Dead End

The air quality meter Rossi finds in the bunker indicates the oxygen level is 82.7%, this indicates that oxygen levels are 82.7% of normal, not that 82.7% of the air inside the bunker is oxygen, breathing air with that much oxygen would actually become toxic in a short period of time. Normal atmospheric composition is 78% nitrogen, 21% oxygen, 0.9% argon and the remaining 0.1% are gases like carbon dioxide, methane, water vapor, and neon. If the oxygen levels in the bunker are 82.7% of normal that would mean the oxygen level would be down to 17.36%. OSHA considers 19.5% oxygen to be the lowest acceptable level, below that the symptoms of hypoxia begin to set in. Rossi would be starting to feel the effects of hypoxia at 17.36% due to him being over the age of 70, different people have different tolerances to low oxygen depending on their age and overall health. Oxygen levels between 19.4% and 10% cause early hypoxic symptoms like increased breathing rate, accelerated heartbeat, impaired thinking and coordination. Levels between 9.9-6% will cause severe hypoxic symptoms like nausea, vomiting, lethargy and unconsciousness. When oxygen levels drop below 6% fatal hypoxia begins to set in causing convulsions, cessation of breathing and finally cardiac arrest, the exact oxygen level that causes death can vary anywhere between 6-1% depending on the aforementioned factors like age and health.

The air quality meter Rossi has indicates that the oxygen level in the container is 19.3% of normal, which would mean a total oxygen concentration of only 4.05% (normal oxygen concentration is 21%). Oxygen levels below 10% cause severe hypoxia, at 4% Rossi would be unconscious and near death, someone his age would likely pass out at around 10% (47.5% of normal).