Effect of respiratory protective equipment on exposure to asbestos fibres during removal of asbestos insulation

Our plain-English summary of Effect of respiratory protective equipment on exposure to asbestos fibres during removal of asbestos insulation, by H. Akkersdijk, C.F. Bremmer, C. Schliszka, et al (The Annals of Occupational Hygiene, 1989).

The study

• Authors: H. Akkersdijk, C.F. Bremmer, C. Schliszka, T. Spee
• Journal: The Annals of Occupational Hygiene
• Published: 1989;33(1):113-6
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos concentrations were measured within powered respirators used by workers involved in the removal of asbestos-containing insulation. Fibre concentrations within the protective gear appeared to be above the Dutch threshold limit value for crocidolite (0.2 f cm-3). Possible sources of exposure were analysed and measures were taken to improve the situation. After this, the fibre concentrations in the breathing area were reduced and were below the Dutch concentration limit.

In plain English

This Dutch study measured asbestos fibre levels inside the powered, filtered-air respirator helmets of workers removing asbestos insulation at two power plants. The insulation contained amosite, chrysotile and crocidolite in varying amounts. At the first job, part of it was pure crocidolite. During crocidolite removal there, the average concentration inside the helmets was about 0.55 fibres per cubic centimetre. The authors assumed this was above the Dutch crocidolite limit of 0.2. They named three possible causes: leaking filters, leaking protective clothing, and contamination in a changing room with no separate clean and contaminated areas. They did not try to tell these apart. Filters were then changed daily instead of weekly, overalls were cleaned and inspected after each shift, and the changing room was cleaned weekly. After this, the average fell to about 0.08, a statistically significant drop. The outside average was 28, which the authors gave as a protection factor of about 350. At the second job, where safety measures were more stringent, all inside readings were below 0.02 and the outside average was 5. The authors again gave a protection factor of about 350.

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 measurement study: personal air sampling inside (and outside) air-purifying respirator helmets at two asbestos removal jobs, with measurements before and after protective measures were improved at the first job
• Who was studied: Workers removing asbestos insulation at two power plants in the Netherlands; Table 1 (first job) gives N = 4 per condition. Measurement dates are not stated.
• Exposure: Removal of asbestos insulation containing amosite, chrysotile and crocidolite in varying amounts. At the first job the asbestos was sprayed and partly pure crocidolite. At the second job it was compressed blocks with a binding agent. Fibres were counted by the AIA light-microscopy protocol.
• Main results:
  • First job, original situation: fibre concentration inside the respirator was about 0.55 f/cm3 (arithmetic mean). Table 1 gives a geometric mean of 0.53 and a range of 0.38-0.75.
  • Because this was during crocidolite removal, the authors assumed first-job exposures were above the Dutch threshold limit value for crocidolite (0.2 f/cm3)
  • First job, after improved measures (daily filter replacement, cleaning and inspection of overalls after each shift, weekly cleaning of the changing facility): inside concentration dropped to about 0.08 f/cm3 (arithmetic mean), with P = 0.0005 by Student's t-test. Table 1 range is 0.04-0.13.
  • First job: concentration outside the helmet was 28 f/cm3 (arithmetic mean), giving a protection factor of about 350
  • Second job (more stringent safety measures): all fibre concentrations inside the respirator were below 0.02 f/cm3. Table 2 gives an arithmetic mean of 0.006.
  • Second job: concentration outside the protective clothing was 5 f/cm3 (arithmetic mean), and the protection factor was also about 350
• The authors' conclusion: The authors reported that after the improvements, fibre concentrations in the breathing area were reduced and were below the Dutch concentration limit
• Limitations the authors state:
  • The authors did not try to determine which of the three possible sources (filter leakage, leaking clothing, changing-room contamination) caused the high first-job exposure, because they considered a quantitative estimate of each contribution impossible

Topics

Medical terms in this study, explained in our Lexicon: Respirator, Threshold Limit Value (TLV), Crocidolite.

Related studies

• Physiological and subjective responses to working in disposable protective coveralls and respirators commonly used by the asbestos abatement industry — M.K. White, T.K. Hodous, et al. (1989)
• Personal exposure to asbestos dust during clearance certification — S. Bailey, A. Conchie, et al. (1988)
• Safety and health of heavy equipment operators at Ground Zero — B.E. Lippy (2002)
• Usage of personal protective devices among Egyptian industrial workers — A.A. Kamal, G.M. Sayed, et al. (1988)
• Performance of power assisted respirators during simulated asbestos removal — M.P. Clayton, A.E. Bailey, et al. (2002)
• Lung fiber burden in the Nottingham gas mask cohort — G. Berry, F. Pooley, et al. (2009)

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