CANARIES IN THE MINES
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 Columbia’s
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.
