Ethanol Waivers (E15 and E10)
A 1977 amendment to the Clean Air Act required gasoline additives to be substantially similar to those used in certifying vehicles to emission standards. EPA may grant a waiver to these requirements under certain circumstances. Ethanol has been granted two such waivers.
In 1978 a Clean Air Act waiver allowed the use of 10 volume percent ethanol in gasoline, known as gasohol or E10. Today, almost all gasoline are E10 blends.
More Information on Waivers: