How important is it to have a good design of the face shield?

By developing the sneeze particle simulation based on published data including sneezing velocity as a function of time as well as droplet particle size and distribution, the results from SIMULIA PowerFLOW are realistic model of a sneeze event. Using the model developed by @JJ, we are in the process of evaluating different face shield designs to guide 3D printing units.

Here we review 4 designs of face shields that are being fabricated by volunteers/ makers around the world and distributed to healthcare workers. Designs 1 to 3 are simple 3D printable face shields with various protective features on the top. Design 4 covers more area on the side but shorter in height.  

Images below highlight the contaminated surfaces using a red/purple scale. As we can see, it is important to cover the top of the frame; otherwise, mucus particles could contaminate the face easily, indicated by the yellow arrow. The flap also helps to protect the forehead.

Is wearing a face shield alone, without a surgical mask, enough?

The video above shows the trajectory of particles near the shielded person’s mouth and nose. The simulations suggest small particles are drawn behind the shield, and the shielded person could inhale those particles. Designs 1 to 3 show the importance of extending the sides of the shield. Whereas Design 4 shows the importance of having the shield extend well below the chin. Among the 4 designs, Design 1 is least optimal because larger amount of particles enter from the top and the side.

These results also suggest that a face shield is an extra protection, but should not replace the use of a  mask.

More evaluation of face shield designs will come soon. Stay tuned!

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The simulation(s) by Dassault Systèmes and other technical or operational information represented in this video are presented as an illustration and are for informational purposes only.  Any use of information presented in or derived from this video is at the viewer’s sole risk and Dassault Systèmes disclaims all related liability.