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.

This experiment evaluated the efficiency of mechanical ventilation, one of the measures to reduce indoor radon concentration in residential spaces. In the most popular ventilation rates of the air conditioning system, the most efficient air conditioning system was confirmed by checking the time when the radon concentration reached the lowest level, the radon reduction rate, and the radon concentration that could be lowered as much as possible. The results showed a reduction rate of up to 80% or more as a result of conducting the experiment by blocking the inflow of outside air. It was confirmed that the time to reach the lowest concentration after starting the mechanical ventilation was about 6 hours to a maximum of 7 hours. Therefore, this study verified that indoor radon concentrations can be efficiently reduced by using a mechanical ventilation 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.

This study aimed at providing fundamental information for development of governmental policy on radon management, investigated the radon levels of residential homes nationwide. It also suggested the necessity for policy development which focuses on management of the degree of harm through the installation of radon alarm devices and radon reduction consulting for homes with radon readings in excess of recommended threshold. Results showed that the radon level of the subjects of this study, 1,167 houses, was 97.3 ± 65.8 Bq/m3. Regionally, Seoul had the highest level, while Jeju had the lowest. In the first round of the investigation, the number of houses, with radon level which exceeded the recommended threshold, 148 Bq/m3, was 171. However, as a result of the radon alarm installation and radon reduction consultation, the indoor radon level of 137 households decreased to less than the recommended threshold. In the second round of the investigation, 80% of the households, the radon concentration of which exceeded the current recommended threshold in the first round, appeared to maintain their radon concentration below the recommended threshold. As a result of the communication about radon's harmfulness and the installation of the radon alarm device for recognition of harmful environments. It could be deduced from this result that the communication about harm contributes to the reduction of radon.

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).

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.

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 March 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/㎥) showed the highest level among the areas, while radon concentration on the first floor of house(50.5 Bq/㎥) 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.