It’s hard to believe that canaries were still used in coal mines in recent decades to detect harmful underground gases. On December 30, 1986, that was largely put to rest. More than 200 birds were phased out of service as modern carbon monoxide detectors were phased in. In fact, some gas detector distributors pay homage to the birds today by creating bright yellow products.
The practice was first suggested by Scottish scientist John Haldane, known as the Father of Oxygen Therapy, who studied oxygen rejuvenation and gas poisoning by experimenting on himself. In the mid-1800s, he suggested carrying canaries or mice into mines to detect toxic gas. (Cool side note: During World War I, Haldane also identified poisonous gas used by the Germans and designed the first gas masks used in chemical warfare.)
Canaries were first used because their anatomy requires more oxygen and makes them more sensitive to toxic gases such as methane and carbon monoxide, both which have no color, odor or taste. Carbon monoxide — CO — is produced through combustion and typically dissipates in the air but can be toxic in a confined space such as mines. When breathed in, the gas binds to red blood cells, halting hemoglobin’s ability to carry oxygen, and causes fatigue, chest pain and difficulty concentrating. The gas can stay in the body for a period of time, which is why some people get sick from slow carbon monoxide leaks often found in cars and faulty appliances in homes.
Canaries reacted quickly to the gas, warning miners visually by fainting and audibly by no longer chirping. Miners evacuated the pits and mineshafts for safety and revived their canaries to use again, if they didn’t die. Some miners even carried small oxygen vials to revive their birds before returning to the surface.
The practice took on significant cultural meaning, the “canary in a coal mine” phrase insinuating that something serves as a warning for others. It has seeped into pop culture as well — The Police released “Canary in a Coal Mine; in 1980 and several books carry the phrase as a subtitle. The phrase has been stretched to describe a harbinger of the future, such as a melting glacier representing global warming. Other times, it’s lost completely on generations that don’t know the origin of the phrase.
“The canary-coal-mine metaphor has seen better days, its health imperiled by overuse,” said Ben Zimmer, who writes the Word on the Street column for the Wall Street Journal. “A once lively figure of speech has been deadened into a cliche for any early warning signal.”
The gases themselves have become metaphorical canaries in coal mines in recent years. Methane — CH4 — is one of the most common gases on the planet and in the universe. Though it’s great for producing energy, it’s also documented as a greenhouse gas responsible for ozone destruction. Methane emissions have doubled since the Industrial Revolution, which could be related to increasing global temperatures. In May 2016, the Environmental Protection Agency established the first national rule to limit methane emissions from oil and gas operations. The goal is to cut methane emissions by 40-45 percent by 2025.
“By emitting just a little bit of methane, mankind is greatly accelerating the rate of climatic change,” said Steve Hamburg, chief scientist of the Environmental Defense Fund.
Methane detection and use has changed significantly in the 30 years since the last canary was used in a coal mine. The next 30 could see another big change.
Carolyn Crist is the assistant editor of Paste Science. She is a freelance health and science journalist for regional and national publications and writes the Escape Artist column for Paste Travel.