What causes diesel exhaust from engine?

Diesel exhaust is primarily generated during the combustion of diesel fuel in an engine. When the fuel is injected into the combustion chamber, it ignites due to high pressure and temperature, leading to the formation of various byproducts, including nitrogen oxides (NOx), particulate matter, carbon monoxide, and unburned hydrocarbons. Incomplete combustion, poor fuel quality, and engine tuning can exacerbate the emission of harmful substances in diesel exhaust. Additionally, factors like engine design and operating conditions also influence the composition of the exhaust.