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An Anaesthetist explaining how stuff works: a thread.....
There has been a lot on Twitter about whether wearing masks reduce your oxygen levels. Some of it, depressingly, from people who should know better: (1)
There has been a lot on Twitter about whether wearing masks reduce your oxygen levels. Some of it, depressingly, from people who should know better: (1)
(2) so let me, with 20 years of living, and managing respiratory physiology, try to explain......
We breath in around 500-600ml of air with an average resting breath. Of this, 21% (roughly 100ml) is oxygen.
We breath in around 500-600ml of air with an average resting breath. Of this, 21% (roughly 100ml) is oxygen.
(3) Take a restful 12 breaths a minute, and you are breathing in 1200ml of oxygen a minute (that’s 100ml x 12 breaths) . However, all that you breathe isn’t useful. The last 100ml you breathe never gets to the lungs. It’s in your throat and windpipe.
(4) This “dead space” is gas that is inhaled but never gets to the bits of the lung where it can enter the bloodstream. That means of the 500ml you inhale only 400ml gets into the lungs. And 21% of 400ml is roughly 80ml of oxygen. So 12 breaths still delivers 80x12= 960ml oxy/min
