Damn good. I taught patient care as part of teaching medical imaging, which included the proper USE of a mask. She nails it. An improperly used mask becomes a fomite that spreads pathogens. Nobody is using a mask properly thus all they can do is spread pathogens. Nevermind the carbon dioxide levels. A mask can only stop fluids; droplets, splatters, squirts, etc. You cannot touch the face of the mask. You must carefully remove the mask by either untying or breaking the straps and then properly dispose of the mask without touching the face.