most study only focus on 3 domain :
3-ply medical grade,
n95,
cloth masked.
all these in-between have no clear evidence
most study only focus on 3 domain :
3-ply medical grade,
n95,
cloth masked.
all these in-between have no clear evidence
a 3-ply face mask is generally good for most time. drs have been using it even before covid. a n95 is only necessary in aerosolized situation (like a dentist doing scaling) while cloth mask is not effective