Carbon monoxide is a chemical compound. It has very low solubility in water but is highly soluble in ammonia solution. Its explosive limits in air range from 12.5% to 74%. Carbon monoxide is a product of the incomplete combustion of carbon-containing substances. It can also be used as a fuel; coal and water can produce water gas (a mixture of carbon monoxide and hydrogen) at high temperatures.

Since carbon monoxide has an affinity for hemoglobin in the body that is 200–300 times greater than that of oxygen, and carbon monoxide hemoglobin dissociates 3,600 times more slowly than oxygenated hemoglobin, carbon monoxide exposure can cause harm to the human body, depending on the concentration and duration of exposure. A concentration of 35 ppm is a recommended occupational exposure limit averaged over a work shift, rather than a universal threshold for poisoning. Exposure to carbon monoxide can result in carbon monoxide poisoning or gas poisoning.

Because carbon monoxide has the property of turning blood a very bright red, some meat merchants treat fresh meat with carbon monoxide to prevent it from oxidizing and discoloring; this treatment can help meat retain its red appearance for an extended period under suitable packaging and storage conditions. However, the specific claim that raw meat can be stored at 10°C for 28 days while still appearing freshly slaughtered requires further verification. This practice has drawn controversy. Consumer advocates have raised concerns that even if this treatment is harmless, it may mask the fact that the meat is no longer fresh, leaving consumers unaware that the meat may be on the verge of spoiling.

By Michael Chiu, MWS, CI – Updated and Revised in 2026