In general, masks are something that the sick person wears to prevent germ spread. Same idea as why surgeons wear them in the operating theater.
The only kind of mask that's going to filter particulate matter out of the air (i.e., be effective against the virus for someone who is not infected) is something that has an airtight seal.
Yes, so you agree, masks hinder transmission by, in your understanding as presented, decreasing the ability of sick people to infect healthy people. That is, masks reduce transmission.
The only kind of mask that's going to filter particulate matter out of the air (i.e., be effective against the virus for someone who is not infected) is something that has an airtight seal.