The idea of placing a warm blooded animal in a mine to detect carbon monoxide was first proposed by John Scott Haldane in 1895, and canaries were used as early as 1896. Well into the 20th century, coal miners brought canaries into coal mines as an early-warning signal for toxic gases, primarily carbon monoxide. The birds, being more sensitive, would become sick before the miners, who would then have a chance to escape or put on protective respirators.
Painting safely in a house with birds
The idea of placing a warm blooded animal in a mine to detect carbon monoxide was first proposed by John Scott Haldane in 1895, and canaries were used as early as 1896. Well into the 20th century, coal miners brought canaries into coal mines as an early-warning signal for toxic gases, primarily carbon monoxide. The birds, being more sensitive, would become sick before the miners, who would then have a chance to escape or put on protective respirators.