These leads to excessive
unburned fuel escaping from the exhaust valve and into the atmosphere, this
unburned fuel is
partially burned in the exhaust and is turned into DEP (diesel exhaust particles) which are primarily just carbon.
In particular, aircraft jet engines produce carbon dioxide (CO2), water vapor (H2O), nitrogen oxides (NOx), carbon monoxide (CO), oxides of sulfur (SOx),
unburned or
partially combusted hydrocarbons (also known as volatile organic compounds, or VOCs), particulates, and other trace compounds.