What I've heard, and it made sense, is that wearing a mask helps 80% to keep the virus in (not infecting other people), but only like 20% to keep it out (not infecting oneself).
That may be true. A mask can restrict how far you might be spewing.
But a respirator is not the same thing as a mask. Due to my assiduous rotation plan, I have enough N95 respirators to hold for the foreseeable future. I'll happily wear one in public.
Still think the governor is overstepping his authority to demand all must be masked.