What's frustrating with data like that is what it doesn't say: is it OK to keep using a mask?.

Obviously what this is saying is that, once contaminated, a mask can't be cleaned and made safe. But in real use, at least at the infection density we see right now, they're not getting contaminated with use. They're just dirty. Is it safer to keep using the same mask for a week or to use it once then go maskless? We just don't know.