Duplicants never run out of oxygen

[TagRag]

Alright, so I recently started playing for the first time after seeing it on YouTube and went through my first colony. As expected, everything quickly went to hell (at cycle 40 is when I decided that all was lost). So, when I hit cycle 40, I decided it would be interesting to test the limits of my Duplicants. So, I set some dig areas so they could get materials as needed, set some construction, set everything to priority 5, and just let them go at full speed unmanaged to see how long they would last. One of my 8 Duplicants died it a week by digging himself into a corner and suffocating, but the remaining 7 went for another 30 cycles before running out of food. The last 20 or so cycles had no algae or oxygen generation of any kind. They started their 40ish cycle survival with about 80,000 food as I recall and only died from starvation. Almost all of them were vomiters, so they would vomit and use the contaminated water as needed. I opened the gas overlay several times and saw almost breathable pockets of air for the last two weeks or so. And I don't mean highly toxic or barely breathable, I mean [unbreathable]. Yet they would continue to work fine. I mean, they would stop to breath in unbreathable air pretty often, but that was it. Had I been managing them, it seemed like I could've just not even worried about water or oxygen and just made sure they were harvesting food and they could've survived almost indefinitely with vomit water and magic lungs. 

I don't think they should vomit dirty water nor do I think it should flow like water. Just have them dirty up an area and have it cost water to clean it. Otherwise, they can supply their own unlimited water, which doesn't really make sense. I also find destruction to be far more dangerous than vomiting, to the point that I wouldn't even take destructive people (except maybe one).

I went a bit off topic, but the biggest thing is that it seems impossible for them to suffocate as long as they can still move around. Maybe make it to where they don't always know where oxygen is unless the player designates safe zones? I mean, if I started suffocating, I wouldn't necessarily know where to find air through the entire facility, but I would know that the main base would be more breathable than newly dug areas. Otherwise the Duplicants find the one block of barely breathable, very toxic air and then hold their breath long enough to do some work (which was almost exclusively moving water)