Interconvertibility of asbestos fibre count concentrations recorded by three most frequent methods.

Simultaneous airborne chrysotile asbestos fibre samples were collected with three types of instruments, namely, the konimeter, the thermal precipitator and the membrane filter, in four asbestos plants (textile manufacturing, asbestos cement production, mining, milling). Linear regression analyses were performed of the membrane filter on the konimeter and thermal precipitator count concentrations, respectively. Sampling was performed at 24-35 locations in each of the processes studied. In order to linearize the relationships and to stabilize the sample variances the data were transformed using the transformation ln(x+1) for both the predictor and the response variables. Eight linear regression equations were developed. The slope coefficients of regressions differed significantly (P < 0.05 or < 0.01) between all the asbestos processes except for the differences of coefficients in mining and milling (P > 0.05). It is concluded that no single conversion factor can be used to reliably convert the konimeter or thermal precipitator to membrane filter asbestos fibre concentrations; a separate conversion factor must be derived for each technological process. In this case the confidence limits of estimates are acceptable for practical occupational hygiene purposes.

[Is it necessary to remove fibrous insulation material from buildings?]. / Je li potrebno uklanjanje vlaknatih izolacijskih materijala iz zgrada?

Because of potential negative health effects of exposure to airborne fibres, removal of fibrous insulating materials from buildings, particularly asbestos, has become a frequent, in many cases unjustified, undertaking. The results are presented of the determination of airborne mineral respirable and non-respirable fibres, fragments and total airborne dust in a public building before the substitution of the insulating material, shortly after, and about two months later. There were no differences (P greater than 0.05) between the mean concentrations of respirable fibres (diameter less than or equal to 3 microns, length greater than or equal to 5 microns, aspect ratio greater than or equal to 3:1) measured before (0.0038 and 0.0031 f/cm3, resp.) and about two months after (0.0038 and 0.0028 f/cm3, resp.) the substitution, suggesting that the substitution was unnecessary. However, the concentrations measured two and eight days after the substitution were significantly elevated (P less than 0.05; P less than 0.01, resp.), indicating that the unnecessary disturbance of the insulating material caused an increase of exposure levels of the employees. It is concluded that the removal or substitution of fibrous insulating materials, solely on the basis of their presence in the buildings, is unjustified. The decision should be based on elevated concentrations of airborne fibres objectively quantified. Unnecessary substitution brings about an increase, not a decrease, of the concentrations through a shorter or longer period of time.

Ventilatory lung function changes in family members of asbestos workers.

A group of 114 adult family members of asbestos workers were examined for the prevalence of chronic nonspecific respiratory symptoms and ventilatory function changes. There was no difference in the prevalence of any respiratory symptom between the examinees and the matching members of the general population in the study areas. No difference was found between the measured and predicted values of FVC or FEV, or FEF50 in either smoking or nonsmoking men (P greater than 0.05). In contrast, all the measured values in women were significantly lower (P less than 0.0001) than their normal predicted values. Airborne chrysotile weight concentrations in five houses of asbestos workers were found significantly higher than those in four houses without inhabitants occupationally exposed to asbestos.