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The same occurs with valve masks, which are even less effective in stopping the emitted drops and with all homemade masks that, unless they are very close to the face and are made of multilayer materials, are of little use. Surgical masks, on the other hand, while they don’t block every drop, are much better. The second, published in Science Advances by researchers at Duke University in Durham, North Carolina, focuses on domestic variants of masks, made with the most disparate materials: it analyzes 14 of them, along with the surgical one and the one called N95 , more protective for the user than the surgical one, with or without a valve.
Also in this case, the best performances are precisely the latter, followed by surgery. All other models, including the valved N95, do not prevent droplet dispersion. The masks in the images above, and object of the study, are of this type:
1.Surgical (3 layers)
2.N95 with valve
3.Fabric
4.PolyPprop (2 layers of propylene, apron)
5.Cape / Cotton (cotton-prolipene-cotton)
6. MaxAT (one layer of Maxima AT, polymer)
7.Cotton 2 (two layers of cotton, pleated)
8. Cotton4 (two layers of cotton, Olson style, more anatomical and linear)
9. Cotton 3 (two layers of cotton, pleated, without a particular style)
10. Cotton 1 (one layer of cotton, pleated)
11. Neck gaiter – neck band (one layer of polyester and elastane, another polymer, weight 0.022 g per cm2)
12. Bandana: double layer bandana, weight 0.014g / cm2)
13. Cotton 5 (two layers of cotton, pleated)
14. N95 without valve
The masks of the near future
Meanwhile, however, bioengineers at Georgia Tech University, who have been involved in the field of innovative materials for many years, are working on the issue, and they have created a two-part mask that could convince many to give up DIY. As illustrated by photos in the Journal of Textile Institute, the first one, which exploits the characteristics of some fabrics created for professional athletes, consists of a pocket that houses a washable filter material in polyester and Spandex (another polymer), surrounded by an edge extremely comfortable, yet allowing you to speak and breathe comfortably, reducing the urge to remove it
The other part, joined to the first to cover the face even laterally, is in stretch, again in polymers (this time Spandex / Lyocell) with eyelets and hooks to fix it, and with holes for the ears, to adapt it. perfectly to the circumference of the head of each (photo also here). The idea is to help people wear it all the time and, at the same time, reduce costs and, above all, the elimination of disposable masks, guaranteeing the maximum possible protection.