I was reading the WHO guidlelines recently. It talks of fabric face coverings that the public could make themselves. The one i remember well was hankerchiefs and that you would have to use FOUR layers. It then followed that up by saying it would only be 13% efficient. There are many other gems in there, including one that I mentioned on here about how they can actually trap your own bacteria on them and if not cleaned thoroughly after EVERY useage, or buying a brand new one each time yours has been soiled or soaked, you put yourself at risk of getting yourself a lung infection. Here in the UK it became mandatory (but not law) to wear them in shops from today but I've seen plenty of people carrying on as normal, and the shop owners, the smaller ones anyway, don't want to piss off their loyal customers so they aren't saying anything to anyone if they aren't wearing them.