Mask hygiene is important. If you’re wearing a surgical mask that you’ve bought at the chemist, you’ve got to follow the instructions. But usually after three or four hours the mask becomes useless because it’s wet and will transmit any infection.
N95 masks, you’ve also got to use the instructions on the leaflet so that you’re wearing that for the prescribed time. If you’ve got a cloth mask, in other words a two layer cotton mask, then you’ve got to use your judgement, once it’s getting damp, it’s losing its effectiveness.
The way to clean a two layer cotton mask, one you’ve either bought or you’ve made for yourself, is to wash it at a 60 degree cycle and at a full cycle. And that will destroy any virus on it.
Dr Norman Swan, Physician and Journalist