The mysterious cloud that killed thousands of people and animals in Cameroon




Toxic gas cloud killed more than 1,700 people and 3,500 head of cattle

Toxic gas cloud killed more than 1,700 people and 3,500 head of cattle

Photo: Getty Images / BBC News Brazil

“Around eleven at night I woke up, but I couldn’t get up. I was confused, I didn’t understand what was going on,” says the survivor of a tragedy that is still astonishing.

It was August 21, 1986. At dawn, residents of several villages in northwestern Cameroon discovered upon awakening that many of their friends and neighbors had died during the night.

“The next morning I saw several people lying in the street. Many of them dead,” the witness reported. “In our village we lost about 75 people.”

The total number, however, was much higher: that day, 1,746 people died after inhaling toxic gases that came from a lake located in the caldera of a volcano, in addition to 3,500 heads of cattle.

All victims lived in villages around Lake Nyos, close to the country’s border with Nigeria.

The disaster was so serious that the president of Cameroon even asked for international help.

The investigation

For several weeks, scientific investigations were carried out to discover what had happened, conducted by experts from around the world. Among them, British doctor Peter Baxter, who arrived in the region about two weeks after the tragedy.



The victims lived in villages near Lake Nyos, near the border between Cameroon and Nigeria

The victims lived in villages near Lake Nyos, near the border between Cameroon and Nigeria

Photo: Getty Images / BBC News Brazil

“There were still bodies of people and animals all over the hills,” Baxter told the program Witness History, from the BBC. “When we arrived in the village of Nyos, which had small mud houses, it was completely silent, there were no signs of life.”

“And as we approached Lake Nyos, which was reached by climbing a small hill, we saw that the waters were calm, and that there were dead plants and fish floating on the surface and on the banks.”

“The only life we ​​saw were frogs, which are very resistant,” says the doctor.

George Kling, a professor at the University of Michigan, USA, was also invited to help with the investigation.

“When we arrived at Lake Nyos, the scene was chilling down my spine. All the people and all the animals were dead,” he says.

“There was a silence, but all the buildings were standing, it didn’t look like there had been a hurricane, a flood or anything like that.”



Nyos is a volcanic lake located in a remote part of Cameroon, West Africa

Nyos is a volcanic lake located in a remote part of Cameroon in West Africa.

Photo: Getty Images / BBC News Brazil

“We saw a scene of destruction. Before the disaster, the lake was a very beautiful place, with crystal clear blue waters. A year before we were swimming in the lake, but now everything was different,” continues George Kling.

“The surface water had a reddish-brown color, there were many plants floating in it. This vegetation came from the banks, where huge waves had done damage, destroying all the vegetation”, recalls the professor.

Mystery

Physical evidence indicated that a wave about 40 meters high had formed as a result of a change in the depth of the lake.

But no one knew yet what had caused this change – and the death of hundreds of residents in the region.



After the release of the gases, the surface water turned a reddish-brown color

After the release of the gases, the surface water turned a reddish-brown color

Photo: Getty Images / BBC News Brazil

There was, however, a suspect. The hypothesis was that the deaths would have been caused by volcanic gases released by an eruption. Peter Baxter, however, was surprised by the lack of traces.

“There have been no reports of a major explosion caused by an eruption,” he told the BBC. “Nor the signs of the devastation such an event would have wrought.”

“We were facing a situation where many people had died, but there was little damage to the land and buildings they lived in,” he adds.

‘Smell of rotten egg’

One of the witnesses reported: “I almost died, but then I decided to drink oil. Soon afterward I vomited something black, which stank of something like egg or gunpowder.”

It was the description of the odors that gave scientists the clues to finding the culprit for the deaths: thousands of tons of carbon dioxide, released from the bottom of the lake and down the slope of the volcano to the valley below.



Scientists knew there hadn't been an explosion because there was no devastation around it.

Scientists knew there hadn’t been an explosion because there was no devastation around it.

Photo: Getty Images / BBC News Brazil

At first, scientists thought it was sulfur, which has a characteristic unpleasant smell and is produced in large quantities by volcanoes.

“But when we went to the lake and started analyzing the samples, we saw that there was no sulfur in the water, nor in the plants surrounding the lake that had been exposed to the gas cloud,” explains Professor Kling, from the University of Michigan.

“It was very difficult to understand these findings. Until we found old documents about combat pilots who had been exposed to a high concentration of CO2,” he adds.

“The gas, in a concentration of 5% to 10%, acts as a hallucinogen. One of the most common reports from the pilots was that they smelled like rotten eggs or gunpowder and that their bodies felt very hot”, says the professor at the University of Michigan, adding that the reports coincided with testimonies from villagers around the lake.



It is not known why some people died from toxic gas, while others survived

It is not known why some people died from toxic gas, while others survived

Photo: Getty Images / BBC News Brazil

Everything indicates that, over the years, a deposit of carbon dioxide was formed at the bottom of the lake.

“Since the lake is very stratified, that is, it is very deep, and the upper layers do not mix with the lower layers, the gas that formed in the lower layers was trapped. This caused it to build up with a lot of pressure.” , explains George Kling.

Scientists say that the same effect is produced when we shake a bottle of champagne and then uncork.

The survivors

But there was another mystery: hundreds of people had died, but others, despite being exposed to CO2 in the same way, survived.

Many of them were children. Thus, it was hypothesized that the gas had enveloped the houses during the night, while the little ones were sleeping inside, but their parents were still outside.

It was also thought that the children could have become unconscious faster and thus breathed in the gas less deeply.



'Surviving or dying from the gas was luck or bad luck', says a doctor who was at the site

‘Surviving or dying from the gas was luck or bad luck’, says a doctor who was at the site

Photo: Getty Images / BBC News Brazil

“Some of the survivors woke up with dead people around them,” says Baxter. “Surviving or dying from exposure to the gas was luck or bad luck.”

“The gas quickly knocks you out, and those who survived felt they were unconscious for a long time, more than 10 hours, until they came to, literally until the gas had dissipated, when day broke and the sun began to warm the earth. .But it’s a very unusual situation, a really extraordinary story,” says Baxter.

The findings of the task force to investigate the causes of the disaster did not stop conspiracy theories from emerging.

“Some locals began to say that foreign countries had dropped a secret bomb, that there was an international conspiracy of scientists,” says Baxter.

It is not known, however, what triggered the release of the gas in 1986. One of the most accepted hypotheses is that there was a landslide at the bottom of the lake.

Nyos remains a potential threat to people living in the region. In an attempt to avoid a tragedy like the one in 1986, a system of pipes was installed to allow the carbon dioxide gas, if expelled, to be safely diverted from the bottom.