Incomplete combustion process(es)

A reaction or process which entails only partial burning of a fuel. This may be due to a lack of oxygen or low temperature, preventing the complete chemical reaction. Carbon monoxide is produced as a byproduct from incomplete combustion of carbon.

Dioxins are produced as a byproduct from incomplete combustion of organic material in the presence of chlorine.

Source: GreenFacts

Carbon monoxide (CO)

Dioxins

Air quality in Europe