Size Characterization of Industrial Products (MMMF) Used in Buildings and Structures as Substitutes of Sprayed Asbestos-Containing Material.
NIOSH 1990 Nov:1312-1315
The size characteristics of manmade mineral fibers (MMMFs) used as substitutes for sprayed asbestos containing mineral materials were examined. Bulk samples of five MMMF containing materials used as sprayed insulation in public buildings in Italy were mechanically dispersed in hydrogen-peroxide and water. The suspensions were filtered, dried, and examined by scanning electron microscopy (SEM). The size distributions based on fiber diameters were determined. Breathing zone samples were collected during removal of one of the materials from a building. They were analyzed by phase contrast optical microscopy and SEM to determine the fiber length and diameter distributions. The chemical composition of the fibers was determined. Approximately 60 to 70% of fibers in three of the bulk materials had diameters of 3 microns (micron) or less. The percentage of fibers of diameter 3micron or less in the other two samples was around 30 to 40%. Approximately 98% of the fibers released during removal of the MMMF insulation had diameters less than 3micron. Approximately 41% were 5 to 10micron long. The lengths of the other fibers ranged from 10 to 100micron. The fibers consisted primarily of silicon (7440213), calcium (7440702), and aluminum (7429905). The author concludes that MMMF containing insulation products typically contain 50% fibers with diameters less than 3micron. During removal operations approximately 98% of the airborne fibers from these materials have diameters less than 3micron. It is recommended that all labels on MMMF containing insulation materials include data on fiber diameters and chemical composition as well as technical instructions so that users can evaluate potential risks.
Fibrous-dusts; Chemical-composition; Synthetic-fibers; Insulation-materials; Microscopic-analysis; Dust-analysis; Respirable-dust; Risk-analysis;
7440-21-3; 7440-70-2; 7429-90-5;
Proceedings of the VIIth International Pneumoconioses Conference