Test of the oxygen percentage in the air in the dead space of a cloth face covering

The hype about mask wearing is that you are rebreathing in your own carbon monoxide and this is causing CO poisoning. But what about the oxygen level in the dead space of your mask? I demonstrate with a 4 gas multimeter and a cloth face covering that the dead space in the mask becomes oxygen deficient very quickly. Prolonged wearing can cause numerous side affects that can be very harmful. I apologize in advance for the poor editing. But feel free to watch again and pause the video.