Is it true that masks only work to prevent germs/diseases from exiting one’s mouth/nose and not from entering one’s mouth/nose? If so, why?

Question

Is it true that masks only work to prevent germs/diseases from exiting one’s mouth/nose and not from entering one’s mouth/nose? If so, why?

In: Other

Answer 1

I presume you’re talking about covid19.

Nothing in biology/medicine is only. In this case, the virus primarily spreads by respiratory droplets, little drops of virus-containing water that are expelled primarily when you cough and sneeze. The mask works as a barrier against these droplets. It works really well to prevent exit from your nose/mouth cause it’s right there to block it, but of course some can get through. The same goes for entry. It does something.

I haven’t seen numbers, but masks are far more effective for preventing exit than preventing entry, but that doesn’t mean they’re useless for preventing entry.