On August 21, 1986, a cloud of toxic gas erupted from Lake Nyos, Cameroon. Lake Nyos is a lake that developed in the crater of an inactive volcano. Lake Nyos absorbs carbon dioxide that sometimes leaks from the volcano below. In 1986, this dissolved carbon dioxide erupted from Lake Nyos, a natural hazard called a limnic eruption. The toxic gas spilled over the crater's rim and flowed into villages in the valley surrounding the volcano. About 1,700 people and 3,500 livestock suffocated after breathing the deadly gas.

Following the Lake Nyos disaster, scientists put large pipes in the lake, leading from the lake bottom to above the surface. The pipes allow carbon dioxide to escape as soon as the volcano releases it. The small amount of gas, piped out continuously over time, is not enough to be dangerous.

carbon dioxide
Noun

greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.

Noun

visible mass of tiny water droplets or ice crystals in Earth's atmosphere.

Noun

bowl-shaped depression formed by a volcanic eruption or impact of a meteorite.

disaster
Noun

terrible and damaging event.

erupt
Verb

to explode or suddenly eject material.

gas
Noun

state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.

Noun

body of water surrounded by land.

livestock
noun, plural noun

animals raised for sale and profit.

toxic
Adjective

poisonous.

valley
Noun

depression in the Earth between hills.

Noun

an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.