Assessment of the NIOSH Head-and-Face Anthropometric Survey of U.S. Respirator Users (2007) / Chapter Skim
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This, in turn, demands having good anthropometric data -- particularly data on facial dimensions -- from a representative sample of the respirator-wearing workforce. Once such data have been collected and analyzed, an appropriate fit-test panel can be designed from them.
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. THREE OVERARCHING THEMES The various elements of the NIOSH-sponsored Anthrotech study -- anthropometric measurements, statistical sampling techniques, fit testing, and so on -- are complicated, and this review must necessarily wade into them in some detail; but the basic message of this report can be summarized with the following three broad statements:
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In their survey, the Anthrotech researchers used traditional tools such as calipers and measuring tapes to take 18 facial and head dimensions from the 4,026 subjects in their survey. They also recorded height and weight for comparison to other similar datasets, and neck circumference was added partway through data collection when it was learned that this measurement plays a role in some national and international respirator standards.
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For these reasons, the committee concluded that the NIOSHsponsored Anthrotech report did not adequately address the potential effects of measurement error on the validity and quality of its anthropometric measurements and makes the following recommendation: Recommendation 2-1: Analyze Measurement Error. In future studies NIOSH should perform additional analyses of the impact of measurement error, includ ing the effects of intraobserver and interobserver variations in measurement.
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In light of the potential advantages, the committee recommends the following: Recommendation 2-2: Consider Utilizing Three Dimensional Scan Data. NIOSH should consider collecting and utilizing data from 3D scans, alone, or in combination with tradi tional manually collected data, to ensure the most ro bust set of data are used to develop future anthro pometric face panels.
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Defining the Target Population Although a clear definition of the target population is critical to survey design, the Anthrotech report does not provide such a definition. In addition, although the survey intends to reflect "respirator users," it was unclear if that included anyone who may ever need to use a respirator, or simply those who use or should be using respirators.
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Benchmarking the Target Population Perhaps the most important consideration in this weighting, however, is to make sure that it is done in such a way as to capture the true demo
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This was the result of a major difference in facial dimensions between the earlier LANL sample and the current one -- of the individuals surveyed in the current sample, 15.3 percent would not have been covered by the LANL face panel, most of them because of having larger faces. Thus the shift in the face panel was necessary to provide coverage for the larger faces in the current survey; but the committee noted that the shift came at the expense of smaller-faced individuals, including many in minority populations, even though small faces still make up a
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NIOSH should perform a study in which it compares the range of quantitative fit provided for specified respirators on subjects representing the LANL face panel and subjects representing the proposed NIOSH-sponsored Anthrotech bivariate face panel (adjusted in accordance with recommendation 4-2)
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The failure to include fit testing with anthropometric facial measurements limited the ultimate utility of the data collected in the NIOSH-sponsored Anthrotech study. Further, half-face respirators in particular have not had proper analyses performed on the relationship between facial dimensions and fit.
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Recommendation 4-6: Perform Facial Dimension Analyses for Half-Face Respirators. NIOSH should perform additional facial dimension analysis when developing anthropometric face panels for half-facepiece respirators, including at least one nasal dimension.
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apply 3D measures to describe the essential fit characteristics of the panel, and (4) rely on quantitative fit testing to determine the extent to which a respirator covers the fit characteristics of the face panel.
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Thus the committee recommends Recommendation 5-4: Modify Certification Require ments. NIOSH should modify its certification requirements to encourage manufacturers to develop specific sizes designed to fit underrepresented anthropometric categories.
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NIOSH should encourage manufacturers to develop improved methods of describing facial sizes and shapes in product literature. For example, NIOSH and manufacturing companies should further explore the use of face panel images, and respirator contain ers should include corresponding pictures of small, medium, and large sizes, and long/narrow and small/wide face pictures.
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Future anthropometric face panel studies undertaken by, or on behalf of, NIOSH should have a statistically rigorous and valid sampling plan and implementation strategy that precisely define the target population, and also ensure that the samples of selected subjects included in the studies are representative of the predefined sample population (e.g., the current workforce that wears respirators, workers who should be using respirators, the general United States workforce)
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Recommendation 4-5: Determine Key Features Related to Fit Using Quantitative Fit Measures. NIOSH should perform research to determine which facial features have the greatest impact on the respiratory protection of face masks in the workplace, using quantitative measures.
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Conclusion 5-2: Qualitative fit testing is a subjective process and does not provide NIOSH certification personnel with a specific value to analyze leakage around the facepiece. Recommendation 5-2: Replace Isoamyl Acetate with Quantitative Measures.
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From page 18... ...
to be certified against a fit-test panel and not specify what portion of the panel each individual size respirator must fit, provided that the family adequately covers the entire panel. Conclusion 5-5: The current size designations of small, medium, and large for respirators in product literature are not adequately informative for wearers and fit testers.
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