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The fit test panels currently used for respirator research, design, and certification are 25-subject panels developed by Los Alamos National Laboratory (LANL) and are based on data from the 1967 and 1968 anthropometric surveys of U.S. Air Force personnel. Military data do not represent the great diversity in face size and shape seen in civilian populations. In addition, the demographics of the U.S. population have changed over the last 30 years. Thus, it is necessary to assess and refine the LANL fit test panels. This paper presents the development of new respirator fit test panels representative of current U.S. civilian workers based on an anthropometric survey of 3,997 respirator users conducted in 2003. One panel was developed using face length and face width (bivariate approach) and weighting subjects to match the age and race distribution of the U.S. population as determined from the 2000 census. Another panel was developed using the first two principal components obtained from a set of 10 facial dimensions (age and race adjusted). These 10 dimensions are associated with respirator fit and leakage and can predict the remaining face dimensions well. Respirators designed to fit these panels are expected to accommodate more than 95% of the current U.S. civilian workers. Both panels are more representative of the U.S. population than the existing LANL panel and may be appropriate for testing both half-masks and full-face piece respirators. Respirator manufacturers, standards development organizations, and government respirator certification bodies need to select the appropriate fit test panel for their particular needs. The bivariate panel is simpler to use than the principal component analysis (PCA) panel and is most similar to the LANL panel currently used. The inclusion of the eight additional facial measurements allows the PCA panel to provide better criteria for excluding extreme face sizes from being used. Because the boundaries of the two new panels are significantly different from the LANL panel, it may be necessary to develop new respirator sizing systems. A new five-category sizing system is proposed.

Sizing data generated by the military for use in fitting respirators have been the normative basis for commercial respirator sizing. Anthropometric data developed for males and females of military age in the 1950s and 1960s are still in use today and form the only comprehensive body of information available on this subject. The twofold objective of this study was to: (1) develop an anthropometric database detailing the face size distributions of respirator users using both traditional measurement methods and three-dimensional scanning systems; and (2) use the database to establish fit test panels to be incorporated into the National Institute for Occupational Safety and Health's respirator certification and international standards. A stratified sampling plan was used with three age strata, two gender strata, and four race/ethnic group strata. The plan called for an equal sample size of 166 in each cell. Subjects were obtained at 41 sites from 8 states. In addition to height and weight, 18 facial dimensions and neck circumferences were measured using traditional methods. A total of 3997 subjects were measured using traditional methods, and 1013 of them were also scanned using a 3-D head scanner. As this was a volunteer sample, subjects did not appear in the specific proportions needed for the sampling plan. The resulting data were weighted to correspond to the U.S. population. This article presents the summary statistics for the traditional measurement data only. Multivariate analyses of the data from this study and military data revealed that using historical, military data would be inadequate for describing the anthropometric variability of the current U.S. work force.

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Four performance measures were used to evaluate the fitting characteristics of 18 models of N95 filtering-facepiece respirators: (1) the 5th percentile simulated workplace protection factor (SWPF) value, (2) the shift average SWPF value, (3) the h-value, and (4) the assignment error. The effect of fit-testing on the level of protection provided by the respirators was also evaluated. The respirators were tested on a panel of 25 subjects with various face sizes. Simulated workplace protection factor values, determined from six total penetration (face-seal leakage plus filter penetration) tests with re-donning between each test, were used to indicate respirator performance. Five fit-tests were used: Bitrex, saccharin, generated aerosol corrected for filter penetration, PortaCount Plus corrected for filter penetration, and the PortaCount Plus with the N95-Companion accessory. Without fit-testing, the 5th percentile SWPF for all models combined was 2.9 with individual model values ranging from 1.3 to 48.0. Passing a fit-test generally resulted in an increase in protection. In addition, the h-value of each respirator was computed. The h-value has been determined to be the population fraction of individuals who will obtain an adequate level of protection (i.e., SWPF >/=10, which is the expected level of protection for half-facepiece respirators) when a respirator is selected and donned (including a user seal check) in accordance with the manufacturer's instructions without fit-testing. The h-value for all models combined was 0.74 (i.e., 74% of all donnings resulted in an adequate level of protection), with individual model h-values ranging from 0.31 to 0.99. Only three models had h-values above 0.95. Higher SWPF values were achieved by excluding SWPF values determined for test subject/respirator combinations that failed a fit-test. The improvement was greatest for respirator models with lower h-values. Using the concepts of shift average and assignment error to measure respirator performance yielded similar results. The highest level of protection was provided by passing a fit-test with a respirator having good fitting characteristics.