The California Air Resources Board (CARB) has initiated a Multimedia Evaluation (MME) to understand any potential environmental or public health impacts from the use of 15 percent ethanol by volume (E15) in California. California law (Health & Safety Code Section 43830.8) generally requires that a Multimedia Evaluation be completed prior to adopting new motor vehicle fuel specifications. More information on E15 MME process is available from CARB FAQ: E15 Evaluation Status. California gasoline is currently blended with up to 10 percent ethanol by volume (E10), the maximum ethanol content allowed by California gasoline regulations.
As a part of the MME for E15, CARB contracted with the University of California at Riverside (UCR) Bourns College of Engineering – Center for Environmental Research and Technology (CE-CERT) to evaluate exhaust emissions from the use of California Reformulated Gasoline (CaRFG) that contains 15 volume percent ethanol (E15). This study looks at the effects of increased ethanol content on exhaust emissions in 20 vehicles, all model year 2016 or newer and equipped with three-way catalysts (TWCs). Measured emissions include: oxides of nitrogen (NOx), total hydrocarbons (THC), non-methane hydrocarbon (NMHC), carbon monoxide (CO), carbon dioxide (CO2), PM mass, particulate number, 1,3-butadiene, benzene, toluene, ethylbenzene, xylene isomers, ethanol, and carbonyl compounds.