Health Journal Entry

Lake Nyos Gas at Dangerous Levels (April 6, 2001)

Carbon dioxide gas trapped below Lake Nyos in Cameroon has reached dangerous levels again. In 1986, a tremendous amount of the gas suddenly erupted from under the lake and killed an estimated 1,700 people.

In small amounts, carbon dioxide is not dangerous. But at extremely high concentrations, the gas can kill by blocking the oxygen supply to the lungs and suffocating its victims.

Lake Nyos is a deep, funnel-shaped basin formed by a volcano that erupted 400 years ago. Although the volcano is no longer erupting, there are stil large amounts of gas that bubble up from under the surface and seep through underground cracks.

The carbon dioxide gas becomes trapped by the weight of the water and builds up in massive amounts on the lake bottom. It may then suddenly erupt, similar to the way gas escapes from a soda bottle that has been shaken.

Carbon dioxide that has built up over the past fifteen years may explode at any time. A team of scientists is constructing a system of vents to allow gas that has built up to escape. They are also adding an alarm system that will detect sudden gas increases.