As you know it's not that simple."Then the next time you (or a family member) has to undergo surgery you should tell the surgeon not to wear a mask. After all, depending on the nature of the operation they may well end up wearing that mask for hours with no interruption ." #1,020
Any scientifically recognized, documented risk of masking does not negate the benefits, such as pathogen filtration.
Even if wearing an N95 decreases O2 exchange efficiency by 5%, that's trivial for a robustly healthy surgeon that runs marathons for fun in her spare time. BUT !!
The opposite end of the spectrum, feeble patients requiring supplemental Oxygen because they can't obtain what they need from natural respiration, are obviously at greater risk, & have little or no margin.
Surely it's a small % of total population, but those few that survive in that narrow band where the 5% makes the difference between life or death, should act accordingly.
And then there are those that may not risk immediate death from such Oxygen intake reduction, but might experience undiagnosed impairment, losing a few brain cells here or there ... whatever. Goldilocks applies.