Asbestos exposure among Seoul metropolitan subway workers during renovation of subway air-conditioning systems

Our plain-English summary of Asbestos exposure among Seoul metropolitan subway workers during renovation of subway air-conditioning systems, by I.J. Yu, C.Y. Yoo, Y.H. Chung, et al (Environment International, 2004).

The study

• Authors: I.J. Yu, C.Y. Yoo, Y.H. Chung, J.H. Han, S.Y. Yhang, G.M. Yu, K.S. Song
• Journal: Environment International
• Published: 2004;29(7):931-4
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Air quality in underground spaces has seldom been evaluated in Korea. Accordingly, the current study recently evaluated asbestos exposure among Seoul metropolitan subway workers during the renovation of the subway's air-conditioning system. To identify possible routes of asbestos exposure, suspected sources, including gaskets, ceiling boards, ceiling materials, and dust settled inside ducts, were all sampled. Personal air samples were also taken to evaluate any asbestos exposure during the renovation. The asbestos fibers found in the samples were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer (EDX). Twelve out of eighteen bulk samples contained asbestos, the majority of which was chrysotile fibers. Asbestos was detected in 9 out of 72 personal air samples and the level ranged from 0.003 to 0.02 fibers/cm(3). While asbestos levels were below Korean occupational limit of 2 fibers/cm(3), they were still detectable and therefore further monitoring would be appropriate.

In plain English

The authors measured asbestos at Seoul subway stations while the stations' air-conditioning systems were being renovated. The renovation began in late December 2000. They took 18 bulk samples of suspected materials at eight stations: duct gaskets, a welding curtain, ceiling and wall coatings, ceiling boards, and dust inside ducts. They also took 72 personal air samples from workers' breathing zones and analysed all samples by electron microscopy. Twelve of the 18 bulk samples contained asbestos. Ten contained chrysotile, and two, ceiling coatings at City Hall station, contained tremolite. Asbestos was found in 9 of the 72 air samples, at 0.003 to 0.02 fibers/cm3. That was below the Korean occupational limit of 2 fibers/cm3 in force at the time. Most of the airborne asbestos was chrysotile, and tremolite and actinolite were also found. The authors concluded that the levels were still detectable, so further monitoring would be appropriate. They wrote that the results showed a risk of asbestos exposure during renovation. They noted that monitoring started only after the renovation was 80% complete and did not cover duct removal, when the most asbestos release was suspected.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Workplace exposure survey: bulk sampling of suspected asbestos-containing materials and personal breathing-zone air sampling, analysed by transmission electron microscopy with energy dispersive X-ray analysis
• Who was studied: Workers renovating air-conditioning systems at eight Seoul subway stations: six on SMSC lines, one SMRTC station under construction, and one connecting station. The renovation started in late December 2000 and was scheduled to end by July 2001. 72 personal air samples were taken.
• Exposure: Asbestos released during renovation work, which included dismantling old ceiling panels and ventilation ducts. Suspected sources sampled were duct gaskets, welding curtains, sprayed ceiling materials, ceiling boards and settled duct dust. Fibers found were chrysotile, tremolite and actinolite.
• Main results:
  • Twelve of the 18 bulk samples contained asbestos.
  • Ten of the asbestos-positive bulk samples contained chrysotile. The ceiling-coating materials at City Hall station contained tremolite.
  • The original four duct-connection gaskets at Euljiro, Yaksu and Sindang stations contained asbestos.
  • Asbestos was detected in 9 of 72 personal air samples, at levels from 0.003 to 0.02 fibers/cm3.
  • In the air samples, most of the asbestos was chrysotile. Tremolite and actinolite were both detected at City Hall station.
  • The highest air level listed was 0.020 fibers/cm3 (TWA, chrysotile), during daytime painting of pipes in a ventilation room at Suyu station.
  • No asbestos was detected at the SMRTC World Cup Stadium station.
• The authors' conclusion: The authors concluded that asbestos levels were below the Korean occupational limit of 2 fibers/cm3 but were still detectable, so further monitoring would be appropriate. They also wrote that the results showed a risk of asbestos exposure during the renovation.
• Limitations the authors state:
  • Asbestos monitoring began only after the renovation was 80% complete, so the results do not represent the whole renovation.
  • No exposure data were collected during duct removal, when the most asbestos release was suspected.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Gasket, Chrysotile.

Related studies

• Mortality among California highway workers — N. Maizlish, J. Beaumont, et al. (1988)
• Composition of heavy metals and airborne fibers in the indoor environment of a building during renovation — M.T. Latif, N.H. Baharudin, et al. (2011)
• Worker exposure to asbestos during removal of sprayed material and renovation activity in buildings containing sprayed material — N.W. Paik, R.J. Walcott, et al. (1983)
• Exposure of sheet-metal workers to asbestos during the construction and renovation of commercial buildings in New York City. A case study in social medicine — E. Drucker, D. Nagin, et al. (1987)
• A respiratory epidemiological study of stevedores intermittently exposed to asbestos in a South African port — J.E. Myers, D. Garisch, et al. (1985)
• Guadalupe corridor transportation project asbestos health risk assessment, San Jose, California — W.E. Steiner, J.L. Koehler, et al. (1990)

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