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Carbon Monoxide (CO) Emissions

Carbon Monoxide (CO) Emissions

There are no EPA monitors for carbon monoxide in Washtenaw County. However, federal regulations on vehicular emissions have reduced allowable levels of CO nationwide. Only a few hotspots of high CO concentrations remain, and Ann Arbor is not within one of these areas.

Source: U.S. Environmental Protection Agency

Last updated: March 2008  

What is carbon monoxide?

Carbon monoxide, or CO, is a colorless, odorless gas that is formed when carbon in fuel is not burned completely.  It is a component of motor vehicle exhaust, which contributes about 56 percent of all CO emissions nationwide.  Other non-road engines and vehicles (such as construction equipment and boats) contribute about 22 percent of all CO emissions nationwide.   Higher levels of CO generally occur in areas with heavy traffic congestion.  In cities, 85 to 95 percent of all CO emissions may come from motor vehicle exhaust.   Other sources of CO emissions include industrial processes (such as metals processing and chemical manufacturing), residential wood burning, and natural sources such as forest fires.  Woodstoves, gas stoves, cigarette smoke, and unvented gas and kerosene space heaters are sources of CO indoors.  The highest levels of CO in the outside air typically occur during the colder months of the year when inversion conditions are more frequent.  The air pollution becomes trapped near the ground beneath a layer of warm air.

Source: U.S. Environmental Protection Agency

How does carbon monoxide affect the environment?

Carbon monoxide can cause harmful health effects by reducing oxygen delivery to the body's organs (like the heart and brain) and tissues.  The health threat from lower levels of CO is most serious for those who suffer from heart disease, like angina, clogged arteries, or congestive heart failure.  For a person with heart disease, a single exposure to CO at low levels may cause chest pain and reduce that person's ability to exercise; repeated exposures may contribute to other cardiovascular effects. E ven healthy people can be affected by high levels of CO.   People who breathe high levels of CO can develop vision problems, reduced ability to work or learn, reduced manual dexterity, and difficulty performing complex tasks. At extremely high levels, CO is poisonous and can cause death.

Additionally, carbon monoxide contributes to the formation of smog ground-level ozone.

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