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Canaries


Carbon monoxide, a potentially deadly gas devoid of color, taste or smell, can form underground during a mine fire or after a mine explosion. Today's coal miners must rely on carbon monoxide detectors and monitors to recognize its presence underground. However, before the availability of modern detection devices, miners turned to Mother Nature for assistance. Canaries -- and sometimes mice -- were used to alert miners to the presence of the poisonous gas. Following a mine fire or explosion, mine rescuers would descend into the mine carrying a canary in a small wooden or metal cage. Any sign of distress from the canary was a clear signal that the conditions underground were unsafe, prompting a hasty return to the surface. Miners who survive the initial effects of a mine fire or explosion may experience carbon monoxide asphyxia.

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Glossary of Terms
    afterdamp - aftergases The mixture of gases that remain in a mine following a mine fire or explosion. It usually consists principally of carbonic acid gas and nitrogen, which can be toxic if inhaled.

    barricading - Enclosing part of a mine to prevent the flow of noxious gases from a mine fire or explosion. A door or an airtight wall constructed from materials such as rock, coal, timber, brattice cloth, mud or clothing will create a fresh air base in which miners can safely wait for rescue. Records kept by the U.S. Bureau of Mines show hundreds of cases where underground miners were saved by barricading and that, in several cases, those who refused to seek refuge behind a barricade ultimately became asphyxiated.

    blackdamp - A mixture of 10-15 percent carbon dioxide and 85-90 percent nitrogen, it is formed by mine fires and the explosion of firedamp. Heavier than air, it hovers in a layer along the floor of a mine, extinguishing light and suffocating its victims. Also known as chokedamp.

    carbon monoxide asphyxia - Affects underground workers who survive a mine fire or explosion. Carbon monoxide combines with the hemoglobin of the blood much more readily than does oxygen, causing the hemoglobin to carry less and less oxygen from the lungs to the rest of the body. To treat this condition, carbon monoxide must be removed from the blood by inducing deep breathing of pure oxygen.

    firedamp - A combustible gas formed in mines by the decomposition of coal, it explodes upon ignition when mixed with atmospheric air.

    monoxor - The trade name of an instrument indicating the percentage of carbon monoxide in a given atmosphere.



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