Not really accurate. The virus particle is 0.125 micrometers. A PM2.5 dust mask stops most 2.5 micrometer particles. But most cloth masks are less effective and leak all around the edges. More like a incomplete chain link fence that the deer just walk around. An N95 mask blocks about 95 percent of particles that are 0.3 microns in size or larger. Still not effective for particles even if properly fitted.
I think the issue is droplets and droplet sizes can be large. Droplets can have a million virus particles. A cheesy mask can prevent outgoing droplets in theory. With the gaps, it can't really stop them, but it can probably stop some spray from people who are talking.
Say it, don't spray it.