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Maryland State Government Maryland Department of the Environment

Carbon Monoxide

Carbon Monoxide is a colorless, toxic gas composed of carbon and oxygen.


carbon monoxideCombustion of carbon containing materials such as coal, oil, refuse or gasoline; 77% of nationwide CO emissions come from transportation sources. Other major sources are wood burning stoves, incinerators and industrial sources.


Breathing carbon monoxide affects the oxygen carrying capacity of the blood, even in otherwise healthy individuals. Low concentrations can affect mental function, vision and alertness. High concentrations can increase fatigue and reduce work capacity. Chronic exposure can adversely affect fetal development and can cause heart damage.


On Animals: Although carbon monoxide has not been found to adversely affect vegetation or materials, it can affect animals in the same manner that it affects humans.

Ozone | Particulate Matter | Sulfur Dioxide
Carbon Monoxide | Nitrogen Dioxide | Lead