https://en.wikipedia.org/wiki/Liquid_breathing

The form of liquid breathing this question is concerned with is total liquid ventilation

Liquid breathing is a process whereby people or animals inhale and breathe an oxygen-rich liquid instead of a gas. Typically perfluorocarbons have been proposed and tested. It has been demonstrated in animals and humans, but there are physical limitations related to the mount of fluid that would need to move through the lungs to remove sufficient CO2 over periods of more than an hour.

Liquid breathing has a lot of medical applications, but should also be useful in deep sea diving and in space* travel, where it offers protection against high-G forces.

*presumably also in aircraft

https://www.youtube.com/watch?v=RzcV3LVbdPM

Resolves YES on widespread media reports, or peer-reviewed journal articles, that total liquid ventilation over periods of several hours has been repeatably demonstrated and judged to be safe.

It will also resolve YES if total liquid ventilation is credibly reported as being utilised in a real world application, even if there are potentially large safety concerns.