Any project that involves more than 4,000 test subjects, 41 measurement sites and 8 states is certainly a massive undertaking, even for our established team here at Anthrotech. Both the size and scope of this respirator database project that was completed for the National Institute for Occupational Safety and Health (NIOSH) contribute to its lasting importance.
In 1973, the NIOSH sponsored a study that resulted in the creation of a test panel of persons who were used to represent the head-and-face variability found in the U.S. population. But test panels based on these data became incredibly outdated 25 years later. Furthermore, the data were obtained from military subjects who do not necessarily represent the civilian working population of interest to NIOSH.
NIOSH contracted Anthrotech to create an updated database of anthropometric information representing the heads and faces of U.S. civilian respirator users – both traditional and 3D – that could be used for respirator design for decades to come. A secondary objective was to obtain a subset of 3D head and face scans to be used for future research in the relationships between head-and-face shape and respirator sizing and design.
How Anthrotech Helped
As with any project, there was ample planning and preparation done before a single measurement was taken. Due to the size and scope of this project, it spanned a couple years’ time from start to finish.
A total of 4,026 subjects were recruited among industrial and service workers using respirators in eight U.S. states. These subjects were measured for 21 dimensions, using traditional anthropometric instruments. More than a thousand of these individuals were also scanned to produce 3D images. The sampling plan called for roughly equal numbers of male and female subjects in four racial/ethnic groups and three age groups. The oversampling in some of these categories was done intentionally to allow modification of the database as sex, age and racial composition of the U.S. working force changes in future years.
A team that included trained measurers and an experienced scanner operator moved around the country to collect the data. Anthrotech editing routines were used in the field to ensure optimum accuracy. Both the traditional measuring data and the 3D scans were further edited and cleaned up before the final products were released. Traditional data were weighted to reflect the percentage of individuals in each sex, age and race category found in the entire civilian population. As population demographics change, the sample can be re-weighted so it is continually correct. These data were analyzed to produce new test panel matrices for the design and sizing of respirators.
Resulting from the new data Anthrotech produced, NIOSH issued new recommendations for respirator test panels. Since the project was completed, Anthrotech has been working directly with manufacturers to help them learn how to correctly measure future test panels, ensuring respirator fit and comfort across the industry. In addition, the database Anthrotech produced enabled NIOSH to create digital headforms based on the scans that were taken in this survey, which will allow manufacturers to design new respirators directly from the 3D data, rather than having to interpret a 3D product from tape and caliper dimensions.
A project of this magnitude doesn’t come along often. When it does, it is important that the data stands the test of time. This work will be used to ensure proper respirator sizing and fit for decades to come.