Exposure to airborne asbestos in thermal power plants in Mongolia

Our plain-English summary of Exposure to airborne asbestos in thermal power plants in Mongolia, by N. Damiran, E.K. Silbergeld, A.L. Frank, et al (International Journal of Occupational and Environmental Health, 2015).

The study

• Authors: N. Damiran, E.K. Silbergeld, A.L. Frank, O. Lkhasuren, C. Ochir, P.N. Breysse
• Journal: International Journal of Occupational and Environmental Health
• Published: 2015;21(2):137-41
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Coal-fired thermal power plants (TPPs) in Mongolia use various types of asbestos-containing materials (ACMs) in thermal insulation of piping systems, furnaces, and other products.

Objective: To investigate the occupational exposure of insulation workers to airborne asbestos in Mongolian power plants.

Methods: Forty-seven air samples were collected from four power plants in Mongolia during the progress of insulation work. The samples were analyzed by phase contrast microscopy (PCM) and transmission electron microscopy (TEM).

Results: The average phase contrast microscopy equivalent (PCME) asbestos fiber concentration was 0·93 f/cm(3). Sixteen of the 41 personal and one of the area samples exceeded the United States Occupational Safety and Health Administration (US OSHA) short-term exposure limit of 1·0 f/cm(3). If it is assumed that the short-term samples collected are representative of full-shift exposure, then the exposures are approximately 10 times higher than the US OSHA 8-hour permissible exposure limit of 0·1 f/cm(3).

Conclusion: Power plant insulation workers are exposed to airborne asbestos at concentrations that exceed the US OSHA Permissible Exposure Limit. Action to mitigate the risks should be taken in Mongolia.

In plain English

This study measured airborne asbestos during thermal insulation work at four coal-fired thermal power plants in Mongolia: all three in Ulaanbaatar and one of two in Erdenet. One researcher collected 47 air samples, 41 from workers' breathing zones and 6 from nearby areas, each lasting 12 to 81 minutes. Fibers were counted by phase contrast microscopy, and 13 samples were also examined by electron microscopy. The researchers observed that materials were not handled wet and that respirators and protective clothing were not used. Personal samples averaged 1.03 fibers per cubic centimeter (f/cm3). In the electron microscopy samples, an overall fraction of 0.97 of fibers was asbestos: chrysotile, plus tremolite at one plant. Sixteen of the 41 personal samples and one area sample exceeded the US OSHA 30-minute limit of 1.0 f/cm3. The authors stated that if these short samples reflect full shifts, exposures were about 10 times the US 8-hour limit of 0.1 f/cm3. No full-shift samples were taken. The authors concluded that the workers were exposed to elevated chrysotile concentrations, and they called for a total ban.

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 air-sampling (exposure assessment) study using personal and area samples, analyzed by phase contrast microscopy (NIOSH 7400) and transmission electron microscopy (NIOSH 7402)
• Who was studied: Insulation workers at four coal-fired thermal power plants in Mongolia: all three in Ulaanbaatar and one of the two in Erdenet. The workers were sampled while doing thermal insulation tasks. The sampling dates are not given.
• Exposure: Asbestos-containing thermal insulation materials (powder, textiles, cords, boards and sheets) used on piping systems and furnaces. The tasks were removing old insulation, disposing of waste, preparing asbestos mixtures and installing insulation. The fiber types found were chrysotile at all plants and tremolite also at plant 2.
• Main results:
  • Across all 47 samples, the average fiber concentration by phase contrast microscopy was 0.96 f/cm3. Forty-six of the 47 samples were above the limit of detection of 0.05 f/cm3.
  • In personal samples, the average fiber concentration was 1.03 f/cm3 (plus or minus 0.68), with a range of 0.09 to 3.15 f/cm3. Area samples were lower, with a mean of 0.49 f/cm3 (plus or minus 0.51).
  • Among the 13 samples analyzed by electron microscopy, the overall fraction of fibers that were asbestos was 0.97 (range 0.91 to 1.0). Plants 1, 3 and 4 had only chrysotile; plant 2 had both chrysotile and tremolite.
  • Sixteen of the 41 personal samples and one of the 6 area samples exceeded the US OSHA short-term (30-minute) exposure limit of 1.0 f/cm3.
  • Assuming the short-term samples represent full-shift exposure, exposures were approximately 10 times the US OSHA 8-hour permissible exposure limit of 0.1 f/cm3. The authors used the US standard because Mongolia has no occupational exposure standard for asbestos.
  • By task, disposing of old thermal insulation produced the highest mean concentration (1.34 f/cm3, plus or minus 0.98). Carrying asbestos bags produced the lowest, at 0.73 f/cm3 from a single sample.
  • Exposures were similar across the four plants. The authors suggested that other Mongolian power plants may have similar exposure levels.
• The authors' conclusion: The authors concluded that power plant insulation workers in Mongolia were exposed to elevated airborne concentrations of chrysotile asbestos. They called for a government action plan aimed at a total ban on asbestos use.
• Limitations the authors state:
  • A relatively small number of samples was collected, each over a short period (12 to 81 minutes), to avoid overloading the filters with non-asbestos dust.
  • Because of limited funding, no full-shift sampling was done. Full-shift exposure was estimated on the assumption, based on observation and worker interviews, that insulation work lasted the entire shift.
  • Data on the workers' age, sex and smoking habits were not collected.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Power plants and utilities.

Medical terms in this study, explained in our Lexicon: Asbestos-Containing Material (ACM), Thermal System Insulation (TSI), Occupational Exposure, Insulator, phase contrast microscopy (PCM), Transmission Electron Microscopy (TEM), OSHA, Short-Term Exposure.

Related studies

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• Mesothelioma in Mongolia: case report — N. Damiran, K. Davaajav, et al. (2015)
• Malignant mesothelioma in thermoelectric power plant workers in Italy — P. Crosignani, F. Forastiere, et al. (1995)
• Asbestos related health hazards among power plant workers — Y. Lerman, A. Finkelstein, et al. (1990)
• Mortality among workers in the geothermal power plants at Larderello, Italy — E. Pira, M. Turbiglio, et al. (1999)

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