Canaries were used extensively in the 19th century, to warn
miners that their lives were in danger. Upon removing coal from
a seam, methane gas, or firedamp, often escapes into the air.
Methane becomes combustible when its quantities comprise 5-15
percent of the air, but in the presence of coal dust, that
number is reduced to 2-5 percent. It was necessary for miners to
be weary of methane, because the slightest spark could ignite
the gas, causing an explosion.
The dangerous nature of methane
gas could not be overlooked. Colourless, odourless and
undetectable to men without technology, miners had no choice but
to devise a test for build-ups of methane gas. In an attempt to
protect themselves, workers often kept caged canaries in the
mines. More sensitive to gas than humans, the canaries would die
if noxious gases were present in quantities beyond their ability
to cope. Thus, miners knew that if they came upon a dead canary,
it was time to head for open air.
By the time Alberta and
British Columbias coal industry started, safety lamps had
replaced canaries as a firedamp indicator. However, the bird
still had its uses, and firebases continued to carry the canary
to detect other harmful gases, such as afterdamp, a combination
of carbon monoxide and carbon dioxide that replaces oxygen in
the air. Budgies faint when exposed to afterdamp, indicating the
presence of gas before it reaches excessively dangerous levels.
Once exposed to clean air, the budgies can be revived.
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