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AIR MONITORING FOR ASBESTOS FIBERS Asbestos is Only Harmful to Humans Inside the Body So Careful Monitoring for Airborne Fibers--and the Quantity--Are Vital to an Effective Environment by Robert N. Hager, Jr. CIH, Hager Laboratories, Inc. /TV ' sbestos is only harmful to / A % humans when it is injested / % into the body. This occurs, in general, by breathing air containing airborne fibers of asbestos. The accepted method for measuring the amount of airborne asbestos dust is to draw a known volume of air through a filter that removes the dust. The amount of dust on the filter is determined analytically and then, the average dust concentration is calcu lated by dividing the amount of dust found on the filter by the volume of air pulled through the filter. Although this procedure sounds fairly simple, and it is, there are several questions that must be answered before proceeding. 1. During monitoring, how dusty is the environment expected to be? Is the dust going to be visible in the air, or is this an operation that very little if any dust should be present? 2. How long should the monitoring be? Should air monitoring be for a full There is a minimum amount ofasbestos that can be accurately counted with the use ofoptical microscopy and only a por tion of the filter is used--so it is essen tial that dust distribution over thefiller face be uniform. MARCH/APRIL 1987 ASBESTOS ABATEMENT 15 GLEASON-OO1137