tive pressure in the facepiece. This may be impractical because the current practice is to assign the same protection factor for both men and women.[1]
Regarding the face-seal-performance data and technical criterion used for determining respirator-class APFSs recommended to NIOSH and OSHA, an important LASL report stated in 1976:
A reasonable basis for assigning a [assigned] protection factor to a single class of respirators would be to require that 95% of the (test) subjects must meet the performance criteria to assign a given protection factor. In addition, the 5% of the people not meeting the [APF] performance criteria and the 5% not included in the panel must be identifiable by a stringent qualitative or quantitative fitting test or by anthropometric facial measurements. It is recommended that this criteria be used in assigning a given protection factor to a single class of respirators such as half-mask high-efficiency filter respirators. This is the criteria that is used in making recommendations where the results of respirator [face-seal] performance measurements are discussed in Sec. VI.[2]
It is important to note that the face-seal-performance measurements made on half- masks by the LASL researchers were performed on test subjects who had not been properly fit tested with qualitative or quantitative fit tests. These measurements. subsequently were used as the basis for the LASL APF recommendations. The LASL researchers stated the following regarding their measurements: Before entering the test chamber, the subject donned the respirator and tested the fit. When wearing a half-mask respirator, the subject tested the fit by either the positive or negative pres- sure method." 55 The 1976 LASL report also stated that face-seal-performance results from each and every NIOSH-certified respirator in a class must meet the preceding criteria when determining a class APF. 56 This criterion is supported by remarks made at a
55Hyatt E.C., J. A. Pritchard, and C. P. Richards: Respirator Efficiency Measurement Using Quantita- tive DOP Man Tests, Am. Ind. Hyg. Assoc. J. 33(10):634-643 (1972), p. 637.
58Tbid., Section VI, pp. 10-14.
