Where face masks for high-risk COVID protection are concerned, there are three types I would recommend: N95 masks (the American gold standard), KN95 masks ... from multiple layers of non-woven ...

The rule isn't foolproof, but it should help weed out masks that aren't very protective. The Centers for Disease Control and Prevention recommends multi-layer cloth ... some KN95 and FFP2 masks ...

Some school districts, such as Oakland Unified, Berkeley Unified and West Contra Costa Unified, have ordered KN95 ... mask or a surgical mask with a cloth mask on top. Students who wear fabric masks ...