Are they? It's unclear whether KN95 masks are better than a piece of fitted fabric around your mouth and nose. That's the trouble with masks; we don't know what works and what doesn't.
I wi work on the assumption that it is at least as good with a probability to be better. We know how this virus is transmitted and what is needed to filter it, it’s just a particle. We have strong evidence from the healthcare community that these masks keep workers COVID-19 free. They definitely work on other viruses of a similar size...