Don't worry too much about effectiveness of DIY face masks - in few months Respilon and other Czech companies will put on market face masks made from nanomaterials which filters virus much more effectively ;)
OK, I think that the mask over your own face is to prevent viral spread in largish water particles caused by coughs and sneezes, not general breathing (I'm not sure general breathing spreads much virus anyway, but I don't know).
So if you are infected and not showing symptoms ie. not coughing/sneezing then arguably the mask is not doing anything.
Arguably not, but we need more data - can anyone comment with sources?
Even if you are breathing calmly mask will catch some small water droplets so spreading is somehow contained. It's true that after ~1 hour wowen mask will become wet and no longer effective. But it's not problem wear some other masks in your bag and change it... Currently there's huge shortage of respiratory protection products globally so your old wowen tshirt will help you :)
You dont know for first ~5-6 days whether you are infected or not.
https://www.businessinsider.com/people-are-making-diy-face-m...
Don't worry too much about effectiveness of DIY face masks - in few months Respilon and other Czech companies will put on market face masks made from nanomaterials which filters virus much more effectively ;)