Canary in a Coal Mine
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[b]Canary in a Coal Mine[/b] means a warning sign of possible danger.
Gases like Methane and Carbon Monoxide are deadly to miners. So miners in the past brought a canary bird with them while mining.
As long as the canary continued to sing, everything was fine. But if the level of methane rises, the bird faints - a very good warning to the miners to evacuate the mine immediately.
Example:
"Your body ache may be a canary in a coal mine for another illness."
Gases like Methane and Carbon Monoxide are deadly to miners. So miners in the past brought a canary bird with them while mining.
As long as the canary continued to sing, everything was fine. But if the level of methane rises, the bird faints - a very good warning to the miners to evacuate the mine immediately.
Example:
"Your body ache may be a canary in a coal mine for another illness."