Environmental Control of Asbestos

Our plain-English summary of Environmental Control of Asbestos, by K. Verrill (1979).

The study

• Author: K. Verrill
• Published: Proceedings of the XIX International Congress on Occupational Health, Dubrovnik, Yugoslavia, September p25-30 (1979)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This conference paper came from the Asbestosis Research Council's Environmental Control Committee in the United Kingdom. It described dust-control methods in the asbestos industry and did not collect new health data. The author described how UK regulations from 1931, which mainly covered asbestos textiles, led to methods for exhausting dust and measuring airborne fibres. The methods included enclosing carding machines with exhaust of approximately 3.5 cubic metres of air per second to keep levels below 2 fibres/ml, fitting exhausts to looms, and requiring approved masks to be provided and worn where exhaust was not practicable. The author called the membrane filter method of counting fibres the most accurate method so far established. It described a UK system that filtered and recirculated factory air against a control level of 0.2 fibres/ml. If repeat readings stayed above that level, fresh air was brought in. Citing an unreadable figure, the author stated that asbestosis in textile workers declined after the 1931 regulations. The author wrote that with proper observation of the regulations no worker should be put at risk.

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: Descriptive conference paper (technical overview of dust-control and fibre-measurement methods); not a study collecting health data
• Who was studied: No people were studied. The paper concerns the UK asbestos industry, mainly asbestos textile plants, including an air recirculation system commissioned in a UK asbestos processing shed
• Exposure: Airborne asbestos dust in asbestos textile manufacture (carding, weaving). The paper describes amosite, crocidolite (blue asbestos) and chrysotile (white asbestos), with chrysotile described as over 90% of world production
• Main results:
  • An enclosed carding operation was described as needing approximately 3.5 cubic metres of air per second of exhaust to keep the working environment below 2 fibres/ml
  • Where dust exhaust was not practicable, for example during maintenance of dust exhaust equipment, the UK regulations required an approved mask to be provided and worn
  • Air removed by exhaust was replaced with about 10% more air than was taken out, to keep a slight positive pressure
  • The membrane filter method, in which fibres are counted on a slide, was described by the author as time-consuming but the most accurate method so far established
  • A photoelectric light-scattering unit for rapid monitoring measured all particles, not only fibres, but was described as ideal for monitoring an asbestos textile plant
  • In the air recirculation system, sampled air was checked against a control level of 0.2 fibres/ml. If repeat readings stayed above it, a warning sounded, fresh air was brought in and the return air was vented
  • The author stated that straight crocidolite fibres do not agglomerate and are readily made airborne, and gave this as one reason crocidolite is considered more dangerous than white asbestos
  • Citing Figure 1 (numbers not readable), the author stated that asbestosis in textile workers began to decline after the 1931 regulations, while cases in insulation workers, who had no controls until 1969, continued to increase
• The authors' conclusion: The author concluded that with proper observation of the regulations no worker should be put at risk. The author hoped the paper would stimulate interest in dust-control methods to reduce and ultimately eliminate the dangers to health in the asbestos industry

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Textiles, Carding, Membrane Filter Method.

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