Abstract
Wearing a protective mask does not necessarily insure the user adequate respiratory protection against toxic aerosols. There are several sources of possible mask leakage; the most common is improper donning. As respirator designs are improved in an attempt to eliminate leakage sources, evaluation techniques must be upgraded so that small amounts of leakage can not only be detected but also be quantitated. Mask evaluation procedures utilizing a large aerosol chamber, bacterial spores, and human subjects permit accurate detection of mask leakage as minute as 1 part in 50 million. This sensitivity is achieved by the use of the various samplers and sampling techniques that operate under the mask. Four types of respiratory samplers are discussed in detail in this paper, and guidance is given concerning the sampler best suited for the evaluation of a particular type of protective mask.