Carbon monoxide is a colorless, odorless, and tasteless gas with the chemical formula CO, consisting of one carbon atom triple-bonded to one oxygen atom. Often called the “silent killer,” this toxic gas forms when carbon-containing materials burn incompletely due to insufficient oxygen, making it a deadly hazard from car exhaust, faulty furnaces, and poorly ventilated combustion appliances. Discovered by William Cruickshank in 1800, carbon monoxide binds to hemoglobin in blood 210 times more readily than oxygen, preventing oxygen transport to vital organs and causing potentially fatal poisoning even at relatively low concentrations. Despite its dangers, CO plays important industrial roles as a reducing agent in metal refining, a building block for numerous chemicals including plastics and acids, and surprisingly, as a neurotransmitter in small amounts naturally produced by the human body.

Find a review of the 50 most important industrial gases here.

20 Fun Facts About Carbon Monoxide

Beyond the basics above, what else should we know about Carbon Monoxide? Check out the 20 fun facts below!

1. Carbon monoxide has the strongest chemical bond in nature among common molecules, with a bond dissociation energy of 1072 kJ/mol.
2. Your body naturally produces about 12 mL of CO daily from breaking down hemoglobin, acting as a cellular signaling molecule.
3. CO detectors use electrochemical sensors that last 5-7 years because the gas slowly poisons the sensor just like it affects blood.
4. The gas is slightly lighter than air (97% density), causing it to mix evenly rather than settling, making detection more challenging.
5. Cigarette smoke contains 400-500 ppm of carbon monoxide, temporarily reducing a smoker’s blood oxygen capacity by up to 15%.
6. Urban legend wrongly claims CO poisoning causes bright red skin – victims actually appear normal or slightly blue from oxygen deprivation.
7. Ice hockey arenas suffered multiple CO poisoning incidents from zamboni exhaust until electric models became standard in the 1990s.
8. Carbon monoxide can pass through drywall and floors, meaning a CO leak in a garage can poison people in rooms above.
9. Miners used canaries to detect CO until 1986 because birds’ faster metabolism made them succumb to the gas before humans.
10. The metal refining industry produces 60 million tons of CO annually, with most immediately burned for heat rather than released.
11. CO burns with a distinctive blue flame, producing twice as much heat per pound as hydrogen but requiring careful handling.
12. Scuba divers can get CO poisoning from contaminated air tanks if compressors intake exhaust fumes during filling.
13. Carbon monoxide forms explosive mixtures with air between 12.5% and 74% concentration, though accumulating this much is rare.
14. Some bacteria near deep-sea volcanic vents use CO as their primary energy source instead of sunlight or organic matter.
15. Automotive catalytic converters transform 98% of CO into CO₂, preventing about 30 pounds of emissions per car annually.
16. The gas was used for executions in some U.S. states before lethal injection, delivered as pure CO rather than car exhaust.
17. NASA monitors atmospheric CO from satellites as a “tracer” gas to track pollution sources and wildfire smoke movement.
18. Methanol fuel cells actually produce CO as an intermediate step, requiring careful catalyst design to prevent poisoning.
19. Hospital hyperbaric chambers treat severe CO poisoning by forcing oxygen into tissues at 3 atmospheres of pressure.
20. Carbon monoxide frost can form on Pluto’s surface at -223°C, creating seasonal patterns as the dwarf planet orbits.

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