Its important that the masks are made from cotton and then fitted with a hoover bag filter or something similar. This
Give them the ability to filter down to even very small particle sizes. They are not substitutes for FFP3 masks its just these are in short supply.
Imperfect solution in an imperfect world.
Stay safe and be kind
HIFA-Zambia profile: Tom Browne is a surgeon at the Mid Essex Hospital Services NHS Trust, MEHT, in the UK. tom.browne AT meht.nhs.uk