How long can you survive in a sealed container?

The instinctive model is that you use up the oxygen, but that is not what happens first. A resting adult exhales around 0.2 litres of carbon dioxide a minute — roughly 12 litres an hour — into a fixed volume, and dangerous concentrations arrive well before the oxygen fraction falls far. In a sealed cubic metre, carbon dioxide passes the 2 per cent mark in under two hours and the 5 per cent mark in around four, by which point breathlessness, headache and confusion are severe. Panic, movement and higher temperature all accelerate the process by raising the metabolic rate. Almost nothing in everyday life is genuinely airtight — cars, wardrobes and most rooms leak enough to change the arithmetic completely — which is why real cases usually involve purpose-built airtight equipment rather than furniture.

What changes the figure

• Staying still and calm can halve the carbon dioxide production rate
• Very few everyday enclosures are actually airtight
• Volume per person is the number that matters, not the size of the container overall

Physiology, not instruction. Every figure here is a population range under particular conditions, and individual variation is large — temperature, exertion, fitness and health move all of them substantially. Nothing on this page is medical advice.

Situations

• Can you survive a plane crash? Usually — across all US airline accidents studied, more than 95 per cent of occupants survived.
• How long do you have to escape a sinking car? Usually 30 seconds to a couple of minutes of floating — and the window is the way out, not the door.
• Can quicksand pull you under? No. Quicksand is roughly twice as dense as a human body, so you float — you sink to about waist depth and stop.
• How far from a nuclear blast do you have to be to survive? It scales with yield: for a one-megaton airburst, survival is unlikely within about 5 km and likely beyond about 10-12 km.
• How long can you survive in a hot car? Under an hour on a warm day for a child — the interior gains about 20 °C in the first ten minutes.
• How long does it take to drown? Under a minute to lose consciousness — and it is almost silent, which is why so many drownings happen in sight of others.
• What happens if a lift cable snaps? Essentially nothing — lifts hang from multiple ropes and have a speed-triggered brake that grips the rails.
• What height can you survive falling from? Survival is common below about 6 metres and rare above 20 — but people have survived falls from thousands.
• How likely are you to survive a shark attack? Very likely — of roughly 60 to 80 unprovoked bites worldwide each year, fewer than ten are fatal.
• What happens if you fall into lava? You would not sink — lava is about three times denser than a body — but you would not survive the heat either.
• What should you do if you are caught in a rip current? Rips pull you out, not under. Swim parallel to the beach until you are out of the flow, then come in.
• Could you survive inside a whale? You cannot be swallowed by almost any whale — their throats are too narrow — and a stomach offers no air.
• How long do you have to escape a burning house? Around three minutes from the alarm sounding in a modern furnished home.
• Can you survive a tsunami? Yes, by moving inland and uphill immediately — 30 centimetres of moving water can knock an adult off their feet.