Volume 6, Issue 1 (January 1978)
Respirable Fraction of Airborne Dust: Quantitative Descriptions, Formal Definitions, and Performance Characteristics of Samplers Matched to Them
A rational system for monitoring atmospheres suspected of containing insoluble toxic particles requires a method that will provide a sample in which all particles are represented in proportion to their “respirable fraction,” that is, in proportion to the probability that they would be deposited in the nonciliated region of the lung, if inhaled by an average man. Various organizations concerned with occupational health have advanced formal definitions of respirable fraction, and samplers operating in accordance with those definitions are widely used for both personal and general area monitoring. In this discussion, quantitative descriptions of respirable fraction, the formal definitions derived from them, and the performance characteristics of respirable fraction samplers are reviewed. The samplers are shown to perform adequately for their respective definitions, but in general the definitions themselves significantly overestimate respirable fraction as determined from recent experimental data.