I have researched all of that. I order mine but not from China. They are 4-ply but easier to breathe in than the N-95. I wore the N-95’s off and on for 30 years at work. The blue ones are too thin. A lot of the blue ones seem to be only 3-ply. When I took my husband to the emergency room in Chattanooga recently we wore the 4-ply. They checked us at the door to make sure they weren’t the thin masks and said ours were good enough. Mine are only worn for very short periods to run into a store that doesn’t do curbside pickup or to go to a doctor. I wear it at the Vet’s office. Never for more than an hour or two. Never outside. I mostly consider the disclaimers to be like disclaimers on everything else we use.
My granddaughter works in the medical field. When I bought the 4-ply masks she came down to “test” them. She said to open one up and run water into it. She said if it holds water it will stop droplets from a sneeze or a cough. She said none will help if worn with gaps along the side. So, according to her, wearing one that doesn’t allow liquid droplets with the virus possibly in them to pass through and wearing them right really can help but she agrees that staying away from people that don’t wear one, even if you are, is better.
LOL, where I live, wearing one can provoke the fist fight. :-)