Digital 3-D Headforms Representative of Chinese Workers

Abstract

Headforms are useful for designing and testing various types of personal protective equipment used to protect millions of workers from occupational hazards in China. Although the Chinese national standard of head-and-face dimensions for adults was first published in 1981, headforms based on those dimensions were never developed. In 2006, an anthropometric survey of 3000 Chinese civilian workers was conducted. As part of the survey, 350 subjects were scanned with a Cyberware 3D Rapid Digitizer. The manual measurements and 3-D digital scans from this survey were used to develop 3-D digital headforms that represent Chinese workers. The objective of this study was to develop headforms that represent today's Chinese workers. Ten facial dimensions relevant to respirator fit were chosen for defining a principal component analysis model which divides the user population into five face size categories. Mean facial dimensions from manual measurements were then computed to target the ideal facial dimensions for each size category. Five scans were chosen from each face size category to be used in the construction process. Selected scans were then averaged to construct a representative headform for each face size category. Five digital 3-D headforms were developed: small, medium, large, long/narrow, and short/wide. These distinct sizes of digital 3-D headforms take into account the linear distance between landmarks as well as the surface contours captured during the 3-D scan. The dimensions of constructed headforms were within approximately 4 mm between the corresponding computed means and manual measurements of anthropometric landmarks for the sample population in each size category. These new headforms represent the facial size and shape distribution of current Chinese workers and may be useful for respirator research and development. The Chinese medium headform has a wider face width, shorter face length, and smaller nose protrusion when compared with the current U.S. standard headforms. Upon validation, it may be useful to incorporate these dimensions into Chinese and international respiratory protective devices standards.