“In 1930, there was no way to detect [hydrogen]—it was a tasteless, odorless, invisible gas,” Prentice says, noting that today you can buy handheld detectors on Amazon that are capable of sensing hydrogen in parts per million. “Hydrogen will not burn at anything less than four parts per hundred, so long before you get to any risk of a fire with hydrogen, you can ventilate the area… Hydrogen is much harder to burn than people think.”