N95 Masks are made to filter particles the size of covid droplets out of the air as it is breathed in through the mask material. This is not new technology. It has been studied and regulated whether in industrial settings (spray paint and dust) or medical settings.
It works. It works much better than cloth or surgical masks which only minimally filter these droplets out of inhaled air.
Mask wearing has very slowly caught on, but the fault has been vague recommendations from experts, from the stiffled CDC on down and always the explanation, "well it really doesn't protect you, but if everybody wears them it may knock down droplets of the infected person." That is not a ringing endorsement. The same paragraph is cut and pasted over and over. No one believes they are the person spreading covid.
N95 masks work in the ER where it was discovered that surgical masks often did not. Early HCW infections occurred when ER personnel were surprised that patients with many complaints also had covid. Many ERs have seen almost constant covid patients, sick and coughing and then sometimes having to be intubated which puts the practitioner at greatest risk of exposure.
In almost any situation, one can imagine, an N95 mask will be better than a cloth mask and certainly none for the person wearing the N95 mask. This is DIFFERENT from the cloth mask argument. An N95 mask protects the wearer, independent of the behaviour of others. Especially if others are not wearing masks, the risk of transmission is high, but the N95 mask, worn consistently, reduces the risk of infection in any circumstance of exposure.
This makes it espeicially important for people nominally at risk for more severe disease, ie those over 65 or so, obese, with diabetes or other chronic diseases and especially with immune deficiencies as in transplants and many cancer treatments.