Practical application of magnetic alignment of mineral fibres for hazard evaluation

Techniques and instrumentation have been developed employing the magnetic alignment of fibrous dust collected on membrane filters coupled with light-scatter measurement for the accurate and reproducible assessment of airborne fibre hazard. This equipment, specifically designed to measure asbestos hazard, is built into a standard microscope, which also incorporates a facility for manual fibre counting and for bulk sample identification. With this new technique, up to 100 samples per day can be analysed automatically, compared with some 10-15 samples per day by manual counting. Collected fibres are assessed from areas of membrane filters some 30 times greater than those with manual methods; consequently, a more representative result ensues. These techniques lend themselves to considerable and varied application and involve relatively inexpensive instrumentation.