Penetration of several filter materials by asbestos as a function of fiber dimensions.

The purpose of this research was to determine the penetration of several filter materials commonly used in building air-handling systems by asbestos fibers. An airstream containing tremolite asbestos fibers was passed through these materials and the upstream and downstream fiber concentrations were measured by membrane filtration and scanning electron microscopy. The penetration of these materials was determined as a function of asbestos fiber diameter and length at two typical air velocities. For glass fiber filter materials, the maximum penetrations were 3.5% and 0.1% compared with American Society for Testing and Materials dust spot efficiency ratings of 80% and 90%, respectively. Thus, the glass fiber filters appear to be capable of greatly reducing the concentration of asbestos fibers in a building air-handling system. Roll and panel filter materials consisting of polyester fibers exhibited penetrations from 15% to nearly 90%. Thus, roll and panel filters tested are not recommended for this purpose.