Relationship of impinger counts to fiber concentrations by membrane filter in asbestos textile plants (1965)

This U.S. Public Health Service report compared two ways of measuring asbestos dust in asbestos textile plants: impinger counts of particles, in millions of particles per cubic foot (mppcf), and membrane filter counts of fibers per cubic centimeter (cc). The authors took simultaneous, side-by-side samples by both methods and examined 46 filters by electron microscope. Rounded averages showed 1 mppcf corresponded to about 10 total fibers per cc, 6 longer than 5 microns, and 3 longer than 10 microns. Average ratios ranged from about 5 to 16 by plant and 7 to 13 by operation. Most fibers were under half a micron thick. The electron microscope showed about 4 times as many fibers longer than 3 microns as the optical filter count, and about 13 times as many fibers overall. The authors noted that their samples were not necessarily typical of each plant and that both methods vary considerably. They concluded that either impinger counts or membrane filter fiber counts at higher magnification could index fiber concentration, the latter being more direct and less subject to variation by plant and operation.

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From J-M's medical library

This copy comes from the Johns-Manville medical library. It was among the papers J-M kept in its medical library without an index entry.