* Adding a third layer to cloth face masks is recommended for preventing the spread of COVID-19. Non-woven polypropylene fabric is the material of choice for this third layer, but many people may not know what this material is, or where to get it.

With masks being made at home and by local clothing companies, using a non-woven layer is recommended by the CDC and Health Canada.  Liza uses a medium weight non-woven polypropylene layer between two layers of natural fibers. This third layer provides filtration and protection and also gives the mask body, structure and breathing space between mask and face.

Every study that has examined layering has found that using additional layers in face masks improves filtration, but some fabrics provide more filtration than others. Liza Heider Design supports the public health recommendation, and specifically recommends the use of industry-grade “spunbond” polypropylene as a middle layer in washable cloth masks.

Spunbond polypropylene destined for the clothing and furniture industries has a fabric-like feel. It is washable and will not divert supply of medical-grade polypropylene from the manufacture of formal personal protective equipment.

Washable spunbond polypropylene is used in the clothing and furniture industry. It is one of several materials used as interfacing, to give structure to waistbands and collars, and around zippers. It is also used to seal the bottom of couches and chairs. It is readily available from fabric distributors and is not currently in short supply since it is not part of the supply chain for personal protective equipment. This material aligns with CDC and Health Canada public health recommendations.