Measurement of 3-D facial contours for the design of half-face respirators.

A portable anthropometric test rig capable of obtaining three-dimensional face shape data was developed and used to obtain information relating to facial shape, stiffness, and variance for a selected subgroup of respirator users in the Australian work force. A respirator seal shape most suited to the sample population was obtained by studying the central portion of the face of all the subjects. The optimum seal shape was established by following the path of minimum variance among all the faces; the method provided information on the shape, dimensions, and stiffness of the optimum seal for a respirator suited to the sample population. The seal surface flexibility required for a comfortable fit was determined by measuring the deflection of the skin caused by an applied pressure and using this information along with face shape variance data. Results indicated that the required flexibility in the seal surface increased toward the lower portion of the face.