Seizures, broken spines and vomiting: Scientific testing that helped facilitate D-Day

Early on in World War II, the leaders of the Allied forces understood that the war effort would hinge on submarine warfare. Though the D-Day invasion wouldn't take place until June 6, 1944, biomedical engineer Rachel Lance says British scientists at University College London were studying issues of submarine survival as early as 1940.

"[They] ... were looking at these problems of undersea survival, of how people breathe inside enclosed spaces," Lance says. "Eventually, that transitioned into diving and diving technologies, and all of those things together were used to scout the beaches of Normandy and facilitate the landings of D-Day."

Lance has conducted research for the military, using a hyperbaric chamber at Duke University in which the air and the pressure can be controlled to mimic what divers and submarines are exposed to. Her new book, Chamber Divers, is about research conducted by scientists at UCL before and during World War II — including protocols for operating the miniature submarines used on scouting missions in advance of D-Day.

"These tiny subs had a smaller gas volume, which made the rules of breathing physiology even more time critical," Lance explains. "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," Lance says. But, she adds, "they were doing it because they were in this context of the Blitz and the bombings and the horrors of World War II happening around them."

Interview highlights

On what inspired to her look into WWII-era underwater research

I read this paper about carbon dioxide and it wasn't extremely exciting. It concluded, essentially, that carbon dioxide is bad for you and it hurts, which I already knew. But something about the date bothered me. It was published in 1941, which was obviously wartime, and it was published by a group of British scientists. In scientific research, the paper usually comes out about a year after the research was done. So that meant that these people were working on this question of carbon dioxide in 1940, in London. The other thing that was happening at that time period was the Blitz. So something about carbon dioxide was so critical to them that they were looking at it while they were being bombed. From there, I just kept pulling at the thread until the entire story became evident of what they were actually working on.

On WWII scientists conducting dangerous experiments on themselves in hyperbaric chambers

They put themselves in there for things that would not be legal today, if I tried to do that. Even if I had subjects who consented, I would possibly be criminally prosecuted. They were putting themselves in there and breathing pure oxygen and rocketing the chamber down as quickly as they go to see if they could kind of outrun the negative effects. They were taking some of these gasses, like oxygen, down to depths that we now know are extremely dangerous and toxic. And they were continuing to do this even after they were having severe injuries. With modern research, we have what are called serious adverse event reporting requirements. So if something bad happens in our research, we have to sit down and have a conversation about the ethics of asking people to continue. Whereas this group, because their goal was to prevent military deaths during the invasion of Normandy, they figured better we do it here in the lab.

On blast injuries on land vs. underwater

There are two major differences. The first is that we don't have to worry about some of the things that we do on land, such as shrapnel and burns, because the density of the water slows down a lot of those effects before they can reach more than a meter or two. The other big difference is that we have to worry a lot more about the shockwave. In air, the shockwave decreases very quickly, but in water, just like sound, it travels a lot more readily. So imagine how far we can hear whale sounds. You can hear whale sounds for miles and miles. This same type of impact, where the density of water moves these waveforms along more efficiently than in air, occurs with the shockwave from explosions. So you see different injury patterns from the underwater explosives, but most of them tend to be internal, which is kind of terrifying.

On the pressure of water

We have one atmosphere that we breathe, that atmosphere of gas we forget about pretty often, but it does sit on top of us all the time. Once we go under the water, we have additional atmospheres that essentially get piled on. So every 33 feet, or 10 meters, if you're metric, is equal to another atmosphere of pressure. The deeper we go, the more that pressure increases simply from the weight of that water pushing down.

On why people who emerge from deep water too quickly experience the bends

Basically, the human lungs are very weak. They're not a strong organ. And so they're really good at what they do in terms of processing gas, but they do it passively. So they essentially just let that gas flow come in and out of the body. What that means for breathing is that when we breathe a gas, we have to breathe the gas of the approximately same pressure as the air around us or the water around us. When you're underwater, that means you're breathing high-pressure gas. That means that that increased pressure can help those gasses absorb into your bodily tissues. The air around us is about 78 to 79% nitrogen. So as we're underwater and we're breathing that higher pressurized gas, that nitrogen and the other gasses absorb into our tissues. ... With decompression sickness — the bends — that's when we come back up ... too quickly, and the nitrogen comes out, instead of harmlessly in the bloodstream processed by the lungs, it comes out as bubbles. That's really bad. It causes all kinds of physiological issues.

On the men who died in the underwater construction of the Brooklyn Bridge

You don't know what's going to be a problem until somebody goes first. ... Those unfortunate caisson workers. They were the first ones who were really experiencing decompression sickness and experiencing how brutal and lethal that can be. ... They sort of just powered through. They were having all these deaths and they just hired more workers — which is perhaps why a lot of the workers there started quitting toward the end of the project.

But after that, it was used by the scientific and research community as an example of a thing to stop. This is kind of why a lot of us, myself included, get into science. When we see things happening, we have the drive to explore them, understand what's happening, and then try and prevent the next case from going on. ... Somewhere down there are wooden caisson shells in which people worked until they literally died. I think that's incredibly powerful in terms of remembering the context of where society comes from and how it's been built.

Sam Briger and Thea Challoner produced and edited this interview for broadcast. Bridget Bentz, Molly Seavy-Nesper and Meghan Sullivan adapted it for the web.