Very interesting, thanks. 

I use N95 level masks for when I'm working in dusty environments, doing jobs around the house and boat repairs none of which is done for a living. I also use special masks when I am painting with spray paints (N95 or N100 does nothing to protect against paint fumes), and again, maybe I do that for a few minutes once a year. The video about the oxygen and CO2 levels under the N95 mask and even a cotton bandana as a mask was quite surprising. I will keep their use, even if just a cotton bandana, to a minimum from now on. BY the way, I re-use the N95 masks till they stink, or else it would cost me a fortune to use them. I do not wear a mask for Corona virus.   

The face shield by itself looks to be the only safe route for a Corona virus shield, if one is forced to wear them. Though all the masks they require are just placebos.