Review of early results of comparative tests with the konimeter and the thermal precipitator in asbestos mines

Our plain-English summary of Review of early results of comparative tests with the konimeter and the thermal precipitator in asbestos mines, by R.S. Du Toit (The Annals of Occupational Hygiene, 1977).

The study

• Author: R.S. Du Toit
• Journal: The Annals of Occupational Hygiene
• Published: 1977;20(3):279-81
• Read it: PubMed · Publisher

In plain English

This short paper compared two instruments for measuring airborne dust in South African asbestos mines: the konimeter, the first instrument used there, and the thermal precipitator (TP). The aim was to see whether past konimeter readings could be expressed in terms of TP readings. The author reviewed four sets of samples taken with both instruments at the same time between 1940 and 1967. The 1940–1945 samples were of unspecified types of asbestos dust. The 1948 samples came from amosite mills (19 sets). The 1965 samples came from amosite and crocidolite mines (16 mines), and the 1967 samples from chrysotile, amosite and crocidolite mills. Counting rules differed between comparisons, and in 1965 particles and fibres were counted together. A significant association between the two instruments was found for the 1940–1945 and 1948 data, and probably for the 1965 data. No significant association could be reported for the 1967 data. The correlation values themselves are not printed. The author concluded that konimeter results may reasonably be equated to TP results in studies of past exposure. The author noted that the comparison applies to high dust levels and to dust with about one fibre for every six particles.

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: Comparison of simultaneous air samples taken with two dust-sampling instruments (konimeter and thermal precipitator); the paper reviews four earlier comparisons
• Who was studied: Air in South African asbestos mines and fiberising mills/plants, sampled in four comparisons between 1940 and 1967. These included 19 sets of simultaneous samples in 1948 in the fiberising mills of an amosite mine, and person-weighted means for 16 mines in 1965.
• Exposure: Airborne asbestos dust: unspecified types (1940–1945), amosite (1948), amosite and crocidolite (1965, underground and surface plants), and chrysotile, amosite and crocidolite (1967 mills). Concentrations are measured in fibres per cubic centimetre.
• Main results:
  • After transformation of the data, a significant association between thermal precipitator and konimeter readings was found for the 1940–1945 and 1948 comparisons, and probably also for the 1965 comparison (P less than 0.01). No correlation coefficient values are printed.
  • A significant association could not be reported for the 1967 comparison. The P value is printed as 'P<0.l' in the scanned text, apparently P less than 0.1.
  • The 1965 comparison counted particles plus fibres, not fibres alone.
• The authors' conclusion: The author concluded that, for past South African conditions and certain selected criteria, the two instruments agreed. It is therefore reasonable to assume that recorded konimeter results may be equated to TP results in studies of past exposure. After 1965 no conversion is needed because the TP replaced the konimeter.
• Limitations the authors state:
  • The comparison applies to high dust concentrations compared with present-day standards.
  • The comparison applies where fibres are only about 1 in 6 of the dust particles. In manufacturing industry, fibres would form a much larger share of the dust cloud.

Topics

Medical terms in this study, explained in our Lexicon: Thermal Precipitator.

Related studies

• Simultaneous airborne dust samples with konimeter, thermal precipitator and dosimeter in asbestos mines — R.S. du Toit, T.C. Gilfillan (1977)
• Conversion of the asbestos fibre concentration recorded by means of the konimeter and the thermal precipitator to that expected by means of the membrane filter method — R.S. du Toit, T.C. Gilfillan (1979)
• Relationships between simultaneous airborne dust samples taken with five types of instruments at South African asbestos mines and mills — R.S. Du Toit, L.W. Isserow, et al. (1983)
• A comparison of historic asbestos measurements using a thermal precipitator with the membrane filter-phase contrast microscopy method — G. Burdett (1998)
• Lung mineral fibers of former miners and millers from Thetford-Mines and asbestos regions: a comparative study of fiber concentration and dimension — A. Nayebzadeh, A. Dufresne, et al. (2001)
• Some investigations into the nature and cause of massive fibrosis (MF) in the lungs of South African gold, coal, and asbestos mine workers — M.C. Leibowitz, B. Goldstein (1987)

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