Their reasoning is that the most dangerous particles are in large droplets that go out when someone sneezes, spreading out like a bomb blast. Supposedly the mask stops the large droplet from escaping. They don't bother to explain why the virus wouldn't go out like a bomb blast anyway from the force of the droplet hitting the mask and the virus passing through.
Actual science isn't their strong point.
Did some painting yesterday and the mask I was wearing didn’t stop me from smelling the fumes. The size of the fumes are larger than the Covid virus, so the mask I was wearing was and is a waste of money. Sorry I lost the link to this information.