As someone with COPD, hypoxia is scary if your not used to it. * Ever drive, and then black out and wonder how you got somewhere? Hypoxia. * Ever just start not seeing things or seeing too much, or your brain tricking you into conjuring random stuff out of nowhere? Hypoxia. * Ever feel perfectly healthy and then have massive bacterial pneumonia because you're wearing a mask and the mask recycled a bacteria from the outside of the mask into your lungs, and decided not to go to the hospital because you're getting too tired? Hypoxia.