 미국 일반인 공기 중 라돈가스 최대허용농도 기준치인 4pCi 이하의 값으로 나타났다. 이러한 결과는 N유치원에서 라돈 가스에 대한 피폭은 문제가 되지 않으나 라돈 가스가 폐에 축척이 되면 폐암과 같은 피해를 입을 수 있다. 따라서 방어적 측면에서 유치원 내의 창문을 자주 열어 환기를 하는 것이 매우 중요함을 알 수 있었다.

Radon exhalation rates have been determined for samples of concrete, gypsum board, marble, and tile among building materials that are used in domestic construction environment. Radon emanation was measured using the closed chamber method based on CR-39 nuclear track detectors. The radon concentrations in apartments of 100 households in Seoul, Busan and Gyeonggi Provinces were measured to verify the prediction model of indoor radon concentration. The results obtained by the four samples showed the largest radon exhalation rate of 0.34314 Bq/m2·h for sample concrete. The radon concentration contribution to indoor radon in the house due to exhalation from the concrete was 31.006 ± 7.529 Bq/m3. The difference between the prediction concentration and actual measured concentration was believed to be due to the uncertainty resulting from the model implementation.