Minimization

"In addition to the expected gasoline constituents, various additives have been used in gasoline. Lead in the form of tetraethyl lead was first added to gasoline in the 1920's to reduce engine "knock". In the early 1960's tetramethyl lead was substituted for tetraethyl. In 1984 the allowable level of lead utilized in gasoline was reduced from 4.2 to 0.1 grams per gallon. Ethylene dibromide and 1,2-dichloroethane were also added to older gasoline formulations as "lead scavengers" in an effort to reduce the amount of lead accumulating and eventually fouling engines.

In 1980 the EPA approved methyl tertiary butyl ether (MTBE) as a gasoline oxygenate. Oxygenates such as MTBE were required by the EPA as a mechanism for reducing carbon monoxide content and increasing oxygen content. The concerns for MTBE's role as an air and water pollutant are rising. MTBE has been found in high concentrations in the air surrounding cities with severe inversion problems."