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.
Source: Chung, Emily, McMurchy, Kieran, McMurchy, Bloomfield, Tyler, Brown, Cheryl, Polypropylene is now recommended in masks. Should I be concerned? Your mask questions answered, Retrieved from CBC