Carbon Monoxide

Carbon Monoxide | Hydrocarbons |
Nitrogen Oxides | Particulate Matter

Although you cannot see or smell carbon monoxide, this poisonous gas is a major air pollutant in many American cities. Carbon monoxide forms when carbon in fuel doesn't burn completely (incomplete combustion). The main source of carbon monoxide in our air is vehicle emissions. As much as 95 percent of the carbon monoxide in typical U.S. cities comes from mobile sources, according to EPA studies.

1999 National Emissions by Source: Carbon Monoxide

Click on a mobile source category for detailed information. General information about other (not mobile) sources can be found at www.epa.gov/air/data/netdb.html and at www.epa.gov/air/urbanair/6poll.html View the entire 1999 Trends Report for detailed information on carbon monoxide emissions by various sources.

Carbon monoxide is harmful because it reduces oxygen delivery to the body's organs and tissues. It is most harmful to those who suffer from heart and respiratory disease. High carbon monoxide pollution levels also affect healthy people. Symptoms may include visual impairment, headache, and reduced work capacity. Unlike many other air pollutants, carbon monoxide levels in the outside air typically peak during colder months. Learn more about carbon monoxide, and find out about carbon monoxide levels where you live.