Reformulated Gasoline

Reformulated gasoline (RFG) is a type of gasoline that has had its chemical composition altered and an oxygenate such as ether or ethanol added to reduce volatile toxic components and increase the oxygen content. RFG reduces the emissions of toxic substances such as benzene and formaldehyde. It also has less tendency to form ozone. RFG can be burned in gasoline engines without modification.

Switching over to reformulated gasoline was mandated by the federal Clean Air Act Amendments of 1990. The U.S. Environmental Protection Agency has been working with states to implement a two-phase reformulated gasoline program to improve air quality.

Phase I, which began in 1995, required RFG to contain a minimum of 2 percent oxygen by weight, a maximum of 1 percent benzene by volume, no heavy metals, and detergents to prevent accumulation of deposits in engines and vehicle fuel supply systems. RFG was also required to reduce volatile organic compounds (VOC) and toxic air emissions. Phase I reduced smog-forming pollutant levels by about 17 percent compared to conventional gasoline.