Polypropylene is now recommended in masks
Canada's chief public health officer recently released updated recommendations for non-medical masks.
In early November, Canada's Chief Public Health Officer Dr. Theresa Tam updated recommendations for non-medical masks. She now recommends that masks be at least three layers instead of two, and that the third layer be a filter-type fabric, such as non-woven polypropylene fabric.
These recommendations are in line with FILTROLIFE's 4-ply filters now available online here.