What is the Difference Between Carbon Monoxide and Carbon Dioxide?

Carbon dioxide and carbon monoxide are both dangerous gases, but in very different ways.

Small amounts of carbon dioxide are normally present in the atmosphere. It gets there from volcanoes, from the decomposition of plant and animal matter, from the burning of coal and petroleum, and from the opening of cans of beer, which, however, is not the primary source in spite of the way it appears in television commercials.

Nevertheless, eleven billion pounds of carbon dioxide are produced annually in the United States alone, and much of it is destined to be burped into the atmosphere via the eight billion cases of carbonated soft drinks and 180 million barrels of beer that Americans guzzle each year.

Obviously, carbon dioxide can’t be toxic in itself. The only real problem is that it doesn’t support burning or breathing, and if given the opportunity, it will extinguish both fires and people. Because carbon dioxide is heavier than air, it will spill down to the lowest level and hang around like an invisible blanket, replacing the air and suffocating anything it covers.

That’s what happened in Cameroon, Africa, in 1986 when Lake Nios belched an enormous, six-hundred-ton bubble of volcanic carbon dioxide gas that spread out over the countryside and suffocated more than seventeen hundred people and innumerable animals.

Light a votive candle, a candle in a small glass cup. Don’t bother to pray. Now make some carbon dioxide by pouring a little vinegar onto a few teaspoons of baking soda in a tall drinking glass. As the carbon dioxide bubbles up and fills the glass, pour it over the votive candle as if you were pouring an invisible liquid. (Be careful not to pour any of the real liquid.) The candle will go out, drowned beneath a sea of unseen gas.

Carbon monoxide, on the other hand, is a real villain, even in tiny amounts. When breathed, it goes straight from the lungs into the blood stream, where it reacts vigorously with the hemoglobin, preventing it from doing its vital job of carrying oxygen to the cells. Oxygen deprivation ultimately leads to a condition known as death. Carbon monoxide is the principal cause of poisoning fatalities in the United States.

Whenever carbon-containing substances burn in air, from the gasoline in a car to the kerosene in a heater to the tobacco in a cigarette, carbon monoxide is formed to some extent.

If they had an unlimited supply of air, these fuels would burn completely, all the way to carbon dioxide, two oxygen atoms for each carbon atom. But there is always a practical limit to how fast the oxygen can feed itself into the conflagration. So invariably, some of the carbon atoms will manage to latch onto only one oxygen atom instead of two. Result: monoxide instead of dioxide.

Automobile engines spew out about 150 million tons of carbon monoxide in the United States each year. In a traffic jam, the carbon monoxide level in the air can build up to sickening (fatigue, headache, nausea), if not dangerous, levels. Kerosene heaters, gas space and water heaters, gas furnaces, gas ranges and ovens, gas dryers, wood stoves, charcoal grills, and cigarettes all produce carbon monoxide and all must be vented to the outdoors or used in a well-ventilated environment.

So don’t smoke and drive. Especially indoors, when the kerosene heater is on.