Vehicle Emissions Reduction

According to the auto/oil study, "NOx emissions were lowered by reducing olefins, raised when T90 was reduced, and only marginally increased when aromatics were lowered." In general, reducing aromatics and T90 caused statistically significant reductions in exhaust mass NMHC and CO emissions. Reducing olefins increases exhaust mass NMHC emissions; however, the "ozone forming potential" of the total vehicle emissions was reduced.

With regard to toxics, the reduction of aromatics from 45% to 20% caused a 42% reduction in benzene but a 23% increase in formaldehyde, a 20% increase in acetaldehyde and about a 10% increase in 1,3-Butadiene. Reducing olefins from 20% to 5% brought about a 31% reduction in 1,3-Butadiene but had insignificant impacts on other toxics. Lowering the T90 from 360 to 280F resulted in statistically significant reductions in benzene, 1,3-Butadiene (37%), formaldehyde (27%) and acetaldehyde (23%).