True, but they did it ahead of time in a controlled way.

In a hospital with an anaesthesiologist?

> In a hospital with an anaesthesiologist?

Well, from the article:

> The men wore masks hooked up to ventilators as an anesthesiologist slowly introduced higher levels of xenon into their systems.

The doctor named in the article seems to be[0] the head of the Department of Anesthesiology at Limburg hospital.

[0] https://www.researchgate.net/profile/Michael-Fries-3

Anesthetic gasses are applied in a lot of environments outside of hospitals.