The classic combustion reaction involves the burning of some kind of fuel in the presence of oxygen. The end result is usually carbon dioxide and water but this isn't always true. Sometimes the the reaction between the fuel and oxygen isn't allowed to complete because there isn't enough oxygen present to complete the reaction. When this happens, instead of carbon dioxide, carbon monoxide is formed. The list of possible sources for carbon monoxide is quite long as there are indoor and outdoor sources that will produce it and while inadvertently creating this carbon monoxide instead of carbon dioxide may not seem very significant, it is definitely not something that people should breathe in.
The sources of indoor carbon dioxide air pollution stem from the many sources of ignition or combustion that occur inside the home or workplace. Just about anything that uses combustion has the potential to produce carbon monoxide. Leaking chimneys, fireplaces, heaters, furnaces, water heaters, generators, stoves (gas or wooden), and a variety of other appliances and instruments can all produce carbon monoxide. Items that are more worn or not properly maintained have increased potential for carbon monoxide production. Should a home have an attached garage, then even the exhaust from an automobile can be a source of carbon monoxide for the home.
Source for carbon monoxide production outdoors can be primarily traced to roadway and non-road mobile sources. Roadway carbon monoxide production is the larger source for the United States. A 1999 EPA study showed that approximately 60% of the present carbon monoxide in outdoor air could be traced to automobiles and in cities the percentage could rise to as much as 95%. The largest producer from the roadway source is from automobiles and motorcycles at 55% of the total roadway produce carbon monoxide. Gasoline using trucks also make up a large percentage, around 41%. Diesel vehicles only amount to a very small percentage of the produced carbon monoxide, 4%.
Nonroad sources account for much smaller percentages of total outdoor carbon monoxide production. In 1999, the EPA measured that the largest source of nonroad mobile carbon monoxide in the United States was gasoline powered equipment at around 86%. Diesel equipment, such as construction vehicles, accounts for only 5% of the total nonroad mobile production. Surprisingly, aircraft only account for 4% of carbon monoxide production. The remaining percentages are divided among Other, railroad, and marine sources with only a total of 5%.
Is it dangerous?
While it may seem harmless, carbon monoxide is quite dangerous to people. The gas is both colorless, odorless, and the danger of inhaling carbon monoxide comes from its interaction with the blood cells. Once the gas is breathed in, it heads to the lungs where it participates in normal functions of the body meant for oxygen delivery. However, instead of oxygen binding to the hemoglobin in the blood cells, the carbon monoxide takes its place. The more carbon monoxide a person breaths in, the less oxygen gets transported to the organs and tissue of the body. The gas is also more difficult to remove from the hemoglobin and won’t be used by the body. It can take hours for carbon monoxide to be removed from the blood cells. The stronger bonding also means that carbon monoxide can build up in the blood even at low exposure levels.
Therefore, exposure to carbon monoxide will slowly or quickly deprived a person of needed oxygen. Because carbon monoxide cannot be seen or smelled, people may be completely unaware that they are breathing in the gas or are in danger. Carbon monoxide poisoning can lead to symptoms such as headache, visual impairment, loss of coordination, reduced brain function, confusion, and nausea. At higher levels of gas exposure or as the result of a long period of exposure to lower levels of carbon monoxide, the body doesn’t get the oxygen it needs which can be fatal as a person will begin to suffocate and may not even realize it.