Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Sangjun Choi - Subway Workers' Exposure to Radon in Korea.

696 views

Published on

This presentation will be available to view as a discussion poster at the 7th International Conference on the Science of Exposure Assessment - X2012.
It will be presented on 04 July 2012 from 09.30 – 11.45 am followed by a chaired discussion of all posters in this session on Chemicals in the Workplace.
Appointments with the authors are available to book at https://x2012discussionposters.acuityscheduling.com

Published in: Technology, Business
  • Be the first to comment

  • Be the first to like this

Sangjun Choi - Subway Workers' Exposure to Radon in Korea.

  1. 1. Sangjun Choi1 , Seongmin Lee2 , Sanghyuk Yim2 1Department of Occupational Health, Catholic University of Daegu, Korea 2Wonjin Institute for Occupational and Environmental Health, Korea Email (Sangjun Choi): junilane@gmail.com Abstract• The purpose of this study is to investigate the relationship between the levels of radon in air and environmental conditions in the underground, and to develop the management strategies for the protection of the subway workers.• The radon levels in air were measured using the US EPA short-term method, and were performed using the electret passive environment radon monitor (E-PERM).• The average radon concentrations in the tunnel, the station office, and the platform were 95.1 Bq/㎥, 74.8 Bq/㎥, and 56.3 Bq/㎥, respectively.• A multiple regression analysis of radon exposure affecting factors showed that the type of tunnel and the frequency of repair work were found to be a statistically significant predictor of exposure to radon.• The estimated average annual effective doses to the technical engineers, subway drivers and the station office workers from radon were 0.5 mSv/yr, 0.47 mSv/yr and 0.44 mSv/yr, respectively.
  2. 2. • Radon is one of the most well known human carcinogens.• The subway workers working at underground have the potential of long-term exposure to radon.• There were radon survey at the platform or station office in several times. However, radon measurements in underground tunnels has never been conducted in Korea. < station office >• The purpose of this study is to evaluate the relationship between the levels of radon in the station office, platform and the environmental conditions at the tunnel of subway.• The radon levels in air were measured using the US EPA short-term method, and were performed using the electret passive environment radon monitor (E-PERM). < Platform>• A total of 118 stations were selected from Seoul, Busan and Daegu subways and radon measurements were conducted at the three points (station office, platform and tunnel) every station.• We also investigated environmental conditions such as the types of bedrocks, the types of tunnel, the amounts of ground water, the covers of the waterway, the depth of station, the numbers of natural ventilating opening, the amounts of ventilation, the frequency of repair works, the types of roadbeds, and the installation of screen doors. < Tunnel>
  3. 3. • The radon concentrations ranged from 3.4 Bq/㎥ to 961.5 Bq/㎥ at the 351 measurement points, and N=351 10% of samples exceeded the indoor air quality guideline of Korea, 148 Bq/㎥ (Figure 1). Figure 1. Cumulative probability of airborne radon concentrations .• The average radon concentrations in the tunnel, the station office, and the platform were 95.1 Bq/㎥, 74.8 Bq/㎥, and 56.3 Bq/㎥, respectively and there was statistically significant differences (p<0.01). (Figure 2) Figure 2. Comparison of radon concentrations at the station office, platform and tunnel.
  4. 4. • Statistically significant predictors of radon concentrations at the1. Tunnels : Tunnel type, frequency of repair work and bedrocks2. Platforms : Radon concentrations at the tunnels, screen door, platform type, bedrocks3. Station office : Radon concentrations at the platforms, volume of office, depth of platform, depth of office Table 1. The summary of multiple regression analyses Dependent variable Independent variable Unstandardized Standardized t Sig. Coefficient Coefficients B Std. Error β Radon concentrations (Constant) 2.36 0.096 24.536 <0.01 at the tunnels 1) Tunnel type -0.239 0.05 -0.385 -4.807 <0.01 Frequency of repair work 0.001 0 0.212 2.615 0.01 2) Bedrocks -0.055 0.022 -0.201 -2.474 0.02 Radon concentrations (Constant) 1.054 0.177 5.947 <0.01 at the platforms Rn at the tunnels 0.429 0.08 0.405 5.373 <0.01 3) Screen door -0.213 0.06 -0.245 -3.537 <0.01 4) Platform type 0.124 0.038 0.234 3.279 <0.01 Bedrocks -0.064 0.02 -0.227 -3.161 <0.01 Radon concentrations (Constant) 0.693 0.183 3.791 <0.01 at the station office Rn at the platforms 0.525 0.088 0.483 5.965 <0.01 Volume of office 0.001 0 0.178 2.104 0.04 Depth of platform 0.009 0.003 0.293 3.12 <0.01 Depth of office -0.015 0.006 -0.237 -2.624 0.01 Note. 1) Tunnel type (single =0, double = 1 ), 2) Bedrocks (granite=0, gneiss=1, alluvium=2, andesite=3), 3) Screen door(no=0, yes=1), 4) Platform type(sided platform=0, island platform=1, one way=3)
  5. 5. Tunnel Platform Station office- with Single rail - with Single rail - with deep platform- with Many cracks - without Screen door - with sided double rail- surrounded with Granite - surrounded with Granite - surrounded with graniteThe estimated average annual effective doses to the technical engineers, subway drivers and thestation office workers from radon were 0.5 mSv/yr, 0.47 mSv/yr and 0.44 mSv/yr, respectively. Thehighest value was estimated 4.59 mSv/yr for the station office workers.This study suggested that radon concentrations at the tunnels should be controlled by repairingthe cracks in order to protect subway workers from radon exposure.

×