No shit. Blocking your mouth and nose with a thick cloth reduces o2 intake.
Real fricking Einsteins doing these studies, huh?
Couple years ago, the local 711 refused me beer because I was maskless. Haven’t been there since. And I went there for over 10 years. Home Depot pushed it too. I went years without going to Home Depot after that. And prior would go there almost monthly.
My wife helping her mom get out of rehab. They said mom had to walk for 10 minutes solid before they would let her home. She got tired after 5 minutes and out of breath and her o2 would drop.
My wife went in and they were walking her in the hallway - where masks were required! She told them how stupid it was, and that mom could walk in the hallway but as soon as she got out of breath it was back to the room and mask off. She told them that for the final test it would be in her room pacing around for ten minutes with no mask on.