I spoke at length with a 30 year surgical veteran. She assured me that all msks come off adap and continually wearing one for 8 to 10 hours a day is causinf fatigue, reducing mental clarity and a generally dangerous atmosphere. Consider that, when your masked surgical team greets you. I did feel better after she confirmed what i have been feeling for months.
I was under the impression, don’t know for a fact, that they pump up the oxygen concentration in surgery rooms to compensate for wearing a mask.
I do know that they raise the O2 concentration on submarines to keep the sailors more alert. Has nothing to do with mask, but it does have relevance to staying alert. I want my surgical team alert.