Canada’s Chief Public Health Officer Dr. Theresa Tam has now recommended adding a “filter layer” to masks to provide Canadians with extra protection against COVID-19.
While the addition of a filter layer is important, Dr. Tam reiterated that the most important factor on mask effectiveness is the fit. Masks need to be large enough to completely and comfortably cover the nose, mouth and chin without gaping.
Non-medical masks should be made of at least 3 layers, of which two should be tightly woven material fabric, such as cotton or linen, with the third (middle) layer being a filter-type fabric, such as non-woven polypropylene fabric.
Reusable masks with a non-woven filter layer should be washed daily, and can be washed multiple times. Disposable filters should be changed daily or as directed by the manufacturer.
This advice is in addition to previous recommendations that masks, allow for easy breathing, and be changed as soon as possible if damp or dirty.