Few of us would sign up to get buried alive. The guys at Britlab, however, seem to be in the minority. In the name of science, a man named Greg found out how long one can survive while buried alive — sort of.

With a doctor and ambulance standing by in case things got out of hand, Greg climbed into a coffin and was sealed in under a clear, airtight panel. This left him with only the oxygen in the coffin, which eventually became a troublesome situation. A device measuring the oxygen in his blood and the makeup of the air trapped in the coffin tracked both as they transitioned to a carbon dioxide takeover.

The box began to cloud up with condensation, and the concentration of CO2 in the air made it more and more difficult for Greg to breathe. Struggling to get out only made him feel worse, he said, because he was using up more oxygen. The doctor decided to release him from the coffin before things got too serious, but estimated that a person struggling to escape a sealed coffin would have about sixty minutes to live. Check out the video to watch Greg’s journey from buried alive to oxygen-deprived.