Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Facial Respirator Shape Analysis using 3D Anthropometric Head Data



Riley Fenlon


For firefighters and first response crews, the facial respirator is the first and last defense against hazardous and potentially harmful airborne agents. That defense is crippled if the seal of the respirator sprouts a leak, exposing the wearer to the dangers of the surrounding environment. Due to the inherent limitations of traditional anthropometric measures in modeling the nuanced and complex human face, fit testing standards for respirators remain imprecise. A recent review of a NIOSH anthropometric survey called for 3D facial data to try and remove some of this uncertainty. Using the Civilian American and European Surface Anthropometry Resource (CAESAR) database finished in 2000, 3D facial models were created to test the rigid body fit of a half-mask respirator across different demographic groups. A good fit, in this study, is defined by a relatively small total distance between the face and the landmark points of the mask. Employing a best fit algorithm, the average face generated for Asians surprisingly accrued the least amount of gap while the male face had the greatest gap. When the landmark points of the mask were superimposed on a contour plot of the standard deviation in the face of each group, the plot revealed that the mask extended into areas of high facial variance. Upon analysis of the gap distance at each landmark, it was found that the sides of the mask were the areas with greatest separation from the face. Further investigation of wider than average faces confirmed a weak to no correlation between head breadth and total gap distance.
NIST Interagency/Internal Report (NISTIR) - 7460
Report Number


3D scans, anthropometry, CAESAR database, facial respirator, fit test


Fenlon, R. (2007), Facial Respirator Shape Analysis using 3D Anthropometric Head Data, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed July 25, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created August 15, 2007, Updated June 2, 2010