Background:
When Covid-19 hit the United States in March 2020, the country faced extreme personal protective equipment (PPE) shortages. Design that Matters responded by rapidly designing and fabricating face shields for local hospitals. These face shields were designed to have as universal a fit as possible. NASA biometrics for head circumferences were used in the design process to achieve this design specification. The biometrics range from a 5% female head to a 95% male head. In order to demonstrate the universal fit we wanted to produce life-sized heads. These heads are currently used to create a visual for the universal fit capability of the Covid-19 face shield.

Design Process:
The National Institute for Occupational Safety and Health (NIOSH) released digital head forms that represent the 5 most common face shapes and sizes. The measurements for the head forms were developed through an anthropometric survey of 3,997 subjects. Using these anthropometric data parameters, five head size categories were developed by NIOSH National Personal Protective Technology Laboratory (NPPTL). Three-dimensional scans of five individuals who most closely represented each size category were averaged together to produce the five head shapes: small, medium, large, short/wide, and long/narrow. These digital head forms were released on the NIOSH website.

NIOSH Heads: https://www.cdc.gov/niosh/data/datasets/rd-10130-2020-0/default.html

We downloaded the digital head forms but decided to make adjustments before fabricating them. A key part of fabricating these heads was ensuring we demonstrated the wide range of NASA biometric head circumferences that the Covid-19 face shield is intended to fit. We measured the circumferences of the five NIOSH heads and found they did not align perfectly with the NASA biometrics. We scaled NIOSH heads to fit the following NASA head circumference biometrics (all of which can be downloaded as stl files from this post):

• NIOSH Small to NASA 5% Female
• NIOSH Medium to NASA 50% Male
• NIOSH Long Narrow to NASA 50% Male
• NIOSH Short Wide to NASA 50% Male
• NIOSH Large to NASA 95% Male 

NASA Biometrics: https://msis.jsc.nasa.gov/sections/section03.htm

The scaling was performed to achieve NASA head circumference biometrics, the adjustments do not preserve all nasal, ear, lip, etc. alignments developed by NPPTL. The scaling factors used to achieve NASA biometrics are found in the attached "NIOSH to NASA Scaling Factors.xlsx" document.

The most significant modification to the original NIOSH digital headforms is the base. The original headforms had necks that were unnaturally long and, without any base, the floating head and neck combination was unsettling. We wanted our visual of the Covid-19 face shield’s capabilities to not distract from the face shield design. To do this we designed an inconspicuous base that does not distract from the face shield product being displayed. The base was designed in Fusion360 and combined with the original headform stl files using Meshmixer.

In this post you will find stl files for the original NIOSH heads (not scaled) with bases as well as the 5 previously mentioned NASA scalings with bases.