Worker exposures to asbestos (1332214) were surveyed at Charlotte Works, H.K. Porter Company (SIC-3292) in Charlotte, North Carolina, during February, 1964. Membrane filter counts were reported for total fibers and for fibers longer than 10 microns. Impinger samples also were taken. At the time of this sampling, no standards existed for asbestos fiber exposure. Fiber counts shown on the same line with an impinger count represent simultaneous adjacent samples collected by the two methods. The author concludes that while there were differences between impinger and membrane counts for the same operation and for similar operations in different facilities, impinger counts of 5 million particles per cubic foot (mppcf) were equivalent to counts of 50 total fibers per cubic centimeter (cc), 30 fibers longer than 5 microns per cc or 15 fibers longer than 10 microns per cc and they suggest additional controls when these concentrations are exceeded even if the impinger counts are within the 5mppcf.