Impacts of ethanol fuel level on emissions of regulated and unregulated pollutants from a fleet of gasoline light-duty vehicles

► THC, NMHC, and CO emissions generally decreased with ethanol, except E85 blend. ► NOx emissions increased with increasing ethanol content for the older vehicles. ► For the newer vehicles the ethanol blends generally had lower NOx emissions. ► Strong increases for carbonyl emissions with ethanol, especially formaldehyde and acetaldehyde for E85. ► BTEX and 1,3-butadiene emissions decreased with increasing ethanol.