“The problem with small pressure vessels is CO2 toxicity. You can have all the oxygen in the world, but once the CO2 gets above 1 percent, you’ll start to get drowsy. At 2 percent, it’s like being drunk. At 5 percent, it’s hard to stay conscious. Eight percent will eventually kill you. Staying alive isn’t about oxygen, it’s about getting rid of CO2.”

“The problem with small pressure vessels is CO2 toxicity. You can have all the oxygen in the world, but once the CO2 gets above 1 percent, you’ll start to get drowsy. At 2 percent, it’s like being drunk. At 5 percent, it’s hard to stay conscious. Eight percent will eventually kill you. Staying alive isn’t about oxygen, it’s about getting rid of CO2.”

— Andy Weir