Date: 202101
Location: ZZZ.ARTCC, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Distraction; Confusion
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Result: General None Reported / Taken
Contributing factors: Company Policy; Human Factors; Environment - Non Weather Related
Primary problem: Environment - Non Weather Related

Narrative: During a restroom break in cruise at FL370; the Captain stepped out of the flight deck and the FA came in.  I had my headset on and was communicating with Center about the rides ahead.  When I was done with ATC; I moved one of my headset ear cups off of my ear and I said hello to the FA and mentioned to her that we would have turbulence ahead.  She said hello and then said 'I see you don't have your mask on; could you please put it on?'  Well; I was in a bit of shock by the request as that has yet to be asked of me.  I then was queried from ATC about our current ride and answered them and then put my mask on for her comfort.But then I became uncomfortable.I have been in a rapid decompression at altitude before and it all started to come back to me about TUC [The Times of Useful Consciousness] and I became concerned about what would happen if I had that happen again in this situation.  The Captain came back though in short order and the FA left but I worry that in my appeal to go along with making her comfortable with putting on my mask I would not have been able to perform my required duties if something bad were to happen.Imagine for a moment being in an aircraft at [fight level] 370; having a rapid decompression and putting your oxygen mask on.  At that altitude a person has a TUC of approximately 19 seconds.  19 seconds seems like a long time even with the startle factor of what is happening and trying to figure out why.  However; most of us in the aircraft type wear full headsets and I would take my headset off before putting the O2 mask on if a rapid decompression where to happen.  19 seconds of TUC minus the startle factor minus the headset and putting on the O2 mask and time is getting pretty tight not to mention if someone has glasses on.  Now throw the surgical mask into the equation and I believe we are now out of time.I wonder how much of this has been explored?  Do we indeed have time to take off all of this stuff with a TUC of 18-20 seconds and still live to save the day?  It's one thing to have the mask on when the door is open or even below 25;000 feet but I believe we are setting ourselves up if we experience a rapid decompression with our headsets; surgical masks and glasses on.It's also fair to say this became a major distraction as the captain and I were discussing how best to deal with this situation in the future. Not so much as missed radio calls or unsafe handling of the aircraft but just a general distraction weighing on our minds and how this can be handled in the future.




Synopsis: Air carrier First Officer reported concerns with having to wear a face mask in the cockpit especially in a rapid decompression situation.