Overall biodiesel emissions are lower than gasoline or diesel fuel emissions (with the exception of NOx, which we discuss on the next page). Compared to diesel, biodiesel produces no sulfur, no net carbon dioxide, up to 20 times less carbon monoxide and more free oxygen. Biodiesel has the following emissions characteristics when compared with petroleum diesel fuel:

Reduction of carbon dioxide emissions (CO2) by 100%
Reduction of sulfur dioxide (SO2) emissions by 100%
Reduction of soot emissions by 40-60%
Reduction of carbon monoxide (CO) emissions by 10-50%
Reduction of hydrocarbon (HC) emissions by 10-50%
Reduction of all polycyclic aromatic hydrocarbons (PAHs) and specifically the reduction of the following carcinogenic PAHs:
Reduction of phenanthren by 97%
Reduction of benzofloroanthen by 56%
Reduction of benzapyren by 71%
Reduction of aldehydes and aromatic compounds by 13%
Reduction or increase in nitrous oxide (NOx) emissions by 5-10% depending on the age and type of engine.