The dude's reached critical oxygen levels cause of faulty equipment, luckily the automatic safety system in surveyor team suits activate a rescue beacon, pop an emergency supply and Chloroform them to sleep so the emergency supply lasts longer.
Edit: yeah I meant Chloroform, edited that to match, can't believe I forgot that especially given it's related to one of my favorite jokes.
Additionally you cannot be poisoned by excess oxygen, more so it's a really funny little oversight by the respiratory system wherein the lack of waste/non-oxygen impurities, results in the Exhalation cycle to not trigger, meaning you just stop breathing, leading to suffocation.