the answer is simple: none.
Dear Spike, if you're going to make such claims as:
all those dust mask that you're wearing are simply useless
Then you need to back it up with some evidence. It's really quite simple, isn't it?
Well I think by now the main purpose of the masks is as a placebo
This is worth a read - medrxiv.org/content/10.1101/2020.04.17.20069567v1.full.pdf - while it hasn't been peer-reviewed yet to my knowledge, they suggest that masks can reduce the amount of particles inhaled by around 75%.
From a Polish perspective, last weekend proved that it's pointless asking people to wear masks if you're not going to enforce the rules.
As for the poster above, it's pretty obvious that he's reposting the messages from Nowogrodzka and ignoring the current trends. He might want to worry more about WKK and Hołowina, as both of them look like a serious threat in the 2nd round.