Dust Measurements and Monitoring in the Asbestos Industry

Our plain-English summary of Dust Measurements and Monitoring in the Asbestos Industry, by C.G. Addingley (1965).

The study

• Author: C.G. Addingley
• Published: Annals of the New York Academy of Sciences (1965)
• 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 paper, by an author from British Belting & Asbestos Ltd. and the Asbestosis Research Council, reported on dust-measuring methods in the British asbestos industry. It did not study workers' health. It described earlier sample-and-microscope methods as slow and laborious, then reported tests of the Royco particle counter, a light-scattering instrument, in chrysotile workrooms. When the Royco counted particles over five microns, membrane filter counts were about 23 per cent higher. With the Royco set at four microns and above, Royco results were about 15 per cent higher than the five-micron membrane count. At one micron and above, relative counts were Royco 100, membrane 85 and midget impinger 47. Over about eight months, many thousands of counts were averaged into between 1000 and 2000 reported results, and carding showed a higher proportion of large particles or fibers than other textile processes. The author noted that the Royco counts all dust, not only asbestos, and was not tested with crocidolite or amosite. Based on nine months' experience, the author concluded the instrument was the best available method for dust testing in asbestos factories.

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: Report comparing dust-measuring instruments (Royco light-scattering particle counter, membrane filter, midget impinger) and describing factory use of the Royco; not a health study
• Who was studied: Air in chrysotile workrooms of asbestos textile factories in Britain, tested as part of a joint program of the member companies of the Asbestosis Research Council; factory use covered about eight to nine months (dates not given)
• Exposure: Airborne chrysotile dust (particles and fibers, including fiber bundles) in asbestos textile processes, counted by size (for example one micron and above, four or five microns and above)
• Main results:
  • With the Royco set to count particles over five microns, the membrane filter count of particles or fibers over five microns was higher by about 23 per cent
  • With the Royco set at four microns and above, compared with the five-micron membrane count, Royco results were about 15 per cent higher
  • For particles one micron and above, relative counts were Royco 100, membrane 85 and midget impinger 47
  • For particles or fibers five microns and over, the membrane filter gave a count 78 per cent higher than the midget impinger
  • With a membrane filter in the exit line of a midget impinger, for every 87 particles (one micron and above) counted on the impinger record, 13 passed through and were collected on the membrane; this was the mean of two experiments only
  • In factory use over about eight months, many thousands of Royco counts were averaged into between 1000 and 2000 reported results
  • A higher proportion of large particles or fibers was found in carding than in other textile processes
• The authors' conclusion: The author concluded, after nine months' experience and stated as a confident belief, that the Royco represented the best available method for dust testing in asbestos factories and allowed enough tests to give statistically reliable results
• Limitations the authors state:
  • The Royco counts all particles passing through it, so where other organic and mineral dusts are present (for example automobile brake lining manufacture) it records only total dust and other methods are needed to estimate asbestos
  • The author doubted that the Royco-to-membrane ratio would be valid for crocidolite or amosite and had not tested either with the Royco
  • The impinger pass-through result was the mean of two experiments only
  • The instrument's physical size made sampling in some locations difficult, requiring a remote sampling method

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Midget Impinger, Carding, Crocidolite, Amosite.

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