Carbon Dioxide (CO2) and Carbon Monoxide (CO) are two gases that are often mistaken for one another but are very different in the way they are created, their place in nature, and how they affect humans.
It’s all in the name
Even their names are so similar that it is easy for one without a degree in chemistry to misspeak when talking of the substances. Carbon Dioxide describes a gas that is one part carbon and two parts oxygen; thus the prefix “Di” before the word “oxide” which literally means “two oxygens” (and I’m 90% certain that “oxygens” is not a real word.) Carbon Monoxide means a molecule that has one carbon atom and one oxygen atom. “Mon” means one; combined with “oxide” we get “one oxygen.” Understanding how chemical nomenclature applies to these gases makes it easier to understand their abbreviations: CO and CO2. The “C” stands for carbon and the “O” stands for oxygen. Using the information that we shared before, we can easily see what these abbreviations mean: CO means one carbon and one oxygen also known as carbon monoxide; CO2 means one carbon and 2 oxygen commonly referred to as carbon dioxide. See how easy it could be to get these two confused when speaking quickly?
Where are you from?
The origins of these two gases is important in understanding how they are both dangerous; let’s start with carbon monoxide (CO). CO does not occur naturally in the atmosphere like other gases such as oxygen or nitrogen. CO is created by combustion or the process of burning. When a carbon-based fuel is burned a chemical reaction takes place; compounds break down and are turned into carbon dioxide (CO2) and water vapor (H2O). When there is not enough oxygen supplied to the chemical reaction carbon dioxide (CO2) cannot be created. What happens is carbon monoxide (CO) is created and escapes into the atmosphere. This is typical of fuel-burning appliances that use oil, gas, kerosene, or wood such as furnaces, water heaters, ovens, space heaters, fireplaces, and woodstoves. Older cars and trucks that do not employ a catalytic converter also dispel CO into the atmosphere when they run.
On the other side of the aisle is carbon dioxide. CO2 is naturally occurring in the atmosphere and is a required gas for plant life. Plants inhale carbon dioxide and exhale oxygen while humans inhale oxygen and exhale carbon dioxide. CO2 is generated by combustion that is properly ventilated such as automobiles that utilize a catalytic converter.
How much is too much?
While both gases can be deadly, it takes much less CO to cause health concerns than CO2. The amount of any given substance in the atmosphere is measured in “parts per million” or “ppm.” PPM is a ration measurement that says for every 1 million parts there is n parts. For instance, OSHA’s work standards requires that long-term exposure to carbon monoxide levels of 50ppm. This mean that for every one million parts of atmosphere (nitrogen, oxygen, hydrogen, etc) there can only be 50 parts of CO.
Now that the measurement is understood, OSHA also limits workplace CO2 exposure where levels are above 5,000 ppm. Levels of CO that are at 700ppm can be deadly whereas it can take up to 80,000ppm of CO2 to be considered life-threatening. Clearly, CO is a much more lethal gas than CO2.
Nature and the Atmosphere
When speaking of the atmosphere, climate change, and greenhouse gases, it is important to understand the different between carbon monoxide and carbon dioxide. A greenhouse gas is a gas that absorbs and then emits heat. Greenhouse gases contribute to the greenhouse effect which is where the gas inside the atmosphere consistently absorbs the sun’s heat and radiation and then emits it back into the atmosphere causing the planet to be warmer than if there was no atmosphere. Without the greenhouse effect the Earth would be a very cold, uninhabitable planet. Too much greenhouse effect, however, and the planet becomes too hot to sustain life. Carbon monoxide is not a greenhouse gas; it does not absorb the sun’s radiation. Carbon dioxide, conversely, is a greenhouse gas and contributes to our planet’s greenhouse effect. Without carbon dioxide the planet would be a cold, cold place. Increasing CO2 levels has also increased the amount of sustainable plant life. The taiga, a large swath of trees in North America which covers about 17% of the Earth’s surface, is growing larger every year.
Since CO is not a naturally occurring molecule, it has no place in the natural balance between plant and human life as well as the greenhouse effect that warms our planet.