Carbon monoxide concentrations typically peak nearest a source, such as roadways, and decrease rapidly as distance from the source increases. Carbon monoxide is readily absorbed into the body from the lungs. It decreases the capacity of the blood to transport oxygen, leading to health risks for unborn children and people suffering from heart and lung disease. A reddish-brown gas with an irritating odor, nitrogen dioxide is emitted from motor vehicles, industrial facilities, and power plants. Nitrogen dioxide and nitric oxide are products of all types of combustion.
Nitric oxide reacts with hydrocarbons in the presence of sunlight to form nitrogen dioxide.
In the summer months NO2 is a major component of photochemical smog. At ambient concentration levels nitrogen dioxide is an irritating gas that may constrict the airways of asthmatics and increase the susceptibility to infection in the general population. The most widespread air quality problem in the state, ozone is a colorless gas with a pungent, irritating odor. Ozone is not emitted directly into the atmosphere but is primarily formed through the reaction of hydrocarbons and nitrogen oxides in the presence of sunlight. Large spatial and temporal separation can exist between the sources of hydrocarbons and nitrogen and the formation of ozone.