Afterdamp is the toxic mixture of gases left in a mine following an explosion caused by

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

-rich

firedamp Firedamp is any flammable gas found in coal mines, typically coalbed methane. It is particularly found in areas where the coal is bituminous. The gas accumulates in pockets in the coal and adjacent strata and, when they are penetrated, the ...

, which itself can initiate a much larger explosion of

coal dust Coal dust is a fine-powdered form of coal which is created by the crushing, grinding, or pulverizer, pulverization of coal rock. Because of the brittle nature of coal, coal dust can be created by mining, transporting, or mechanically handling it. ...

. The term is etymologically and practically related to other terms for underground mine gases—such as

, white damp, and

black damp Blackdamp (also known as stythe or choke damp), sometimes found in enclosed environments such as mines, sewers, wells, tunnels and ships' holds, is an asphyxiant, reducing the available oxygen content of air to a level incapable of sustaining huma ...

, with afterdamp being composed, rather, primarily by

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

and

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

, with highly toxic

stinkdamp Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist Car ...

-constituent

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

possibly also present. However, the high content of carbon monoxide is the component that kills, preferentially combining with

haemoglobin Hemoglobin (haemoglobin, Hb or Hgb) is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobi ...

in the blood and thus depriving victims of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. Globally, afterdamp has caused many of the casualties in disasters of pit coalfields, including British, such as the Senghenydd colliery disaster. Such disasters continue to afflict working mines, for instance in mainland China.

Etymology

The meaning of "damp" in this term, while most commonly understood to imply humidity, presents evidence of having been separated from that newer, irrelevant meaning at least by the first decade of the 18th century, where the original relevant meaning of "vapor" derives from a Proto-Germanic origin, ''dampaz'', which gave rise to its immediate English predecessor, the Middle Low German ''damp'' (with no record of an Old English intermediary). The proto-Germanic ''dampaz'' gave rise to many other cognates, including the Old High German ''damph'', the Old Norse ''dampi'', and the modern German ''Dampf'', the last of which still translates as "vapor".

Detection

Animal sentinel Sentinel species are organisms, often animals, used to detect risks to humans by providing advance warning of a danger. The terms primarily apply in the context of environmental hazards rather than those from other sources. Some animals can ac ...

s, such as

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

or canaries, are more sensitive to carbon monoxide than humans, so will give a warning to miners. Canaries were introduced into British collieries in the 1890s by

John Scott Haldane John Scott Haldane (; 2 May 1860 – 14/15 March 1936) was a Scottish physician physiologist and philosopher famous for intrepid self-experimentation which led to many important discoveries about the human body and the nature of gases. He al ...

, the noted physiologist. Gas detectors are available now which detect toxic gases such as carbon monoxide at very low levels. They are widely available to protect domestic premises. The levels of gas detection depend on the methods used.

Etymology

Detection

See also

References

Further reading