Memo on Equipment for the Membrane Filter and Personal Air Sampler Method of Measuring Asbestos Fiber (1973)

An unsigned three-page memo of March 5, 1973, "Equipment for Membrane Filter/Personal Air Sampler Method of Evaluating Asbestos Fiber Dust Levels." It lists what is needed to sample and count asbestos fibers: a plastic field monitor with a 37 mm Millipore filter, a battery-powered pump running at about 2 liters a minute (from Willson, Mine Safety Appliances or National Environmental Instruments), hose, calibration equipment, and a binocular microscope of 400 to 450 power with phase contrast illumination (from Bausch and Lomb, American Optical or Leitz).

What it shows

The memo is a shopping list for the membrane filter method, the fiber-counting method used under the federal asbestos standard, with samples taken in the worker's breathing zone and fibers counted by phase contrast microscopy. It names no writer, recipient or company; it probably comes from J-M's files and may have been prepared for customers or contractors who had to start measuring fiber levels.