Relationships between simultaneous airborne dust samples taken with five types of instruments at South African asbestos mines and mills

Our plain-English summary of Relationships between simultaneous airborne dust samples taken with five types of instruments at South African asbestos mines and mills, by R.S. Du Toit, L.W. Isserow, T.C. Gilfillan, et al (The Annals of Occupational Hygiene, 1983).

The study

• Authors: R.S. Du Toit, L.W. Isserow, T.C. Gilfillan, K. Robock, U. Teichert
• Journal: The Annals of Occupational Hygiene
• Published: 1983;27(4):373-87
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Simultaneous airborne dust samples were taken with five types of instrument, namely, konimeter, thermal precipitator, membrane filter, tyndallometer and VC 25 gravimetric sampler, on the surface and underground at two types of asbestos mine, producing amosite and Cape crocidolite respectively. The results were analysed and compared in terms of five different concentration parameters, namely, particles plus short fibres (p+sf), long fibres (lf), particles plus short fibres plus long fibres (p+sf+lf), the volume (tyndallometer readings) and the mass of dust (VC 25). The Kolmogorov-Smirnov statistic was used to test for normality and the Bartlett statistic for equality of variance of the transformed concentration data recorded by each type of instrument.

Fourteen linear relationships were investigated. In those cases where replicates were given these were used to obtain estimates of the error variances for the predictor and the response variables. With these estimates an additional regression equation to the least squares equation was determined. This new equation is recommended in preference to the corresponding least squares equation, as it is based on information which is discarded when only the position means are used.

All but one of the fourteen relationships reached statistical significance.

The konimeter and the thermal precipitator can be linked with the membrane filter, the tyndallometer can reveal short time variations in the fibre level and the VC 25 can disclose the asbestos content of the fine dust.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This study compared five types of dust-measuring instruments used side by side at South African asbestos mines and mills in 1977. A German team and a South African team took simultaneous air samples at 15 positions, on the surface and underground, at one amosite mine and three Cape crocidolite mines. The instruments were a konimeter, a thermal precipitator, a membrane filter, a tyndallometer and a VC 25 gravimetric sampler. The aim was to link past konimeter and thermal precipitator measurements with the membrane filter method. Of 14 relationships tested, all but one were statistically significant. The exception was tyndallometer versus membrane filter (correlation 0.5108). For long fibres, the correlation between konimeter and thermal precipitator was 0.9739. For the samples taken, the authors estimated that 2 long fibres per millilitre by konimeter equalled 1.3 by membrane filter, and that about 30% of the fine dust consisted of asbestos. The authors stated that these factors are not representative of average conditions in the industry, and they did not suggest using them to convert present measurements.

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: Field comparison study: simultaneous airborne dust samples taken with five instrument types, compared using regression and correlation analysis
• Who was studied: Air at 15 sampling positions (mills and mines), on the surface and underground, at one amosite mine and three Cape crocidolite mines in South Africa, sampled in 1977 by a German team and a South African team
• Exposure: Airborne dust at amosite and Cape crocidolite mines and mills. It was measured as particles plus short fibres, long fibres (5-100 micrometres), particles plus all fibres, dust volume (tyndallometer), mass of fine dust and its asbestos content (VC 25).
• Main results:
  • Of the 14 instrument relationships investigated, all but one reached statistical significance.
  • The one relationship that was not significant was tyndallometer versus membrane filter (equation 14), with a correlation coefficient of 0.5108. The authors attributed this to the two instruments measuring different things.
  • The highest correlation coefficient, 0.9739, was for long fibres between the konimeter and the thermal precipitator.
  • For long fibres, the correlation coefficients were 0.9284 for thermal precipitator versus membrane filter (equation 3) and 0.9394 for konimeter versus membrane filter (equation 4), as listed in Table 3.
  • For the samples taken, the authors estimated the following equivalences: 2 long fibres per ml by konimeter equalled 1.6 by thermal precipitator; 2 by thermal precipitator equalled 2 by membrane filter; 2 by konimeter equalled 1.3 by membrane filter.
  • VC 25 fine dust and VC 25 asbestos dust had a correlation coefficient of 0.9575. The authors estimated that about 30% of the fine dust consisted of asbestos.
  • Of the 64 membrane filter samples, 43 (67%) had a fibre loading within recommended limits, 3 (5%) were above the upper limit and 18 (28%) were below the lower limit.
• The authors' conclusion: The authors concluded that, for a particular source of dust, long-fibre concentrations measured by the konimeter and the thermal precipitator can be related to those measured by the membrane filter. They also concluded that the VC 25 enables the asbestos content of fine airborne dust to be determined.
• Limitations the authors state:
  • The authors stated that the conversion factors are not representative of average conditions in the industry and that additional samples would be needed.
  • The authors did not suggest using the conversion factors to convert present measurements. Doing so would need additional site-specific simultaneous sampling.
  • Konimeter data from three positions appeared contaminated and were left out of all analyses involving konimeter data.
  • After transformation, the long-fibre data could be assumed normally distributed at only four of the twelve positions analysed.

Topics

Medical terms in this study, explained in our Lexicon: Thermal Precipitator, Amosite, Crocidolite, Statistical Significance.

Related studies

• Simultaneous airborne dust samples with konimeter, thermal precipitator and dosimeter in asbestos mines — R.S. du Toit, T.C. Gilfillan (1977)
• Variation in fibre and dust counts in an asbestos mine and mill — R.C. Parsons, D.G. Bryant, et al. (1986)
• 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)
• A comparison of parallel dust and fibre measurements of airborne chrysotile asbestos in a large mine and processing factories in the Russian Federation — E. Feletto, S.J. Schonfeld, et al. (2017)
• Size and shape of airborne asbestos fibres in mines and mills — C.Y. Hwang (1983)
• Rheumatic complaints and pulmonary response to chrysotile dust inhalation in the mines and mills of Quebec — F.M. White, J. Swift, et al. (1974)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.