Journal of Korean Society of Occupational and Environmental Hygiene (한국산업보건학회지)

Korean Industrial Hygiene Association (한국산업보건학회)
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Characteristics of airborne radon and thoron levels monitored in Seoul Subway stations and circulation lines

서울 일부 지하철 공기 중 라돈과 토론 발생 특성

  • Kwak, Hyunseok (Institute of Occupational and Environmental Health, Korea Workers' Compensation and Welfare Service) ;
  • Kim, So-Yeon (Department of Environmental Health, Korea National Open University) ;
  • Park, Jihoon (Institute of Health and Environment, Graduate School of Public Health, Seoul National University) ;
  • Choi, Sangjun (Department of Occupational Health, Daegu Catholic University) ;
  • Park, Dong-Uk (Department of Environmental Health, Korea National Open University)
  • 곽현석 (근로복지공단 직업환경연구원) ;
  • 김소연 (한국방송통신대학교 환경보건학과) ;
  • 박지훈 (서울대학교 보건환경연구소) ;
  • 최상준 (대구가톨릭대학교 산업보건학과) ;
  • 박동욱 (한국방송통신대학교 환경보건학과)
  • Received : 2019.05.13
  • Accepted : 2019.06.20
  • Published : 2019.06.30
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Abstract

Objective: This study aims to characterize airborne radon and thoron levels ($Bq/m^3$) generated from working environments in three subway stations in Seoul. Method: A radon and thoron detector (EQF3220) was used to monitor real-time airborne radon and thoron levels ($Bq/m^3$) and their daughters ($Bq/m^3$) every two hours. They were monitored not only in the driver's cabin of seven circulation lines, but also three offices, platforms, and water pump reservoirs in the three stations. Results: The average levels of radon and thoron were $67.9Bq/m^3$ (range; $7.2-619.4Bq/m^3$) and $44.4Bq/m^3$ (range; $4.3-819.2Bq/m^3$), respectively. Notably, higher than legal airborne radon levels ($600Bq/m^3$) were frequently monitored in the driver's cabin of seven circulation lines. Airborne radon levels monitored in the platforms and administrative offices were found to be over $100Bq/m^3$. The average equilibrium factors (F) were 0.12 and 0.06, respectively. The percentages detected were found to be 84.9 for radon and 72.4 for thoron, respectively. Conclusions: Significant airborne radon and thoron levels were frequently found to be generated in subway facilities including water reservoirs, platforms and driver's cabins. Further study is necessary to thoroughly investigate airborne radon and thoron in all subway stations and to devise proper measures.

Keywords

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Figure 1. Radon and thoron levels measured at the personal zone in driver room. Two lines were excluded due to either low level or short time monitored

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Figure 2. Temporal variations of radon and thoron at the office. platform and pump station in each station. All results monitored at slow mode.

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Figure 3. Differences of radon(a) and thoron(b) levels between the monitoring locations. All results monitored at slow mode.

Table 1. Summary of airborne radon and thoron levels by subway environment or location

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Table 2. Proportion of radon, thoron and their daughter detected(%)

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Table 3. Equivalent equilibrium factor for radon and thoron by subway environment or area

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Table 4. Ratios of radon and thoron, and their daughter levels by subway environment or area

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