Federal Regulations: RFG Required Areas

The federal Clean Air Act Amendments of 1990 established that cities with the worst smog pollution (ozone nonattainment areas) use reformulated gasoline (RFG) beginning in 1995.

Today, about 30 percent of the nation's gasoline is RFG. EPA estimates that as many as 75 million people today breathe cleaner air because of RFG.

In the Clean Air Act, Congress specified that RFG contain oxygen — 2 percent by weight. Ethanol and MTBE (methyl tertiary butyl ether) have been the two most commonly used substances that add oxygen to gasoline. State actions to ban MTBE led ethanol to become the oxygenate of choice in the RFG program. The Energy Policy Act of 2005 (H.R. 6) removes the oxygenate requirement 270 days after enactment, in lieu of a nationwide renewable fuels standard (RFS).

Click here to view the list of RFG required areas.