Pollutant formation

Exhaust gas composition
In the complete combustion of a so-called CxHy fuel, consisting only of C and H atoms, the exhaust gas contains the components oxygen (O2), nitrogen (N2), carbon dioxide (CO2), and steam (H2O). In real, incomplete combustion, carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxide (NOx), and particulates also appear in addition to the above components. As opposed to these substances, which are detrimental to human health, CO2, which is partially responsible for the greenhouse effect, is not viewed as a pollutant, since it does not pose a direct health hazard and appears as the final product of every complete oxidation of a hydrocarbon. A reduction of CO2 in the exhaust gas is thus only to be achieved through a reduction in consumption or through an altered fuel having a smaller amount of carbon with reference to its heating value.
A cloudless hemisphere is mainly transparent to short-wave solar radiation but is quite opaque to long-wave infrared rays emitted from the surface of the earth. Carbon dioxide (CO2) has the greatest blocking effect of all; water vapor and synthetic CFCs also play important roles in blocking the direct escape of infrared energy. The phenomenon of transparency to incoming solar radiation and blanketing of outgoing infrared rays is called the greenhouse effect. The increase of the CO2, water vapor, CFCs, and other gases, often called greenhouse gases (GHGs), eventually will result in a rise in air temperature near the earth’s surface. This is known as the global warming effect