Medical Institutions of the Seoul Metropolitan Area's Internal Air Radon Atmostphere Emission: Suggestions for Density Measurement and Improvement

서울시 종합의료기관의 실내공기 중 대기로 방출되는 라돈(²²²Rn) 농도 측정 및 개선 방안

We have started this study in an attempt to measure facility spaces' Radon density and minimize Radon damages to human health accounting for measurement values. The subject of this study is a general hospital situated within the Seoul metropolitan area, the Seoul Medical Center. The Radon density measurement points were dispersed as following for comparison among spatial categorization: 17 spots within office areas(places where only hospital employees occupy), 25 spots within patients' waiting area (occupied by employees, patients, patient caretakers, general passerby), 22 spots within treatment areas (occupied by employees or patients). For comparison among building levels, 10 places were picked within the basement area (5 on the first basement level, 1 on the second basement level, 2 on the third basement level, 2 on the fourth basement level), 54 places above ground (25 on the first floor, 27 on the second, 2 on the third). For comparison based on the factor of window existence, 21 spots without windows and 43 spots with windows were compared. Measurement was carried out for the duration of four months by Alpha track detectors with the removal of LR-115 tapes. These detectors are fixed to the wall with a one meter length string hanging from a half-circle shaped link fixed upright at a right angle on the ceiling at the center of the measurement area. As a manual detector, for Alpha track detector measurement to be properly conducted, it should be used under minimized circumstantial changes from the usual status quo for the duration of measurement. Study collaborators have kept the environmental factors constant while measuring Radon density, with indoors detectors being comprised of two types, passive and active detectors. These two types could be differentiated apart by their electric power source. Passive detectors are easier to maneuver and are more economical in their costs than their active counterparts. Few demerits persist, however, in that passive detectors have more difficulty achieving prompt long term measurements and are more prone to lowered reliability in their measurements due to external environmental factors. Despite these shortcomings, for its relative low costs and efficiency, collaborators have decided on using Alpha track detector LR-115 device for the purpose of this study. The mean Radon concentration level of the 21 places with windows was $58.00Bq{\cdot}m^{-3}$, with the 43 places without windows mean level being $62.93Bq{\cdot}m^{-3}$, The mean difference of approximately $5Bq{\cdot}m^{-3}$ with windowed places being lower in Radon concentration levels were nonsignifican t (p>0.05). The reason why lower Radon density was measured in windowed areas could be postulated to be due to airing and emission of Radon from measured indoors to outdoors. In the comparisons between workspace categorizations, the mean Radon density level of the 17 places within office areas (occupied only by hospital employees) was $58.18Bq{\cdot}m^{-3}$, a mean of $64.50Bq{\cdot}m^{-3}$ in 22 patient waiting areas (occupied by employees, patients, caretakers, and passersby), and a mean of $61.31Bq{\cdot}m^{-3}$ was achieved in 22 treatment areas. Radon density level was ranked from highest to lowest from office areas, treatment areas, and patient waiting areas. There were, however, no statistical significance achieved among the three spatial categorizations(p>0.05). We could postulate lower Radon level was achievable through frequent airing from multiple windows. Comparisons between floor levels led to the result of mean of $55.90Bq{\cdot}m^{-3}$ in the 10 areas in the basement levels, and mean of $62.31Bq{\cdot}m^{-3}$ in the 54 areas in the above ground level floors. While not achieving statistical significance (p>0.05), Radon levels were measured to be $7Bq{\cdot}m^{-3}$ lower in the basement areas compared to the above ground levels. Based on these results, we believe reducing lung cancer inducing Radon density by appropriately measuring and controlling radon concentration levels would be conducive to lowering radiation exposure to on facility employees, patients, and caretakers.