NIOSH Anthropometric Data and ISO Digital Headforms

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In 2003, the National Institute for Occupational Safety and Health (NIOSH) conducted a comprehensive nationwide survey of 3,997 subjects. The resulting head and face measurements were used to create an extensive anthropometric database detailing the face size distributions of respirator users using both traditional measurement methods and advanced three-dimensional scanning systems. This database was utilized to establish standardized fit test panels for incorporation into NIOSH respirator certification and international standards. One of the developed panels, called the principal component analysis (PCA) panel, uses the first two principal components obtained from a set of 10 facial dimensions, adjusted for age and race, and divides the user population into five distinct face-size categories. These 10 dimensions are directly associated with respirator fit and leakage and can accurately predict the remaining face dimensions. Respirators designed to fit these panels are expected to accommodate more than 95% of current U.S. civilian workers. From the comprehensive 3,997 subject anthropometric survey, 1,013 subjects were also scanned using a Cyberware 3D Rapid Digitizer. Three-dimensional scans of five individuals who most closely represented each given size category were averaged to construct representative headforms for each category (small, medium, large, long/narrow and short/wide). The NIOSH digital headforms are highly symmetrical and accurately represent the facial size and shape distribution of current U.S. respirator users. In addition, ears have been placed on the headforms to match the average position for the chosen heads of a given size. These headforms have been incorporated into a technical specification standard for ISO TC94 Personal Protective Equipment, SC15 Respiratory Protective Devices, WG1 General, PG5 Human Factors. That standard is titled “ISO 16976-2 Respiratory Protective Devices — Human Factors — Part 2: Anthropometrics”. In an assessment of the 2003 NIOSH anthropometric survey of U.S. respirator users, the Institute of Medicine concluded that “Having effective respiratory protection can be, and often is, a matter of life and death. The scientific bases for developing and fitting effective respiratory protection remain more art than science.” Therefore, NIOSH strongly encourages application of the data and results to address critical occupational safety and health issues.