The polypropylene can be cleaned as recommended by Health Canada: a hot wash with detergent. It can be washed with the mask or separately. It should not be tumble dried: it should be removed from the mask and hung or laid flat to dry before reinserting. Do not iron it: it is plastic and will melt
For community mask manufacture, we suggest using industry-grade spunbond polypropylene. (Catherine Clase)
The material can be integrated as a middle layer when masks are being made.
Alternatively, a rectangle of spunbond polypropylene can be inserted between the two outer layers of a cloth mask. The material does not fray easily. If using two layers of polypropylene, we suggest folding the material in half and sewing it together with a simple stitch or an overlock, to make a washable filter.