Benzene and toluene, as aromatic carcinogenic compounds,
which can cause harmful effects on the bone marrow
and a decrease in red blood cells leading to anemia, were presented
in great amount in motorcycle exhaust. At test-driving
stages, benzene and toluene emissions were from 1.85 to
5.9 mg/km and from 0.92 to 4.2 mg/km for two test fuels.
Compared for base fuel, benzene at idle stage was reduced
by 2.4% for E10, whereas the reduction of HC emissions was
nearly 31.7% at corresponding mode. This indicates that the
effect of using ethanol–gasoline blend fuels on the benzene
oxidation is comparatively poorer. This phenomenon was
the same as that of toluene. Other aromatic emissions
were relatively lower for these two fuels at all test-driving
conditions. In sum, ethanol of E10 fuel plays insignificant
effect on aromatic emissions, as compared to base gasoline.