The scientists … did this experiment by just putting themselves in a tank, closing the door and waiting to see how long they could physically handle the amount of carbon dioxide in there before they ended up with migraines and projectile vomiting.

Lance notes that UCL scientists subjected themselves to extremes that would be considered “wildly unethical and illegal today.” Some sustained serious injuries — including seizures and broken spines — in the hyperbaric chamber. One of them … dislocated her jaw five times in the same dive